ApolloHoax.net
Apollo Discussions => The Hoax Theory => Topic started by: anywho on March 16, 2013, 09:55:10 AM
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Hi, I posted an argument on a science forum that the apollo rovers are nonsensical for driving on the moon, it is derived from another posting of mine on a different science forum that has already been posted on this site (I was just going to bump that thread but because the original link does not work, and a message came up asking me to consider making a new thread, I have started this thread)
Here is what I wrote:
There are so any problems associated with the Lunar Rover that it would seem almost farcical to believe they could possibly be real.
The construction:
It is often said that if astronauts could not even sit on a Lunar Rover here on Earth because the Rovers were built of such lightweight construction that they "would have collapsed in 1 g if the crew sat on it." (1), and that the " The vehicle could support its own weight on earth, but no more" (2).
It would seem to defy basic physics to build a weak design because the astronauts on the moon are not just gently putting their weight onto the vehicles, they are also imparting their considerable momentum onto the vehicles and that momentum will be the same on earth as it is on the moon, the mass of the astronauts and their suits do not change. If we take as an example the method the astronauts supposedly used for getting onto the Rovers we can see that they jump up and onto the vehicles:
Getting to sit on the Rover seat in a stiff pressure suit from the lurain was not so easy. The astronauts found they had to stand facing forward, then with an upward and sideways kick, jump up with their legs and arms stretched out ahead to hopefully land in the middle of their seat.
http://www.honeysucklecreek.net/msfn_missions/Apollo_15_mission/hl_Apollo15.html
p=mv tells us that the momentum that the astronauts have, and therefore the forces they will impart, are the same on the Earth as they are on the Moon as long as they are traveling at the same speed. This means that if the astronauts, in the final stage of jumping onto the rover, fall from a height of 6 inches on the moon then the forces they impart onto the rover will be the same as if they fell from a height of 1 inch here on earth.
Once we understand that the forces of momentum are independent of weight then it is nonsensical to suggest you cannot even sit on a rover on earth, but you can jump on one on the moon. The astronauts and their suits have the same mass on earth as they do on the moon and it is very hard to imagine that jumping onto the rovers on the moon they would have less velocity than sitting on them here on earth.
Similarly, driving the rovers on an uneven terrain where the chassis is often forced to change directions vertically, the forces will be very similar, if not the same as here on Earth. Hitting a mound at 10kph will impart the same forces on the vehicle as hitting a mound at 10kph here on earth, the mass and velocity are the same. If you can't hoon around a crater filled terrain here on earth with the vehicles then you can't do it on the moon. If you can't sit on a rover on earth then you can't jump onto one on the moon.
Traction:
To take a 4WD onto a loose ungroomed surface here on Earth would not be counter-intuitive to most people, however, most people would balk at the idea of taking a 2wd vehicle onto a loose ungroomed terrain here on earth because, quite sensibly, it is unlikely a 2wd, with half the traction of a 4WD, would have enough traction. Well, on the Moon a 4WD does not have anywhere near half the traction of a 4WD on earth, it has only a piddly 1/6 the traction and that is true for steering, braking, and accelerating.
Fully loaded the rovers on the moon have a mass of approx 1,500lbs, yet they only have approx 250lbs of weight on the ground to try and accelerate, steer, and brake the 1500lb mass, and they are on a loose surface. The suggestion anyone can go 4WD driving on a loose surface in 1/6g is ludicrous.
I know defenders of the apollo missions will say that the lunar dust binds together so it is not loose, and will quote astronauts as saying they had big trouble controlling the rovers. The problem with both these excuses is that it is not what we see in the video and photographic footage, instead we see a surface that is very loose with dust being disturbed very easy by the astronauts moving around in it, and we see no control problems with the rovers either in driving or the photos of the tracks. It would appear as though they are merely paying homage to the physics while, at the same time, not bothering to fake any traction difficulties for TV.
Power:
The rovers would appear to be massively underpowered, they have 4 x 1/4hp motors giving a grand total of 1hp to drive a 1,500lb vehicle. One horsepower is low powered even for a mobility scooter, imagine putting seven big blokes on a low powered mobility scooter and seeing what performance you get out of it, yet on the moon they hooned around no problems at all.
Uphill there would be some benefits from being on the moon but driving on a flat surface on the moon you would get the same performance as on earth, simply because it is the same mass that has to be accelerated.
Balance:
The rovers are horribly unbalance vehicles, they weigh approximately 460lbs and the astronauts weigh approx 400lbs each fully suited (3), this means when one astronaut is driving there is approximately 3/4 of the weight on one side of the vehicle:
(https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcR4ltPrsNCLcRmVuvSCYeoMO_OSEvaHnWo1JNOeCmUgCDq31h4Pmg)
I doubt many of us would want to drive such an unbalanced vehicle over an uneven terrain here on earth, but on the moon where 1/6 g means it is much more likely to roll the suggestion becomes untenable. If the driver were to hit a rise on the unweighted side of the vehicle then the rover will rise 2, 3, or 4 times higher than it will hitting the same bump on earth (depending on the degree of the slope).
In conclusion:
We are supposed to believe they took a 4WD to the moon that was of such a lightweight design that they couldn't sit on it on earth, but they could jump on it on the moon?
They had no traction problems on a loose surface in 1/6g even though 1/6g equals a whooping 1/6th of the traction?
They had ample power driving a 1500lb mass with a 1hp vehicle?
They could hoon around with one astronaut on one side of the vehicle (approx 3/4 the weight on one side), on an uneven terrain hitting bumps in 1/6g, with no worries at all about rolling?
(1) http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/docs/ApolloCat/Part1/LRV.htm
(2) http://www.hq.nasa.gov/office/pao/History/SP-4204/ch23-3.html
(3) http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.pdf
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Sorry, I forgot the link to the original posting:
http://www.thenakedscientists.com/forum/index.php?topic=47147.0
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Why do you think the rovers need a lot of traction? Are they doing high-g turns, massive acceleration, heavy braking? Do they even have to keep to a particular course?
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The discussions of the LRV's inability to withstand an astronaut's mass on Earth clearly refer to the flight versions.
As you point out several times, it was 1/6g, and the flight version was designed to cope with loadings in that environment. Feel free to provide actual calculations proving the design was inadequate for the environment in which it was designed to operate.
1/6g also applies to the resistance to movement of the rover - there is less gravitational force holding it in place, so less energy is required to get it moving.
As for rolling, why would a low centre of gravity vehicle be in any more danger of rolling on the moon than on Earth? All the forces involved in making that likely are relatively the same Is everyone who has every driven a jeep or a go kart terrified it will tip at the drop of a hat?
I'll let the physics and engineering guys go for the rest!
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Why do you think the rovers need a lot of traction? Are they doing high-g turns, massive acceleration, heavy braking? Do they even have to keep to a particular course?
They need traction to accelerate, brake, and steer. Taking a 2wd onto a loose surface on earth is a dodgy prospect no matter how easy you take it.
They are relatively high performance compared to say an unmanned rover, and you certainly wouldn't want to end up going sideways on such an uneven surface, with such unbalanced vehicles, on the moon where rolling would be many times easier.
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We are supposed to believe...
3 things....one...welcome to the board.
Two...who is this "we" you speak of?...I certainly do not think your ideas have a lick of merit, so please do not "include" anyone but yourself in your "we are supposed to believe..."
...and three...I really do not care what you believe, only what you can prove with evidence. So far, all you have done us make unsubstantuated ignorant claims regarding what YOU think.
Awaiting the evidence that the LRV's were faked...good luck...
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The discussions of the LRV's inability to withstand an astronaut's mass on Earth clearly refer to the flight versions.
As you point out several times, it was 1/6g, and the flight version was designed to cope with loadings in that environment. Feel free to provide actual calculations proving the design was inadequate for the environment in which it was designed to operate.
1/6g also applies to the resistance to movement of the rover - there is less gravitational force holding it in place, so less energy is required to get it moving.
As for rolling, why would a low centre of gravity vehicle be in any more danger of rolling on the moon than on Earth? All the forces involved in making that likely are relatively the same Is everyone who has every driven a jeep or a go kart terrified it will tip at the drop of a hat?
I'll let the physics and engineering guys go for the rest!
It wasn't just the static weight of the suited astronauts that the rovers had to be designed to withstand, it was also the momentum of the mass as they jumped up and onto them, and that mass doesn't change from the earth to the moon.
The rovers are significantly higher than a "go cart", and when only one astronaut is on board they are not sitting in the middle like they would on a go cart. A jeep might weigh 4,000lbs with a 200lb driver so one wouldn't expect to feel too unbalanced in that situation.
It is undeniable that rolling would be many times easier on the moon than earth, if you hit a bump you will rise higher for longer, you essentially have the same mass thrashing about with only 1/6 the weight to keep it anchored.
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So let's see your numbers, then. You can't prove anything without them. You can just speculate, and anyone can speculate without merit.
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It is undeniable that rolling would be many times easier on the moon than earth, if you hit a bump you will rise higher for longer, you essentially have the same mass thrashing about with only 1/6 the weight to keep it anchored.
I'm not at all surprised that the Astronauts didn't "race" the rover...so they drove "conservatively"...so what?
Please present your evidence (not speculation) that the rovers were in fact faked, or retract that claim.
Thankyou.
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So let's see your numbers, then. You can't prove anything without them. You can just speculate, and anyone can speculate without merit.
I wouldn't think any numbers are necessary to prove that the mass of the astronauts is the same on the moon as it is on earth, and because the astronauts on the moon have to jump onto the rovers it is therefore apparent that the rovers had to be designed to withstand that mass at a certain velocity, yet it is claimed that they could not withstand being sat on here on earth.
And that is just the astronauts getting onto the rovers, when they drive them over an uneven surface hitting bumps etc the forces on the chassis as it is forced to change direction will be largely the same as here on earth simply because the mass and velocity are the same.
I will check in again tomorrow.
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I wouldn't think any numbers are necessary to prove that the mass of the astronauts is the same on the moon as it is on earth, and because the astronauts on the moon have to jump onto the rovers it is therefore apparent that the rovers had to be designed to withstand that mass at a certain velocity, yet it is claimed that they could not withstand being sat on here on earth.
No, but it is your responsibility to provide the numbers that show it's relevant. Weight and mass being different things, there are different requirements for them.
And that is just the astronauts getting onto the rovers, when they drive them over an uneven surface hitting bumps etc the forces on the chassis as it is forced to change direction will be largely the same as here on earth simply because the mass and velocity are the same.
I assume you mean "the same as they would be on Earth." As opposed to "the same as each other." Which would make no sense. But either way, the only way to demonstrate that your premise as to why it shouldn't work is correct is to do the math. Common sense lies. The Moon is not the Earth, and things that are intuitive to us on Earth aren't always reliable on the Moon because of the different gravity, etc. You think the mass is important, but you haven't shown that it is important. You haven't demonstrated that the mass of the astronauts as they jump into the rovers would create the same stresses as their sitting in the rover in Earth gravity, and without demonstrating that, you have shown precisely nothing except that you, at least, understand that mass and weight aren't the same thing.
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As you are unwilling to provide the numbers or, say, a force diagram to show that the LRV was "massively unbalanced" (quote from your other thread) with one astronaut on it, perhaps you could proceed by explaining us how all the LRV footage from the Moon was faked. Please pay special attention to the behaviour of regolith when it's ejected from the wheels.
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I will check in again tomorrow.
Please change your "argument" before then...your current one isn't "working".
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I wouldn't think any numbers are necessary to prove that the mass of the astronauts is the same on the moon as it is on earth,
No, but they are necessary to prove that the rover could not do what is claimed. You have not actually worked from any technical description of the rover, just some hyperbole about its lack of weight-bearing ability on Earth. This is odd (and common among HBs) since all the information you need to assess the capabilities of the rover quantitatively is freely available from a variety of sources. Have you checked any of them?
and because the astronauts on the moon have to jump onto the rovers it is therefore apparent that the rovers had to be designed to withstand that mass at a certain velocity, yet it is claimed that they could not withstand being sat on here on earth.
Why do you think that how an astronaut in training would get on a rover differently on Earth than the Moon? He's just as encumbered in his mobility by the suit in training.
And that is just the astronauts getting onto the rovers, when they drive them over an uneven surface hitting bumps etc the forces on the chassis as it is forced to change direction will be largely the same as here on earth simply because the mass and velocity are the same.
And naturally you have at your disposal all the reams of data on the construction of the rover and the research and development that went into it, so can easily provide us with the source that shows conclusively that the rover as constructed could not operate under these conditions.
No? Oh well...
I'll just pop upstairs and read the rather interesting book about how the rovers were designed and built.
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...you have at your disposal all the reams of data on the construction of the rover and the research and development that went into it, so can easily provide us with the source that shows conclusively that the rover as constructed could not operate under these conditions.
This really is the bottom line, anywho...you see, it is established historical fact that the rovers worked "as advertised". Since you think differently, the onus is on you, and you alone to provide evidence that the rovers could not operate in the Lunar enviorment.
Simply saying, "I don't understand how it could have been done" is only evidence that you come to this subject from ignorance.
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They need traction to accelerate, brake, and steer. Taking a 2wd onto a loose surface on earth is a dodgy prospect no matter how easy you take it.
I used to go rallying many years ago. I have personal experience of two-wheel drive on loose surfaces. We used to go well over six times faster than the rovers.
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So lemme get this straight; an unsourced, undocumented quote from "somebody" at NASA giving a poetic description of hypothesized performance of a Rover on Earth is used -- in lieu of any technical documentation -- to contrast the desired performance of the real thing on the Moon?
I think next time I hang a show I'll use the first adjective I find in Century's advertising instead of bothering to look up the actual capacity of the dimmers in watts. After all, "high power" is all the real information I need to design my plot, right?
The onus isn't to show that physics is wrong and that the Rover could operate properly whilst still adhering to all possible hyperbole from non-technical sources. The onus would be to show the actual construction of the Rover is incapable of bearing the projected loads.
Question #2 gets closer to being meaningful, but also stops well short. Many, many things have a higher required acceleration or a lower coefficient of friction. Yet, drag racers and toy cars and snow tires still work. Why assume that the Rover looks exactly like a car in all respects, except that it is operating at 1/6 g? Do you think the LM looks exactly like a quonset hut, only is operating in vacuum? Or do you assume, in gross ignorance of both physics and design, that it is impossible to design a vehicle to provide better traction? Are you really that ignorant to the variety of contact area and tire design that exist already down here on Earth?
This is nonsense. Practically techno-babble. And not a hint of a number anywhere in it (not that numbers can't be bafflegab too, but numbers are a heck of a lot harder to weasel away from when you get them wrong.)
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Incidentally, all this 4wd v. 2wd stuff is just distraction. The Rover had individual wheel motors in an arrangement not found on any car on the highway down here. My guess is the OP wanted to make a statement about the Rover "only being" 2wd when he first came up with his claim, but either realized after doing the most basic research it wasn't sustainable, or floated it in yet some other forum and got shot down.
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Power:
The rovers would appear to be massively underpowered, they have 4 x 1/4hp motors giving a grand total of 1hp to drive a 1,500lb vehicle. One horsepower is low powered even for a mobility scooter, imagine putting seven big blokes on a low powered mobility scooter and seeing what performance you get out of it, yet on the moon they hooned around no problems at all.
1 Horsepower vehicle moving at speed in 1 Earth gravity. Total weight > 1,800lbs
(http://1.bp.blogspot.com/_PiNYwFaLd94/TDMhX2TYecI/AAAAAAAAAFg/yFUR2cIWRe8/s1600/horse+and+buggy.jpg)
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Let me weigh in on one point. Mass is the same, but with a lower gravitational acceleration, the speed when they hit the seat will be less. This means less momentum.
So yes, gravitational field does make a difference to the impact force on the seat, not because m is different, but because v is different.
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They need traction to accelerate, brake, and steer. Taking a 2wd onto a loose surface on earth is a dodgy prospect no matter how easy you take it.
I used to go rallying many years ago. I have personal experience of two-wheel drive on loose surfaces. We used to go well over six times faster than the rovers.
Love rallying. Spectator though. Took an interest before the Quatro came along. Watch some of them cars on loose surfaces and insane speeds. Never did get to the 1000 lakes. Yeah, two wheel drive useless. And rear two wheel at that when I were a nipper.
Got a ride a rally school once, 70 or so on loose gravel road and being on a training stage in Mid Wales, not straight.
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To take a 4WD onto a loose ungroomed surface here on Earth would not be counter-intuitive to most people, however, most people would balk at the idea of taking a 2wd vehicle onto a loose ungroomed terrain here on earth because, quite sensibly, it is unlikely a 2wd, with half the traction of a 4WD, would have enough traction. Well, on the Moon a 4WD does not have anywhere near half the traction of a 4WD on earth, it has only a piddly 1/6 the traction and that is true for steering, braking, and accelerating.
I would imagine that training plays a bigger part than the car. The amount of people in the UK that seemed to have been caught out in the recent years dusting of white stuff in the UK. Tyres also play a part I think in the cold and snow. Wonder what impact they had on the rover? Do you know?
I would think that many people that drive a 4be4 would be a bit wonky on the grass verge outside a school let alone a track. Why this argument?
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Notwithstanding your utter refusal to supply any figures whatsoever, nor anything anywhere near an engineering analysis, there does seem to be another
elephan tiny flaw in your fantasy, anywho.. (it is certainly not a theory, let alone a hypothesis).
There is an awful lot of footage showing the LRV in operation. All that footage shows, without exception, all the telltales of 1/6 gravity. All that footage shows, without exception, all the telltales of operation in a vacuum. All that footage shows operation in a vast sunlit environment without the scattered light from an atmosphere. That footage shows the way it was deployed, the speed at which they traveled, their entry and exit, the beautiful parabolas of dust - impossible on earth. Do I need to go on? And much of it is in very high definition...
Now, bearing in mind that you, 'anywho', have already comprehensively shown your ignorance of what would be needed to actually debate this issue in any serious way, there seem to be a few obvious options:
1. The LRV was well, and adequately, designed to do the job it had to, and you are totally out of your depth and completely wrong (or trolling).
or
2. That footage was faked by using an LRV on Earth instead. Now that obviously has serious problems for your claim, because if it worked that flawlessly in 6x the gravity and an atmosphere, then your entire argument is even more discredited.
or
3. That footage was faked entirely, ie by some type of special effects. Given that no CG techniques existed at the time, it would have to be by models, hand drawing, animation or similar (feel free to speculate..).
I'm going with option 1. Option 2 is equally damning for you, anywho, and as for option 3.. can you show us *any* special effects footage that come anywhere near the perfection of the movie footage of the LRV (which I take it you have actually seen..)? Even today, with the computer graphics processing power that is now available, such fakery would be close to impossible to pull off - as even the very best graphics wizards on our planet (the ones who did Avatar, Lord of the Rings, etc) will tell you.
This claim is possibly as silly as the one about the stars visibility...
ADDED:
Here's just a short example of some of that footage, anywho:
Examine it closely - note the MANY telltales of 1/6 g and vacuum, also note in the second half how much terrain is being covered and all the tiny details like the (single) shadows.. It is beautiful footage (and there are even better transcriptions of it around..)
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Traction:
To take a 4WD onto a loose ungroomed surface here on Earth would not be counter-intuitive to most people, however, most people would balk at the idea of taking a 2wd vehicle onto a loose ungroomed terrain here on earth because, quite sensibly, it is unlikely a 2wd, with half the traction of a 4WD, would have enough traction. Well, on the Moon a 4WD does not have anywhere near half the traction of a 4WD on earth, it has only a piddly 1/6 the traction and that is true for steering, braking, and accelerating.
Fully loaded the rovers on the moon have a mass of approx 1,500lbs, yet they only have approx 250lbs of weight on the ground to try and accelerate, steer, and brake the 1500lb mass, and they are on a loose surface. The suggestion anyone can go 4WD driving on a loose surface in 1/6g is ludicrous.
I know defenders of the apollo missions will say that the lunar dust binds together so it is not loose, and will quote astronauts as saying they had big trouble controlling the rovers. The problem with both these excuses is that it is not what we see in the video and photographic footage, instead we see a surface that is very loose with dust being disturbed very easy by the astronauts moving around in it, and we see no control problems with the rovers either in driving or the photos of the tracks. It would appear as though they are merely paying homage to the physics while, at the same time, not bothering to fake any traction difficulties for TV.
Here's a one-wheel drive vehicle seemingly doing OK in loose sand and dust.
Is that fake too?
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So lemme get this straight; an unsourced, undocumented quote from "somebody" at NASA giving a poetic description of hypothesized performance of a Rover on Earth is used -- in lieu of any technical documentation -- to contrast the desired performance of the real thing on the Moon?
I think next time I hang a show I'll use the first adjective I find in Century's advertising instead of bothering to look up the actual capacity of the dimmers in watts. After all, "high power" is all the real information I need to design my plot, right?
The onus isn't to show that physics is wrong and that the Rover could operate properly whilst still adhering to all possible hyperbole from non-technical sources. The onus would be to show the actual construction of the Rover is incapable of bearing the projected loads.
This is actually the best defense against the argument that the rovers could not be so weak that they could not be sat on here on earth, yet could be jumped onto on the moon, namely that all the talk about the astronauts not being able to sit on them here on earth is something of an urban myth.
Perhaps we can find common ground by all agreeing that if the rovers cannot withstand the static weight of the astronauts here on earth, then they cannot be jumped onto on the moon.
And, if the chassis are not strong enough to hit bumps at 10kph here on earth, then they are not strong enough to hit bumps at 10kph on the moon.
Let me weigh in on one point. Mass is the same, but with a lower gravitational acceleration, the speed when they hit the seat will be less. This means less momentum.
So yes, gravitational field does make a difference to the impact force on the seat, not because m is different, but because v is different.
Absolutely, but we are often told the astronauts cannot even sit on the rovers here on earth, but they can jump rather clumsily onto them on the moon. They wouldn't possible be able to jump onto them on earth fully suited so when people say the rovers can't withstand being sat on here on earth they cannot be referring to the astronauts, fully suited, trying to jump onto them.
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Power:
The rovers would appear to be massively underpowered, they have 4 x 1/4hp motors giving a grand total of 1hp to drive a 1,500lb vehicle. One horsepower is low powered even for a mobility scooter, imagine putting seven big blokes on a low powered mobility scooter and seeing what performance you get out of it, yet on the moon they hooned around no problems at all.
1 Horsepower vehicle moving at speed in 1 Earth gravity. Total weight > 1,800lbs
(http://1.bp.blogspot.com/_PiNYwFaLd94/TDMhX2TYecI/AAAAAAAAAFg/yFUR2cIWRe8/s1600/horse+and+buggy.jpg)
Well, that motor could be more than 1hp in the context we are talking about, mobility scooters can be 1hp (they can be up to 3hp) so they might be a more accurate comparison.
(http://t3.gstatic.com/images?q=tbn:ANd9GcS3h-MTbpukLrBotOMEPHsnuAYAbCYQlsA4r07L906TnV3HoIR6ng)
I think they used the power to weight ratio to decide 1hp would be adequate, but power to weight is a bit of a misnomer and it really should be power to mass.
1hp to drive 250lbs would seem to be almost standard, but 1hp to accelerate 1500lbs is ridiculously low.
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Perhaps we can find common ground by all agreeing that if the rovers cannot withstand the static weight of the astronauts here on earth, then they cannot be jumped onto on the moon.
No, we can't. Not until you provide some numbers.
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And naturally you have at your disposal all the reams of data on the construction of the rover and the research and development that went into it, so can easily provide us with the source that shows conclusively that the rover as constructed could not operate under these conditions.
No? Oh well...
I'll just pop upstairs and read the rather interesting book about how the rovers were designed and built.
I have spend quite a bit of time looking to see how they tested the rovers for 1/6g, and all I can find is a comment that the wheels were tested on some machine but I cannot find any more about what that was, and also that they used a scale model for testing.
A scale model reduces the mass as well as the weight so it will only test if a lightweight rover will work on earth, not 1/6g. The best testing would probably be something like a skidcar where the weight is reduced but the mass is the same, but it would be hard to make an off road version.
(https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTsS2vjcAlxOl_jwltPnbc4q4-fkuJQDdTHoHMjchvNOHhZGGng)
If you find anything in your book about how they tested for 1/6g I will be interested if you want to post it.
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Perhaps we can find common ground by all agreeing that if the rovers cannot withstand the static weight of the astronauts here on earth, then they cannot be jumped onto on the moon.
No, we can't. Not until you provide some numbers.
Do I really need numbers to say that if the astronauts, in jumping onto the rover, clear the rover by 6 inches on the moon then the forces on the rover will be the same as a fall onto the rover of 1inch here on earth?
Do I need numbers to say that a fall from 1inch puts more stress on the frame than the static weight weight of an astronaut?
It's basic physics and common sense (although, admittedly, for most people, myself included, it does take a bit of time to stop thinking of weight and instead think in terms of mass)
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This is actually the best defense against the argument that the rovers could not be so weak that they could not be sat on here on earth, yet could be jumped onto on the moon, namely that all the talk about the astronauts not being able to sit on them here on earth is something of an urban myth.
Perhaps we can find common ground by all agreeing that if the rovers cannot withstand the static weight of the astronauts here on earth, then they cannot be jumped onto on the moon.
No, I'm not taking that one either. The Moon is not the Earth. Not only that, you are still creating non-measured conditions. What is "withstand?" What is "jumped onto?" If you want to talk about the engineering of the Rover, talk about it in the context of the job it was designed to do -- not about some job that in your mind is similar.
Sorry for excerpting, but when I get three deep of quotes unquotes of quotes I start feeling like I'm in a Groucho Marx sketch ("Jamison, take a letter!")
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You do realize that horsepower and torque are not the same thing? Gasoline engines run very poorly at high torque, low speeds. Electric motors, practically the opposite. Electric vehicles tend to have smaller horsepower, all else being equal, because starting power needs are not the same as maintaining power.
(I had a nice chat not all that long ago with a guy who works on the electrical systems of the local ferries. They use diesels to generate power which is sent to electric motors to drive the props. Why? It makes sense when you think about the kind of conditions a ferry faces.)
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You do realize that horsepower and torque are not the same thing? Gasoline engines run very poorly at high torque, low speeds. Electric motors, practically the opposite. Electric vehicles tend to have smaller horsepower, all else being equal, because starting power needs are not the same as maintaining power.
I compared the rovers power to an electric mobility scooter (and a low powered one at that), not a gasoline vehicle, and not a horse like someone else did.
It is undeniable that 1hp to accelerate a vehicle with a 1500lb mass is ridiculously low even under perfect conditions like a flat, even, solid, surface with solid tyres. Yet on the moon where conditions are anything but perfect the rovers performed amazingly well.
Most people would think in terms of power to weight and consider the performance perfectly fitting, but when we correctly consider power to mass.... 1hp to accelerate 1500lbs... valid questions are raised.
Back later.
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You do realize that horsepower and torque are not the same thing? Gasoline engines run very poorly at high torque, low speeds. Electric motors, practically the opposite. Electric vehicles tend to have smaller horsepower, all else being equal, because starting power needs are not the same as maintaining power.
I compared the rovers power to an electric mobility scooter (and a low powered one at that), not a gasoline vehicle, and not a horse like someone else did.
It is undeniable that 1hp to accelerate a vehicle with a 1500lb mass is ridiculously low even under perfect conditions like a flat, even, solid, surface with solid tyres. Yet on the moon where conditions are anything but perfect the rovers performed amazingly well.
Most people would think in terms of power to weight and consider the performance perfectly fitting, but when we correctly consider power to mass.... 1hp to accelerate 1500lbs... valid questions are raised.
Like what? It's acceleration?
Why don't you tell us how fast it could accelerate?
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Do I need numbers to say . . . .
Yes. You need numbers, because numbers are the language of science. If you don't have the numbers, you cannot say that you are right. You can only say that you believe you are right, and we have no reason to assume that you know what you're talking about.
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I used to go rallying many years ago. I have personal experience of two-wheel drive on loose surfaces. We used to go well over six times faster than the rovers.
I used to rally a 1974 Ford Escort RS1600. On loose gravel, I would typically hit top speeds of around 130 km/h with average stage speeds of about 80 km/h. The Ford Escort was a rear-wheel drive, making a lot harder to handle than modern AWD rally cars.
One of my favourite tracks was the Ashley Forest Rally Sprint, a single stage sprint where a typical time was about 1:15 to 1:30.
Enjoy
Best ever winning time was about 56 seconds!!!!
Now who says you wouldn't want to be "going sideways on such an uneven surface".
Well, that is just "business as usual" for a rally driver
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It is undeniable that 1hp to accelerate a vehicle with a 1500lb mass is ridiculously low
Why?
The primary source of vehicle drag on earth, aerodynamic drag, is completely absent on the moon. Moreover, rolling resistance is proportional to vehicle weight so on the moon it is only 1/6 of what it would be on earth.
That leaves the kinetic energy requirement. 1 hp = 745.7 W. The kinetic energy of 1500 lbm (680 kg) moving at 10 km/hr (2.78 m/s) is 2626 J. It would take about 3.5 sec to accelerate to 10 km/hr using a 1 hp motor. What's so ridiculous about that?
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(I had a nice chat not all that long ago with a guy who works on the electrical systems of the local ferries. They use diesels to generate power which is sent to electric motors to drive the props.
Not just ferries but nearly all modern cruise ships are also diesel-electric.
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Do I really need numbers to say that if the astronauts, in jumping onto the rover, clear the rover by 6 inches on the moon then the forces on the rover will be the same as a fall onto the rover of 1inch here on earth?
Yes.
Do I need numbers to say that a fall from 1inch puts more stress on the frame than the static weight weight of an astronaut?
Yes.
It's basic physics and common sense (although, admittedly, for most people, myself included, it does take a bit of time to stop thinking of weight and instead think in terms of mass)
Unfortunately it's the basic physics and common sense bit that is lacking here. You keep talking about the forces involved, and weight is a product of those forces.
Mass may be the same on Earth and Moon, but the forces a body is subjected to are different because gravity is different. Your confusion comes from interchanging mass and weight depending on the point you're trying to make, and getting it wrong.
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Mass may be the same on Earth and Moon, but the forces a body is subjected to are different because gravity is different. Your confusion comes from interchanging mass and weight depending on the point you're trying to make, and getting it wrong.
anywho
IMO, onebigmonkey above has hit on the "failure of understanding" that is leading you to your false conclusions.
Weight only equals mass in a 1G environment. When you take the environment away, mass and weight are no longer equal.
In Zero G, an object with a mass of 1kg has a weight of 0kg
On the moon an object with a mass of 1kg has a weight of approx 167g because its a 0.167 G environment
On Mars an object with a mass of 1kg has a weight of approx 380g because its a 0.38G environment
So, your 1500kg LRV, while it only weighs 250kg on the moon, its mass remains 1500kg. However, that isn't the kicker. The power required to move it horizontally is unaffected by its weight; it affected only by its mass.
Here's a primer for you
http://www.school-for-champions.com/science/gravity_horizontal_motion.htm
If all other aspects are equal (air resistance, friction) it takes the same amount of force to move a vehicle with a mass of 1500kg horizontally on the surface of the moon as it does on the surface of the earth, and moving 1500kg horizontally on the Earth can easily be done with a very small motor. Its more a matter if gearing than it is of power. I've seen a homebuild two seater golf cart (all up weight with two males and two sets of golf clubs, 500kg) powered by a 24v 1/2HP motor.
Of course, you could always go the way of most other HB's who come to this site; deny the science because you don't / can't / won't understand it.
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Often wonder what I produce on my bicycle. I have gears to make life easy and those spindly spoke look like they will snap if I bend them the wrong way. Indeed, I know well that they do.
Anywho. Tell me about the motors. I like learning and when a subject like this comes up I get a lot of information that I did not know yesterday.
So. We have a motor. What type and benefits is it to this, I have seen the manual but my motoring (electric) days with regard benefits of DC series wound vs other never appeared on my training as an apprentice. Then there is the harmonic drive. Sounds like something from Star Trek to me, why was this not fit for purpose. End result here is if you can show the drive train is up to the job or not. Not a comparison you have used, the kit used when it went there.
Your proposal sends you down a path that will be fraught with engineering that I suspect could not be done....
Edit. My spokes would bend I think I meant to say. Though I have snapped a few by poor adjustment, the ping is a dead give away and not wanted on voyage when you are head down on a good hill.
Edit 2. It has been a long time since I dealt with levers and forces and momentum and all that, might kick the old grey cells back into life.
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This is actually the best defense against the argument that the rovers could not be so weak that they could not be sat on here on earth, yet could be jumped onto on the moon, namely that all the talk about the astronauts not being able to sit on them here on earth is something of an urban myth.
Perhaps we can find common ground by all agreeing that if the rovers cannot withstand the static weight of the astronauts here on earth, then they cannot be jumped onto on the moon.
It is extremely difficult to find common ground when you are approaching this from a totally different direction from the rest of us. Faced with the aparently contradictory information your entire argument is based on, there are three possible conclusions:
1: The statement is not actually true but is a bit of hyperbole to illustrate the differences in performance requirements between a rover on Earth and on the Moon.
2: The statement is actually true, though counter-intuitive, because the physics involved is a little bit specialised and not readily understood without some degree of effort.
3: The statement is true and proof that the hours of footage of a rover on the moon, and everything else related to them, was actually faked.
Conclusion 1 is the simplest. Conclusion 2 can either be accepted as the case by realising that your own knowledge of physics is not as extensive as that of the engineers who designed and built the thing. Conclusion 3 requires the dismissal of vast piles of material evidence of the rover doing exactly what it was said to have done.
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Quick bit of engineering here...the spokes on a bicycle wheel are under tension. The hub does not "press" on the lower spokes, it "hangs" from the upper ones. That tries to pull in/bend the rim, but since the rim is a circle, any attempt to flatten it merely increases the tension tangential to the load. Gets a little more interesting under dynamic loads, and a little sheer comes into play, but at no point are the spokes under useful compressive load. They aren't shaped for it.
Back in the day, we used to knock on them lightly with a metal tool to listen for the right tone. Any dull ones weren't tensioned right.
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It is undeniable that 1hp to accelerate a vehicle with a 1500lb mass is ridiculously low even under perfect conditions like a flat, even, solid, surface with solid tyres.
If it is undeniable, provide the numbers to prove it.
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If you find anything in your book about how they tested for 1/6g I will be interested if you want to post it.
Not my burden of proof. You are the one making the claim that the rovers were unable to perform as advertised. It is therefore your burden to explain all the evidence that says they actually did just that. That includes showing the calculations that led you to the conclusions you are presenting here, and showing the depth of research you have undertaken.
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Of course, what everyone is missing here is the blindingly obvious; that the whole thing is a "self defeating proposition".
If the lunar rover footage was faked along with the whole Apollo programme, why would NASA need to lie about the size and power of the LRV motors. They could just have used four 1 HP (instead of four ¼ HP) motors, and not made any claims that they were the smaller motors
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Well the NASA hoaxers could do anything... except proof read.
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Quick bit of engineering here...the spokes on a bicycle wheel are under tension. The hub does not "press" on the lower spokes, it "hangs" from the upper ones. That tries to pull in/bend the rim, but since the rim is a circle, any attempt to flatten it merely increases the tension tangential to the load. Gets a little more interesting under dynamic loads, and a little sheer comes into play, but at no point are the spokes under useful compressive load. They aren't shaped for it.
Back in the day, we used to knock on them lightly with a metal tool to listen for the right tone. Any dull ones weren't tensioned right.
Aye, I was picking more on the fragile item doing something strong, regarding the claims on the rover. Bit obtuse maybe whilst I was asking about gearing.
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I lose track of the original comment in all the quotes unquotes and quotes, but I can never resist trying to brainstorm the physics of something. Especially when I have such talented people to come along after and explain where I got it wrong!
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If the rover didn't work, Anywho, what were they driving?
While by no means an expert, I do like old school special effects, like stop motion, and stop motion, especially then, looks nothing like the rover moving. This scene (http://www.youtube.com/watch?v=8X7W-oPhY48), while effective, highlights a problem, the lack of motion blurring. COmpare that to to the famous Apollo 16 'Grand Prix' (http://www.youtube.com/watch?v=7o3Oi9JWsyM). To my eye, they look nothing alike in technique, the rovers motion being far, far, smoother, yet Clash of the Titans was almost 20 years older.
OK, let's look at another technique, CGI. Even now it would be tricky, but then?
This (http://www.youtube.com/watch?v=T5seU-5U0ms) was at the forefront, the absolute bleeding edge of technology back then. Shading was primitive, textures were unknown, bump mapping, what's that?
So no dice.
Traditional 2D animation, do I even need to give an example?
So, again, if the special effects of the time weren't up for it, you need an actual working 'prop', something that could be driven. So just what were they driving?
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I lose track of the original comment in all the quotes unquotes and quotes, but I can never resist trying to brainstorm the physics of something. Especially when I have such talented people to come along after and explain where I got it wrong!
I don't mind, this is a great place for learning. I know the spokes are weak this way and strong that way, that is the end of what I know about spokes. That and too tight thet are going to go.... I did not consider the rest of it would not not claim it.
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...1hp to accelerate 1500lbs is ridiculously low.
Tell that to a horse.
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I used to rally a 1974 Ford Escort RS1600. On loose gravel, I would typically hit top speeds of around 130 km/h with average stage speeds of about 80 km/h. The Ford Escort was a rear-wheel drive, making a lot harder to handle than modern AWD rally cars.
My rallying was back in the 1970s too, mainly involving Escorts. On occasion, I navigated for a friend who had a 240Z. Now that really was a handful, with a distressing tendency to terminal understeer.
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Do I need numbers to say that a fall from 1inch puts more stress on the frame than the static weight weight of an astronaut?
So what if it does? You've done nothing to demonstrate that the rover couldn't withstand such stresses.
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Do I need numbers to say that a fall from 1inch puts more stress on the frame than the static weight weight of an astronaut?
So what if it does? You've done nothing to demonstrate that the rover couldn't withstand such stresses.
Do we even have a citation for the loading limits of the LRV? Or is it just a bit of hyperbole taken too literally, which is often a trap HBs fall into.
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Can I make a general plea to everyone to use the right units for mass and weight.
Every time you talk about weight in kg or mass in lbs you make a unicorn cry.
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Can I make a general plea to everyone to use the right units for mass and weight.
Every time you talk about weight in KG or mass in lbs you make a unicorn cry.
Did you just capitalize the symbol for kilogram?
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I have spend quite a bit of time looking to see how they tested the rovers for 1/6g, and all I can find is a comment that the wheels were tested on some machine but I cannot find any more about what that was, and also that they used a scale model for testing.
This youtube clip has a sequence at the 2:04 mark showing how they tested for 1/6g.
https://www.youtube.com/watch?feature=player_detailpage&v=FVMfjPXwRO4#t=124s
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Can I make a general plea to everyone to use the right units for mass and weight.
Every time you talk about weight in KG or mass in lbs you make a unicorn cry.
Did you just capitalize the symbol for kilogram?
whoops :)
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In response to Trebor's plea...
Weight only equals mass in a 1G environment. When you take the environment away, mass and weight are no longer equal.
Weight does not equal mass anywhere. Weight is the effect produced by mass in a gravitational field. Weight = mass times gravitation.
In SI (http://en.wikipedia.org/wiki/International_System_of_Units), the unit of weight (http://en.wikipedia.org/wiki/Weight) is the newton. It is defined in SI as mass * gravitation. 1 newton is 1 kilogram*meter/second2. Thus, on Earth, 1kg weighs 9.81 newtons. One pound is 4.45 newtons; one newton is 0.225 pounds (3.56 ounces) (all values rounded to 3 significant digits; pounds here refers to "pounds force").
In Zero G, an object with a mass of 1kg has a weight of 0kg
In zero g, the weight of 1kg is 0 netwons.
On the moon an object with a mass of 1kg has a weight of approx 167g because its a 0.167 G environment
On the moon, 1kg weighs 1.62 newtons.
On Mars an object with a mass of 1kg has a weight of approx 380g because its a 0.38G environment
On Mars, 1kg weighs 3.71 newtons.
So, your 1500kg LRV, while it only weighs 250kg on the moon, its mass remains 1500kg. However, that isn't the kicker.
1500kg weighs 1500kg * 1.62m/s2 = 2430 newtons.
Fred
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In Zero G, an object with a mass of 1kg has a weight of 0kg
In zero g, the weight of 1kg is 0 netwons.
Funny thing is, we can fix that one in another way as well.
"In Zero G, an object with a mass of 1kg has the weight of an object with a mass of 0kg" ;D
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In Zero G, an object with a mass of 1kg has a weight of 0kg
In zero g, the weight of 1kg is 0 netwons.
Funny thing is, we can fix that one in another way as well.
"In Zero G, an object with a mass of 1kg has the weight of an object with a mass of 0kg" ;D
But in what gravitational field, sir, what gravitational field?
The kilogram-force is sometimes used in an effort to be annoying and that is 9.81N, basically the weight of 1kg in Earth standard gravity.
If it must be used, qualify the symbol by writing is as kgf.
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In Zero G, an object with a mass of 1kg has a weight of 0kg
In zero g, the weight of 1kg is 0 netwons.
Funny thing is, we can fix that one in another way as well.
"In Zero G, an object with a mass of 1kg has the weight of an object with a mass of 0kg" ;D
But in what gravitational field, sir, what gravitational field?
In any Zero G gravitational field! One without even tidal forces.
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But if it has the weight of an object with 0kg mass, it must be moving at the speed of light! ;)
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Do we even have a citation for the loading limits of the LRV? Or is it just a bit of hyperbole taken too literally, which is often a trap HBs fall into.
All I've seen is a vague "it is often said" statement that it wouldn't support the astronauts on Earth, and a completely unsupported claim that this means it couldn't withstand the impact of an astronaut falling a short distance on the moon.
First, it's entirely possible that the rover never experienced forces in excess of six times its static load. There's plenty of margin there to bring the falling astronauts to a halt in a reasonable distance. If the flexing rover exerted a continuous upward force of 5 times the astronauts lunar weight as it compressed underneath them, it would bring them to a halt in 1/4 the distance they fell without ever exerting as much force as would be needed to support them on Earth...and the actual thing had a very flexible structure with soft wheels and suspension.
However, it needn't be even that limited. The rover's a massive, damped elastic structure. It's entirely reasonable for the rover to withstand forces for a brief period that it could not withstand continuously, it just needs to bring the landing object to a halt before it gets permanently deformed by those forces. A 500 g stone dropped onto the rover from 1 m, being brought to a halt in 1 millisecond by the impact, would briefly apply the same force as a 550 kg object resting on the rover, but the rover is obviously not going to react in the same way. The rover would flex and compress in response to the astronaut landing on it, but the force between the rover and the astronaut would drop to the astronaut's lunar weight as it did so. The same goes for travel over bumpy terrain...the peak force experienced during a bump could easily exceed the maximum static force the rover could withstand, but not be sustained over enough distance to irreversibly deform the rover's structure.
So...yes, anywho, you do need to give numbers showing that the rover couldn't operate on the moon. Show it couldn't withstand the dynamic loads involved. A vague statement by a non-authoritative source about its behavior under static loads in an environment with six times the gravitational acceleration does not qualify.
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Yes, I guess the slightest force would do that.
Have you seen my new 0kg virtual car keys? Oh, there they are, on the table. No wait, don't touch them, oh - bugger, gone!
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To sum the claim up then.
My gut feeling says no and I think you should agree with me? (My as in OP claim)
Been having a look around in my un expert way.
Drive Ratio 80:1. RPM max 10,000. Wheel diameter 32 inches. I am assuming torque is in here somewhere? Then having a quick shufty at the specs for an industrial 100hp motor at 1000 rpm, it has more torque than my petrol engine. Torque is a word I know about, not what it is fully. So the basic ingredients get more complicated if you delve? More to this than meets the claim then. Get back to this later.
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Can I make a general plea to everyone to use the right units for mass and weight.
Every time you talk about weight in kg or mass in lbs you make a unicorn cry.
Aww. And no-one has had to resort to slugs or poundels yet, even.
(I'm with you -- mks all the way.)
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I haven't used any! Of course, this is because I'm refusing to have a conversation on any level deeper than "if you don't know the numbers, you don't know what you're talking about." Also because, well, I don't know the numbers and can't have an intelligent discussion about the whole thing myself. However, I at least know enough to know that, without the numbers, there is no intelligent discussion possible.
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In Zero G, an object with a mass of 1kg has a weight of 0kg
On the moon an object with a mass of 1kg has a weight of approx 167g because its a 0.167 G environment
On Mars an object with a mass of 1kg has a weight of approx 380g because its a 0.38G environment
<nitpick mode>
The kilogram is a unit of mass, not force -- even though many people abuse it for that purpose. A mass of 1 kg has an earth weight of 9.8 newtons, that being the proper unit to measure force, including the force of gravity on mass.
</nitpick mode>
So, your 1500kg LRV, while it only weighs 250kg on the moon, its mass remains 1500kg. However, that isn't the kicker. The power required to move it horizontally is unaffected by its weight; it affected only by its mass.
This isn't right. The power was greatly reduced by the lower lunar weight.
Although the energy (not power) needed to accelerate a given mass to a given velocity remains the same, in wheeled transport this is usually swamped by drag even when you don't recover kinetic energy through regenerative braking. (The LRV had non-rechargeable batteries.)
Earth vehicles have three main forms of drag: mechanical friction in the drive train, aerodynamic drag on the vehicle body, and rolling resistance in the tires. The aerodynamic drag force increases with the square of velocity while the rolling resistance and drive train frictional forces are independent of velocity once static friction is overcome (see Coulomb's law of friction). The power needed to overcome aerodynamic drag therefore increases with the cube of the velocity but only linearly with velocity for the other two forms. This causes aerodynamic drag to dominate total drag at high (e.g., freeway) speeds but to vanish at very low speeds (e.g., a golf cart).
Aerodynamic drag is of course completely absent on the moon. We don't know the friction in the LRV drive train, but with a motor in each wheel it's reasonable to assume it was small and in any event unaffected by gravity (though air pressure, or lack thereof, might have had a small effect). Rolling resistance was dominant, and since it is linear with weight (see Amonton's first law), on the moon it's only 1/6 of what it would be on earth with the same surface.
All this makes the energy losses of a vehicle on the moon much less than it would be on earth. On earth, the range per charge of my Nissan Leaf electric car is about 80 miles; on the moon, if paved roads were built it could be over 1,000 depending mainly on non-propulsive overhead loads.
So the Apollo LRV performed very well with only 1 hp of propulsive power.
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Weight is the effect produced by mass in a gravitational field. Weight = mass times gravitation.
Actually, weight is the force produced by accelerating a mass (F=ma) and gravity is just one way to do it. According to the equivalence principle of general relativity, the effect of the earth's surface pushing up against you as it resists gravity is completely indistinguishable from being accelerated by a rocket engine in deep space far from any gravitational field.
Similarly, you can experience weightlessness even in a strong gravitational field by free falling within it, e.g., in orbit.
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Maybe we should call it, instead of "weightlessness," something like "net forceless-ness relative to self inertial frame?"
Meanwhile, out in Apollo Denier land, there are still people whose understanding of lunar gravity is best summed up by the quote, "Heavy boots!"
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Maybe we should call it, instead of "weightlessness," something like "net forceless-ness relative to self inertial frame?"
What's wrong with 'free fall'?
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Actually, weight is the force produced by accelerating a mass (F=ma) and gravity is just one way to do it.
I was trying to dumb it down for the OP.
Fred
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Someone else has probably said something like this by now, but I don't think we even need to address the numbers to discount the OP's assertion (I'm certainly not saying it's a waste of time, it's very educational to us more math challenged types, and the more thoroughly a claim such as this is debunked, the better). We have hours of footage of the rover moving, both from the rover and observing the rover, all taken in what would be an impossibly large movie set, in a vacuum no less. We are also to believe that the LRV wouldn't be rugged enough for a 1/6 g environment, yet would handle the 1g found on the impossible Earth film set with no problem.
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Someone else has probably said something like this by now, but I don't think we even need to address the numbers to discount the OP's assertion (I'm certainly not saying it's a waste of time, it's very educational to us more math challenged types, and the more thoroughly a claim such as this is debunked, the better). We have hours of footage of the rover moving, both from the rover and observing the rover, all taken in what would be an impossibly large movie set, in a vacuum no less. We are also to believe that the LRV wouldn't be rugged enough for a 1/6 g environment, yet would handle the 1g found on the impossible Earth film set with no problem.
All of this is true. However, I do still firmly believe that, if the OP cannot provide the numbers to back up his assertion, it's proof he doesn't know what he's talking about. I am so math-challenged that I don't get the numbers even when they're presented, and I acknowledge this. However, that's also why I'd never make the assertion in the first place. I know I don't know enough to make it. I know the assertion is ridiculous on its face for several reasons, but if you can't present it in the right language, there's no reason to believe you know enough to know why it is ridiculous. Even with the whole "impossible Earth film set" aspect thrown in.
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JAQing around, pretending expertise, random bicycles -- should we start up a special Bingo card, you think?
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Someone else has probably said something like this by now, but I don't think we even need to address the numbers to discount the OP's assertion (I'm certainly not saying it's a waste of time, it's very educational to us more math challenged types, and the more thoroughly a claim such as this is debunked, the better). We have hours of footage of the rover moving, both from the rover and observing the rover, all taken in what would be an impossibly large movie set, in a vacuum no less. We are also to believe that the LRV wouldn't be rugged enough for a 1/6 g environment, yet would handle the 1g found on the impossible Earth film set with no problem.
All of this is true. However, I do still firmly believe that, if the OP cannot provide the numbers to back up his assertion, it's proof he doesn't know what he's talking about. I am so math-challenged that I don't get the numbers even when they're presented, and I acknowledge this. However, that's also why I'd never make the assertion in the first place. I know I don't know enough to make it. I know the assertion is ridiculous on its face for several reasons, but if you can't present it in the right language, there's no reason to believe you know enough to know why it is ridiculous. Even with the whole "impossible Earth film set" aspect thrown in.
No argument here. He's the one who brought up the physics aspects, and his feet should be held to the fire, since he wants to play that game.
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Some Real Numbers:
According to a 1972 Boeing handout, the Apollo 17 LRV had a weight capacity of 1,140 pounds [517 kg] Earth weight). This allowed for 400 lbs for each astronaut (and his gear) and 340 pounds of equipment and samples.
That's about 86 kilos earth equivalent, so yes, two astronauts even in street clothes would be over its capacity on earth. The document seems to be some kind of public or press handout, so it's not really very long on technical specs.
http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.html (http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.html)
Edit:
I'm aware that the onus is not, um, on us to provide the numbers, but I was getting a little tired of the sound of beating this particular dead horse.
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This youtube clip has a sequence at the 2:04 mark showing how they tested for 1/6g.
https://www.youtube.com/watch?feature=player_detailpage&v=FVMfjPXwRO4#t=124s
Thanks for that, I don't have sound so I don't visit youtube much.
I can't hear what is being said but looking at the footage it shows that they did indeed use a skidcar equivalent setup for testing.
If you look at the testing it shows the difficulty of driving on the moon, even at those slow speeds (looks like walking pace) you can see wheels rising up into the air and that is on a very smooth surface compared to the mogully type terrain in the famous "grand prix" footage which was posted earlier.
I see the last test where they had to steer a bit, and lost a bit of control, that they appear to have not made it all the way across the test bed.
The biggest criticism I would have of the test is that they don't start on the loose surface. Why not? that is the most obvious test for traction. I live in a very sandy area and if I want to drive my 2wd over a sandy area that is a bit dodgy the way to do it is to get a bit of a run up and don't, under any circumstances, stop.
My 2wd is not suitable for sandy terrain yet it would pass that test.
To be honest, looking at that car bouncing around on that relatively smooth surface, at relatively slow speeds, I can't see how anyone could have confidence to drive at much higher speeds over much worse terrain, and, when only one person is on board, in a significantly unbalanced vehicle.
And, they seemingly have to have have a run up to help the vehicles across the test bed. At 2.18 it looks like both rear wheels rise up off the ground.
Thanks for posting it though, and I will take the time to look at the whole rover series later when I am at a better computer.
I am a bit stretched for time but I will address a some other comments later.
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To be honest, looking at that car bouncing around on that relatively smooth surface, at relatively slow speeds, I can't see how anyone could have confidence to drive at much higher speeds over much worse terrain, and, when only one person is on board, in a significantly unbalanced vehicle.
You keep saying but you have not provided any evidence it was "significantly" unbalanced or unbalanced at all.
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I am not an engineer, not do I play one on TV, (though I do a dandy fake Scottish accent) but the LRV looks quite the opposite of unbalanced to me. Wide, soft, tires, low looking centre of gravity, It shares a gross similarity to a dune buggy to my, uneducated, eyes.
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To be honest, looking at that car bouncing around on that relatively smooth surface, at relatively slow speeds, I can't see how anyone could have confidence to drive at much higher speeds over much worse terrain, and, when only one person is on board,in a significantly unbalanced vehicle.
Others have discussed the "unbalanced" and other faulty physics claims very well, but I just want to point out the problem with the bolded.
Just because you wouldn't have the confidence to do something, doesn't mean no-one else would. The astronauts were highly trained and disciplined - and already doing something incredibly dangerous even without bringing the lunar rover into it. Why would they balk at it?
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More than that, they were test pilots.
The "Grand Prix" was exactly that; it was testing the Rover to find the practical limits, within the safest framework they could find (close to the LM, only one astronaut on the thing so if the other rolled and was knocked out his buddy could carry him back inside).
When they hit the trails on geology expeditions following, they knew what they could drive on or up with a very high probability of not crashing in the process.
And they were STILL within walking distance of the LM (just, a bit longer of a walk!)
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Not to mention that "high speeds" aren't that high. The top speed of the LRV was about 12 mph [20 kph] which is a fast trot for a person - about the average speed of a marathon runner. We're not talking about zipping around at 100 kph here.
Anywho, if this is a point you have serious questions about, do some research first. So far, all you've really presented is an Argument From Incredulity - i.e., your common sense tells you that it doesn't look right.
But your "common sense" (and mine, and everyone elses) comes from a lifetime of experience here on planet Earth in a one-gee field, a 14.7 psi atmosphere, and a 24-hour day/night cycle. The surface of the moon is a wildly different environment; the engineers at NASA and elsewhere spent years and years working out solutions to the multitude of problems they faced. You can't, for example, judge the extent of testing of the LRV by a couple of minutes of video. Here's a link to get you started:
http://www.hq.nasa.gov/alsj/alsj-LRVdocs.html (http://www.hq.nasa.gov/alsj/alsj-LRVdocs.html)
All text, no sound needed.
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At least Anywho isn't asking how they got it out the LM hatch. So much ignorance packed into one sentance, and so easily refuted too (http://www.youtube.com/watch?v=-ShauSWcTC4).
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Anywho, what research did you do?
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If you look at the testing it shows the difficulty of driving on the moon, even at those slow speeds (looks like walking pace) you can see wheels rising up into the air and that is on a very smooth surface compared to the mogully type terrain in the famous "grand prix" footage which was posted earlier.
I can see the wheels doing exactly what would be expected on such a vehicle with the suspension it had. What I don't see is this causing any difficulties for control or balance, so why is this an issue?
The biggest criticism I would have of the test is that they don't start on the loose surface.
So because there's some short film of them not starting on the test bed you think that's all there was? Do you honestly think they made that entire setup for less than two minutes of testing?
To be honest, looking at that car bouncing around on that relatively smooth surface, at relatively slow speeds, I can't see how anyone could have confidence to drive at much higher speeds over much worse terrain, and, when only one person is on board, in a significantly unbalanced vehicle.
You keep saying the vehicle is 'significantly unbalanced' with only one person on board. Yes, the centre of mass is shifted to one side, but why is this an issue? The rover is wide, flat, and the astronaut sits well inboard of the wheels. Do you have any calculations to show just how 'unbalanced' the rover is with one astronaut on it?
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I used to have as my desktop a dirt bike being tested in the vomit comet. That must have been an exciting few minutes...
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More like an exciting 20 seconds. That's all the weightlessness you get even on the vomit comet.
It would be fun to see the papers documenting this research. If it was NASA sponsored, they should be out there somewhere...
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Wow, that sounds fun, lunar motocross. They get some amazing height here on Earth. Imagine doing it in 1/6th gravity! I'd wait until mechanical pressure suits are perfected though.
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Somehow I have just of thought how far the Dukes of Hazard might go on the Moon. How long can you shout yeeee ha for?
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This youtube clip has a sequence at the 2:04 mark showing how they tested for 1/6g.
https://www.youtube.com/watch?feature=player_detailpage&v=FVMfjPXwRO4#t=124s
Thanks for that, I don't have sound so I don't visit youtube much.
I can't hear what is being said but looking at the footage it shows that they did indeed use a skidcar equivalent setup for testing.
If you look at the testing it shows the difficulty of driving on the moon, even at those slow speeds (looks like walking pace) you can see wheels rising up into the air and that is on a very smooth surface compared to the mogully type terrain in the famous "grand prix" footage which was posted earlier.
Point of view rather than an authoritative statement?
I see the last test where they had to steer a bit, and lost a bit of control, that they appear to have not made it all the way across the test bed.
One test, did they lose control? Was that part of the test?
The biggest criticism I would have of the test is that they don't start on the loose surface. Why not? that is the most obvious test for traction. I live in a very sandy area and if I want to drive my 2wd over a sandy area that is a bit dodgy the way to do it is to get a bit of a run up and don't, under any circumstances, stop.
My 2wd is not suitable for sandy terrain yet it would pass that test.
Wonder if there have been any 2 wheel drive entrants in the Dakar Rally? Genuinely, I do not know. But it is a bit different to using your car on a bit of sand where you live compared to the Moon. I live near some of the largest dune systems in Europe and they make great places for walking. The conditions vary greatly but I would not compare any part of those dunes to the Moon.
To be honest, looking at that car bouncing around on that relatively smooth surface, at relatively slow speeds, I can't see how anyone could have confidence to drive at much higher speeds over much worse terrain, and, when only one person is on board, in a significantly unbalanced vehicle.
I can't see how a rally driver can keep a car on track but they do. My incredulity is not proof that a car cannot drive at 70+mph on a dirt track.
And, they seemingly have to have have a run up to help the vehicles across the test bed. At 2.18 it looks like both rear wheels rise up off the ground.
Thanks for posting it though, and I will take the time to look at the whole rover series later when I am at a better computer.
How many tests were there?
I am a bit stretched for time but I will address a some other comments later.
I expect that a full investigation would have notes to hand, calculations and other evidence so a quick copy and paste from your own notes would suffice?
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More than that, they were test pilots.
Yes, I meant to say that but it was half three in the morning (couldn't sleep!) and I wasn't thinking clearly.
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Some Real Numbers:
According to a 1972 Boeing handout, the Apollo 17 LRV had a weight capacity of 1,140 pounds [517 kg] Earth weight). This allowed for 400 lbs for each astronaut (and his gear) and 340 pounds of equipment and samples.
That's about 86 kilos earth equivalent, so yes, two astronauts even in street clothes would be over its capacity on earth. The document seems to be some kind of public or press handout, so it's not really very long on technical specs.
http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.html (http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.html)
Edit:
I'm aware that the onus is not, um, on us to provide the numbers, but I was getting a little tired of the sound of beating this particular dead horse.
400lb for each astronaut? That's 2kN. More than enough for an astronaut in Earth gravity, who would probably weigh no more than 1kN.
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The biggest criticism I would have of the test is that they don't start on the loose surface. Why not? that is the most obvious test for traction.
Do you really believe that this was the only test that they did before sending it to the Moon????
I live in a very sandy area and if I want to drive my 2wd over a sandy area that is a bit dodgy the way to do it is to get a bit of a run up and don't, under any circumstances, stop.
So what?
The relevance to where you live to a Lunar Rover is what exactly????
My 2wd is not suitable for sandy terrain yet it would pass that test.
Again, so what?
The relevance of your ICE vehicle to a Lunar Rover is what exactly??
To be honest, looking at that car bouncing around on that relatively smooth surface, at relatively slow speeds, I can't see how anyone could have confidence to drive at much higher speeds over much worse terrain, and, when only one person is on board
Appeal to incredulity.
The problem is with how you see things and not with the Lunar Rover program.
in a significantly unbalanced vehicle.
Why on Earth do you think that it's unbalanced?
Its got a low CoG, a wide wheeltrack and a relatively long wheelbase. All the components of a very balanced vehicle.
And, they seemingly have to have have a run up to help the vehicles across the test bed.
So what?
Do you know what was being tested in that particular test? Do you really think that they test the whole thing at once?? Come to think of it, what exactly is your experience in testing? In engineering? In vehicle design? In space-related industries?
Thanks for posting it though, and I will take the time to look at the whole rover series later when I am at a better computer.
I am a bit stretched for time but I will address a some other comments later.
Excuse me?? Your "research" is based on YouTube segments of poplar science TV shows?? Do yourself (and us) a favour and do some proper research before you come here spouting rubbish hoax theories.
Here's a good place to start:
Nasa Technical Reports Server (http://ntrs.nasa.gov/search.jsp?Ntx=mode%20matchallpartial%20|mode%20matchall|mode%20matchall&Ntk=All|All|All&N=0&Ntt=lunar%20rover|lunar%20rover|%22Lunar%20Roving%20Vehicle%22)
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Wonder if there have been any 2 wheel drive entrants in the Dakar Rally? Genuinely, I do not know. But it is a bit different to using your car on a bit of sand where you live compared to the Moon.
The Dakar Aggressor. A rear-engined, V8, 2WD car. It finished 35th place out of the 161 starters in the 2013 rally.
I assume that Anywho can realise that there may be some differences between his 2WD commuter car (designed for comfort, reliability, cheapness, long service intervals, market-place) and a 2WD vehicle designed for a single purpose??? I wonder why he/she cannot make the same mental leap to assume that there may be one or two differences between the performance of his/her car and the LRV??
(http://img.photobucket.com/albums/v239/Gadfium/Forum%20Uploads/2423169_700b_zps519d4437.jpg)
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Is it just me, or do these two statements crop up a lot in HB's posts :
"I've got a really crap computer so I can't access the information you've given me right now."
"I lead a really busy life so I'll come back and address your comments later."
Stalling for time much?
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Is it just me, or do these two statements crop up a lot in HB's posts :
"I've got a really crap computer so I can't access the information you've given me right now."
"I lead a really busy life so I'll come back and address your comments later."
Stalling for time much?
Yep. From computers that won't play sound, that keeps crashing, that won't allow quotations, that won't run graphics programs, that can't download from the Internet.....
Collectively the HB community must hold the world's repository of crappy PCs. :o
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The biggest criticism I would have of the test is that they don't start on the loose surface. Why not? that is the most obvious test for traction.
Do you really believe that this was the only test that they did before sending it to the Moon????
Well, just in case you haven't been following the thread my position is that they didn't send it to the moon :)
It's the only test they show, and who's position does it support?
It is a farcical test which tests nothing, not braking, not steering, not acceleration, and the only way it tests traction at all is in a way that is designed not to fail, ie: take a run up on a solid surface and see if you can keep going in a straight line over short test bed.
Admittedly, that test doesn't prove they didn't, and couldn't, go 4WDriving in 1/6g on the moon, but it is certainly more indicative of a farce than it is of serious testing, and the limited results that can be seen would support my position also.
https://www.youtube.com/watch?feature=player_detailpage&v=FVMfjPXwRO4#t=124s
To everyone who says that the rovers had a low center of gravity, what are you comparing it to, a truck? The chassis height is comparable to a family car, and that is without considering the one or two 400lb gorillas sitting high up on a lightweight 460lb vehicle.
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Anywho, do yourself a favour and read this book before you come back again:
http://www.amazon.co.uk/Lunar-Rover-Manual-Technology-Development/dp/0857332678/ref=sr_1_1?ie=UTF8&qid=1363606263&sr=8-1
Also, watch this DVD:
http://www.spacecraftfilms.com/apollo15manmustexplore.aspx
Again you are arguing from personal incredulity, and we are still waiting for the numbers we asked for.
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It's the only test they show, and who's position does it support?
It's the only test an episode of a TV show that condensed down the entire development and operation of the rover into one hour showed. The question was if you think it was the only test they did. Do you expect all the test footage to just drop into your lap?
The chassis height is comparable to a family car, and that is without considering the one or two 400lb gorillas sitting high up on a lightweight 460lb vehicle.
And unlike a family car it has no bodywork over the chassis, and doesn't have a large engine block sitting above the axles at one end. Compared to a family car it does have a low centre of gravity, because none of the mass is involved in anything that encloses the driver and passenger.
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Well, just in case you haven't been following the thread my position is that they didn't send it to the moon
So what is your position on what they actually did then?
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Well, just in case you haven't been following the thread my position is that they didn't send it to the moon
So what is your position on what they actually did then?
Ohhhh, you had to ask....
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Wonder if there have been any 2 wheel drive entrants in the Dakar Rally? Genuinely, I do not know. But it is a bit different to using your car on a bit of sand where you live compared to the Moon.
The Dakar Aggressor. A rear-engined, V8, 2WD car. It finished 35th place out of the 161 starters in the 2013 rally.
Thought so, cheers. This years was in S America I think? Previous years have been through the Sahara, but there were deserts on this one as well.
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To everyone who says that the rovers had a low center of gravity, what are you comparing it to, a truck? The chassis height is comparable to a family car, and that is without considering the one or two 400lb gorillas sitting high up on a lightweight 460lb vehicle.
Not a field I have particularly studied (or any field for that matter, apart from ones with cows in). What are your findings with regards centre of gravity in comparison to other vehicles? What measurements do you have.
Edit To add to this. Been mulling this over. I have over the years driven many vehicles. All of the family cars sized shall we say have had certain characteristics with regards handling. Some have been like fighting jelly around corners whilst others have be OK after a fashion. But one thing a family car is not meant to do is go to the extremes that, say, a Mini could do without modification. I am talking Cooper days not BMW days. But there are ones that will do it despite the barge that holds the family. So your analogy is a bit wayward. It does not fit, it cannot fit. I expect that despite a similar height, talking family cars only here, what attached the wheels to the chassis is also important. That makes the difference between a jellymobile and a rather stable platform.
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It's the only test they show
Who exactly are "they"? And please evidence that this short video clip is the "only test". I showed you a link to tens, if not hundreds, of highly detailed documents relating to the LRV....did you even bother to look at one of them?
In reality, the true translation of your sentence is "I didn't do ANY research, just posted a load of supposition, nonsense, and personal beliefs based on incredulity onto a board that is full of people that know their stuff, professional engineers and people that actually work in this field".
It is a farcical test which tests nothing, not braking, not steering, not acceleration, and the only way it tests traction at all is in a way that is designed not to fail, ie: take a run up on a solid surface and see if you can keep going in a straight line over short test bed.
Again, how do you know what is being tested (or indeed demonstrated) in that short clip?
I am also waiting for you to detail what makes you qualified to claim the test as farcical. What are your qualifications? Do you have an recognised experience in engineering? Space industries? Vehicle design?
The chassis height is comparable to a family car,
Again, so what?
without considering the one or two 400lb gorillas
Save your personal insults for people who are in the room to defend them. All you re doing is showing that you have a personal axe to grind and that you have to reduce the conversation to the level of a street brawl.
Admittedly, that test doesn't prove they didn't, and couldn't, go 4WDriving in 1/6g on the moon, but it is certainly more indicative of a farce than it is of serious testing, and the limited results that can be seen would support my position also.
And again, your position is that it was faked. Yet you have offered nothing of substance to support that claim. What you have done is shown a belief system that is based on incredulity and ignorance. Did you even pay a cursory glance at the reports that I linked to in my other post?
You have shown no calculations to support your claims. You have displayed no knowledge of the design, construction and testing of the LRV. You have provided no evidence of your qualifications or experience in any field that would add any credence to your hypothesis. You have provided nothing other than personal observations of a YouTube video and your own erroneous conclusions based on driving your personal car.
Do you know what a house of cards is?
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Thought so, cheers. This years was in S America I think? Previous years have been through the Sahara, but there were deserts on this one as well.
Yes, Lima to Santiago
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Some Real Numbers:
According to a 1972 Boeing handout, the Apollo 17 LRV had a weight capacity of 1,140 pounds [517 kg] Earth weight). This allowed for 400 lbs for each astronaut (and his gear) and 340 pounds of equipment and samples.
That's about 86 kilos earth equivalent, so yes, two astronauts even in street clothes would be over its capacity on earth. The document seems to be some kind of public or press handout, so it's not really very long on technical specs.
http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.html (http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.html)
Edit:
I'm aware that the onus is not, um, on us to provide the numbers, but I was getting a little tired of the sound of beating this particular dead horse.
400lb for each astronaut? That's 2kN. More than enough for an astronaut in Earth gravity, who would probably weigh no more than 1kN.
Uhhh... the weight/force conversion always leaves me a little confused. The AL7B suit used on Apollo 15-17 are listed at 96 kg (212 lbs) total earth weight, which would leave 85 kg (188 lbs) for the astronaut which seems reasonable. I don't quite understand your question - do the numbers seem off to you?
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Do I really need numbers to say that if the astronauts, in jumping onto the rover, clear the rover by 6 inches on the moon then the forces on the rover will be the same as a fall onto the rover of 1inch here on earth?
Do I need numbers to say that a fall from 1inch puts more stress on the frame than the static weight weight of an astronaut?
It's basic physics and common sense (although, admittedly, for most people, myself included, it does take a bit of time to stop thinking of weight and instead think in terms of mass)
I'm an engineer, so yes you do need numbers if I'm going to pay attention to your argument. Don't talk to me about "basic physics" unless you're going to start there and show your work all the way up to your final answer. Don't talk to me about "common sense" while you're contradicting the world's engineering community.
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Allow me to repeate my question, which seems to have gotten missed somewhere. Anywho, what research did you do? Exactly? What books have you read? Websites? Manuals?
Note that I'm asking about reading. That's the important kind of research, and if you didn't do any reading, you didn't do any research. There's a right way and a wrong way to go about this; kindly prove that you've done it the right way.
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All I've found after an EXTREMELY short search is the thing was called the Lunar Motorcycle and was considered as an option for Apollo 15 if the Rover didn't get shipped in time for the flight. The one pic I saw is the one that shows up a lot, and is very much in the vomit comet (presumably trying to simulate 1/6 g) and shows a man in pressure suit or mock-up thereof sitting on the bike and a couple of handlers beside him.
Just to throw in my own totally-apocryphal-and-boy-how-did-I-ever-survive-to-reach-thirty I used to take my Mustang II out on the sandy dirt fire trails of North Carolina, around the military base I was stationed at. Somewhere above thirty MPH I'd lose direct traction, and after that it felt more like using the rudders on a boat...basically planning along. Could still keep it slithering down more-or-less the middle of the road up to seventy or so. Like I said, I dunno how I ever reached thirty! On the other hand, Mustang was low, study suspension, and I could do a controlled slide on dry road (even -- shudder -- did that once to PARALLEL PARK it.)
In my partial defense, at the time the government was paying me to walk out of airplanes. While they were still in the air.
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Absolutely, but we are often told the astronauts cannot even sit on the rovers here on earth, but they can jump rather clumsily onto them on the moon. They wouldn't possible be able to jump onto them on earth fully suited so when people say the rovers can't withstand being sat on here on earth they cannot be referring to the astronauts, fully suited, trying to jump onto them.
You are aware that the suits worn by Apollos 15 to 17 were
given the designation "A7LB" by NASA,[6] the new suit incorporated two new joints at the neck and waist. The waist joint was added to allow the astronaut to sit on the LRV and the neck joint was to provide additional visibility while driving the LRV.
http://en.wikipedia.org/wiki/Apollo/Skylab_A7L#Apollo_15-17 (http://en.wikipedia.org/wiki/Apollo/Skylab_A7L#Apollo_15-17)
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... it is certainly more indicative of a farce than it is of serious testing, and the limited results that can be seen would support my position also.
Please provide evidence (not opinion) that the rovers could not operate under Lunar conditions, or retract that claim.
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Basically, the position seems to be, as it so often is:
"I believe the US government is an unmitigated, monolithic evil that could never do anything constructive. And since the Apollo missions conflict with this belief I don't want to accept that they were real no matter how much evidence may exist for them.
So I'm going to focus on this one small detail that I don't understand and demand that you prove it to me without my having to evaluate any evidence or accept the judgment of those who actually know this stuff. And should you still succeed in doing so, I'll just pick something else to complain about."
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Basically, the position seems to be, as it so often is:
"Despite the mountain of evidence for their reality, for various ideological reasons I don't want to believe the Apollo missions happened. So I'm going to focus on this one small detail that I don't understand and demand that you prove it to me without my having to evaluate any evidence or accept the judgment of those who actually know this stuff. And should you still succeed in doing so, I'll just pick something else to complain about."
Nicely put. May I steal that?
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Sure, or you could use my just-expanded version.
I'm open to any suggestions on how to boil this down to its most succinct form. (I tend to be a little wordy sometimes...)
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Basically, the position seems to be, as it so often is:
"I believe the US government is an unmitigated, monolithic evil that could never do anything constructive. And since the Apollo missions conflict with this belief I don't want to accept that they were real no matter how much evidence may exist for them.
So I'm going to focus on this one small detail that I don't understand and demand that you prove it to me without my having to evaluate any evidence or accept the judgment of those who actually know this stuff. And should you still succeed in doing so, I'll just pick something else to complain about."
I'm open to any suggestions on how to boil this down to its most succinct form. (I tend to be a little wordy sometimes...)
Blue pencil in hand, just for shiggles:
"So I'm going to focus on this one small detail that I don't understand and demand that[.] you p [P]rove it[;] to me without my having to evaluate any evidence or accept the judgment of those who actually know this stuff. And should you still succeed in doing so, I'll just pick something else[.] to complain about."
There. I think that's the Reader's Digest version.
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I expect to see a flounce in the next 24 hours. Don't disappoint me anywho!
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I expect to see a flounce in the next 24 hours. Don't disappoint me anywho!
Even odds on a stealth flounce...
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Bo bets here. He surprised me by sticking around this long - I had thought of him as sort of a circling seagull.
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Does anyone here detect the distinctive odour of socks?
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Basically, the position seems to be, as it so often is:
So I'm going to focus on this one small detail....
To you guys 1/6g is only a small detail that has to be overcome because you see, and believe, the rovers hooning around with no traction problems and not even looking like rolling is a possibility, so driving in 1/6 is all just fun with one of you even mentioning the "dukes of hazard" yeehaa.
In reality 1/6g equals 1/6 the traction, and that is a big problem, not a "small detail". In the link is a coefficient of traction table which lists Dirt (packed dry) .5 and Ice (free of snow) .07, so on the moon that .5 becomes approx .08 which is more comparable to ice than any other surface (and that is being generous because on the moon it is loose dirt).
http://www.saltflats.com/traction.html
So on the moon there should be all the traction difficulties of driving on ice...
...The surface is at times more like a mogul run than a road....
...On earth you would not want to end up sideways on such an uneven surface, on the moon it is many times easier to roll a vehicle...
..when one astronaut is on board approx 3/4 of the weight is on one side of the vehicle, so yes, it is a very unbalanced vehicle especially for the moon where, once again, it is many times easier to roll a vehicle than on earth.
Can we all agree on some points?
Traction on a loose surface on the moon will be similar to ice on earth
It is many times easier to roll a vehicle on the moon than the earth
There are no groomed roads on the moon and the driving surface was at times very uneven (might stop all the irrelevant anecdotes about driving, and going sideways, on dirt roads)
A balanced vehicle has, by definition, the weight relatively well balanced, ergo, a vehicle with 3/4 the weight on one side is unbalanced.
On the moon where it is many times easier to roll a vehicle having a balanced vehicle would be significantly more important than on earth.
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Basically, the position seems to be, as it so often is:
So I'm going to focus on this one small detail....
To you guys 1/6g is only a small detail that has to be overcome because you see, and believe, the rovers hooning around with no traction problems and not even looking like rolling is a possibility, so driving in 1/6 is all just fun with one of you even mentioning the "dukes of hazard" yeehaa.
In reality 1/6g equals 1/6 the traction, and that is a big problem, not a "small detail". In the link is a coefficient of traction table which lists Dirt (packed dry) .5 and Ice (free of snow) .07, so on the moon that .5 becomes approx .08 which is more comparable to ice than any other surface (and that is being generous because on the moon it is loose dirt).
http://www.saltflats.com/traction.html
So on the moon there should be all the traction difficulties of driving on ice...
...The surface is at times more like a mogul run than a road....
...On earth you would not want to end up sideways on such an uneven surface, on the moon it is many times easier to roll a vehicle...
..when one astronaut is on board approx 3/4 of the weight is on one side of the vehicle, so yes, it is a very unbalanced vehicle especially for the moon where, once again, it is many times easier to roll a vehicle than on earth.
Can we all agree on some points?
Traction on a loose surface on the moon will be similar to ice on earth
It is many times easier to roll a vehicle on the moon than the earth
There are no groomed roads on the moon and the driving surface was at times very uneven (might stop all the irrelevant anecdotes about driving, and going sideways, on dirt roads)
A balanced vehicle has, by definition, the weight relatively well balanced, ergo, a vehicle with 3/4 the weight on one side is unbalanced.
On the moon where it is many times easier to roll a vehicle having a balanced vehicle would be significantly more important than on earth.
What tires were used in that table? How do you calculate the balance? What is the CoG for the LRV? If I am to agree on anything, I'd like to see why. The LRV didn't exceed 18 km/h. What kind of g-loads did that inflict on the frame?
The CoG is very critical to your claim. If the Cog (loaded or unloaded) isn't higher above the ground than the distance between the tires, the vehicle will be quite stable.
Also, you're disregarding the fact, that the people who developed the LRV KNEW the kind of enviroment it was to be used in. Is it possible that they actually made some hardware designed specifically to deal with the dangers it would face on the moon?
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I'm pretty sure you can't just divide a given earth traction coefficient by 6 to get the a lunar traction coefficient...but there is one obvious big problem with the numbers you are using...
Coefficient of Traction for Rubber Tires on Various Surfaces
Source: Forestry Handbook by Karl F. Wenger (1984)
Concrete (dry) .70
Asphalt (dry) .50
Asphalt (wet) .45
Gravel (packed, oiled, dry) .50
Gravel (packed, oiled, wet) .45
Dirt (packed, dry) .50
Mud .15-.40
Snow (dry, on loose gravel) .25
Ice (free of snow) .07
Does this look like a rubber tire to you?
(http://thumbnails104.imagebam.com/24408/db9e8e244078635.jpg) (http://www.imagebam.com/image/db9e8e244078635)
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Googling around, I see that the LRV is quite stable. It can pitch up to 45 degrees in any direction, and still be able to drive on. It can traverse obstacles 30 cm high, climb and descend 25 degrees slopes.
Now, if the LRV was 182 cm wide (distance between the centers of the wheels), the CoG should be lower than 91 cm, even fully loaded. Draw a line from the bottom of the wheels 45 degrees up, and you'll find the CoG.
Removing one astronaut, putting about 30 kg 46 cm (half of the half with of the LRV) offset from the centerline, would that make the LRV unbalanced? You'll be moving the CoG 30kg/50kg x 46/182 cm = 15 cm off the centerline. Is that unbalanced?
Edit: removing one astronaut would also LOWER the CoG, increasing the stability of the LRV.
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I'm pretty sure you can't just divide a given earth traction coefficient by 6 to get the a lunar traction coefficient...but there is one obvious big problem with the numbers you are using...
Coefficient of Traction for Rubber Tires on Various Surfaces
Source: Forestry Handbook by Karl F. Wenger (1984)
Concrete (dry) .70
Asphalt (dry) .50
Asphalt (wet) .45
Gravel (packed, oiled, dry) .50
Gravel (packed, oiled, wet) .45
Dirt (packed, dry) .50
Mud .15-.40
Snow (dry, on loose gravel) .25
Ice (free of snow) .07
Does this look like a rubber tire to you?
(http://thumbnails104.imagebam.com/24408/db9e8e244078635.jpg) (http://www.imagebam.com/image/db9e8e244078635)
Those numbers are very outdated. Modern tires have a friction coefficient up to .85 on dry asphalt. More if it's specialized racing tires.
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To you guys 1/6g is only a small detail that has to be overcome because you see, and believe, the rovers hooning around with no traction problems and not even looking like rolling is a possibility, so driving in 1/6 is all just fun with one of you even mentioning the "dukes of hazard" yeehaa.
In reality 1/6g equals 1/6 the traction, and that is a big problem, not a "small detail". In the link is a coefficient of traction table which lists Dirt (packed dry) .5 and Ice (free of snow) .07, so on the moon that .5 becomes approx .08 which is more comparable to ice than any other surface (and that is being generous because on the moon it is loose dirt).
http://www.saltflats.com/traction.html
Nonsense. Who was it who said, "Simplify as much as possible, but no further?"
What is the friction co-efficient between a shovel and a scoop of dirt held in it?
Snow chains here on Earth are CHAINS. They are steel, which is very hard and smooth, unlike the sticky rubber of a tire. Yet, they work better. Why? Because they mechanically interact with the material.
You are attempting to describe the performance of the LRV as if it is simply a light-weight automobile, only in less gravity. It is not. It does not have pneumatic tires. It has individual motors in each wheel. There is no differential. There are no treads, per se. There are chevrons of metal attached to the mesh of the wheel.
The only way to understand the performance of that vehicle under those conditions is by addressing the actual mechanism of that vehicle and how it interacts with those actual conditions.
So on the moon there should be all the traction difficulties of driving on ice...
...The surface is at times more like a mogul run than a road....
...On earth you would not want to end up sideways on such an uneven surface, on the moon it is many times easier to roll a vehicle...
..when one astronaut is on board approx 3/4 of the weight is on one side of the vehicle, so yes, it is a very unbalanced vehicle especially for the moon where, once again, it is many times easier to roll a vehicle than on earth.
Where is the astronaut in relation to the wheelbase? It is the length of the lever that matters, not some arbitrary comparison with some other vehicle. And, yes...both seats are WITHIN the wheelbase.
Can we all agree on some points?
Traction on a loose surface on the moon will be similar to ice on earth
It is many times easier to roll a vehicle on the moon than the earth
There are no groomed roads on the moon and the driving surface was at times very uneven (might stop all the irrelevant anecdotes about driving, and going sideways, on dirt roads)
A balanced vehicle has, by definition, the weight relatively well balanced, ergo, a vehicle with 3/4 the weight on one side is unbalanced.
On the moon where it is many times easier to roll a vehicle having a balanced vehicle would be significantly more important than on earth.
None of these strike me as particularly descriptive of the LRV.
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Those numbers are very outdated. Modern tires have a friction coefficient up to .85 on dry asphalt. More if it's specialized racing tires.
I suspected as much. I copied the full list from the link Anywho provided to point out that the list he's quoting was specifically for rubber tires.
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Nonsense. Who was it who said, "Simplify as much as possible, but no further"?
According to my research, it was Einstein speaking a bit disparagingly of Occam's Razor, though I also believe that it's the best description I've ever heard. (My research, I confess, was some time ago. I have also corrected your punctuation.) This is one of those situations where we are clearly trying to separate farther than possible. And by "we," I mean "Anywho," who still hasn't answered my research question.
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I don't get this assertion that the LRV is unstable. It looks stable to me. It is low and flat. I would have thought the risk of rolling over was very low.
Sounds like someone is twisting observations to fit desired conclusions.
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You know, even if the LRV got stuck somehow, as I believe happened on at least Apollo 15 once, you know what the astronauts could do?
They could get off their butts, perhaps unload experiments, go at each end, and simply move the darn thing.
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I'm pretty sure you can't just divide a given earth traction coefficient by 6 to get the a lunar traction coefficient...but there is one obvious big problem with the numbers you are using...
Coefficient of Traction for Rubber Tires on Various Surfaces
Source: Forestry Handbook by Karl F. Wenger (1984)
Concrete (dry) .70
Asphalt (dry) .50
Asphalt (wet) .45
Gravel (packed, oiled, dry) .50
Gravel (packed, oiled, wet) .45
Dirt (packed, dry) .50
Mud .15-.40
Snow (dry, on loose gravel) .25
Ice (free of snow) .07
Does this look like a rubber tire to you?
(http://thumbnails104.imagebam.com/24408/db9e8e244078635.jpg) (http://www.imagebam.com/image/db9e8e244078635)
Those numbers are very outdated. Modern tires have a friction coefficient up to .85 on dry asphalt. More if it's specialized racing tires.
Who cares if they are outdated and technology has improved, it would have improved for ice as well so the comparison is still valid. Find another set of figures if you want, I have seen other tables in the past and the results are always very similar, those were just the easiest to find with a quick google.
Snow chains here on Earth are CHAINS. They are steel, which is very hard and smooth, unlike the sticky rubber of a tire. Yet, they work better. Why? Because they mechanically interact with the material.
Snow chains, which are often plastic today, work because they have low surface area and are designed to bite into the snow, they would have a fraction of the value on the moon because they rely on weight.
The chevrons look nothing like snow chains, they are flat and with a comparatively large surface area. I spent a fair bit of my youth at ski resorts and those chevrons would be useless in most slippery conditions.
The Soviets supposedly sent a rover to the moon and the tracks on their 8WD rovers are more like chains, the soviet rover was nowhere near as high performance as the apollo rovers were yet they seem to take low traction a lot more seriously.
(http://upload.wikimedia.org/wikipedia/commons/thumb/7/78/Lunokhod_1_%28high_resolution%29.jpg/200px-Lunokhod_1_%28high_resolution%29.jpg)
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To you guys 1/6g is only a small detail that has to be overcome because you see, and believe, the rovers hooning around with no traction problems and not even looking like rolling is a possibility, so driving in 1/6 is all just fun with one of you even mentioning the "dukes of hazard" yeehaa.
No, to us 1/6th G is a significant detail but not a major obstacle because we are qualified to judge it/ This board includes a whole raft of scientists and engineers. Moreover they have demonstrated their understanding of this subject here in this thread. And yet you insist we just believe it because we see it. What are your qualifications in any relevant field?
In the link is a coefficient of traction table
Which is irrelevant because it applies to rubber tyres. The rover did not use rubber tyres.
...On earth you would not want to end up sideways on such an uneven surface, on the moon it is many times easier to roll a vehicle...
A comparative statement that is meaningless unless you can show how easy it would be to roll the rover on Earth. It is low, flat and has no weight of bodywork.
Traction on a loose surface on the moon will be similar to ice on earth
No, because you have no characterised the lunar surface beyond 'loose dirt'. You have taken no account of the cohesive qualities of the regolith, nor of the type of wheel the rover used, which was flexible and a wire mesh, providing much more interaction with that dirt.
It is many times easier to roll a vehicle on the moon than the earth
So how easy is it to roll the rover on Earth? Your answer needs to take into account the rovers speed, low centre of gravity, and the capabilities of the suspension system to absorb the deflection of the vehicle caused by hitting an obstacle.
There are no groomed roads on the moon and the driving surface was at times very uneven (might stop all the irrelevant anecdotes about driving, and going sideways, on dirt roads)
So what?
A balanced vehicle has, by definition, the weight relatively well balanced, ergo, a vehicle with 3/4 the weight on one side is unbalanced.
But this is meaningless. The important question is not where its weight is but where that puts its centre of gravity. Show your calculations that indicate where the centre of mass is and what angle the rover would have to reach before it would tip.
On the moon where it is many times easier to roll a vehicle having a balanced vehicle would be significantly more important than on earth.
Agreed. now show us how easy it would be to roll the vehicle in either location.
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I don't get this assertion that the LRV is unstable. It looks stable to me. It is low and flat. I would have thought the risk of rolling over was very low.
Sounds like someone is twisting observations to fit desired conclusions.
It looks stable for earth but you have to consider that it is many times easier to roll on the moon, and that the rovers are very lightweight with drivers that are very heavy (comparatively).
We are used to seeing vehicles that weigh a few thousand pound with drivers that weigh a few hundred so in that way these don't "look" too unstable.
But in this case the rovers weigh 460lbs and the astronauts weigh 400lbs, with one driver on that is 3/4 the weight off to one side, this is extraordinary, it would be the equivalent of having 10 blokes sitting on the one side of a normal earth vehicle, or 5 if you have a fiat bambina. Would that still look stable to you?
Adding to that very abnormal imbalance is the fact that the ground is very uneven, and as said earlier, it is many times easier to roll a vehicle on the moon. How many times easier it is to roll would depend on the degree of the slope hit but I would suggest 3or 4 times easier to roll would not be unreasonable.
If you ended up going sideways on the slippery and uneven surface I think it would be a straight 6 times easier to roll, or at least I can't see why it wouldn't be.
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No evidence yet then, just a point of view. So easy to copy and paste from your findings, why don't you?
Edit. I have just realised that range rovers are so dangerous, they cannot ever go off road, they will fall over for certain.
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Then show it. Show your calculations to demonstrate that under the driving we see, it was at high risk of toppling.
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It looks stable for earth but you have to consider that it is many times easier to roll on the moon,
Is it?
and that the rovers are very lightweight with drivers that are very heavy (comparatively).
Are they?
We are used to seeing vehicles that weigh a few thousand pound with drivers that weigh a few hundred so in that way these don't "look" too unstable.
Are they? Looks to me that you are long on assertion, short on evidence.
But in this case the rovers weigh 460lbs and the astronauts weigh 400lbs, with one driver on that is 3/4 the weight off to one side, this is extraordinary,
The environment on the moon is extraordinary, And?
it would be the equivalent of having 10 blokes sitting on the one side of a normal earth vehicle, or 5 if you have a fiat bambina.
Would it? you have yet to demonstrate that.
Would that still look stable to you?
The evidence to date is that it is stable. You cannot present anything beyond your unreasonable expectations.
Adding to that very abnormal imbalance is the fact that the ground is very uneven, and as said earlier, it is many times easier to roll a vehicle on the moon. How many times easier it is to roll would depend on the degree of the slope hit but I would suggest 3or 4 times easier to roll would not be unreasonable.
How many times slower did they drive?
If you ended up going sideways on the slippery and uneven surface I think it would be a straight 6 times easier to roll, or at least I can't see why it wouldn't be.
Not if you drive slow, like the astronauts did.
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You're mixing up your balance of forces between Earth and moon again.
The forces on the moon are proportionately less for everything - including the the force that would act on a vehicle to cause it to roll.
It is exactly as likely to topple on a lunar slope as on a terrestrial one. To counter this they came up with this totally wild and crazy idea: they didn't drive it on steep slopes.
Your suggestion that the ground was very bumpy is completely contradicted by the facts - check the photos.
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A comparative statement that is meaningless unless you can show how easy it would be to roll the rover on Earth. It is low, flat and has no weight of bodywork.
Once again "low" compared to what, a truck? Why do you people keep saying it is low as though it is some kind of go-cart or something, it is an off road vehicle and needs the clearances all off road vehicles need.
The "weight of no body work" comment is a joke, it weighs 460lbs and has an astronaut sitting up high on it that weighs 400lbs, this would certainly lift the center of gravity higher than the bodywork does on a normal earth vehicle.
No, because you have no characterised the lunar surface beyond 'loose dirt'. You have taken no account of the cohesive qualities of the regolith, nor of the type of wheel the rover used, which was flexible and a wire mesh, providing much more interaction with that dirt.
It is the flat smooth chevrons that are the main part interacting with the regolith, not the wire mesh.
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To you guys 1/6g is only a small detail that has to be overcome because you see, and believe, the rovers hooning around with no traction problems and not even looking like rolling is a possibility, so driving in 1/6 is all just fun with one of you even mentioning the "dukes of hazard" yeehaa.
You seem to think that the LRV was just some kind of modified "dune buggy". On the contrary, it was a complex, purpose built machine with very specific requirements for its operation. A very short web search should turn up the LRV Operations Handbook, which goes into very tedious detail how the LRV should be loaded, powered up, driven, parked, and anything else it was expected to do. The astronauts spent a considerable number of hours in trainers practicing LRV operation.
In fact, each LRV was fitted to the specific astronauts that would be operating it to make sure that seats, footrests, controls, etc. would be in the correct positions. Here's a photo of The Apollo 17 LRV being fitted to Jack Schmitt and Eugene Cernan before it is stowed on the LM seen in the background. Notice that there are supports under the frame so it will hold their weight in Earth gravity.
(http://i627.photobucket.com/albums/tt353/jarvisn/LRV17Fit_zpseca113b8.jpg)
As far as center of gravity goes, there were very specific loading requirements for the vehicle. Here's a diagram from the LRV Ops Handbook showing the allowable range for the CoG.
(http://i627.photobucket.com/albums/tt353/jarvisn/LRV-CG_zpsf7015c4a.jpg)
I hate to keep hammering this point, but it seems to be one that's chronically overlook by the Hoax Believers: These machines and devices were not just casually thrown together; they were the result of thousands of hours of work by people who were the best at what they did, based on the best research they had available, which by the time the LRVs were used was considerable.
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You're mixing up your balance of forces between Earth and moon again.
The forces on the moon are proportionately less for everything - including the the force that would act on a vehicle to cause it to roll.
The mass is not proportionately less.
Consider that the vehicles still have the same mass being thrashed around but on have 1/6 the weight anchoring it to the ground.
Or consider that if the vehicle hits a bump on one side then that side of the rover will rise up many times higher than on earth so therefore it would take significantly less to roll on the moon.
Your suggestion that the ground was very bumpy is completely contradicted by the facts - check the photos.
(https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSi1F7ctsk_5Rl7kdPu_uhvzpDjhnwyjCEeb4nX6dZMf5Nxb7x79Q)
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQY9vOpO8_1-fEUKCKTPlZClC1LuDN69aOK-soJspOOKXIY4577ig)
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Still no workings out yet or definitive work? Highlight the text in your work and Control C then Control V to paste it in. Easy.
From one experience in one car I will draw the conlusion that all cars are inherently un stable. This seems to be close to your approach?
I know different cars act differently and this one was built for one place. I need to see more than a gut feeling.
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It looks stable for earth but you have to consider that it is many times easier to roll on the moon,
How much easier? Is it at all possible to roll the rover on Earth at its top speed? Numbers are needed, no matter how many times you avoid them.
Would that still look stable to you?
How it looks is irrelevant. Plans of the rover are readily available. You should be able to calculate where its centre of mass is unladen, with one or with two astronauts on it. Why don't you do that and then show what angle it would need to tip to before it will roll.
How many times easier it is to roll would depend on the degree of the slope hit but I would suggest 3or 4 times easier to roll would not be unreasonable.
And I for one don't care what you think would be 'reasonable'. Show your working. This is an engineering issue, and you cannot solve engineering issues without numbers. If you don't know the numbers you can't draw conclusions just because something 'looks' unstable to you.
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The "weight of no body work" comment is a joke, it weighs 460lbs and has an astronaut sitting up high on it that weighs 400lbs, this would certainly lift the center of gravity higher than the bodywork does on a normal earth vehicle.
One astronaut is about 200 lb. 400 lb is the combined weight of two of them. *
It is the flat smooth chevrons that are the main part interacting with the regolith, not the wire mesh.
No, the entire wheel is sufficiently flexible that all of it interacts with the regolith. The wheels threw up huge amounts of dust because the dust could get in through the mesh and then be thrown out again. You don't get to dismiss the main construction of the wheel so you can focus on the smooth metal parts just because they fit your argument better.
* Note I was corrected on this further down. I leave the mistake here, though, as it illustrates that we do make them now and again, and don't mind being corrected when they are pointed out.
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Or consider that if the vehicle hits a bump on one side then that side of the rover will rise up many times higher than on earth
So, accounting for the suspension systems and the speed the rover is going, how high would the rover lift on Earth?
You keep saying something would be many times higher on the Moon, but can't provide the basis for comparison you need to make your point. Why?
I can say it would be many times easier for me to lift a 200 lb astronaut, a 460 lb rover or a two tone car on the Moon than it would be on Earth, but since I can't lift any of those on Earth that doesn't mean anything. So it is with your argument. You can't offer comparative arguments with no baseline.
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One astronaut is about 200 lb. 400 lb is the combined weight of two of them.
Err - no. One astronaut with PLSS had a mass close to 400 lb. The suit and PLSS alone was 95 kg.
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Ah yes, you're right. I stand corrected.
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Consider that the vehicles still have the same mass being thrashed around but on have 1/6 the weight anchoring it to the ground.
The roll-causing sideways force between the wheel and the ground is proportional to weight, so also 1/6.
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Once again "low" compared to what, a truck? Why do you people keep saying it is low as though it is some kind of go-cart or something, it is an off road vehicle and needs the clearances all off road vehicles need.
The "weight of no body work" comment is a joke, it weighs 460lbs and has an astronaut sitting up high on it that weighs 400lbs, this would certainly lift the center of gravity higher than the bodywork does on a normal earth vehicle.
It is the flat smooth chevrons that are the main part interacting with the regolith, not the wire mesh.
Once again, Anywho, all you are doing is thrashing around, basing your viewpoint on nothing more than supposition and your understanding of commonsense. You clearly have no qualifications, skill or experience in any of what you are talking about (if you did, you wouldn't be making the basic mistakes that you are making, and you would have replied to the repeated questions asking you to supply evidence of the qualifications).
So, given that you are completely lost with this subject then perhaps a change of tack is required? Instead of going "Its all a fake because the LRV couldn't possibly work", why don't you try something along the lines of "Guys, I do not understand the mechanics of how this works. Here's a list of the things that I have researched, but still cannot grasp. Could you please help me with them?". In my experience, people tend to go to great lengths to help others learn, as long as the desire to learn is there.
I assume that you won't do this and I can only suppose at the reasons. I guess that your reasons for taking the approach that you have taken may include:
- I have a personal axe to grind
- I don't want to admit to myself that my knowledge and abilities are not enough to work this stuff out
- I am too lazy to do any research even when pointed at sources of the information that could help me
- I don't want to admit to myself that others have more skill than me
- I cannot allow myself to admit that I might be wrong (which is probably why I am not learning)
- Hey! I am a man of the world. I know everything that there is to know. My guesses and stabs in the dark are no match for your puny degrees and years of experience
Am I near to the mark?
And again, just in case you missed these the last two times:
What is your experience in the field of testing?
What are your qualifications in engineering? Vehicle design?
Have you read any of the documents that I linked to? If so, then please point out exactly where you disagree with them and provide your calculations that led you to that disagreement.
I wait with bated breath*
*no I don't because you will ignore this.
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Or consider that if the vehicle hits a bump on one side then that side of the rover will rise up many times higher than on earth so therefore it would take significantly less to roll on the moon.
The vehicle had suspension (double wishbone and the deflection of the tyres), designed to cope with bump absorption. You do know how suspension works, right? If you do, then you will know that vehicle suspension is designed to work in the vehicle's range of speed (0-14Km/h). Do you not realise that the manufacturer will have specified the maximum impact that the suspension could cope with?
it would take significantly less to roll on the moon.
Why would it take less to roll?
The vehicle was designed to not roll unless the angle exceeded 450. What size of bump and at what speed would the vehicle have to hit in order to cause the vehicle to roll? Numbers and calculations please.
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I think suspension does not factor one iota for anywho theory to have an inkling of being in the ball park of possibility. That much is obvious. Examples have already been suggested. He/she will not go down that path perhaps? That way leads to the dark side of evidence.
But maybe I am wrong.
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No, the entire wheel is sufficiently flexible that all of it interacts with the regolith. The wheels threw up huge amounts of dust because the dust could get in through the mesh and then be thrown out again. You don't get to dismiss the main construction of the wheel so you can focus on the smooth metal parts just because they fit your argument better.
How ironic that someone who describes the tyre setup as "flexible and a wire mesh", thereby completely ignoring the chevrons, should accuse me of focusing on the area that suits my argument :P
We'll look at the witness marks should we? It looks to me as though the wire mesh does not touch the ground at all except for maybe between the chevrons, of the two of us I certainly represented the tyres in a way that is supported by the evidence.
(http://comps.canstockphoto.com/can-stock-photo_csp0672620.jpg)
Here's a photo of The Apollo 17 LRV being fitted to Jack Schmitt and Eugene Cernan before it is stowed on the LM seen in the background. Notice that there are supports under the frame so it will hold their weight in Earth gravity.
(http://i627.photobucket.com/albums/tt353/jarvisn/LRV17Fit_zpseca113b8.jpg)
Yes those supports are needed under the frame because it is such a delicate little flower that it can't even "hold their weight", yet on the moon those same masses can literally jump onto the rovers and then slam them into bumps all they want without any concerns.
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQY9vOpO8_1-fEUKCKTPlZClC1LuDN69aOK-soJspOOKXIY4577ig)
[/quote]
Were they delicate, or sturdy? Apparently both.
So delicate they can't be sat on, yet sturdy enough that they can be driven on bumpy uneven surfaces with confidence. The "with confidence" part is very important, on the moon any accident could result in death so they had to be confident that these vehicles, that could not even be sat on, would not fail over bumpy terrain.
Normally the opposite is true, you might be able to sit on and even ride a kids bike on a smooth surface for example, yet not ride it over a bumpy surface.
Whatever ye do don't question this paradigm shift lest ye be called a conspiracy nutter.
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Anywho, instead of repeating the same thing over and over, is there any chance that you will answer some of the outstanding questions that have been posed to you?
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It looks to me as though the wire mof the two of us I certainly represented the tyres in a way that is supported by the evidence.
Please explain why you think that this mesh would not be in contact with the regolith?
(http://www.armaghplanet.com/blog/wp-content/uploads/2013/01/image_of-wiremesh-tyre.jpg)
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If the mesh didn't touch the ground, then what on the Moon excavated those tracks?
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[Please explain why you think that this mesh would not be in contact with the regolith?
(http://www.armaghplanet.com/blog/wp-content/uploads/2013/01/image_of-wiremesh-tyre.jpg)
I did say the mesh would be in contact between the chevrons, perhaps in the interest of fairness you could ask Jason Thompson why he ignored the chevrons.
It is a very good photo anyhow, it's interesting how the chevrons are as pronounced as they are in the tracks when they lack depth against the mesh. The mesh must just allow the dust straight through.
'Night all
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Still be good to see any evidence that the vehicle is unstable and not strong enough for the job in hand. Not convinced that a gut feeling on a family motor counts as evidence. Somehow. Don't know why.
Some actual real evidence would be nice anywho. I do not expect it off you somehow, I expect this to get derailed and go off on a tangent. But down them paths there will be no evidence either. I expect a lot of dodging as well.
Am I psychic? Heck, I ought to be.....
Edit to add. Heck, my physic abilities made me forget about the motors not up to the job, that one has slipped off the radar.
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How ironic that someone who describes the tyre setup as "flexible and a wire mesh", thereby completely ignoring the chevrons, should accuse me of focusing on the area that suits my argument
I ignored no part of the construction. Do not try to twist my arguments in lieu of actually dealing with the substance of them. You were the one who wanted to imply the smooth nature of the chevrons was the main part of the surface in contact with the regolith. I was pointing out that the wire mesh cannot be discounted.
We'll look at the witness marks should we? It looks to me as though the wire mesh does not touch the ground at all except for maybe between the chevrons,
Please explain why you think I was suggesting anything else.
(http://comps.canstockphoto.com/can-stock-photo_csp0672620.jpg)
You know, it sure looks from those clear imprints as if the rover wheels had no difficulty gaining traction on that loose surface. I certainly see no evidence of skidding or slipping. Do you?
Yes those supports are needed under the frame because it is such a delicate little flower that it can't even "hold their weight", yet on the moon
What exactly is your source for this statement you keep repeating?
those same masses can literally jump onto the rovers and then slam them into bumps all they want without any concerns.
You have had the difference between static and dynamic loading explained already.
Whatever ye do don't question this paradigm shift lest ye be called a conspiracy nutter.
Questioning is fine. Ignoring the answers and the other questions that arise is what marks you out as a 'conspiracy nutter'.
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Notice that there are supports under the frame so it will hold their weight in Earth gravity.[/b]
Can you please provide a source for this?
The wheels were designed to deform when in use. They were designed to be used in Lunar regolith. How do you know that loading the vehicle under Earth's gravity would not exceed the design rating for the wheel and permanently deform it? Especially when you consider that it would be sitting on a hard concrete floor, which would present a point load to the wheel, rather than the wheel digging into regolith and spreading the load. The supports under the frame may have been for that very purpose-to prevent damage to the wheels.
Are you allowing your desire that the LRV was a fake to totally blind you to alternative explanations?
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It is the flat smooth chevrons that are the main part interacting with the regolith, not the wire mesh.
How ironic that someone who describes the tyre setup as "flexible and a wire mesh", thereby completely ignoring the chevrons, should accuse me of focusing on the area that suits my argument :P
We'll look at the witness marks should we? It looks to me as though the wire mesh does not touch the ground at all except for maybe between the chevrons, of the two of us I certainly represented the tyres in a way that is supported by the evidence.
(http://comps.canstockphoto.com/can-stock-photo_csp0672620.jpg)
The impressions of the chevrons are pretty deep in the dirt for something that is a flat and smooth. It is pretty obvious from looking at the photos and video of the moving rover that the tires regularly go into the dirt, a fact that makes your comparison to any rubber tired vehicle traveling on earth useless. Please provide an numerical analysis of the traction of the actual tires used with the characteristics of the actual material the rover was driven in. Remember, the rover designers new the characteristics of the lunar surface before the rovers flew. For example, compare an estimate of the observed depth of the chevron impression to that of the foot prints. Even simple guess on the depths will be OK as a place to start an informed analysis. I am sure many people here could help you refine the work in a way that would lead to a clarification on why you disagree with us.
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It is a very good photo anyhow, it's interesting how the chevrons are as pronounced as they are in the tracks when they lack depth against the mesh.
Do you see the bands under the mesh? What are they made of and how strong are they? What function do they play in the tire design?
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It is a very good photo anyhow, it's interesting how the chevrons are as pronounced as they are in the tracks when they lack depth against the mesh. The mesh must just allow the dust straight through.
Of course, if you had bothered to read an of the links that I previously posted, then you would have come across a document called "The Development of Wheels for the Lunar Roving Vehicle" which explains exactly how the wheels work.
Or you could read the "Performance of Boeing LRV Wheels in a Lunar Soil Simulant" (reports 1 & 2) which describe the testing done on the wheels including traction and slip coefficients.
Or you could go here: http://www.hq.nasa.gov/alsj/alsj-LRVdocs.html and read to your hearts content about the LRV.
But I guess that you won't do any of that, will you? And I guess that you won't answer a single one of the questions that I have posed to you. It's much easier to watch YouTube videos and make assumptions about things that you have absolutely zero knowledge of. Isn't that right Anywho?
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No, the entire wheel is sufficiently flexible that all of it interacts with the regolith. The wheels threw up huge amounts of dust because the dust could get in through the mesh and then be thrown out again. You don't get to dismiss the main construction of the wheel so you can focus on the smooth metal parts just because they fit your argument better.
How ironic that someone who describes the tyre setup as "flexible and a wire mesh", thereby completely ignoring the chevrons, should accuse me of focusing on the area that suits my argument :P
We'll look at the witness marks should we? It looks to me as though the wire mesh does not touch the ground at all except for maybe between the chevrons, of the two of us I certainly represented the tyres in a way that is supported by the evidence.
(http://comps.canstockphoto.com/can-stock-photo_csp0672620.jpg)
I'm going to go out on a limb here and say that's a photo taken on the Earth, not on the Moon. The edges of the tracks are too rounded for the cohesive lunar dust. Also, a very quick check of all the surface photos on Apollos 15, 16 and 17 didn't show anything equivalent.
Here's a photo from Apollo 16 of a track - one of the best I could find in a quick search...
(http://www.hq.nasa.gov/alsj/a16/AS16-117-18843.jpg)
See how crisp the edges are.
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The first photo is from Sahara. Put the photo ID into google, and it pops right up
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Hoax believers seem to like that photo. I've seen it before as part of the body of evidence of a HB representing how they thought Rover tracks appear.
http://www.canstockphoto.com/mark-of-the-moon-rover-0672620.html (http://www.canstockphoto.com/mark-of-the-moon-rover-0672620.html)
anywho, why did you think that this was a NASA photo, or that it in any way represented the Lunar Rover? And if this is the quality of your research, why should we take your argument seriously?
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We'll look at the witness marks should we? It looks to me as though the wire mesh does not touch the ground at all except for maybe between the chevrons, of the two of us I certainly represented the tyres in a way that is supported by the evidence.
(http://comps.canstockphoto.com/can-stock-photo_csp0672620.jpg)
And it is pretty clear from your photo that the tires dug in and got a very good grip on the lunar regolith; hardly comparable to driving on ice.
Here's a photo of The Apollo 17 LRV being fitted to Jack Schmitt and Eugene Cernan before it is stowed on the LM seen in the background. Notice that there are supports under the frame so it will hold their weight in Earth gravity.
(http://i627.photobucket.com/albums/tt353/jarvisn/LRV17Fit_zpseca113b8.jpg)
Yes those supports are needed under the frame because it is such a delicate little flower that it can't even "hold their weight", yet on the moon those same masses can literally jump onto the rovers and then slam them into bumps all they want without any concerns.
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQY9vOpO8_1-fEUKCKTPlZClC1LuDN69aOK-soJspOOKXIY4577ig)
Were they delicate, or sturdy? Apparently both.
So delicate they can't be sat on, yet sturdy enough that they can be driven on bumpy uneven surfaces with confidence. The "with confidence" part is very important, on the moon any accident could result in death so they had to be confident that these vehicles, that could not even be sat on, would not fail over bumpy terrain.
Normally the opposite is true, you might be able to sit on and even ride a kids bike on a smooth surface for example, yet not ride it over a bumpy surface.
Whatever ye do don't question this paradigm shift lest ye be called a conspiracy nutter.
Apples and oranges. Or, more appropriately, apples and grapes.
No, the LRV cannot support a total of 800 lbs [363 kg] of astronauts and equipment in Earth gravity.
Yes, it can easily support a 67 lb [30 kg] astronaut jumping onto the seat in lunar gravity. Driven with confidence, yes. It did have a top speed of 20 kph, but according to the transcripts the more usual speed was 8 to 10 kph, not much faster than a brisk walk on Earth. They weren't slamming the thing around like a Baja Buggy - they were well aware of the danger.
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We'll look at the witness marks should we? It looks to me as though the wire mesh does not touch the ground at all except for maybe between the chevrons, of the two of us I certainly represented the tyres in a way that is supported by the evidence.
From the image source :
Tyre tracks imprinted in the Sahara desert sands - resemblance to lunar rover tracks
So your 'evidence' is tracks not made in lunar regolith; and that were not made by the lunar rover.
Good job.
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So your 'evidence' is tracks not made in lunar regolith; and that were not made by the lunar rover.
Good job.
PMSL
Typical "research" done by a typical hoax believer. Nice work Anywho...you must feel proud. ::)
A slight zoom in the picture and you can see loads of footprints made by ordinary boots.
(http://img.photobucket.com/albums/v239/Gadfium/Forum%20Uploads/Boot_zpsa5a3c20d.jpg)
http://www.canstockphoto.com/mark-of-the-moon-rover-0672620.html
What a howler! ;D ;D
No doubt this image will start cropping up on HB websites as proof of the "hoax". I can see the headlines now..."Whistle-blowers leave bootprints in faked Lunar image as proof of the hoax" ;D ;D ;D
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Hey, at least you guys got answered at all. Apparently, confessing my own engineering ignorance made me not worth answering.
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Hey, at least you guys got answered at all. Apparently, confessing my own engineering ignorance made me not worth answering.
Same here. I think he/she was fishing for a responder.
Problem is even in my non engineer/scientist doings in the world, I can see the problem with the argument. That does not bode well to take it further.
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To you guys 1/6g is only a small detail that has to be overcome because you see, and believe, the rovers hooning around with no traction problems and not even looking like rolling is a possibility, so driving in 1/6 is all just fun with one of you even mentioning the "dukes of hazard" yeehaa.
No, it's a small detail because I've computed the roll stability factors for the lunar rover and I'm satisfied it was safe to operate as we saw it operate.
All I see from you is a lot of childish handwaving. Compute the roll moments and rates and critical roll angle, showing your work, and then we'll talk. Otherwise I don't see your argument as anything more than desperate question-begging.
...and that is being generous because on the moon it is loose dirt).
No, it isn't loose dirt. Study chemical cementation and physical matrixing, then revisit your estaimate. Your qualitative assumption fails, therefore the quantities you estimated based on that also fail.
http://www.saltflats.com/traction.html
Interesting link. Look at my nick and guess where I race. You really don't know what you're talking about. Oddly enough we also get chemical cementation out at Bonneville. That's why I have to hose off my street car after I drive out to the speedway.
..when one astronaut is on board approx 3/4 of the weight is on one side of the vehicle, so yes, it is a very unbalanced vehicle especially for the moon where, once again, it is many times easier to roll a vehicle than on earth.
Compute the roll moment/rate or no dice. I'm an engineer. Show me your numbers or go home.
Traction on a loose surface on the moon will be similar to ice on earth
Disagree.
It is many times easier to roll a vehicle on the moon than the earth
Compute the roll moment/rate for a vehicle on Earth and the same vehicle, identically loaded, on the Moon. Show me the difference between the two numbers; don't just tell me your guesses for how they relate.
There are no groomed roads on the moon and the driving surface was at times very uneven...
I agree there are no groomed roads. I agree that the surface was "uneven," but you have failed to quantify the surface variation (or even intimate that you know how such factors are commonly described). You seem to expect that agreement here is a stipulation that the LRV was improbable. I do not so stipulate: if you claim the LRV cannot have handled the "uneven" terrain, then you have the burden of proof. Waving your hands is not proof.
A balanced vehicle has, by definition, the weight relatively well balanced, ergo, a vehicle with 3/4 the weight on one side is unbalanced.
I do not agree with this definition of balanced vehicle. I do not agree with the conclusion you've drawn. The science of vehicle stability is well-established and employs several models to help engineers reason about vehicle designs. Your ignorance of them and reluctance to employ any of them is not a substitute for proper knowledge. Your willingness to draw a conclusion without investigating proper reasoning suggests you are not interested in whether your claim is true.
On the moon where it is many times easier to roll a vehicle having a balanced vehicle would be significantly more important than on earth.
This is a complex question fallacy because you have included a premise in the proposition to which I do not agree. I agree that any vehicle must be appropriately engineered for its purpose. Proper engineering for a wheeled vehicle requires a proper quantification of stability relative to its intended operating environment. You have argued that the LRV is not engineered for its purpose. You have failed to demonstrate a working understanding of the environment and a working knowledge of engineering principles. You have not even attempted to make an engineering argument. While you allude to engineering factors, you cannot discuss them with any competency.
How would "common sense" suggest we respond to a proponent who simply demands we believe him without being able to give a proper reason?
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Hey, at least you guys got answered at all. Apparently, confessing my own engineering ignorance made me not worth answering.
In my observation, it is asking specifly for information from the HB that will get any of us ignored. While those who mix rebuttals and new information will grab their attention, whether or not they ask questions. Because the HBs are primarily arguing an emotional case, they get no real charge from being queried about thing they don't know.
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In my observation, it is asking specifly for information from the HB that will get any of us ignored. While those who mix rebuttals and new information will grab their attention, whether or not they ask questions. Because the HBs are primarily arguing an emotional case, they get no real charge from being queried about thing they don't know.
Yes, but my most recent question has been "what research have you done?" Surely he knows the answer to that!
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Wasn't this the same Sahara photo that tripped up Jack White & James Fetzer on the Education Forum? :D It sure looks familiar.
Perhaps the reason is that it's one of the top image results in Google for "lunar rover tracks", and the first that looks like a close-up. Kudos to the photographer for the joke. :)
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I remember seeing the picture before -- don't remember where -- and am ashamed at almost falling for it again.
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I remember someone on youtube posting a still (http://img5.imageshack.us/img5/4926/walking3d.jpg) that showed two astronauts that obviously wasn't from the television camera or the DAC, claiming it was a Hasselblad shot. Something about it looked familiar however and then I remembered where I'd seen it. It was from the IMAX film, Magnificent Desolation: Walking on the Moon 3D.
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Did the person who cited the Magnificent Desolation frame claim that it was faked? If so, that's actually a pretty good argument that even today Hollywood can't fake Apollo lunar pictures.
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Did the person who cited the Magnificent Desolation frame claim that it was faked? If so, that's actually a pretty good argument that even today Hollywood can't fake Apollo lunar pictures.
They claimed it was from Apollo, so by default they claimed it was fake, but they said knew it was fake because it showed both astronauts, not because of technical failures.
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Did the person who cited the Magnificent Desolation frame claim that it was faked? If so, that's actually a pretty good argument that even today Hollywood can't fake Apollo lunar pictures.
They claimed it was from Apollo, so by default they claimed it was fake, but they said knew it was fake because it showed both astronauts, not because of technical failures.
Yanno, it's probably just as well that Pete and Al lost their timer.
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They claimed it was from Apollo, so by default they claimed it was fake, but they said knew it was fake because it showed both astronauts, not because of technical failures.
Yanno, it's probably just as well that Pete and Al lost their timer.
No doubt. ;D
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Well, I'm waiting for poo!!
Sooner or later, the subject of poo is bound to come up.
1. How did astronauts do poos if they were a long distance away from the LM on an LRV jaunt when they were caught short?
2. Did the astronauts suffer from "sphincter impaction" from bouncing up and down on the LRV.?
3. If they did it in their suits, how would the dispose of it?
You know its only a matter of time before P1000 anywho starts asking about poo!
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It's actually somewhat interesting reading (http://lsda.jsc.nasa.gov/books/apollo/s6ch2.htm) if you want to know.
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Apples and oranges. Or, more appropriately, apples and grapes.
No, the LRV cannot support a total of 800 lbs [363 kg] of astronauts and equipment in Earth gravity.
Yes, it can easily support a 67 lb [30 kg] astronaut jumping onto the seat in lunar gravity. Driven with confidence, yes. It did have a top speed of 20 kph, but according to the transcripts the more usual speed was 8 to 10 kph, not much faster than a brisk walk on Earth. They weren't slamming the thing around like a Baja Buggy - they were well aware of the danger.
That 67lb astronaut jumping onto the seat in lunar gravity still has a 180kg (400lb) mass, and once something is moving it has momentum, and that momentum is determined by the mass and velocity, not weight.
It is a 180kg (400lb) mass free falling onto the seat (albeit slower than on earth) when the astronauts jump up and onto the rovers on the moon, not a 67lb weight.
Likewise, when they hit a bump that causes the chassis to change direction, it is the mass and velocity that will determine the forces on the vehicle, not the weight.
Perhaps the reason is that it's one of the top image results in Google for "lunar rover tracks", and the first that looks like a close-up.
Yep, my mistake.
I've computed the roll stability factors for the lunar rover
You have computed the "roll stability factors for the lunar rover" and yet you question the premise that it would be many times easier to roll on the moon?
Why do you ask for numbers when you have already done them, you should know that it either is or isn't "many times easier to roll on the moon".
By questioning the premise are you indirectly saying it isn't many times to roll a vehicle in 1/6g than it is on earth?
I'm an engineer.
You're an engineer who disputes the premise that the vehicles are unbalanced with 3/4 the weight on one side?
Why don't you ask a truck driver? They would roll their eyes at anyone who thinks you can have a weight similar to that of the vehicle itself, load it entirely on one side, and then call the vehicle balanced. Most would probably refuse to drive the vehicle until it was properly loaded no matter what any engineer says, and that is on earth.
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Why don't you ask a truck driver? They would roll their eyes at anyone who thinks you can have a weight similar to that of the vehicle itself, load it entirely on one side, and then call the vehicle balanced. Most would probably refuse to drive the vehicle until it was properly loaded no matter what any engineer says, and that is on earth.
What in the name of your deity does a truck on earth have to do with the LRV on the moon? Nothing as far as I can tell. Can you provide some numbers with your analysis please?
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That 67lb astronaut jumping onto the seat in lunar gravity still has a 180kg (400lb) mass, and once something is moving it has momentum, and that momentum is determined by the mass and velocity, not weight.
And what acceleration is causing that mass to move? Hint: I've bolded the answer above.
It is a 180kg (400lb) mass free falling onto the seat (albeit slower than on earth)
Which, by definition, means less momentum.
Likewise, when they hit a bump that causes the chassis to change direction, it is the mass and velocity that will determine the forces on the vehicle, not the weight.
Which means the lower lunar gravity will not make the rover more prone to roll over.
Why do you ask for numbers when you have already done them, you should know that it either is or isn't "many times easier to roll on the moon".
I'll re-phrase your question and pose it back to you. If you know that it is "many times easier to roll on the moon," does that mean you've done the necessary computations?
Why don't you ask a truck driver?
Are you a truck driver? If not, have you actually asked any truck drivers, or are you just assuming what they'd say and/or roll their eyes at?
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Why don't you ask a truck driver?
Are you a truck driver?
:o
It's déjà vu, all over again!
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No info yet. Quelle surprise!
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Apples and oranges. Or, more appropriately, apples and grapes.
No, the LRV cannot support a total of 800 lbs [363 kg] of astronauts and equipment in Earth gravity.
Yes, it can easily support a 67 lb [30 kg] astronaut jumping onto the seat in lunar gravity. Driven with confidence, yes. It did have a top speed of 20 kph, but according to the transcripts the more usual speed was 8 to 10 kph, not much faster than a brisk walk on Earth. They weren't slamming the thing around like a Baja Buggy - they were well aware of the danger.
That 67lb astronaut jumping onto the seat in lunar gravity still has a 180kg (400lb) mass, and once something is moving it has momentum, and that momentum is determined by the mass and velocity, not weight.
It is a 180kg (400lb) mass free falling onto the seat (albeit slower than on earth) when the astronauts jump up and onto the rovers on the moon, not a 67lb weight.
Likewise, when they hit a bump that causes the chassis to change direction, it is the mass and velocity that will determine the forces on the vehicle, not the weight.
Well, DataCable beat me to the response, so I'll not rehash what he said except to point out that the statements bolded in red are self-contradictory; you seem to be saying that "mass and velocity" are unrelated to "weight".
Look at it this way: the effect of a local gravity field is measured in units of acceleration; i.e., in calculations, gravity can be treated as acceleration. So in considering only vertical movement:
Velocity is determined by acceleration x time;
Weight is determined by mass x acceleration;
Momentum is determined by mass x velocity.
All standard definitions, right out of the book. If we then substitute the definition of velocity for velocity in the momentum definition, we can say that:
Momentum is determined by mass x acceleration x time.
But look at this! The section in blue is the definition of weight! So, substituting again, we find that:
Momentum is determined by weight x time.
How about that? Momentum in a vertical motion caused by gravity - an astronaut jumping up and coming down on the rover seat - is directly proportional to weight.
[One of you actual engineers please check my work - if I made a mistake please point it out and I'll gladly retract it.]
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That 67lb astronaut jumping onto the seat in lunar gravity still has a 180kg (400lb) mass, and once something is moving it has momentum, and that momentum is determined by the mass and velocity, not weight.
And you have already had it explained to you that the ability of a material or structure to withstand brief forces is different from its ability to withstand sustained force without deforming or failing. It is not remotely suspect to read that a vehicle could withstand the force of an astronaut jumping onto it but could not support the weight of a man for sustained periods in Earth's gravity.
You haven't deigned to supply us with the source of your initial comment about the rover's abilities, but in any case the comment says nothing about the rover failing immediately if it is sat on by an astronaut on Earth. That's your implication so you can spin a whole argument based on the unsupported notion that you can compare its ability to withstand the brief effects of a suited astronaut jumping into the seat on the Moon and its ability to support a suited astronaut for unspecified periods on Earth.
Likewise, when they hit a bump that causes the chassis to change direction, it is the mass and velocity that will determine the forces on the vehicle, not the weight.
And how have you accounted for how the structure of the vehicle absorbs that force? Hitting a bump will cause the wheel to deform, the suspension to respond and even the chassis to flex a little before it will cause the entire chassis to change direction. That's what those systems were for, after all. What force would be required to overcome all that designed-in flexibility and cause the entire vehicle chassis to shift direction?
You have computed the "roll stability factors for the lunar rover" and yet you question the premise that it would be many times easier to roll on the moon?
Why do you ask for numbers when you have already done them, you should know that it either is or isn't "many times easier to roll on the moon".
Let me tell you something about who you are talking to, anywho. I have been talking to Jay via forums like this for over ten years now. He has proven expertise, experience and credentials in the fields we are talking about here. If he tells me he has done the computations and disputes your assertions, I will accept his word because I know he can do those computations, and I know that if I ask him to he will, when he has the time, provide those computations and explanations to support his assertions. He has done so many times before. That is how you get your arguments taken seriously in discussions like this one.
You, on the other hand, despite repeated requests, have proved unwilling or unable to provide the numbers to back up your position. Jay does know the numbers. He is asking you for them not because he needs them himself but for the same reason we are: because you need to present them to prove to the people you are trying to persuade that you actually know the first thing about what you are arguing about.
By questioning the premise are you indirectly saying it isn't many times to roll a vehicle in 1/6g than it is on earth?
Show us the computations that show it is. So far your demonstrated knowledge of physics hasn't left the high school textbook level, and your application of it isn't even up to that standard. Unfortunately for your arguments, large portions of physics, when you get into detailed applications like the rolling of a vehicle in the lunar environment, go waaaaay beyond the level of physics understanding you have so far demonstrated. Prove us wrong and support your assertions with actual numbers and computations, and show they are appropriate. All you have so far is handwaving, appeals to intuitive reasoning (which often lets us down when we apply it because a lot of science and engineering is not intuitive: his is why we have specialists rather than just getting any old joe off the street to design our spacecraft), and invalid comparisons to other vehicles like mobility scooters.
I'm an engineer.
You're an engineer who disputes the premise that the vehicles are unbalanced with 3/4 the weight on one side?
No, he is disputing that it is significantly unbalanced and that this makes it very easy to roll.
However, he definitely is an engineer. What are you?
Why don't you ask a truck driver? They would roll their eyes at anyone who thinks you can have a weight similar to that of the vehicle itself, load it entirely on one side, and then call the vehicle balanced. Most would probably refuse to drive the vehicle until it was properly loaded no matter what any engineer says, and that is on earth.
And when you can show that comparing a single-function lunar vehicle to a truck on Earth is in any way valid we'll start taking you seriously.
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As I already explained, the velocity is affected because of the lower gravity. Therefore, the force on impact will be lower.
You can see this by thinking of the energy. When the astronaut drops onto the LRV, gravitational potential energy is converted to kinetic energy. Since the former is less, the latter must also be less.
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And you have already had it explained to you that the ability of a material or structure to withstand brief forces is different from its ability to withstand sustained force without deforming or failing. It is not remotely suspect to read that a vehicle could withstand the force of an astronaut jumping onto it but could not support the weight of a man for sustained periods in Earth's gravity.
It would be highly unusual, as I said earlier, normally you might expect to be able to sit on something like a kids bike, and even ride it on a smooth surface, but possibly not be able to ride it over bumpy terrain without it breaking.
What makes this claim even more unusual is that, unlike the kids bike, the rovers are engineered to be driven over bumps, yet we are told they cant be sat on. It's a complete paradigm shift where something is engineered for dynamic loading but not able to be sat on.
Added to that is that the astronauts are allowed to drive over the speed limit so there is enough redundancy to hit those bumps even harder, yet not enough to be even sat on?
Let me tell you something about who you are talking to, anywho. I have been talking to Jay via forums like this for over ten years now. He has proven expertise, experience and credentials in the fields we are talking about here. If he tells me he has done the computations and disputes your assertions, I will accept his word because I know he can do those computations, and I know that if I ask him to he will, when he has the time, provide those computations and explanations to support his assertions.
Let me tell you something about him, he hasn't disputed one of my assertions so far.
All he has done is ask for numbers in an attempt to infinitely complicate simple assertions, this is unfortunate because many here see his demands for numbers as disputing the assertion and perhaps leads people to think, incorrectly, that it is no easier to roll a vehicle on the moon than it is on earth.
As I already explained, the velocity is affected because of the lower gravity.
Yes, the velocity of falling from 6 inches onto the rovers will be slower on the moon than falling from 6 inches on earth, the velocity will be the equivalent to falling onto the rovers from 1 inch on earth.
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All he has done is ask for numbers in an attempt to infinitely complicate simple assertions, this is unfortunate because many here see his demands for numbers as disputing the assertion
No, we all see it as asking you to prove your assertions with your calculations. Simple as that.
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Why all this assuming the astronauts jumped into their seats anyway? They could barely move in their suits so how could they jump into their seats?
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It would be highly unusual,
Prove it. Don't just waffle on meaninglessly, support your assertions with numbers and sound engineering principles.
Added to that is that the astronauts are allowed to drive over the speed limit so there is enough redundancy to hit those bumps even harder, yet not enough to be even sat on?
The rover was designed to tolerate things at its maximum speed. Not at a speed limit: at the maximum speed it was capable of achieving regardless of what the astronauts try and get out of it. And once again you completely ignore the difference between a fleeting impact and a sustained load.
Let me tell you something about him, he hasn't disputed one of my assertions so far.
All he has done is ask for numbers in an attempt to infinitely complicate simple assertions,
No, he asks for numbers for the same reason we do: so you can demonstrate to us that you actually understand the engineering principles on which you are attempting to draw conclusions. Your assertions may be simple, but the engineering and the physics is not, no matter how much you assert that it is.
Engineering and science are done with numbers and computations. If you really had this argument so sewn up it was indisputable, you would be able to produce those computations and calculations and prove it beyond the point where engineers can argue with you over it. Your inability to do so speaks volumes, as does your assertion that Jay's request for numbers is just an attempt to obfuscate and confuse. Sorry, no. This is a science and engineering problem. No competent engineer would argue things the way you are.
leads people to think, incorrectly, that it is no easier to roll a vehicle on the moon than it is on earth.
Prove that it is incorrect. Don't just say it, prove it.
Yes, the velocity of falling from 6 inches onto the rovers will be slower on the moon than falling from 6 inches on earth, the velocity will be the equivalent to falling onto the rovers from 1 inch on earth.
And the effect of that is what? Numbers numbers numbers.
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...we are told they cant be sat on.
Please cite your source for this claim.
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normally you might expect to be able to sit on something like a kids bike, and even ride it on a smooth surface, but possibly not be able to ride it over bumpy terrain without it breaking.
And engineering and physics often throw up things that are unexpected to the layman, or even to the physicist who just doesn't happen to have all the relevant facts to hand.
I used to work behind a bar. One night I dropped a pint glass from a shelf above my head. It hit the floor and bounced around a little but remained completely intact. Another night I knocked a pint glass of exactly the same type from a work surface into a sink, and it shattered. Now, 'normally' would you expect a glass that broke after a fall of less than 8 inches into a steel sink to survive a fall of about seven feet onto a concrete floor? Surely that glass had more momentum when it hit the floor than the one falling into the sink did, right?
Unexpected results are how science progresses. The fact that most science does not conform to everyday expectations is why we have specialists rather than laymen doing certain jobs in those fields, and they have to study them for years before they are allowed to work in the field.
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Momentum is determined by weight x time.
How about that? Momentum in a vertical motion caused by gravity - an astronaut jumping up and coming down on the rover seat - is directly proportional to weight.
[One of you actual engineers please check my work - if I made a mistake please point it out and I'll gladly retract it.]
Not an actual engineer, but I feel qualified to go at least part way with this.
It all depends on what else you hold fixed. If we're talking about someone jumping up and then landing on something, how high do they jump? Just to simplify it, let's suppose they start off level with the thing they're landing on. If they are on the moon, but take off by applying the same amount of force for the same amount of time as they would on earth, then they're taking off with the same velocity, the same mass, and the same momentum. And they're coming down with the same momentum. Here, the lower weight is exactly offset by the greater amount of time spent falling - they're going to go higher in the moon's weaker gravity, take longer to get to the top of the jump, and take longer to fall back down. So you have a smaller weight, multiplied by a larger time, giving the same momentum.
If on the other hand, the astronaut on the moon jumps with less force for less time than he would on earth, then the smaller weight will be offset less by the time spent falling, or not at all, if the time spent falling is the same. For example, suppose that the astronaut shoots for a maximum height of 20 cm above the seat, on earth or on the moon. On earth, it will take two tenths of a second to fall from this maximum height onto the seat (ballpark). On the moon, it will take the square root of six times as long, or just under a half second. So you'd land on the seat with one-sixth the weight, after spending the square root of six times as long falling, so 1/sqrt(6) times as much momentum - about 41% as much.
For purposes of determining whether you're going to break something when you land on it, I'm not sure if we should use momentum or kinetic energy. But, mass is invariant to gravitational field, so if momentum is the same on the earth and the moon, then so is kinetic energy - if the astronaut takes off with a fixed momentum on the earth and on the moon (and therefore reaches a much higher height, taking much longer to do so, on the moon), then he comes down with the same momentum and the same kinetic energy in both places. If he jumps the same height above the seat before coming down, the momentum will be 1/sqrt(6) as much on the moon, and the kinetic energy will be 1/6 as much.
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You have computed the "roll stability factors for the lunar rover" and yet you question the premise that it would be many times easier to roll on the moon?
Yes, I dispute your claim. I have asked you to support it by showing the proper computations and engineering study.
Why do you ask for numbers when you have already done them, you should know that it either is or isn't "many times easier to roll on the moon".
Because I'm asking you to show your work. Either you have done the work necessary to support your claim or you have not. If you have, show it.
By questioning the premise are you indirectly saying it isn't many times to roll a vehicle in 1/6g than it is on earth?
Do not try to rewrite my disputation into some sort of affirmative claim. You have claimed the LRV is impossibly unstable. Show your work.
You're an engineer who disputes the premise that the vehicles are unbalanced with 3/4 the weight on one side?
I dispute your analysis of static weight distribution and your ad hoc formulation of "balance." Show me the math.
Why don't you ask a truck driver? They would roll their eyes at anyone who thinks you can have a weight similar to that of the vehicle itself, load it entirely on one side, and then call the vehicle balanced. Most would probably refuse to drive the vehicle until it was properly loaded no matter what any engineer says, and that is on earth.
Supposition and question-begging.
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Let me tell you something about him, he hasn't disputed one of my assertions so far.
Nonsense, I've disputed nearly all of them.
All he has done is ask for numbers in an attempt to infinitely complicate simple assertions...
No, I have asked you for proper engineering rigor in your claim. You are making engineering claims but you aren't doing any engineering. You're simply waving your hands and demanding that people believe your conclusions.
Calling your assertions "simple" does not prove they are correct. Oversimplifying a problem and then finding fault with a proposed solution because of it is a common layman's mistake.
You can either show your work or you can't. Clearly you can't, and clearly you somehow believe you don't have to. Hence I see no reason why rational people need to believe your outlying conclusions.
What would the proper "common sense" reaction be to a person who disputes the universal, informed belief of the entire engineering community, who offers only simplified arguments, who merely demands to be believed, and who is unwilling to show any depth or rigor? Would the common-sensical approach be to consider that this unknown person above all others is knowlegeable and qualified to dispute a widely-accepted fact? Or would the proper common-sensical reaction be to surmise that this person hasn't a clue what he's talking about and is therefore likely wrong?
Now perhaps you see the reason why rigor is required.
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For purposes of determining whether you're going to break something when you land on it, I'm not sure if we should use momentum or kinetic energy.
Generally kinetic energy determines fracture or deformation behavior.
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And engineering and physics often throw up things that are unexpected to the layman, or even to the physicist who just doesn't happen to have all the relevant facts to hand.
That's the point of science. Engineering is just applied science sold for money. We evolved science because intuition is often wrong. Science is a set of methods that systematically attempt to avoid improper assumptions and thus develop objective, dispassionate models that predict actual behavior. This is why showing your work is important. Simply stating a belief and demanding that others accept it as the likely truth is the antithesis of reason. We have to see the quantitative reason that leads to a quantitative conclusion so that we can tell whether it hides any assumptions or guesses that need to be investigated.
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For purposes of determining whether you're going to break something when you land on it, I'm not sure if we should use momentum or kinetic energy.
Generally kinetic energy determines fracture or deformation behavior.
In that case, the difference (in my example where a mass is dropped from a given height about the rover) between the earth and the moon would be larger, a ratio of 6 for kinetic energy, vs. the square root of 6 for momentum.
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What makes this claim even more unusual is that, unlike the kids bike, the rovers are engineered to be driven over bumps, yet we are told they cant be sat on. It's a complete paradigm shift where something is engineered for dynamic loading but not able to be sat on.
I keep having problems with resolving this unless you divvy up the goodies. I see the evidence behind the rovers that there is back them up. It is there, it is documented. I can find out a lot, except what you claim. There is nothing, what am I missing?
Anyway, main reason for this. How are the motor workings out coming on? You said they were not up to the job as well.
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Your assertions may be simple, but the engineering and the physics is not, no matter how much you assert that it is.
Indeed that's the classic layman's ploy -- "I must be correct because my line of reasoning is simple enough for me to understand." What matters is whether the line of reasoning accurately captures the important factors. Dumbing down a problem to where it fits within one's understanding is not a viable way to solve the problem, especially when you come up with a different answer than everyone else who has the appropriate understanding.
Engineering and science are done with numbers and computations.
More specifically, with the correct models. A correct model appropriately captures all the qualitative relationships as well as the quantitative effects. It is most often expressed in mathematical notation. "Roll moment" applies in airplanes. It also applies in wheeled vehicles. But a vastly different model applies in each case. If I want to compute a car's moment of inertia in the roll axis, I can certainly apply the airplane model to it because the car has a well-defined roll axis and a center of mass. However that moment of inertia would be inapplicable to the determination of roll stability in a car, while it is perfectly applicable to the roll behavior of an airplane.
It is important to get the concepts right. The concepts are embodied in the model, which then goes on to quantify the concepts toward a meaningful prediction. If you want to talk about wheeled vehicle stability in a roll, you need to be talking about TTR versus SSF and other qualitative relationships that imply further quantitative computations.
"Several times more likely to roll" is just a guess.
Sorry, no. This is a science and engineering problem. No competent engineer would argue things the way you are.
Indeed. Engineering in the real world is not just high school physics. It's certainly not handwaving. And you definitely must show your work. These days the engineer of record by law must stamp and sign not only his drawings, but also his computations. This is so his choice of model and his ability to work the implied computations is part of the public record of his work.
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Dumbing down a problem to where it fits within one's understanding is not a viable way to solve the problem, especially when you come up with a different answer than everyone else who has the appropriate understanding.
^Quote of the thread just there, folks.^
And it describes the majority of HB's thinking IMHO.
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And it describes the majority of HB's thinking IMHO.
I won't disagree, but do not find this mode of thinking confined to HBs. Maybe the percentages are different.
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Indeed. Engineering in the real world is not just high school physics. It's certainly not handwaving. And you definitely must show your work. These days the engineer of record by law must stamp and sign not only his drawings, but also his computations. This is so his choice of model and his ability to work the implied computations is part of the public record of his work.
And really, I'm not sure high school physics covers quite as much as gets thrown about here. Oh, my own high school physics class was not typical in any way; we did less than I think most people did in theirs, though for excellent reasons. However, I don't think my sister (whose experience was much more typical) learned all that much more than I did. Certainly I don't think she learned enough to do the requisite work to prove some of the HB assertions. Most of what we learned was completely irrelevant--the two things I specifically remember learning were lenses and circuits. You can't extrapolate from that to any of the issues under discussion here.
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Well someone is going to have run some numbers.
The LRV has a mass of about 200kg. Each astronaut had a similar mass. So the all-up mass should be about 600kg.
I'm not sure where the centre of mass would be. For the empty LRV, it's probably about the chassis, maybe a little above, so about 50cm. The astronaut sitting on top will raise that significantly, so I'm just going to go with 1m above the ground.
The wheel base is a little over 2m, so in order for the loading angle to be on the verge of tipping the vehicle over, it will need to be at least 45°.
So simple trig tells us that the lateral acceleration will be the same as the gravitational field at the point of tipping, which is 1.6m/s².
The LRV had a minimum turning radius of 3m. Since centripetal acceleration = v²/r, the speed required to achieve this acceleration is 2.2m/s or about 8km/h.
So in order to roll the vehicle, they would have had to be doing more than half the top speed of vehicle while in the tightest turn possible.
And that's assuming the wheels gripped the surface successfully in such a situation.
Is anyone amused by anywho trying to saying at the same time that the vehicle wouldn't have enough traction and that the vehicle would easily roll over? In order to roll over, you need traction or the vehicle will just slide.
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Momentum is determined by weight x time.
How about that? Momentum in a vertical motion caused by gravity - an astronaut jumping up and coming down on the rover seat - is directly proportional to weight.
[One of you actual engineers please check my work - if I made a mistake please point it out and I'll gladly retract it.]
Not an actual engineer, but I feel qualified to go at least part way with this.
It all depends on what else you hold fixed. If we're talking about someone jumping up and then landing on something, how high do they jump? Just to simplify it, let's suppose they start off level with the thing they're landing on. If they are on the moon, but take off by applying the same amount of force for the same amount of time as they would on earth, then they're taking off with the same velocity, the same mass, and the same momentum. And they're coming down with the same momentum. Here, the lower weight is exactly offset by the greater amount of time spent falling - they're going to go higher in the moon's weaker gravity, take longer to get to the top of the jump, and take longer to fall back down. So you have a smaller weight, multiplied by a larger time, giving the same momentum.
If on the other hand, the astronaut on the moon jumps with less force for less time than he would on earth, then the smaller weight will be offset less by the time spent falling, or not at all, if the time spent falling is the same. For example, suppose that the astronaut shoots for a maximum height of 20 cm above the seat, on earth or on the moon. On earth, it will take two tenths of a second to fall from this maximum height onto the seat (ballpark). On the moon, it will take the square root of six times as long, or just under a half second. So you'd land on the seat with one-sixth the weight, after spending the square root of six times as long falling, so 1/sqrt(6) times as much momentum - about 41% as much.
For purposes of determining whether you're going to break something when you land on it, I'm not sure if we should use momentum or kinetic energy. But, mass is invariant to gravitational field, so if momentum is the same on the earth and the moon, then so is kinetic energy - if the astronaut takes off with a fixed momentum on the earth and on the moon (and therefore reaches a much higher height, taking much longer to do so, on the moon), then he comes down with the same momentum and the same kinetic energy in both places. If he jumps the same height above the seat before coming down, the momentum will be 1/sqrt(6) as much on the moon, and the kinetic energy will be 1/6 as much.
Reading through that (without moving my lips; I was so proud*) I believe I agree with everything you say. The single - hopefully simple - point that I was trying to get across to Anywho is that he is insisting that "momentum" is unrelated to "weight", in the case of an object whose motion is a fall caused by gravity, the two are directly proportional
* That is not intended to be insulting in any way. My physics is so weak that I have to go slowly, with frequent backtracking.
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Why all this assuming the astronauts jumped into their seats anyway? They could barely move in their suits so how could they jump into their seats?
It's not an assumption. It was the usual technique.
From the Apollo 17 Lunar Surface Journal:
117:42:47 Cernan: Let's see if there is any life in this here baby. (Burps; Long Pause) Okay. Getting up and on.
[Gene is mounting the Rover, climbing into the left-hand seat. He will fasten his seatbelt, turn on the Rover power, and take a test drive.]
<snip for space>
[Gene's breathing can be heard as he climbs on the Rover and attaches his seat belt. His breathing can be heard primarily because he is leaning forward to get the belt. Getting on the Rover is a relatively simple matter of standing alongside and then jumping up and inward, aiming for the seat. A slight jump and a pull on the handhold does the trick.]
Here's a photo series of Jack Schmitt hopping in:
(http://i627.photobucket.com/albums/tt353/jarvisn/AS17-134-20452_zpsfa3aa88f.jpg)
(http://i627.photobucket.com/albums/tt353/jarvisn/AS17-134-20453_zpsfdd9b71c.jpg)
(http://i627.photobucket.com/albums/tt353/jarvisn/AS17-134-20454_zps4a958fd6.jpg)
I think the somewhat limited mobility is what engendered this technique. No bending or twisting was required, as it would have been in trying to get in in a more 'conventional' manner.
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...we are told they cant be sat on.
Please cite your source for this claim.
To be fair, he did cite a footnote to a NASA publication in his first post. However, I do think he stretched the meaning slightly from "the rovers could not support the astronauts on Earth" with "can support no more than their own weight on Earth". The astronauts in full gear would be very heavy in Earth gravity; they would weigh only 1/6 of that on the Moon, while the Rovers would still maintain their rated strength.
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I'll ask again, if this was fake, what were they driving?
Why didn't some contractor notice that 'Hey, that's not what we built!'
I already went over the special effects techniques as available at the time and, frankly, they weren't up to snuff.
Therefore. it would have to be a practical effect, something that could do all that the LRV could do, be unfolded from the quad in the side of LM and be driven around at the same speeds, (or even faster if you claim the slow-motion was how they allegedly simulated lunar gravity) but work on Earth, in Earth gravity, but look, even in close up, identical to the LRV.
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Anywho, you claim the rover could not be "sat on" in Earth gravity.
So where did they film it being driven by astronauts, if not on the Moon?
Your hand waving arguments are not even consistent.
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I'll ask again, if this was fake, what were they driving?
Why didn't some contractor notice that 'Hey, that's not what we built!'
I already went over the special effects techniques as available at the time and, frankly, they weren't up to snuff.
Therefore. it would have to be a practical effect, something that could do all that the LRV could do, be unfolded from the quad in the side of LM and be driven around at the same speeds, (or even faster if you claim the slow-motion was how they allegedly simulated lunar gravity) but work on Earth, in Earth gravity, but look, even in close up, identical to the LRV.
You've highlighted the fatal flaw in the HB argument- faking it successfully is actually much harder that just doing it!
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I'm not sure where the centre of mass would be. For the empty LRV, it's probably about the chassis, maybe a little above...
The unladen LRV had a c.g. 20.1 inches above the ground (3.1 inches above the bottom of the chassis). The wheelbase is 72 inches wide, for an unladen SSF of 1.79.
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Must--- resist--- Monty--- Python--- reference!
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Must--- resist--- Monty--- Python--- reference!
Do LRV's migrate? ;)
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Anywho, you claim the rover could not be "sat on" in Earth gravity.
So where did they film it being driven by astronauts, if not on the Moon?
Your hand waving arguments are not even consistent.
Mars has just a bit over 1/3 earth gravity.
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You have computed the "roll stability factors for the lunar rover" and yet you question the premise that it would be many times easier to roll on the moon?
Yes, I dispute your claim.
Seriously? As an engineer who has done research into this area you dispute that claim?
This is quite unbelievable.
So if the rollover threshold for a car is 1g on earth it is not 1/6g on the moon?
If hitting a bump on one side causes the vehicle to rotate on it's axis will it not basically be gravity that stops that rotation? In space it will theoretically rotate forever, on earth 1g gravity will stop the rotation, and on the moon 1/6g will act against the rotation?.
On the moon if you hit a bump on one side will that side not rise up higher, and for longer, allowing for more rotation?
So simple trig tells us that the lateral acceleration will be the same as the gravitational field at the point of tipping, which is 1.6m/s².
So basically 1/6th lateral acceleration is needed to roll a vehicle on the moon as on earth, can we move on from disputing that it is many times easier to roll a vehicle on the moon than it is on earth? (this comment, although posted after quoting you, is not directed at you, Glom)
Is anyone amused by anywho trying to saying at the same time that the vehicle wouldn't have enough traction and that the vehicle would easily roll over? In order to roll over, you need traction or the vehicle will just slide.
Oh, I don't dispute that on a perfectly smooth surface with very low traction it would be nigh on impossible to roll a car, but the moon is not a perfectly smooth surface. At times it was a very uneven surface they were driving on, and in this situation very low traction is more dangerous for rolling because you are more likely to end up sideways, therefore increasing the chances of a tripped rollover, which is by far the most common cause of rollovers.
Even if you don't slide sideways, just hitting bumps and dips will toss the unbalanced vehicle around a lot more than on earth.
I know I would not drive such an unbalanced vehicle (3/4 the weight on one side) over such an uneven surface at 10 or 15kph here on earth, let alone the moon where the low traction and low gravity both work against you making it many times easier to roll.
To be fair, he did cite a footnote to a NASA publication in his first post. However, I do think he stretched the meaning slightly from "the rovers could not support the astronauts on Earth" with "can support no more than their own weight on Earth".
To be even more fair, the comment "can support no more than their own weight on Earth" is not from me but is a quote from a NASA document for which I supplied a reference.
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Seriously? As an engineer who has done research into this area you dispute that claim?
This is quite unbelievable.
Yes, it is unbelievable that the assertion of a trained engineer who has done research into the field won't cause you to change your mind. Won't even make you think that the issue isn't as cut-and-dried as you think it is. However, we're used to that. If you really wanted to impress people, you'd think for a while about what it means about your assumptions, you'd recognize your ignorance (or else show your work), and you'd apologize for your attitude. Somehow, I don't think this is what you're going to do.
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Must--- resist--- Monty--- Python--- reference!
Do LRV's migrate? ;)
Yes, but only once.
(I'm assuming here they didn't pack the thing up and bring it back with them.)
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Must--- resist--- Monty--- Python--- reference!
Do LRV's migrate? ;)
Yes, but only once.
(I'm assuming here they didn't pack the thing up and bring it back with them.)
No, they left it there so the TV-camera could film the liftoff from the moon. And it couldn't fit through the hatch anyway.
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The moon's a good neighbourhood. You can leave your car out and not have to worry about it being stolen.
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The moon's a good neighbourhood. You can leave your car out and not have to worry about it being stolen.
There was a photoshop of the rover up on bricks. Probably still on the net if you look for it. Quite funny.
Anyway, anywho. I am still having issues with your claim. Using your methodology I can see how an astronaut can hit/land/jump/handstand whatever into the rover. My intuition, using the same as you here, and I have no maths to back me up, same as you, says there will be a tipping point but it will take a wallop before it goes. That point is the bit I fail to see from your claim, I think it will be OK. Using your methods here don't forget. I am not an engineer. Don't mind being proven wrong and shown why I am wrong.
So, for example I know tyres comes in different flavours. They are usually round and black but dig deeper and there is a lot to them. The composition of the tyre has an effect. The side wall stiffness, tread pattern profile, wheel diameter and width and so on. All this will alter your family cars handling, ride quality, MPG, same car you are using for a comparison I think. And that is before you get to suspension. What points are attached, how, what dampers, spring rates and so on, this is the same as your generic family car that you are using. The Moose test showed what happens when you get it wrong. So we do not have a ridged welded and bolted solid structure as far as we can see and this will have a bit of give a stability. Enough for the moon. Using your methodology here.
Now comes the fun part. I take your family car that flips over if you look at it funny, and modify it a tad, I can make it do things the maker never envisaged. That includes not falling over at the slightest gust. So I have the same frame/chassis/shell/sub frames whatever and it is more stable. Rally and race teams do this all the time.
Give the car designers a big cheque and say we want this in silver, open top, oh, and it needs to run on the moon, I expect there to be a solution that is not beyond the bounds of credibility. Looking at the solution, as a lay person, it looks the biz for not falling over. The evidence behind it is there and your claim makes an assumption that I cannot see ever being done. That is filming on Earth.
By the way. You have the info on why the motors could not do it yet?
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The moon's a good neighbourhood. You can leave your car out and not have to worry about it being stolen.
There was a photoshop of the rover up on bricks. Probably still on the net if you look for it. Quite funny.
I'll have a look.
Of course, if you have to call for a tow, it's going to take a while, and be really expensive :(
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Seriously? As an engineer who has done research into this area you dispute that claim?
This is quite unbelievable.
Much engineering and science is to those who haven't spent years of their life studying it. Jay has. What have you done?
On the moon if you hit a bump on one side will that side not rise up higher, and for longer, allowing for more rotation?
Again you offer comparison with no baseline.
What force is required by an impact on the front tyre to tip the vehicle to such an angle that it will roll, taking into account the effect of the vehicle's maximum possible speed, the deformation of the tyre that will be the first effect of any impact on the wheel, and the suspension system? You maintain it is easier to roll the rover on the Moon than on Earth. Have you done anything to show that it is even possible to roll a rover on Earth, given its characteristics? As I said before, it would be considered 'easier' for me to lift a ten ton truck on the Moon than on Earth, but that doesn't translate into making it any more possible for me to lift that truck on the Moon than on Earth.
I know I would not drive such an unbalanced vehicle (3/4 the weight on one side) over such an uneven surface at 10 or 15kph here on earth, let alone the moon where the low traction and low gravity both work against you making it many times easier to roll.
What you would or would not do is irrelevant. 'On one side' is meaningless. Where is the weight in relation to the pivot point? What angle do you have to tip the vehicle to in order for it to roll? How could that be achieved? Where are your numbers?
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The moon's a good neighbourhood. You can leave your car out and not have to worry about it being stolen.
There was a photoshop of the rover up on bricks. Probably still on the net if you look for it. Quite funny.
I'll have a look.
Of course, if you have to call for a tow, it's going to take a while, and be really expensive :(
Quick search and I cannot find it, but it was on a forum with a suggestion that certain elements in society had made it to the moon. Not sure if it was that persons work or linked from the web.
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There was a photoshop of the rover up on bricks. Probably still on the net if you look for it. Quite funny.
I'll have a look.
Of course, if you have to call for a tow, it's going to take a while, and be really expensive :(
Indeed it was, even if you're only make it around the moon (http://img708.imageshack.us/img708/3138/towingfee.gif).
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There was a photoshop of the rover up on bricks. Probably still on the net if you look for it. Quite funny.
I'll have a look.
Of course, if you have to call for a tow, it's going to take a while, and be really expensive :(
Indeed it was, even if you're only make it around the moon (http://img708.imageshack.us/img708/3138/towingfee.gif).
It's a bit hard to read, but is this for Apollo 13?
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It's the best copy I can find at the moment, but, yes, this is for Apollo 13.
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It's the best copy I can find at the moment, but, yes, this is for Apollo 13.
Did they collect?
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It's the best copy I can find at the moment, but, yes, this is for Apollo 13.
Did they collect?
Sources say no. North American Aviation apparently refused because they didn't charge Grumman for ferrying the LM to the moon on Apollo 10, 11, and 12.
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Sources say no. North American Aviation apparently refused because they didn't charge Grumman for ferrying the LM to the moon on Apollo 10, 11, and 12.
Yes, if the rate is fixed per km then NAA would be way ahead.
Of course, NAA's component was a lot bigger, so maybe there should be some surcharge for that.
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So if the rollover threshold for a car is 1g on earth it is not 1/6g on the moon?
Please explain how to calculate "rollover threshold."
On the moon if you hit a bump on one side will that side not rise up higher, and for longer, allowing for more rotation?
How much roll rotation is required for an LRV with only 1 driver to pass its tipping point? Calculate this for roll in both directions.
I know I would not drive such an unbalanced vehicle (3/4 the weight on one side)
Please calculate the center of mass of an LRV with only one driver.
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To amuse myself, I had a go at solving this particular problem of overturning the rover.
First, we need to decide how to quantify "how difficult" it is to overturn the rover, whether here or on the Moon.
One way is as described above - will a sharp turn at maximum speed impart enough torque to lift the wheels?
If the centre of gravity is located a distance y (vertical) and x(horizontal) from the inner wheel, and the turning radius is R, the vehicle will lift from the ground if v2/R * y > g * x. This should be simple to evaluate using no more than high-school math. Now, even if you get the outer wheels to lift, it would be very simple for the astronauts to correct - just turn the wheel the other way and the rover rights itself. Someone with more patience than me can calculate for how long you need to go at max speed and turn rate to flip the rover completely given the various scenarios. However, it's easy to see that the necessary speed to overturn is proportional to the square root of the gravity, so that it takes roughly 2.5 times as much speed to flip the rover on the Earth as on the Moon.
The other way has to do with hitting bumps on the surface - rocks etc. It would be difficult to model exactly how the force impacts the rover, but we can simplify by thinking in terms of stunts. One method often used in stunt filming is using ramps, so that a certain horizontal speed will impart a corresponding vertical speed. This means that on both Earth and the Moon, the same initial motion can be used - gravity does not impact this.[1]
To model exactly how the rover behaves here is unfortunately very difficult - the rover can be seen as a pendulum pivoting around the pair of wheels on the ground, but you quickly find yourself having to solve a nonlinear differential equation. However, we can sidestep this completely by simply asking ourselves how much rotational kinetic energy the rover needs to obtain an angle of 45° (at which points the wheels would start to crumple from the sideways load - the actual overturn angle is higher)
This turns out to be very simple. Rotational kinetic energy is simply Er = 1/2 I w2, and since the angular velocity is proportional to the horizontal speed when we hit the ramp, Er = 1/2 I C2 v2, where C depends on the exact geometry of the situation.
To find the moment of inertia, it needs to transposed to the axis we are using from the usual centre-of-gravity oriented one, so using the x and y from before and taking the angle b = atan(y/x), and radius r = sqrt(x2 + y2), Iwheel = ICoG + m * r2
For potential energy, we need the difference between the initial state with both wheels on the ground and the one with the wheels at 45 degrees angle: Ep = m * g * (r sin (b + 45°) - y) [2]
Summing up, the rover will crumple or flip if Er > Ep, or 1/2 I C2 v2 > m * g * (r sin (b + 45°) - y)
Now, there are a lot of factors in all this, but we're interested in comparative scenarios. Everything except g is the same, so again, the necessary velocity is proportional to the square root of the gravity, or 2.5 times more difficult on the Earth as on the Moon.
[1] In reality, the suspension would take up much of the impact, and on the Earth the springs would be compressed more by the gravity load, meaning they're more likely to behave nonlinearly. In other words, on the Earth the same bump would impart a greater force on the rover, but the difference is too small to matter in this equation.
[2] By definition, y = r sin b
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So if the rollover threshold for a car is 1g on earth it is not 1/6g on the moon?
Please explain how to calculate "rollover threshold."
On the moon if you hit a bump on one side will that side not rise up higher, and for longer, allowing for more rotation?
How much roll rotation is required for an LRV with only 1 driver to pass its tipping point? Calculate this for roll in both directions.
I know I would not drive such an unbalanced vehicle (3/4 the weight on one side)
Please calculate the center of mass of an LRV with only one driver.
I'm not sure anywho understands *why* it's necessary to do these calculations, when it's so easy to say, "let's assume it's 3-4 times as much as on Earth," with absolutely no reason to make that assumption.
S/he is also assuming that the drivers would not, for example, change speed when travelling over rougher terrain. In fact, I get the feeling s/he assumes they were going at the same general speed as a typical off-road racer.
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Seriously? As an engineer who has done research into this area you dispute that claim?
This is quite unbelievable.
Yes, I'm an engineer. Yes, I've studied this particular problem. Yes, I dispute the claim that the LRV as designed would have had insufficient roll stability to be used as depicted (i.e., and therefore fake).
Your disbelief is irrelevant. You have drawn an engineering conclusion but you have failed to present an engineering case or rationale. I'm not sure how much longer you intend to bluff your way along. I have asked you to present your case with appropriate rigor. I have hinted to you at how that may be done. I've computed one of the critical stability factors for you. At this point I can only conclude that you have absolutely no interest in actually studying the matter or discovering the truth.
Arguments that the LRV may be less stable that some other vehicle are irrelevant. Arguments that the Moon's lesser gravity necessarily creates unacceptable instability, regardless of a quantitative treatment, beg the question.
I have given you ample opportunity to demonstrate that you know what you're talking about. While you can allude to some of the physical properties that pertain, your knowledge of them is scant and your competence with the entire problem of vehicle stability is negligible. Hence I reject your conclusion.
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Must--- resist--- Monty--- Python--- reference!
Why? That's pretty much what I was thinking the whole time.
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Must--- resist--- Monty--- Python--- reference!
Why? That's pretty much what I was thinking the whole time.
I was trying out a new word I learned: apophasis.
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[1] In reality, the suspension would take up much of the impact, ...
Also in reality the suspension has to be accounted for in the canonical rollover (tripped or untripped) above. Hence meaningful models are based on empirical measurements of a candidate vehicle's configuration when tilted statically to its critical roll angle. Empirical testing always incorporates a tripping mechanism. That compresses the suspension appropriately, and the force and angle measurements are taken from there.
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Seriously? As an engineer who has done research into this area you dispute that claim?
This is quite unbelievable.
So if the rollover threshold for a car is 1g on earth it is not 1/6g on the moon?
If hitting a bump on one side causes the vehicle to rotate on it's axis will it not basically be gravity that stops that rotation? In space it will theoretically rotate forever, on earth 1g gravity will stop the rotation, and on the moon 1/6g will act against the rotation?.
On the moon if you hit a bump on one side will that side not rise up higher, and for longer, allowing for more rotation?
Lets be clear about this discussion.
None of this has anything to do with the actual vehicle under discussion. Your reasoning by analogy is unproductive and irrelevant when we have the design of the vehicle in question(the LRV), information on the environment in which it operated and actual video of its operation in that environment. Your failure to analyze the actual vehicle negates the validity of your opinion as to how it operates. Your assertions are unfounded and your arguments from those assertions are therefore meaningless.
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To amuse myself, I had a go at solving this particular problem of overturning the rover.
... it's easy to see that the necessary speed to overturn is proportional to the square root of the gravity, so that it takes roughly 2.5 times as much speed to flip the rover on the Earth as on the Moon.
I looked up how fast you have to be going to roll in a "tripped rollover", most cars and 4wds have a sideways rollover speed at between 5 and 6mph, which on the moon would mean a little over 2mph.
The rover has a wider wheel base but a higher COG so it will fit somewhere into the 5 to 6mph.
vehicle SSF Track
(ft)
Track/2
(ft)
Center of
Gravity (ft)
Sideways Rollover
Speed (mph)
Honda Passport 1.06 4.48 2.24 2.35 5.01
Jeep Grand
Cherokee 1.07 4.46 2.23 2.32 5.05
Jeep Cherokee 1.08 4.33 2.17 2.24 5.14
Chevrolet Suburban 1.08 4.96 2.48 2.53 4.88
Chevrolet Blazer
2WD
1.09 4.06 2.03 2.09 5.27
Chevrolet Blazer
4WD 1.09 4.08 2.04 2.14 5.26
Nissan Pathfinder 1.10 4.56 2.28 2.30 5.13
Chevrolet Astro van 1.12 4.93 2.46 2.42 5.06
Chevrolet S-10
pickup 1.14 4.04 2.02 1.99 5.42
Mazda MPV van 1.17 4.57 2.28 2.17 5.36
Honda CR-V SUV 1.19 4.53 2.27 2.11 5.43
Jeep Wrangler 1.20 4.33 2.17 2.01 5.51
Dodge Caravan van 1.23 4.79 2.40 2.15 5.47
Toyoto Tacoma
pickup 1.26 4.27 2.13 1.89 5.67
Saturn SL sedan 1.35 4.20 2.10 1.74 5.86
Toyoto Corolla
sedan
1.36 4.28 2.14 1.76 5.87
Nissan Sentra sedan 1.40 4.33 2.16 1.72 5.94
Honda Civic sedan 1.43 4.33 2.16 1.69 5.99
Dodge/Plymouth
Neon 1.44 4.33 2.16 1.68 6.01
Nissan Maxima
sedan 1.44 4.48 2.24 1.73 5.99
Toyota Camry sedan 1.46 4.54 2.27 1.73 6.02
Honda Accord sedan 1.47 4.57 2.28 1.72 6.04
Chevrolet Camaro 1.50 4.55 2.28 1.68 6.09
Stupid computer, the last figure is the sideways rollover speed (mph)
http://www.accidentreconstruction.com/research/suv/rollovers%5B1%5D.pdf
So they went 8 to 10mph over a sometimes very uneven surface with a very low coefficient of traction. If they end up sideways which will be very easy given the low traction and the uneven surface, and if they hit a trip hazard like an embedded rock, crater wall, or mound, then they will possibly roll at as little as 2 1/2mph.
And that is with the rover nicely balanced with two astronauts on board.
No roll cage is deemed necessary, no upper body harnesses, no worries.
It might be time to wake up and smell the coffee.
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Anywho, you claim the rover could not be "sat on" in Earth gravity.
So where did they film it being driven by astronauts, if not on the Moon?
Your hand waving arguments are not even consistent.
It might be time to answer this question.
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I looked up how fast you have to be going to roll in a "tripped rollover", most cars and 4wds have a sideways rollover speed at between 5 and 6mph, which on the moon would mean a little over 2mph.
Which is why cars are rolling over all across the streets and highways.
Heck, I rarely drive at under 6 MPH, even in a parking lot. I have driven a bit less than 20 times that -- and on just a two-lane blacktop.
Could it be that most people -- and that includes astronauts -- figured out somewhere around their first bicycle that it was a bad idea to turn the wheel hard over at speed?
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Now, I know you were hoping to lose the connections in the forest of uneeded detail, but your scenario requires the LRV -- a vehicle with a top speed of 15 MPH, typically driven at half that -- to be traveling SIDEWAYS at 2.5 MPH or more. On a regular basis! Perhaps you will show me the clip some time of the Apollo 16 astronauts pulling a bootlegger reverse in order to escape from pursuing Selenites...
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Which is why cars are rolling over all across the streets and highways.
Yes, but when they have those concrete barriers on the side of the road, then they just bounce right back and continue on.
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Perhaps you will show me the clip some time of the Apollo 16 astronauts pulling a bootlegger reverse in order to escape from pursuing Selenites...
I wouldn't be surprised if I could find some low-budget film with just that :)
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Note that the calculation of the LRV's SSF that Jay provided is a good margin higher than any of the Earth vehicles.
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I was gonna say, "Thrilling LRV chase scene" is not a phrase you will ever encounter. But then I remembered "Space Mutiny."
Slab Bulkmeat -- only hero who could roll a floor buffer...
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So they went 8 to 10mph over a sometimes very uneven surface with a very low coefficient of traction.
10 mph was the maximum speed. They rarely got that high.
If they end up sideways
And how will they end up sideways?
Here's a suggestion: work out how many scenarios cause cars here on Earth to end up traveling sideways, then work out how many of those could possibly transpire on the Moon.
which will be very easy given the low traction
Since it is the traction between the wheels and the road that causes a car on Earth to turn enough to travel sideways from a forward direction of travel, your statement is contradictory. The low traction would make it less likely that any sudden turn of the steering would translate to a 90 degree turn in the rover's attitude.
No roll cage is deemed necessary, no upper body harnesses, no worries.
It might be time to wake up and smell the coffee.
It might be time for you to stop pretending to be an engineer by pulling some numbers from Google.
It might also be time to answer the other questions that have been put to you, such as what research you have done and what exactly you propose was done if not what the Apollo record appears to show.
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So they went 8 to 10mph over a sometimes very uneven surface with a very low coefficient of traction. If they end up sideways which will be very easy given the low traction and the uneven surface, and if they hit a trip hazard like an embedded rock, crater wall, or mound, then they will possibly roll at as little as 2 1/2mph.
And that is with the rover nicely balanced with two astronauts on board.
No roll cage is deemed necessary, no upper body harnesses, no worries.
It might be time to wake up and smell the coffee.
Whilst the moose test is not quite a trip over test, I would think it shows that there is more to this than meets the eye. Interesting to see what they can do.
How is the proof that the motors could not cope coming on? Been 17 pages and might have missed it.
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Which is why cars are rolling over all across the streets and highways.
Heck, I rarely drive at under 6 MPH, even in a parking lot. I have driven a bit less than 20 times that -- and on just a two-lane blacktop.
Your parking lot is not a very uneven surface with extremely low traction, nor are the streets and highways.
Now, I know you were hoping to lose the connections in the forest of uneeded detail, but your scenario requires the LRV -- a vehicle with a top speed of 15 MPH, typically driven at half that -- to be traveling SIDEWAYS at 2.5 MPH or more. On a regular basis!
Why on a regular basis? It only has to happen once to roll the vehicle therefore it only has to be a possibility before a rollcage and harness are needed.
And, on an uneven surface with an extremely low coefficient of traction it is not exactly an unforeseeable possibility, more likely a highly probable event.
Note that the calculation of the LRV's SSF that Jay provided is a good margin higher than any of the Earth vehicles.
Not with two astronauts sitting up high and weighing 800lbs, especially when the vehicle only weighs 460lbs.
And how will they end up sideways?
Here's a suggestion: work out how many scenarios cause cars here on Earth to end up traveling sideways, then work out how many of those could possibly transpire on the Moon.
One scenario is gong off road onto uneven terrain in slippery conditions, then it is very easy to end up sideways. If you are ever in that scenario you would be well advised to crawl along, even here on earth.
Can we all agree that scenario is very likely to happen on the moon? Or do you guys just want to relate your experiences in parking lots to the moon.
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One scenario is gong off road onto uneven terrain in slippery conditions,
How slippery is the lunar surface?
The surface of the Moon is uneven and covered in regolith, but the regolith is quite cohesive. The rover wheels also can dig into it quite a bit. How does that affect the momentum of the rover as it moves sideways?
Can we all agree that scenario is very likely to happen on the moon?
No, we can't. It is your burden to prove that.
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It only has to happen once to roll the vehicle therefore it only has to be a possibility before a rollcage and harness are needed.
Wrong. It has to exceed a certain level of probability, with an appropriate level of severity of consequence, before the extra engineering complexity and weight are considered necessary over, say, training the astronauts for months on how to drive the rover without slipping sideways on uneven, loose terrain. Guess which they favoured.
There is a chance while driving along a motorway I might get my small two-seater car hit head on by an oncoming articulated truck, both of us going at 70 mph. Or I might get hit by a train driving over a crossing (as has just recently been in the news here in the UK). By your logic, since that only has to happen once before safetey measures are 'needed', my little car should be engineered to survive that. It won't. In both cases it will be wrecked and I will be very probably not only dead but in several pieces.
Why isn't my car engineered to survive those impacts and protect me? Because the designers reckoned that the probability was low enough that it didn't need to be designed for in favour of teaching people how to drive safely and reduce the risk of such events occurring.
But we'll just add risk assessment to the list of things you know nothing about.
And, on an uneven surface with an extremely low coefficient of traction
Numbers for this?
it is not exactly an unforeseeable possibility, more likely a highly probable event.
Probability is another thing that works with numbers. Where are yours?
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Can we all agree that scenario is very likely to happen on the moon? Or do you guys just want to relate your experiences in parking lots to the moon.
Bold mine.
Eh?
For my part I compare what I know about earth bound cars with your claims on earth bound cars to show you do not have all the info and perhaps getting it wrong. This is the info you are using to compare to the rover.
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You know, anywho, instead of guessing about the LRV's characteristics you could actually read all about them:
http://www.lpi.usra.edu/lunar/documents/NTRS/collection2/NASA_TM_X_66816.pdf
A look at Fig 2-8, showing how the wheels deflected with load, just might give you a clue as to why the flight units could not support the astronauts' weight on earth.
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[Snip long list of irrelevant information]
So they went 8 to 10mph over a sometimes very uneven surface with a very low coefficient of traction. If they end up sideways which will be very easy given the low traction and the uneven surface, and if they hit a trip hazard like an embedded rock, crater wall, or mound, then they will possibly roll at as little as 2 1/2mph.
And that is with the rover nicely balanced with two astronauts on board.
No roll cage is deemed necessary, no upper body harnesses, no worries.
It might be time to wake up and smell the coffee.
I wound up going sideways at about 40-50 MPH one time when my back end lost traction in a curve. The car went into a field with no hint of a roll over. It naturally preferred to roll on the tires than slide so it eventually came to be pointing backwards before it stopped.
Once again, your reasoning by analogy fails you. A long list of analogies is no better than one example if they are all irrelevant. The only thing that matters is the LRV operated on the lunar surface, You must address that particular vehicle if you want to make your point. If not you are just another in a line of one trick HBs.
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Anywho, if the rover was faked, what is going on in all that TV footage with a rover in it?
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Anywho, if the rover was faked, what is going on in all that TV footage with a rover in it?
Faked using a specially-weighted rover. What else could the Saturn V launch have been for, if the official mission was a hoax?
And to revive an earlier question that anywho keeps avoiding...anywho, do you have a demonstration that the rover couldn't withstand the impact of an astronaut hopping into the seat yet?
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I looked up how fast you have to be going to roll in a "tripped rollover", most cars and 4wds...
And if cars and SUVs were anything like the lunar rover, that comparison would mean something.
The rover has a wider wheel base but a higher COG so it will fit somewhere into the 5 to 6mph.
Try again.
It might be time to wake up and smell the coffee.
It might be time to get an engineering degree. Handwaving argument by irrelevant analogy is growing tedious.
The most road-gripping car in your study had an SSF of only 1.5. It happens to be a car I've driven and can't say much good about its gushy suspension, but on my favorite canyon drive it happens to hold the road reasonably well through some pretty nasty hairpins. What was the SSF of the LRV again? Can you compute it? Did you compute it? Since there is a roughly linear relationship between SSF and tripped rollover speed, please continue the analysis.
It appears you still can't decide whether the LRV would skid or trip. If you believe it will trip, then your adhesion argument is bunk. (BTW there is a very lengthy engineering analysis available on the LRV's tire-soil interface, complete with 1/6 g empirical tests.) If it won't trip, then your rollover speed argument lacks foundation.
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Your parking lot is not a very uneven surface with extremely low traction, nor are the streets and highways.
You were asked to quantify these. You have not. I conclude that you are unable to (or at least unwilling to) and are thus willfully drawing conclusions in the absence of evidence.
Why on a regular basis? It only has to happen once to roll the vehicle therefore it only has to be a possibility before a rollcage and harness are needed.
That is you imposing your personal rationale on NASA and its contract engineers. No one is bound to accept your advice.
Not with two astronauts sitting up high and weighing 800lbs, especially when the vehicle only weighs 460lbs.
If you believe the unladen SSF is unacceptable for your argument, then compute a new c.g. and a new SSF and show your work. I do not accept handwaving or "guesses" for where some other c.g. might lie. You have belatedly discovered one of the four common models used to discuss rollover mechanics in automotive design. However you don't get to simply guess what values to apply it to, or suppose that they will work out in your favor. That's not rigor. And it's certainly not engineering.
And since you are so late to this party, comments such as "wake up and smell the coffee" are inappropriate. A more appropriate comment would be, "I see I have not yet done the proper study to support my conclusions. Therefore I withdraw them until such time as I can investigate them." Your approach is more consistent with a died-in-the-wool conspiracy theorist who arrived at his belief first, and is now play-acting at engineering in the firm hope that his pre-existing belief will be vindicated. Since it is very much You vs. The Entire Engineering Profession, a little humility would be in order.
Here's a suggestion: work out how many scenarios cause cars here on Earth to end up traveling sideways, then work out how many of those could possibly transpire on the Moon.
Here's a suggestion: do your own homework and some real engineering. This is your argument, so you come up with the scenarios, the rationales, the operational requirements, the models, and the computations. For the past dozen or so pages your argument has been based on the notion that driving the LRV on the Moon ought to embody the same requirements as driving an SUV on Earth. In case it's not obvious, no one accepts that premise and they've given you good reasons for not accepting it.
Can we all agree that scenario is very likely to happen on the moon?
No. Do not beg the question. You are the one whose opinion differs from the entire engineering community. Therefore if you're going to mount that type of arrogant challenge, you get to take nothing for granted. Please provide the information we have asked for and show your work.
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A little hint, Anywho. No, we can't all agree to whatever claims you're making. Or at any rate, you have to show that they're something we should agree with if they contradict the established historical record.
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Which is why cars are rolling over all across the streets and highways.
Heck, I rarely drive at under 6 MPH, even in a parking lot. I have driven a bit less than 20 times that -- and on just a two-lane blacktop.
Your parking lot is not a very uneven surface with extremely low traction, nor are the streets and highways.
I've driven fire trails. Parked on dirt and gravel, including when it was rutted and soaked with rain. I've driven down from Tahoe without snow chains (THAT was fun!) I used to drive my old micro-pickup out of the parking lot, down a walking trail, across the grass, and down the beach with a bunch of tools and lumber in the back. Never managed to roll any of those, either.
Now, I know you were hoping to lose the connections in the forest of uneeded detail, but your scenario requires the LRV -- a vehicle with a top speed of 15 MPH, typically driven at half that -- to be traveling SIDEWAYS at 2.5 MPH or more. On a regular basis!
Why on a regular basis? It only has to happen once to roll the vehicle therefore it only has to be a possibility before a rollcage and harness are needed.
And, on an uneven surface with an extremely low coefficient of traction it is not exactly an unforeseeable possibility, more likely a highly probable event.
Please describe the scenario by which a vehicle, particularly one with such a "poor grip" (your description) on the ground, manages to wrench its full mass (torque applies to mass, not weight) a full 90 degrees. Without expending all of the forward velocity in doing so, either!
Note that the calculation of the LRV's SSF that Jay provided is a good margin higher than any of the Earth vehicles.
Not with two astronauts sitting up high and weighing 800lbs, especially when the vehicle only weighs 460lbs.
You can't calculate, okay.
And how will they end up sideways?
Here's a suggestion: work out how many scenarios cause cars here on Earth to end up traveling sideways, then work out how many of those could possibly transpire on the Moon.
One scenario is gong off road onto uneven terrain in slippery conditions, then it is very easy to end up sideways. If you are ever in that scenario you would be well advised to crawl along, even here on earth.
Can we all agree that scenario is very likely to happen on the moon? Or do you guys just want to relate your experiences in parking lots to the moon.
Amazing a couple of test pilots couldn't think of that, then!
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Hey, I just realized:
The astronauts are trying to walk around in 1/6 g. Not only do they still have their Earthly mass, they are wearing extremely heavy packs that make them even more unbalanced. Their boots have no more contact area than my tennis shoes, but at 1/6 g get only 1/6 the traction. It should have been impossible for them to move. They would have slid across the landscape like a kid on his first day at the skating pond, then toppled over with all that extra mass.
So all the EVAs are fake.
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(BTW there is a very lengthy engineering analysis available on the LRV's tire-soil interface, complete with 1/6 g empirical tests.)
I would be interested in seeing this, is there an accessible version about?
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Hey, I just realized:
The astronauts are trying to walk around in 1/6 g. Not only do they still have their Earthly mass, they are wearing extremely heavy packs that make them even more unbalanced. Their boots have no more contact area than my tennis shoes, but at 1/6 g get only 1/6 the traction. It should have been impossible for them to move. They would have slid across the landscape like a kid on his first day at the skating pond, then toppled over with all that extra mass.
So all the EVAs are fake.
First of all, their boots had much bigger contact area than any tennis shoe you could buy - probably about 4 times the area. Secondly, the tread had big deep grooves, to improve the traction. Third, they pushed into the surface with their boots. Fourth, you confuse mass and weight (hint: the PLSS weren't heavy in lunar gravity).
Edit: Aldrin's boot prints were 13x6 inches - about 511 cm2.
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AllanF, I'm fairly certain there was an implied wink at the end of nomuse's post.
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AllanF, I'm fairly certain there was an implied wink at the end of nomuse's post.
Sorry - Dogs and bells.
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I would be interested in seeing this, is there an accessible version about?
With NTRS down, perhaps not. I may have a local copy I can post.
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Here's another thing for anywho to consider, though still just a sideline really.
In a car on Earth if you roll it it flips quickly and you're strapped inside a metal box, powerless to stop physics from doing its thing. If the rover flipped, how quick would it be, and given that the astronauts are not confined within, wouldn't just sticking a leg outhave some effect in slowing the roll? Or maybe they could just jump off. Either way, rolling an open vehicle you're not strapped into at speeds lower than normal human walking speed hardly seems like a catastrophe....
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Here's a suggestion: work out how many scenarios cause cars here on Earth to end up traveling sideways, then work out how many of those could possibly transpire on the Moon.
Here's a suggestion...
I apologize: Jason points out I've misattributed his remark to anywho and demanded an explanation from him. No explanation needed, obviously, and I regret the error.
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No worries, Jay. Thanks for the correction. :)
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Hey, I just realized:
[...]
So all the EVAs are fake.
What, you think he wasn't building up to that?
Sorry - Dogs and bells.
<Eddie_Izzard>Pavlov's debunker: Day 1...</Eddie_Izzard>
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Which is why cars are rolling over all across the streets and highways.
Heck, I rarely drive at under 6 MPH, even in a parking lot. I have driven a bit less than 20 times that -- and on just a two-lane blacktop.
Your parking lot is not a very uneven surface with extremely low traction, nor are the streets and highways.
Now, I know you were hoping to lose the connections in the forest of uneeded detail, but your scenario requires the LRV -- a vehicle with a top speed of 15 MPH, typically driven at half that -- to be traveling SIDEWAYS at 2.5 MPH or more. On a regular basis!
Why on a regular basis? It only has to happen once to roll the vehicle therefore it only has to be a possibility before a rollcage and harness are needed.
And, on an uneven surface with an extremely low coefficient of traction it is not exactly an unforeseeable possibility, more likely a highly probable event.
Note that the calculation of the LRV's SSF that Jay provided is a good margin higher than any of the Earth vehicles.
Not with two astronauts sitting up high and weighing 800lbs, especially when the vehicle only weighs 460lbs.
And how will they end up sideways?
Here's a suggestion: work out how many scenarios cause cars here on Earth to end up traveling sideways, then work out how many of those could possibly transpire on the Moon.
One scenario is gong off road onto uneven terrain in slippery conditions, then it is very easy to end up sideways. If you are ever in that scenario you would be well advised to crawl along, even here on earth.
Can we all agree that scenario is very likely to happen on the moon? Or do you guys just want to relate your experiences in parking lots to the moon.
This really is mostly personal incredulity on your part, you know.
No, the LRV's frame wasn't tremendously strong. Weight was a major consideration, along with the ability to fit into a small space for transport. It was made as strong as it needed to be (plus a safety margin) and no stronger. But it was strong enough for the planned task.
It wasn't terribly powerful. Again, as much as was needed and no more. The motor and steering were designed to provide sufficient power, with a maximum of reliability and maneuverability and a minimum of weight, to cart 121 kg around at an average 10 kph. Making comparisons to earth vehicles is an unreliable comparison, but E-Z-Go of Georgia does make an all terrain utility vehicle called the Terrain 1000 which weighs 595 kg, has a cargo capacity of 450 kg, and a top speed of 26 kph. Its battery-powered electric drive motor is rated at 2.5 hp; it seems reasonable that 1 hp would be sufficient power in the lunar gravity.
Yes, the ultra-light LRV's traction on regolith was low enough that the rear end tended to break loose when turning. But the designers weren't working in the dark; they had soil samples and data acquired from the first landings to go by. They also had experienced test pilots, accustomed to and proficient at cautiously feeling out the handling characteristics of new vehicles, to operate their creation in the lunar environment.
It was built low and wide for stability. The astronauts weren't sitting "up high"; their seats were bare inches above the floor pan. Operating it with only one astronaut aboard did have some effect on the lateral stability -the Apollo 15 crew felt that "... roll instability would be approached on the 15-degree slopes if the vehicle were traveling a contour line with one crewmember on the downhill side. Except for the brief "Grand Prix" and short movements near the LM, the LRV was always occupied by both astronauts while in motion, so this wasn't a factor.
Actually, your "slide sideways and hit a rock" scenario was almost realized at one point. In the same report quoted above the crew described it:
"There was one instance of breakout and lateral skidding of the rear wheels into a crater approximately
1/2 meter (1-112 feet) deep and 1-1/4 meters (4 feet) wide. This resulted in a rear wheel contacting
the far wall of the crater and subsequent lateral bounce. There was no subsequent roll instability or
tendency to turn over, even though visual motion cues indicated a roll instability
might develop.*".
*[I think the phrase in blue is test-pilot speak for "I was afraid my butt was going to bite a hole in my pressure suit trying to grip the seat"]
They were well aware of the theoretical possibility of a rollover, but all three crews agreed that the vehicle did not show any noticeable tendency to roll. Although it was definitely something to be avoided, they didn't seem to regard the possibility as a catastrophic event; the Apollo 15 crew's main concern (in the event of a rollover) was how difficult it would be to release their seat belts so they could crawl out from under the 35 kg machine and turn it back over.
Exercising due caution was the obvious approach; As CDR Dave Scott put it, "It was just a matter of going slow when you had obstacles, and catching up on your rate when you had a clear field."
You make the statement that problems controlling the rovers is "not what we see in the video and photographic footage", which is just silly. What video footage we have of the LRVs being driven is during the "Grand Prix" runs which were deliberate speed runs done on familiar terrain near the LM and certainly not typical of operation during the long traverses.
You haven't presented a single piece of evidence that doesn't amount to "I don't believe this would work", which puts your premise on the level of a coffee house bull session, not intelligent discussion.
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Has it been established if it was the frame, the suspension or the wheels that was the load-limiting factor?
Also, I believe, the two-point seatbelts were velcro straps.
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Looking at the LRV Operations Handbook Performance Data (still available on the ALSJ site) I found a plot showing wheel deflection as a function of radial load. (Figure 2-8, document page A-11, pdf page 20). It was set so that on the moon it would be halfway through its range before hitting the bump stop. I think that makes it the limiting factor; on earth the wheels would have bottomed out, possibly damaging the inner frames. That's why you see the LRV up on blocks as the astronauts are fit-testing it on earth.
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Hmm. I just realised I failed to account for the gyroscopic effect from the wheels. That's one effect that won't be gravity-related, but will relate directly (well, probably quadratically) with the vehicle's speed.
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They also had experienced test pilots, accustomed to and proficient at cautiously feeling out the handling characteristics of new vehicles, to operate their creation in the lunar environment.
And true to their nature, nearly all of them drove sports cars on earth, typically Chevy Corvettes. While they didn't always exhibit the same amount of skill driving them as they did test-piloting aircraft and flying spacecraft, they probably knew the basics of how to keep a car right-side up.
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They also had experienced test pilots, accustomed to and proficient at cautiously feeling out the handling characteristics of new vehicles, to operate their creation in the lunar environment.
And true to their nature, nearly all of them drove sports cars on earth, typically Chevy Corvettes. While they didn't always exhibit the same amount of skill driving them as they did test-piloting aircraft and flying spacecraft, they probably knew the basics of how to keep a car right-side up.
Suggestion: if you and a test pilot are going anywhere by car, you drive. Trust me on this - you'll thank me later (nothing like being anywhere near an airport with those guys when they're driving "Look - it's an F18!" "No! You look at the semi cutting us off!!")
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Suggestion: if you and a test pilot are going anywhere by car, you drive. Trust me on this - you'll thank me later (nothing like being anywhere near an airport with those guys when they're driving "Look - it's an F18!" "No! You look at the semi cutting us off!!")
Personally, the person whose lifestyle does not involve taking insane risks strikes me as the better driver ninety-nine times out of a hundred. In the hundredth time, you're probably not having fun either way.
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Here's another thing for anywho to consider, though still just a sideline really.
In a car on Earth if you roll it it flips quickly and you're strapped inside a metal box, powerless to stop physics from doing its thing. If the rover flipped, how quick would it be, and given that the astronauts are not confined within, wouldn't just sticking a leg outhave some effect in slowing the roll? Or maybe they could just jump off. Either way, rolling an open vehicle you're not strapped into at speeds lower than normal human walking speed hardly seems like a catastrophe....
Keep in mind that the astronauts had to wear seatbelts, so they couldn't just leap out if the rover started to roll.
However, if it started to roll, I suspect the driver would have had enough time to steer away from the lifted wheels, and thus bring the rover back down.
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OK, this is me, "just asking a question".
I was wandering around in the ALSJ (I could get lost in there for days if I could find someone to bring me sandwiches) and I found a spot where Dave Scott, Apollo 15 CDR and first man to operate the LRV on the lunar surface, had some comments about the stability of the Rover and what it might take to cause a rollover. He and Eric Jones are talking about their (Scott and LMP James Irwin) return from Geo Station 2, driving downhill from Hadley Delta when the front wheels dug in and sent them into a sudden 180o spin.
[Jones - "You remember the 180? Which way did the back end go?"]
[Scott - "I think to the right. I don't really recall, but I remember it was real quick, before you could do anything about it. As I said here, the front wheels dig in. We were trying to maneuver around stuff, and it just broke. It was over before we even knew it. That's why we're laughing. Tsuuuu! and around it went. And then we went uphill, turned around, and came back downhill. And I know that the people in the back row at the Control Center were probably all crossing their legs tight."]
[Jones - "And it was basically a really stable little vehicle."]
[Scott - "Very stable. There was never any feeling of maybe turning over, at all. That's why it (incidents like the 180) was interesting: even though the rear end broke out - several times - and you spin all the way around, you don't have any feeling that it's going to turn over. It's sliding"]
[Jones - "Gene said that on their third EVA, when they were doing a fair bit of cross-slope driving on the North Massif, they had the feeling that if the upslope wheels started bouncing that they were getting toward the margins of stability. Did you ever have that feeling?"]
[Scott - "Nope. Gee, it's hard to imagine. I think you'd have to go look at the c.g. (center-of-gravity) and it would be easy to calculate. 'Cause if you know the c.g. and you know the angle the Rover is driving, you know the difference between the center of gravity and the center of pressure and you can figure our how much force it would take to push it over. And I think'd be really difficult to turn over."]
[Jones - "You'd have to be well tilted and you'd really have to bounce the uphill wheels."]
[Scott - "And you don't get a lot of angular momentum from the force, because of the low g. It's just kinematics, freshman physics."]
[Jones - "Assume you're going along at some tilt angle and at some speed and you hit a crater which gives you a force."]
[Scott - "And your force would be a reactive force from the Rover, which is limited by the Rover mass. There's nobody pushing you, so it has to be a wheel going into a crater to create a reactive force. Boy, I think it would be hard to get enough reactive force, with the suspension system which damps out the force. Boy, tough to do, but it could probably be done. It'd be interesting. If you were going very fast, then you've got a lot of energy in the system and, you might translate the energy into an overturning moment. It would be a great little exercise for somebody at school."]
Would someone be so kind as to clarify the part of the conversation I've marked in red, especially the underlined sentence? I get the general principles, but I'm not clear on what is meant by "reactive force" in this context and how it relates to the mass of the rover.
Thanks.
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The CoG is easy to find, with regards to sideways tilt. If it's correct what I've read, the LRV could stay on it's wheels up to 45 degrees sideways tilt. If you view the LRV from the front, draw a 45 degree angle with the ground, and the top at the bottom center of the wheels. Do this from both sides. Where the lines intersect at the center, you have the CoG. This cannot move outside the wheel, or the LRV would fall over. At any slope, draw a line from the CoG in the direction of gravity. That's the Center of Pressure. There is a drawing a couple of pages back.
Since the mass is much greater than the weight (about 6 times bigger) bumps wouldn't upset the LRV much. The momentum is proportional to weight on wheel, but the angular momentum would be proportional to mass. It's a little counter-intuitive, but if you divide the two events up, and look at them separatly, it's easier to understand.
The wheel presses on the surface, and the surface presses back with the same force. A bump will transfer momentum to the chassis in proportion to the pressure against it. No pressure - no force.
The momentum imparted by the bump will have an effect relative to the mass. And since the mass is much greater than the weight, you don't get much movement. On the other hand, the low weight would make the gravity-dampening effect slower.
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The CoG is easy to find, with regards to sideways tilt. If it's correct what I've read, the LRV could stay on it's wheels up to 45 degrees sideways tilt. If you view the LRV from the front, draw a 45 degree angle with the ground, and the top at the bottom center of the wheels. Do this from both sides. Where the lines intersect at the center, you have the CoG. This cannot move outside the wheel, or the LRV would fall over. At any slope, draw a line from the CoG in the direction of gravity. That's the Center of Pressure. There is a drawing a couple of pages back.
No kidding. Go back and note who posted that diagram.
Since the mass is much greater than the weight (about 6 times bigger) bumps wouldn't upset the LRV much. The momentum is proportional to weight on wheel, but the angular momentum would be proportional to mass. It's a little counter-intuitive, but if you divide the two events up, and look at them separatly, it's easier to understand.
The wheel presses on the surface, and the surface presses back with the same force. A bump will transfer momentum to the chassis in proportion to the pressure against it. No pressure - no force.
The momentum imparted by the bump will have an effect relative to the mass. And since the mass is much greater than the weight, you don't get much movement. On the other hand, the low weight would make the gravity-dampening effect slower.
Sorry. That just confuses me. I don't understand your statement that "the mass is much greater than the weight". Mass is measured in kg and weight in newtons; you can't compare them directly, although they are directly proportional. I'm also not sure what you mean about a bump 'transferring' momentum to the chassis (assuming that by "bump" you mean an actual physical feature of the surface), since a bump has no velocity and therefore no momentum.
But. Hmmm. A bump could and does change the velocity vector of some of the vehicle's linear momentum to angular momentum, with the bottom of the opposite wheel as the center of rotation. I'll crunch some numbers on that and see where they lead.
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Also, I believe, the two-point seatbelts were velcro straps.
The seat belts were a textbook example of simplicity of design; a strap with a hook on it to hook over the side ingress handle:
(http://i627.photobucket.com/albums/tt353/jarvisn/a16LRVseatbelt1_zps02ef2b7a.jpg)
This is one of the reasons I love hanging around engineers - the combination of complexity where required and simplicity where possible is positively elegant.
Engineering: The Art Of The Practical.
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Sorry. That just confuses me. I don't understand your statement that "the mass is much greater than the weight". Mass is measured in kg and weight in newtons; you can't compare them directly, although they are directly proportional. I'm also not sure what you mean about a bump 'transferring' momentum to the chassis (assuming that by "bump" you mean an actual physical feature of the surface), since a bump has no velocity and therefore no momentum.
But. Hmmm. A bump could and does change the velocity vector of some of the vehicle's linear momentum to angular momentum, with the bottom of the opposite wheel as the center of rotation. I'll crunch some numbers on that and see where they lead.
Sorry if I was unclear. I tend to see the rover as stationary, and the surface moving beneath it. That way, the surface bump hitting the wheel will give the rover an upward push at that wheel. Then the opposite wheel is the center of rotation, and the CoG is lifted with 1/2 the speed and travel as the wheel hitting the bump. And we're just interested in the upward thrust at the moment.
Also, english isn't my first language. I might not express myself as clearly as I wish.
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Sorry. That just confuses me. I don't understand your statement that "the mass is much greater than the weight". Mass is measured in kg and weight in newtons; you can't compare them directly, although they are directly proportional. I'm also not sure what you mean about a bump 'transferring' momentum to the chassis (assuming that by "bump" you mean an actual physical feature of the surface), since a bump has no velocity and therefore no momentum.
But. Hmmm. A bump could and does change the velocity vector of some of the vehicle's linear momentum to angular momentum, with the bottom of the opposite wheel as the center of rotation. I'll crunch some numbers on that and see where they lead.
Sorry if I was unclear. I tend to see the rover as stationary, and the surface moving beneath it. That way, the surface bump hitting the wheel will give the rover an upward push at that wheel. Then the opposite wheel is the center of rotation, and the CoG is lifted with 1/2 the speed and travel as the wheel hitting the bump. And we're just interested in the upward thrust at the moment.
Also, english isn't my first language. I might not express myself as clearly as I wish.
That's more or less what I was thinking. I'm trying to figure out how you calculate the amount of "upward" movement for a given forward velocity and size of "bump". Just to simplify, for an initial figure I'm ignoring the damping effect of the suspension.
Your english is excellent, but we may have to clarify terms occasionally. Oh, how did you like the seat belt design?
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The best designs are those, who do the job while adhering to the 'kiss'-principle. "Keep it simple, stupid!"
The momentum delivered, is of course dependent on the shape of the bump. Something like sin(a) x height x v^2 where a is the angle between flat ground and the peak of the bump, v is the velocity of the LRV. It's probably more complicated than that - this only works for simple shapes.
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This is one of the reasons I love hanging around engineers - the combination of complexity where required and simplicity where possible is positively elegant.
Engineering: The Art Of The Practical.
I'm not an engineer, but the way that I've always looked at it is that any eejit (http://www.urbandictionary.com/define.php?term=eejit) can design something to be overly complicated. It takes a skill to xome up with the simplest, most elegant solution possible.
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Simple is hard. That's the fun part.
The story I tell sometimes is my own mangled version of "Basho and the Merchant."
A well-to-do merchant asks a well-known sumi-e artist to paint him a fish, which he will then frame in his shop in a prominent place. The artist agrees. Six months pass, and the painting hasn't been delivered. The merchant drops by again, "How's my fish coming along?"
"In a little," says the artist.
Ten months, same thing. The merchant is getting a little sharp at this point. Twelve months, a full year after placing the order, the merchant stalks into Basho's little place. "Paint my fish or return my money!"
Basho says nothing. He quietly puts out a fresh piece of paper, wets a brush. Swish, swoop, pop! Twenty seconds, and there is this absolutely gorgeous fish painted in fresh black ink. The merchant is instantly mollified. "This is," he says, "This is wonderful! But...it only took you twenty seconds to paint. Why did I have to wait a year to get it done?"
Basho says quietly, "It took me a year to learn how to paint it in twenty seconds."
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I have learned much again. I did not think about this. But looking back through the excellent replies and information I cannot help but think that the only option for Anywho is to build a simple replica weighted accordingly to test it. Would this work? Then burn it when it does not go his/her way.
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It takes a skill to xome up with the simplest, most elegant solution possible.
One of my favorite engineering sayings (I wish I could take credit for it, but I can't) is that the job isn't done when there's nothing left to add, but when there's nothing left to take out.
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It takes a skill to xome up with the simplest, most elegant solution possible.
One of my favorite engineering sayings (I wish I could take credit for it, but I can't) is that the job isn't done when there's nothing left to add, but when there's nothing left to take out.
I have a variation on this from the many times I have dismantled laptops and re-assembled them:
If there are screws left over, you didn't need them.
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I have a variation on this from the many times I have dismantled laptops and re-assembled them:
If there are screws left over, you didn't need them.
Not always true. The importance of those screws might not show until (for example) the one left holding the screen hinge breaks or the one missing from the board by the USB sockets lets the board flex just enough to break their fixing.
By the time something like a Laptop reaches the shops any screws or other parts that aren't needed have been pared away to save cost.
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Not always true. The importance of those screws might not show until (for example) the one left holding the screen hinge breaks or the one missing from the board by the USB sockets lets the board flex just enough to break their fixing.
Or the board now has freedom to flex enough to short out against something, frying potentially thousands of dollars of hardware and destroying who knows what data.
Cutting screws not only saves cost in the BOM and in assembly, it saves room, a scarce commodity in laptops. If they used an unusually large number of screws for something, it was probably to fix a possibly non-obvious problem.
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It is often said that if astronauts could not even sit on a Lunar Rover here on Earth because the Rovers were built of such lightweight construction that they "would have collapsed in 1 g if the crew sat on it." (1), and that the " The vehicle could support its own weight on earth, but no more" (2).
Yes those supports are needed under the frame because it is such a delicate little flower that it can't even "hold their weight", yet on the moon those same masses can literally jump onto the rovers and then slam them into bumps all they want without any concerns.
Hi All, my first topical post... Anywho you appear to be talking with total emotional conviction and no subject knowledge whatsoever!
WHO exactly said that the Lunar Rover would have collapsed under 1G? You see it's really no good saying 'oh someone (with obvious and total authority) has said that xxx occurred"... you really do have to say who that 'Someone' is, otherwise you could be quoting your sister's 5 year old son and expect us to go 'oooh!....ahh! an enlightened one!" ( I am of course hypothesising that you do indeed have a sister with a 5 year old son for illustrative purposes only....if not please do not take it to mean that I am saying with any great authority that you do have a sister with a 5 year old son....just as we will not take it to mean that because you THINK someone said the Lunar Rover would collapse under 1G that that is indeed true!)
The second quote here makes me believe that you appear to think that the LR would suddenly collapse with bits bouncing everywhere to the loud sound of 'BOING!!!!' just like in a Wily Coyote cartoon! Please peruse the attached photograph. Its a NASA photograph of Two Astronauts (Cernan and Schmitt) fully suited and booted and ready to rock and roll, and sat on a Lunar Rover...here on earth under 1 G...please note that there are not bits flying off everywhere, and had this been filmed I very much doubt if the sound 'BOING' would have been heard!
we can see that this is in a NASA clean environment, the Lunar Rover has its Kapton coating and all the bits and bobs it needs on the moons surface, so this is pretty much obviously not a 'test hack' used to hoon around here on earth during training. The chassis of the Lunar Rover itself is certainly strong enough to support weight here on Earth, but it is on stands, so the limiting factor is obviously in the suspension/wheels. Even then had it not been on stands I doubt very much whether it would have collapsed like a delicate little flower!
One of my hobby's is building motorbikes (don't do design just throw off the shelf bits together!) now in my riding kit I weigh over 100Kg (sorry don't do pre-decimalisation) if I were to fit a shock absorber on my bike that had a rating of 50Kg and I suddenly sat on my bike would it collapse like a delicate flower?...no of course it wouldn't.... I may however damage components and I certainly wouldn't be able to ride the bike let alone ride it safely!
So come on Anywho leave the emotion at the doorstep and look at the hard evidence!
(edited: because of spelling and leaving words out..doh! I really should proof read before pressing the 'post' button)
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Nice picture - you can almost see the supports under the frame (which were there), keeping it from deforming and damaging the wheels.
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Nice picture - you can almost see the supports under the frame (which were there), keeping it from deforming and damaging the wheels.
I just pulled the pic off Google, the original is 3.56 MB so the detail is really quite good, there is also a Black and White photo taken at the same time(ish) as this one which I think is even better!
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Here's a picture of the Apollo 15 crew sitting in the Rover with no supports. Shock, horror, there's even a third crew-member leaning on it. Now, by the standard of evidence the anywho uses, this must prove that the LRV wasn't a fake and it was OK in 1G
(http://www.honeysucklecreek.net/images/images_Apollo_15/hskap15crewrov_med.jpg)
Care to comment, anywho?
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Here is a short clip showing the rover being tested in earth gravity...
www.youtube.com/watch?v=vzfWuMFrJuU
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It is often said that if astronauts could not even sit on a Lunar Rover here on Earth because the Rovers were built of such lightweight construction that they "would have collapsed in 1 g if the crew sat on it." (1), and that the " The vehicle could support its own weight on earth, but no more" (2).
Yes those supports are needed under the frame because it is such a delicate little flower that it can't even "hold their weight", yet on the moon those same masses can literally jump onto the rovers and then slam them into bumps all they want without any concerns.
Hi All, my first topical post... Anywho you appear to be talking with total emotional conviction and no subject knowledge whatsoever!
WHO exactly said that the Lunar Rover would have collapsed under 1G? You see it's really no good saying 'oh someone (with obvious and total authority) has said that xxx occurred"... you really do have to say who that 'Someone' is, otherwise you could be quoting your sister's 5 year old son and expect us to go 'oooh!....ahh! an enlightened one!"
WTF? Are you for real? Do you see the little (1) and (2) next to the quotes? That means I have a reference for each quote and both are NASA sources, not a nephew of mine.
if I were to fit a shock absorber on my bike that had a rating of 50Kg and I suddenly sat on my bike would it collapse like a delicate flower?...no of course it wouldn't.... I may however damage components and I certainly wouldn't be able to ride the bike let alone ride it safely!
Lol, this actually fits with my position more-so than any arguments against it.
If you can't sit on it, you can't ride it over bumpy terrain.
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Here's a picture of the Apollo 15 crew sitting in the Rover with no supports. Shock, horror, there's even a third crew-member leaning on it. Now, by the standard of evidence the anywho uses, this must prove that the LRV wasn't a fake and it was OK in 1G
(http://www.honeysucklecreek.net/images/images_Apollo_15/hskap15crewrov_med.jpg)
Care to comment, anywho?
You people seem to have a problem comprehending that it is not me who is saying it can't be sat on here on earth, it is something which often comes up in official NASA documents. I am saying it is a load of rubbish and I am glad many of you seem to agree.
Myth busted?
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I have had a bit of a browse through some of the articles and files that are linked to in the "Were the Lunar Rovers faked" thread, and I find it interesting that I have not seen any guidelines or testing done for one astronaut on board.
As I pointed out throughout the thread, the rovers with one astronaut are horribly unbalanced with basically 3/4 the weight on one side, so one might expect for there to be some guidelines given for when only one astronaut is on board, but there appears to be no guidelines, nor any specific testing done.
Of course there may some testing done, and some guidelines, but in the links I've looked at I can't see any so I will be interested if anyone else knows of some.
I can see that one argument might be that if the imbalance of one astronaut is not outside of the acceptable limits for the vehicle then there is no reason for any specific guidelines.
The problem with this is that it does indeed appear as though only one astronaut shifts the CoG outside the acceptable limits which, if true, begs the question as to whether the rovers were ever designed for one astronaut, and if that is the case what were they doing driving in the most extreme manner when only one astronaut was on board?
In particular, one might expect a lower speed limit for one astronaut, yet by all accounts the highest speeds were reached with only one on board, such as Gene Cernan claiming a lunar speed record of 18 kilometers/hour (1).
So what is the allowable CoG envelope?
(http://i627.photobucket.com/albums/tt353/jarvisn/LRV-CG_zpsf7015c4a.jpg)
The allowable center of gravity location or the total LRV, including payload, is shown in figure 5-1. Loading the LRV such that the center of gravity falls outside the defined envelope will cause degradation of performance, including:
a. Possible steering discontinuity
b. Possible traction drive discontinuity
c. Possible periods of instability
http://www.hq.nasa.gov/alsj/LRV_OpsNAS8-25145Pt6.pdf
Now, my back of the envelope calculations put the CoG about 7 inches off center with one astronaut, and that is well outside the envelope, so it would seem to be valid to question if the rovers were ever designed to be driven with one astronaut at all, let alone driven to the extreme.
(1) http://www.space-pictures.com/view/pictures-of-earth/pictures-of-the-moon/moon-landing/apollo-17.php
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You people seem to have a problem comprehending that it is not me who is saying it can't be sat on here on earth, it is something which often comes up in official NASA documents. I am saying it is a load of rubbish and I am glad many of you seem to agree.
Myth busted?
My understanding (and I'm happy to be corrected on this) is that your proposition went as follows:
The LRV couldnt support the weight of itself and 2 x astronauts under 1G. You used quoted from NASA documentation as evidence. from there you then jumped to a whole load of unproven, unsupported conclusions, namely:
- There wasn't enough traction on the Moon
- The LRVs were underpowered and couldn't move
- The vehicles were unbalanced and would roll over at the slightest provocation
- There wasn't enough traction on the Moon
From that, you then concluded that it was "farcical to believe they could possibly be real." All of your assertions leading up to your final conclusion have been debunked. Ergo, your conclusion is erroneous.
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As I pointed out throughout the thread, the rovers with one astronaut are horribly unbalanced with basically 3/4 the weight on one side
But that is your assertion. Where is the evidence or calculations to support it???
but in the links I've looked at I can't see any so I will be interested if anyone else knows of some.
If you dont know this ^^,
then how can you claim this?? VV
The problem with this is that it does indeed appear as though only one astronaut shifts the CoG outside the acceptable limits which, if true, begs the question as to whether the rovers were ever designed for one astronaut, and if that is the case what were they doing driving in the most extreme manner when only one astronaut was on board?
Now, my back of the envelope calculations put the CoG about 7 inches off center with one astronaut, and that is well outside the envelope,
Have you considered that your calculations are incorrect?
Please post your calculations so they can be checked by someone who will use more rigour than your "back of the envelope" calculations
so it would seem to be valid to question if the rovers were ever designed to be driven with one astronaut at all, let alone driven to the extreme.
The question lies in one article that you previously linked to " Since the handling characteristics of the LRV could not be fully tested on Earth, a "grand prix" test was performed by the CDR on A-15 & 16. The trainer provided adequate simulation, the major difference was the necessity to pay constant attention to the lunar terrain in order to have adequate warning of obstacles, especially in adverse lighting situations. Braking required ~2 x the 1 g distance. Steering was not as responsive between 8 - 10 kph with hard-over inputs. "
From
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As I pointed out throughout the thread
You mean as you repeatedly and dishonestly claimed based on your credo of
- i don't understand
- i don't want to understand
- i simply want my idea to be true
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I am still waiting for an answer to my question, Anywho.
If the rover could not hold the weight of the crew, where do you believe the film of the crew driving the rover was shot?
You have already claimed Apollo was faked, yet your claim about the rover collapsing in 1g means that it cannot have been faked. That is the contradiction you are ignoring, because you know you don't have an answer. To throw your own question back at you, are you for real?
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It is often said that if astronauts could not even sit on a Lunar Rover here on Earth because the Rovers were built of such lightweight construction that they "would have collapsed in 1 g if the crew sat on it." (1), and that the " The vehicle could support its own weight on earth, but no more" (2).
Yes those supports are needed under the frame because it is such a delicate little flower that it can't even "hold their weight", yet on the moon those same masses can literally jump onto the rovers and then slam them into bumps all they want without any concerns.
Hi All, my first topical post... Anywho you appear to be talking with total emotional conviction and no subject knowledge whatsoever!
WHO exactly said that the Lunar Rover would have collapsed under 1G? You see it's really no good saying 'oh someone (with obvious and total authority) has said that xxx occurred"... you really do have to say who that 'Someone' is, otherwise you could be quoting your sister's 5 year old son and expect us to go 'oooh!....ahh! an enlightened one!"
WTF? Are you for real? Do you see the little (1) and (2) next to the quotes? That means I have a reference for each quote and both are NASA sources, not a nephew of mine.
if I were to fit a shock absorber on my bike that had a rating of 50Kg and I suddenly sat on my bike would it collapse like a delicate flower?...no of course it wouldn't.... I may however damage components and I certainly wouldn't be able to ride the bike let alone ride it safely!
Lol, this actually fits with my position more-so than any arguments against it.
If you can't sit on it, you can't ride it over bumpy terrain.
I do sincerely apologise, My mistake I will go back and look at your 'references'...... then get back to you!
And as for your second point... to paraphrase yourself...WTF? Are you for real?.... who says I can't sit on it?... have a reality check fella! stop assuming that what you don't know means it ain't so
If I fit a 50 Kg shock for my fat +100Kg body I can, repeat can, sit on it! Just like the astronauts in full kit can, repeat can, sit on the Lunar Rover. I can not, repeat can not, drive it safely (or probably without causing damage) . But it will not, repeat not, burst apart like a delicate little flower, which is the position you seem to hold with the Lunar Rover.
It clearly can support the weight (its alright no need to thank me for proving your initial premise wrong!) but cannot be used on Earth...but its not supposed to be used on Earth is it?
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You people seem to have a problem comprehending...
Not at all...we simply do not accept your "interpretation".
The rovers worked on the Moon "as advertized". If you disagree...if you have some form of evidence (other than misinterpretations of NASA documents) then by all means, present that evidence.
Myth busted?
The myth that the rovers were faked...yes...
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"If I ran the zooo..."
(Sung to the tune of "If I were a rich man. ..")
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Anywho, why do you need two Rover threads?
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I have had a bit of a browse through some of the articles and files that are linked to in the "Were the Lunar Rovers faked" thread, and I find it interesting that I have not seen any guidelines or testing done for one astronaut on board.
I find it "interesting" that you are incapable of googling "one man lunar rover".
...and I'm not doing your "homework" for you...
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So Anyhow do you accept that the LR can be sat on (even if not actually operated) on Earth? do I need to go back and look at your links and respond to my mistake?
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Oh, look; it's shadow-boxing again.
"I didn't mean what I appeared to be arguing. We all agree now, right? Good thing I was there to instruct everyone else, because now we've all learned something, right?"
Will he EVER make an honest, open retraction?
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Is there any reason outside of the OP's vanity to have a second thread? I vote it be locked.
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Anywho, why do you need two Rover threads?
Because everyone knows the rover can't balance on just one thread.
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You people seem to have a problem comprehending that it is not me who is saying it can't be sat on here on earth, it is something which often comes up in official NASA documents. I am saying it is a load of rubbish and I am glad many of you seem to agree.
Myth busted?
Are you just left with arguing whether it could be sat upon on earth? Whether you have some NASA PR document that says it couldn't is really irrelevant, just give it up because that doesn't matter. All that is important is weather the LRV could operate on the moon, and you have yet to make any case aside from irrelevant comparisons to terrestrial circumstances and vehicles. If you want to demonstrate that the LRV could not operate on the moon, then show us why it could not operate on the moon. It is a pretty simple request although one whose answer requires a great deal of knowledge about the environment and considerable engineering skills.
Until you are able to demonstrate those attributes, why should we take you seriously? And I'll reiterate the earlier question that you have dodged, where was the LRV footage made? I'll add another question, if the rovers were incapable of operating on the moon, which of the Apollo missions do you think were faked and which were real? Please include the reasons for your answers.
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...the rovers with one astronaut are horribly unbalanced....
Still begging the question are we?
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You people seem to have a problem comprehending that it is not me who is saying it can't be sat on here on earth, it is something which often comes up in official NASA documents. I am saying it is a load of rubbish and I am glad many of you seem to agree.
Okay, you've provided one. Which isn't "often." But even leaving that aside, do you know who wrote the line? Not just "a NASA document." I mean a specific person and their specific qualifications to say anything relevant. The people writing press releases were not engineers, and it's what the engineers said that mattered more. It's, and I am a bit tired of repeating this, the numbers that matter.
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...I find it interesting that I have not seen any guidelines or testing done for one astronaut on board.
I believe that you have not yet seen them. There is a vast amount of material easily available on the lunar rover. It takes the average person several weeks to read it all carefully. It's not exciting reading, but then again most engineering documents are not meant to be entertaining. And with the NTRS down until further notice, alternate sources must be sought out.
But consider this. Given the characterization of what you have already read, which likely goes into meticulous detail, what is the most likely explanation for your inability yet to find documentation for single-occupant testing: (a) the tests were never done, or (b) you just haven't run across them yet?
As I pointed out throughout the thread, the rovers with one astronaut are horribly unbalanced...
Asserted, but no quantitative argument provided. Begging the question does not convince me.
The problem with this is that it does indeed appear as though only one astronaut shifts the CoG outside the acceptable limits...
By what argument and computation? It's not necessarily inappropriate to anticipate your critics' objections and attempt to account for them. It borders on the straw-man fallacy, but not in this case. However if you anticipate that we will make a certain argument, and it is a quantitative argument according to a physical model, you cannot just handwave away the objection. If you claim the LRV would be unacceptably unstable when operated by one person, you bear the burden to provide the computations that support that conclusion.
In particular, one might expect a lower speed limit for one astronaut, yet by all accounts the highest speeds were reached with only one on board, such as Gene Cernan claiming a lunar speed record of 18 kilometers/hour (1).
Did he execute any turns at that speed?
So what is the allowable CoG envelope?
For what purpose? The practical c.g. limits for vehicles are determined by intended use, as discussed later.
When a contractor says "acceptable" in his documentation, it means the envelope of operation inside which he guarantees the performance will meet the acceptance criteria imposed by the customer. It does not mean the equipment may not be operated successfully outside that envelope, perhaps with degraded performance. It means that if the equipment is operated outside the contractor-specified envelope, the contractor cannot be held liable for degradation, malfunction, damage, injury, or loss that ensues.
Conversely the practical envelope varies by use. The real-world c.g. envelope for straight-and-level operation at high speed is different than the real-world c.g. envelope for operation on an incline or for low-speed, high-maneuverability operation on any terrain. The speed envelope is different along uneven terrain than for flat ground. The Grand Prix was intended to investigation the relationship between the practical limits and the as-specified limits. Given that NASA has an acceptable design in-hand, the exercise was to determine confidence in the margins surrounding that accepted envelope.
The allowable center of gravity location or the total LRV, including payload, is shown in figure 5-1. Loading the LRV such that the center of gravity falls outside the defined envelope will cause degradation of performance...
I can think of many things that degrade a vehicle's performance. Does that mean that operating them under those conditions is impossible, such that by such inference we can conclude that claims to have operated them as such must be fraudulent?
You may have noticed I haven't posted for a few days. I was down in Moab, Utah, enjoying a little thing called Jeep Safari where we take a bunch of 4x4s and drive them through all kinds of circumstances that happily exceed the manufacturer's specifications. The Jeep reps were there, handing out color glossies. Yes, from them can be computed the manufacturer's stated operational envelopes. Did we see people happily exceeding them? Yes, all the time. Did we exceed them ourselves? You betcha. Did we roll over, skid, panic, die, or otherwise experience anything that would convince a non-believers that red-rock four-wheeling was a hoax? Nope. Did we all meet at the Blu Pig for KC BBQ and beers? Yup. Is Pasta Jay's named after me? No, but I'm in there often enough that it might be.
In other words, I don't believe your handwaving.
Now, my back of the envelope calculations put the CoG about 7 inches off center with one astronaut...
Show your calculations. You are making an engineering argument without providing any engineering. I'm not buying your handwaving one bit, and you won't show your work. You've tried this same rhetorical stunt before. You convince us that you really aren't interested in knowing.
...let alone driven to the extreme.
Your one example of "driven to to the extreme" with only one occupant is a single claimed speed record. However you have previously emphasized roll instability as the reason single-occupant operation would be problematic. Do you understand that speed and maneuverability are not the same thing, and that "extreme" operation in one mode is not necessarily problematic in another mode? Why are you blurring important distinctions? Your handwaving didn't work at the other forum where you tried these identical claims and it work work here either. When you are discussing engineering with engineers and calling them liars, you need more game than this.
Again we return to the Grand Prix example, which would be a test of roll stability with one occupant. In that test the on-site crew even joked about the likely roll instability that would occur with an eccentric load in a sharp, high-speed turn. The Grand Prix also tested lateral breakaway traction. The operator discovered that he could steer quickly enough to correct loss of back-end traction before a tripping roll became likely.
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I've used the drawing a few pages back as reference, and drawing on piece of paper, measuring and calculating, I've reached the conclusion, that the distance between the wheels and the astronauts positions in relation to each other and the LRV, means that each astronaut puts 28.6% of his weight on the opposite side wheels. If they weight 30 kilos in lunar gravity, that's around 8.6 kilos. With 2 astronauts on board, the LRV is supposed to be perfectly balanced. With it's own weight, each side carries 25 kilos LRV and 30 kilos of astronauts. That's a total of 55 kilos on each side. Take one astronaut out, and the loads should be 46.4 kg and 33.6 kg. Total 80 kilos. That's a weight distribution of 42/58.
This is based on the LRV's mass of 300 kg in fully assembled state. I know there's lower weight quoted, but I think those numbers represent the weight of the frame/motors without batteries and instruments.
Edit: That's pretty far from 25/75 (or threequarters as somebody wrote).
Edit2: With a LRV weight of 210 kg, the distribution would be 33/67.
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Anywho, why do you need two Rover threads?
Because everyone knows the rover can't balance on just one thread.
Ah crap, beaten to the punch . . .
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Anywho, why do you need two Rover threads?
Because everyone knows the rover can't balance on just one thread.
Ah crap, beaten to the punch . . .
For those of us whose pretensions at being hip left us years ago (unlike Jay and Not Myself who are hip), what is the reference to.
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Oh, hello.
http://www.thenakedscientists.com/forum/index.php?topic=47147.0 (http://www.thenakedscientists.com/forum/index.php?topic=47147.0)
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In particular, one might expect a lower speed limit for one astronaut, yet by all accounts the highest speeds were reached with only one on board, such as Gene Cernan claiming a lunar speed record of 18 kilometers/hour (1).
I'm not sure where you got that idea. The "Cernan Speed Record" was claimed after coming down the steep slope from the "Scarp" with both astronauts firmly on board.
BTW, I'm still not clear on what your actual contention is.
Are you saying that:
A) They shouldn't have done it that way.
B) They wouldn't have done it that way.
C) They couldn't have done it that way.
It seems to me that A & B are matters of opinion and professional judgment, and not really a subject for second guessing.
Only if it's "C" do you have anything to debate, in which case, please trot out the evidence.
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I'm not sure where you got that idea. The "Cernan Speed Record" was claimed after coming down the steep slope from the "Scarp" with both astronauts firmly on board.
My mistake
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To everyone who questions that the CoG with one astronaut moves outside of the acceptable envelope I would seriously question why you are being so difficult, I would suggest even someone innumerate would, upon understanding the astronaut weight is similar to the rover, put the CoG somewhere under the astronauts right buttock.
I used a simple formula for seesaws, I had my datum 3 feet from the center giving me a moment of 3*460 for the vehicle, and I did 2 possibilities for the astronaut, one at 1.5ft and one at 2ft from the datum (I believe these are both extreme for the CoG of the astronauts and the answer is somewhere in between). Then I divided the two moments by the combined weights giving me:
(1380 + 600)/860 for 1.5ft which is 2.3ft from the datum, or 8 inches off center
(1380 + 800)/860 for 2ft which is 2.5ft from the datum, or 6 inches off center
Like I say, I think that the true position of the astronauts is in between these two, and that is why I say 7 inches, I am being genuine and not trying to bend things in my favour.
I believe that you have not yet seen them. There is a vast amount of material easily available on the lunar rover. It takes the average person several weeks to read it all carefully. It's not exciting reading, but then again most engineering documents are not meant to be entertaining. And with the NTRS down until further notice, alternate sources must be sought out.
But consider this. Given the characterization of what you have already read, which likely goes into meticulous detail, what is the most likely explanation for your inability yet to find documentation for single-occupant testing: (a) the tests were never done, or (b) you just haven't run across them yet?
Lock in "a" Eddie.
If they were done I would have expected to have run across them by now, and I would expect any such findings to be in the operations handbook along with speed recommendations and CoG calculations etc.
The Grand Prix was intended to investigation the relationship between the practical limits and the as-specified limits. Given that NASA has an acceptable design in-hand, the exercise was to determine confidence in the margins surrounding that accepted envelope.
Well the question I was asking was whether the LRV's were ever designed for one astronaut, so there should be no need to see if it could be done while on the moon, they should know before they get there, and should have appropriate guidelines.
Ostensibly, it is looking as though the rovers were never designed for one astronaut, and one astronaut takes the rover outside it's design parameters.
You are essentially saying the grand prix were testing limits, yet they went well outside the recommended CoG and well outside the speed limits, on the moon where any failure could be disastrous, and in vehicles with low tolerances.
The grand prix was certainly "rough mare"
Maximum speed for design limit loads
Rough mare 8.5 km/hr
http://www.lpi.usra.edu/lunar/documents/NTRS/collection2/NASA_TM_X_66816.pdf
Young puts the lunar rover through its paces by driving at speed and performing sharp turns and stops so that Duke can record it on film for the rover engineers using the data acquisition camera. This silent 16mm clip begins with the ALSEP site in the background. The rover speeds up to 10 kph and bounces dramatically in the craters, sending the wheels into the air. The wheels send up “rooster tail” sprays of dust and skid sharply in the turns. The clip concludes with Young driving off, bouncing in the craters towards the lunar module.
http://www.hq.nasa.gov/alsj/a16/video16.html
My emphasis.
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I used a simple formula for seesaws . . . .
Why? What's the relevance?
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I used a simple formula for seesaws,
You start from the beginning. Like my old maths teacher used to say, show your workings out, this will get you more marks than a simple answer even if wrong but the method was correct. This way I can learn. I have seen what others here have put up and on purpose not worked through it (I like to do that when the mood takes me, understand what is going on). That is where you come in, if you are claiming it, you can show the sums that back it up and I can follow what you have painstakingly worked out and I might learn something. So far I see my gut feeling outdoing your gut feeling, so there has to be more or its a rum do.
How are the sums on the motors coming along?
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I would like anywho to comment on the fact that we have film of the Rovers operating. We even have film of them operating with one man aboard. In fact, it is these films that he refers to in the thread.
How does he reconcile his belief that the Rovers don't work with the fact he is using film of them working to support his belief?
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If they were done I would have expected to have run across them by now, and I would expect any such findings to be in the operations handbook along with speed recommendations and CoG calculations etc.
Have you ever considered the possibility that you might be wrong? Why would these calculation be in the operations handbook? To use an analogy that you are fond of, when you read you car's handbook does it contain the calculations on roll-over angles????
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Anywho, I bet these chaps are glad they don't share your wisdom and expertise on vehicular CoG parameters and roll stability!
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Anywho, may I point out several blindingly obvious points?
You have not one single supporter. Hey, why not go talk to a REAL CREDENTIALLED engineer of your choice, one with some verifiable background in this field, and get them to log in here and weigh in with the analysis YOU won't provide..? Or isn't it that important to you?
You are studiously and obviously avoidng the question asked of you MANY TIMES. I think it's high time you were pulled up and REQUIRED to answer:
1. What is being shown in the lengthy films of the LRV? What is the vehicle and where/how was it filmed?
You are also studiously avoiding posting a REAL analysis of the LRV, one that includes the proper (and relatively simple) approaches to determine the REAL factors that are relevant to your (spurious and false) claims. You have been shown the sources and given the basic information - spoonfed, in fact. So why are you refusing to do that?
2. Provide that analysis and show your workings and logic.
No more ridiculously inapplicable (indeed, laughable) analogies. Get to work and stop the handwaving.
And yes, we all know....
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I haven't done any CG calculations at all, let alone roll over calculations, but, if we're going to go on intuition alone, looking at the wheelbase of the LRV, especially in the photo in the "Mystery Watch" thread, the vehicle just looks very stable and fairly difficult to roll.
Anywho, ponder this: picture a vehicle that weighs 90 tons loaded, is about 19 feet tall, 11 feet wide, and rides on a wheelbase of 56.5 inches. Can't be done because the CG is too high, right?
Can anyone figure out what I just described? :)
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Yeah but they use glue like the stuff on post it notes.
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Abaddon said:
Oh, hello.
http://www.thenakedscientists.com/forum/index.php?topic=47147.0
Anywho said:Lock in "a" Eddie.
You started a thread on this topic on the (Australian) ABC Science Forum too, didn't you?
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To everyone who questions that the CoG with one astronaut moves outside of the acceptable envelope I would seriously question why you are being so difficult...
Because engineering requires such rigor. If you are unable to meet that rigor, you do not get to question the work of practicing engineers. The better question is why you're being so haphazard and lackadaisical. You're simply begging the question over and over again.
I would suggest even someone innumerate would, upon understanding the astronaut weight is similar to the rover, put the CoG somewhere under the astronauts right buttock.
Why would you submit in evidence what you suppose an innumerate person would do?
I used a simple formula for seesaws...
Wrong method. Use the proper method. You don't get to dumb down the problem until it fits your limited understanding -- not if your goal is to tell professionals on that basis that they are liars and frauds.
I am being genuine and not trying to bend things in my favour.
You're making it up as you go and trying to pretend this allows you to challenge the work and belief of the entire engineering community.
If they were done I would have expected to have run across them by now, and I would expect any such findings to be in the operations handbook along with speed recommendations and CoG calculations etc.
Straw man. They weren't in the one place you looked, so rather than conduct an appropriate study you decide that everyone else should have done it your way and if they didn't then they're hiding something.
Well the question I was asking was whether the LRV's were ever designed for one astronaut, so there should be no need to see if it could be done while on the moon, they should know before they get there, and should have appropriate guidelines.
No, that's not how testing philosophy works in real life engineering. Some things you can only learn through operational test, and you can't have those until you have at least an early working model of the vehicle and you test it in its destined environment. Every airplane has a test flight. Every ship or submarine has sea trials. These occur in environments that become immediately hostile to the human occupant if something goes wrong.
The LRVs were extensively tested and studied. You have only scratched the surface of the design, development, and testing efforts behind it, and are patently unschooled in the methods underlying such an effort. Yet you have arrogantly drawn the conclusion that they must be implausible and further impose arrogantly imagined rules for proper practice and conduct upon the industry that developed them.
Ostensibly, it is looking as though the rovers were never designed for one astronaut, and one astronaut takes the rover outside it's design parameters.
No, you decided all that before you ever entered this forum, because you drew the same conclusions elsewhere. You came here presenting the same conclusions with the same handwaving rationale, even after you were shot down previously. You're shopping around for approval for your beliefs and praise for your cleverness, not actually investigating an engineering design.
You are essentially saying the grand prix were testing limits, yet they went well outside the recommended CoG and well outside the speed limits, on the moon where any failure could be disastrous...
I already addressed the c.g. "limits" and you have failed to respond.
They did not exceed speed limits in the Grand Prix. If you had read the astronauts' report of the experience you would have known that. You clearly have not studied the LRV well enough to make the outrageous claims you're making with any sort of objective confidence.
"Any failure would be disastrous" is hyperbole. Layman conspiracy theorists typically hype up such imagined dangers in order to invent new rules to impose on NASA, so that they can accuse NASA of breaking them suspiciously. You do not get to decide for everyone what is an acceptable risk.
...and in vehicles with low tolerances.
You only suppose the vehicle has low tolerances. You are unwilling and unable to prove anything of the sort.
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Can anyone figure out what I just described? :)
Some piece of railroading rolling stock, I'm sure. And I'm equally sure you'd take the same sort of exception to a non-railroader who claimed railroad operations were unacceptably hazardous because they didn't conform to that person's misguided, simplistic conceptions of vehicle dynamics.
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Abaddon said:Oh, hello.
http://www.thenakedscientists.com/forum/index.php?topic=47147.0
Anywho said:Lock in "a" Eddie.
You started a thread on this topic on the (Australian) ABC Science Forum too, didn't you?
Yep, I noted both in the opening post, and I posted a link to the naked scientist thread in my second post
Hi, I posted an argument on a science forum that the apollo rovers are nonsensical for driving on the moon, it is derived from another posting of mine on a different science forum that has already been posted on this site (I was just going to bump that thread but because the original link does not work, and a message came up asking me to consider making a new thread, I have started this thread)
Sorry, I forgot the link to the original posting:
http://www.thenakedscientists.com/forum/index.php?topic=47147.0
JayUtah, are you seriously saying that one astronaut does not move the CoG outside of the designated envelope?
They did not exceed speed limits in the Grand Prix. If you had read the astronauts' report of the experience you would have known that. You clearly have not studied the LRV well enough to make the outrageous claims you're making with any sort of objective confidence.
I gave a reference saying they went 10kph and a reference that the speed limit over rough mare is 8.5kph, and the 8.5kph is the speed limit over rough terrain when the vehicles CoG is within the designated envelope, which it is not with only one astronaut.
So I gave my reasons for saying that they were over the speed limit, and references, yet you just ignore them and simply say "They did not exceed speed limits in the Grand Prix." and then babble on about reading the report without any specifics as to what you're alluding to.
Edit: to change a misspelt name, genuine mistake :-[
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The drawing a few pages back references specifically to the acceptable CoG for a LRV with TWO astronauts. What is the acceptable CoG for a LRV with ONE astronaut?
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[derogatory name], are you seriously saying that one astronaut does not move the CoG outside of the designated envelope?
Do not attempt to put words in my mouth.
You are the one claiming the LRV was not designed for one-occupant operation. Design intent aside, you further claim the LRV cannot be operated with one occupant because you allege it would have unacceptable roll stability. In support of this claim you offer two lines of reasoning: first, the supposition that an uninformed layman would intuitively assume the c.g. were in a particular place; and second, that your computation by an incorrect ad hoc method places the c.g. in a different particular place.
You present no accompanying roll stability computations. You present no definition or rationale for the acceptability of performance. You demonstrate no competence in the notion of "designated envelope."
We get nothing from you but repeated question-begging and handwaving. Either supply suitable rigor or concede.
...babble on about reading the report without any specifics as to what you're alluding to.
The astronauts' debriefing.
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So I gave my reasons for saying that they were over the speed limit, and references, yet you just ignore them...
Yeah, that's right...Jay "runs away" when confrounted with ignorant hoax believers...NOT.
Sheesh.
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The drawing a few pages back references specifically to the acceptable CoG for a LRV with TWO astronauts. What is the acceptable CoG for a LRV with ONE astronaut?
Good question, I am yet to come across any such workings, and the two person CoG is the only envelope they designate that I can find.
This is why I posed the question as to whether the rovers were ever actually designed for one astronaut.
...babble on about reading the report without any specifics as to what you're alluding to.
The astronauts' debriefing.
What in the debriefing refutes the two valid links I supplied? One which is the speed limit set at 8.5kph over rough mare, and one which says they went 10kph over what is obviously rough mare (and with one astronaut so the CoG is outside the acceptable envelope)
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The drawing a few pages back references specifically to the acceptable CoG for a LRV with TWO astronauts. What is the acceptable CoG for a LRV with ONE astronaut?
Good question, I am yet to come across any such workings, and the two person CoG is the only envelope they designate that I can find.
This is why I posed the question as to whether the rovers were ever actually designed for one astronaut.
...babble on about reading the report without any specifics as to what you're alluding to.
The astronauts' debriefing.
What in the debriefing refutes the two valid links I supplied? One which is the speed limit set at 8.5kph over rough mare, and one which says they went 10kph over what is obviously rough mare (and with one astronaut so the CoG is outside the acceptable envelope)
You just admitted not knowing what the acceptable envelope for CoG with one astronaut was - and now you know it?
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The drawing a few pages back references specifically to the acceptable CoG for a LRV with TWO astronauts. What is the acceptable CoG for a LRV with ONE astronaut?
Good question, I am yet to come across any such workings, and the two person CoG is the only envelope they designate that I can find.
This is why I posed the question as to whether the rovers were ever actually designed for one astronaut.
Well, it appears to me that the document you referenced (NASA-TX-X-66816, the LRV Performance Data Appendix) pretty much answers all the questions you've posed.
Specifically, they evaluated the stability of the LRV when occupied by one astronaut:
(http://i627.photobucket.com/albums/tt353/jarvisn/Figure3-4_zpseacc740e.jpg)
And they evaluated what happens when the CoG is outside the normal position:
(http://i627.photobucket.com/albums/tt353/jarvisn/Figure3-10_zpsf6efcc6b.jpg)
They even evaluated your question about sliding-sideways-and-hitting-a-rock:
(http://i627.photobucket.com/albums/tt353/jarvisn/Figure3-5_zpsc8f1068a.jpg)
Isn't that amazing? The engineers who built this particular spacecraft actually considered all these questions you bring up. And, I dare say, a few thousand that you haven't thought of. Then, being engineers rather than scientists, they evaluated everything they could about the real-world performance of the LRV - including its performance in the "Grand Prix" exercise - in order to refine their data.
...10kph over what is obviously rough mare...
I don't know that I agree that the terrain was "rough mare". On Apollo 15, at least, they looked for the flattest stretch they could find for the run and Young avoided the larger craters.
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As we have film of the Rover operating with one occupant and not turning over how did they get it if the Rover wouldn't work?
How can you use film of the rover driving around with one occupant to claim that it couldn't drive around with one occupant?
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As we have film of the Rover operating with one occupant and not turning over how did they get it if the Rover wouldn't work?
How can you use film of the rover driving around with one occupant to claim that it couldn't drive around with one occupant?
Especially since, as I already pointed out, a visual effect would not cut it. You could need a practical effect, i.e. something that worked. Actually, it would have to work better than the rover ever would, yet be visually identical, even in close up.
Got an answer, anywho?
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The drawing a few pages back references specifically to the acceptable CoG for a LRV with TWO astronauts. What is the acceptable CoG for a LRV with ONE astronaut?
Noldi400 beat me to the punch, but the document you reference already contains expected performance deviation for operational considerations outside the nominal envelope. I tried to have a discussion with you about what these envelopes mean, but you just accused me and others of being "difficult." You quote nominal c.g. envelopes as if they were some hard-and-fast limit to what can be done. It's especially disingenuous that if you had actually read the document you quoted, you likely would have come to the realization that the LRV can indeed be suitably operated outside those envelopes given certain accommodations, even if you didn't understand the details. If the document gives peformance data for the three major LRV configurations, why would you say they weren't studied or tested? If the document provides graphs telling you how performance degrades if the c.g. is eccentrically located, or if speed or slope are out of nominal ranges, then why would you suggest the vehicle cannot be operated under those conditions?
Your whole notion of "allowable envelope" is naive. There is the nominal envelope and then there is a less well defined degradation of performance. If your hoax theory depends on the assumption of hard-and-fast limits, beyond which operation is impossible, then you're out of luck.
This is why I posed the question as to whether the rovers were ever actually designed for one astronaut.
Yes, it was a specific design requirement. The LRV had to be able to operate either with up to 100 pounds-mass of equipment plus two astronauts at 370 pounds-mass each, or one astronaut plus up to 470 pounds-mass of cargo -- and up to 70 pounds-mass of accumulated samples in both configurations. (Lunar Roving Vehicle Statement of Work. Doc. RFP#1L-LRV-1. Huntsville, Ala. (MSFC). July 3, 1969. p. 15)
However, you've been asserting ever since your arrival here that a one-occupant LRV was too badly "unbalanced" to be used as depicted. This was before you did any appreciable research, performed any computation, or indeed investigated the problem with any sort of rigor. Now you're trying to backfill your predetermined belief by trumped-up accusations of missing requirements and performance data and continued handwaving attempts at vehicle engineering. You don't seem to entertain the possibility that all the word's engineers might be right after all and you, fumbling as you go, might be wrong.
What in the debriefing refutes the two valid links I supplied?
"[transcribing John Young] I didn't get up to any great speed, maybe 10 clicks at the most, but the terrain was too rough and too rocky for that kind of foolishness." (Apollo 16 Technical Crew Briefing. Houston, Tex. (MSC). May 5, 1972. p. 10-59) While Young's top speed may have been 10 km/h, we know his typical speed in the Grand Prix was much less. We take Young at his word when he reports the top speed reached as 10 km/h, but we note that later in the debrief he admits being unable to accurately estimate speeds between 7 and 10 km/h by eye, and that he didn't have his eye on the speedo very often.
We can also photographically (i.e., photogrammetrically) reconstruct the two out-and-back jaunts Young did on the film. We know the film speed and we know key LRV dimensions, so we can determine how far he went and how long it took him to get there. The average speeds of his out-and-back trips are in the 7-8 km/h range, if I recall correctly.
Finally, item B on the commander's EVA checklist for the Grand Prix instructs him to call out his maximum speed. Why? Because the three goals of the Grand Prix were to test max acceleration, extreme steering, and max braking. To test max acceleration you accelerate flat-out from a standing stop in a straight line until you get to the fastest speed you're comfortable with, and then call it out. This is what Young did. The time (as recorded by the film) and the highest speed reached give acceleration. But the steering and braking tests weren't conducted at full speed, or indeed at any designated speed. So Young's stability and braking tests took place at much lower speeds. He did two rounds of this. To insinuate that the Grand Prix was recklessly conducted at excessive speeds is simply incorrect.
One which is the speed limit set at 8.5kph over rough mare...
No. First, "rough mare" is defined in Exhibit 1 of the SOW. Young's "rough and rocky" comment notwithstanding, you may not substitute your personal interpretation of it. Stanley Kaufman at Bell Labs did the mathematical modeling of terrain and established those breakpoints based on modeled vehicle performance. They are criteria that relate to how the vehicle actually behaves differently due to terrain, not some eyeball or wishful-thinking estimate.
Second, the table from which you quote "top" speeds is qualified, not absolute. You may not disregard the qualifications. The contract top speed for flat and level terrain was 16 km/h. According to your table the "top speed" was 13 km/h for flat and level terrain. So how did Boeing get away with delivering a vehicle that didn't meet specifications? The answer is that the results Boeing publishes here are not "top speeds." They're recommended speeds, given certain conditions and additional requirements. That's the qualification.
The specific qualification here is astronaut fatigue. You have to hold on, and the Apollo 15 crew discovered that the faster you go for long periods, the more fatiguing it is to hold on tight enough. Going slower reduces the fatigue of riding. The recommended speeds beginning with Apollo 16 are for sustained travel, where fatigue becomes a factor. For a ten-second acceleration test, the cruise-speed recommendations are irrelevant.
...and one which says they went 10kph over what is obviously rough mare...
I know Eric Jones (the ALSJ author) and I'm sure I can convince him to forgive you for misinterpreting his narration. He merely quotes the estimate of momentary top speed provided by the crew, not some imaginary sustained speed.
...and with one astronaut so the CoG is outside the acceptable envelope.
Outside the nominal envelope. Do not impose your interpretation or layman's notion of requirements. And you have provided no correct computation for where the one-occupant c.g. would be, so you have no basis for the premise that the c.g. was outside any sort of envelope.
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That was pretty much my point, Jay. If Anywho had actually read the document he cited, it should have covered all his questions.
BTW, thanks, Anywho, for that link. I hadn't seen that particular one and it's a welcome addition to my collection.
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Can anyone figure out what I just described? :)
Some piece of railroading rolling stock, I'm sure. And I'm equally sure you'd take the same sort of exception to a non-railroader who claimed railroad operations were unacceptably hazardous because they didn't conform to that person's misguided, simplistic conceptions of vehicle dynamics.
Tri-level or tall bi-level (for trucks) auto rack.
Anywho - think about one loaded with 15 automobiles, 5 to a deck. We move 'em at up to 70MPH. By your reasoning, we couldn't do it as the CG would be too high.
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So what is the allowable CoG envelope?
(http://i627.photobucket.com/albums/tt353/jarvisn/LRV-CG_zpsf7015c4a.jpg)
If you read the document you quoted yourself, note where it says "Allowable C.G envelope for vehicle fully loaded".
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If you read the document you quoted yourself, note where it says "Allowable C.G envelope for vehicle fully loaded".
He wants the c.g. for other loadouts. What he doesn't seem to realize is that there are several pages of graphs in his document that relate recommended operational limits to displacement of the c.g. both vertically and laterally (since roll stability seems to be the prime concern). That is, "If your c.g. is laterally displaced by this many inches, your maximum turn radius and speed are..." and then you read the graph for whatever property you're interested in. The allowable (i.e., nominal) c.g. envelope promises that if you keep the c.g. within these boundaries under the given loadout, the LRV can be counted on to fulfill its other obligations, such as 16 km/h maximum speed over flat level ground, turn radius governed by nominal velocity, static roll and pitch excursions due to terrain up to 45 degrees in any axis, and so forth. Basically it says, "If you keep the c.g. in here, you can do everything in the statement of work without worry."
It's the difference between required performance under contract acceptance conditions, and real-world performance under exceptional conditions. The Boeing documentation provides the results of their testing and modeling that, first, prove the vehicle meets contractual requirements, and second, shows what the vehicle is likely to do when contractual requirements are exceeded. For example, at full speed with the c.g. displaced 7 inches laterally from the longitudinal axis, Boeing recommends increasing the turn radius from 34 feet to 40 feet. This is based in part on Kaufman's model, but also in part on empirical tests. It doesn't matter why the c.g. would displaced. The one- or two-astronaut dilemma is a red herring. The point is that the data are there. At 8 km/h, the nominal maneuvering speed, you can displace the c.g. laterally by two feet and the turning radius goes from 10 feet to 20 feet. Yes, the c.g., is well outside the "allowable" envelope at this point. But that doesn't mean the vehicle suddenly becomes undrivable. It means it will likely fail if the nominal turning radius were attempted, but that's just stupid. anywho reads far too much into "allowable."
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You are studiously and obviously avoidng the question asked of you MANY TIMES. I think it's high time you were pulled up and REQUIRED to answer:
1. What is being shown in the lengthy films of the LRV? What is the vehicle and where/how was it filmed?
I have asked that question twice. Anywho, take this post as the third time of asking.
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He wants the c.g. for other loadouts. What he doesn't seem to realize is that there are several pages of graphs in his document that relate recommended operational limits to displacement of the c.g. both vertically and laterally (since roll stability seems to be the prime concern).
I'm sure anywho will correct me if i'm wrong, but i would be willing to bet a factor in his insistence that his source material did not contain such information is an inability to interpret the graphs. I suspect he wants pretty pictures of the rover with one astronaut and a big black dot where the centre of mass is in that configuration.
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I have asked that question twice. Anywho, take this post as the third time of asking.
Take this as another, anywho. There is film (and some video) of the rover being operated with one astronaut. There is footage of it being operated full stop. Will you please explain exactly what that is actually shoting if not an operational rover, paying particular attention to the fact that these bits of film and video either show clear evidence of low gravity and vacuum or else are part of longer pieces of footage that show clear evidence of same even if the rover footage itself is not so clear on those points.
What is your alternative scenario to 'the rovers were operated on the Moon as described'?
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What is your alternative scenario to 'the rovers were operated on the Moon as described'?
I imagine something along the lines of the Rover in the film not being built to the Specs put out by NASA and the footage is somewhere on Earth.
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I think the alternative is not to go down the road of alternatives if that makes sense. This seems to be the basis for this little theory, unless a hole can be proven or doubt shown then other paths will not be looked into in public as they cannot be backed up without this perceived issue. I suspect he/she is waiting for a typo or slight error to try to capitalise. Lack of any reasoning other than gut feeling and waiting for someone to slip up, albeit in error, and use that.
I rather suspect people like me who are not qualified do not count here. Some form of authority is required to bolster the attempt.
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Well, it appears to me that the document you referenced (NASA-TX-X-66816, the LRV Performance Data Appendix) pretty much answers all the questions you've posed.
Specifically, they evaluated the stability of the LRV when occupied by one astronaut:
(http://i627.photobucket.com/albums/tt353/jarvisn/Figure3-4_zpseacc740e.jpg)
Yep lol, the one time they specifically acknowledge one astronaut is when the rover is static, not moving, parked.
They even evaluated your question about sliding-sideways-and-hitting-a-rock:
(http://i627.photobucket.com/albums/tt353/jarvisn/Figure3-5_zpsc8f1068a.jpg)
No they don't, not fully anyhow, they evaluated it for fully loaded only. A tripped rollover is the most common cause of rollovers and yet they ignore evaluating when only one astronaut is on board. You are even more likely to end up sideways if you are driving around over slippery, uneven terrain, in an unbalanced vehicle.
And, yes, it is unbalanced with a 400lb astronaut sitting on one side of a 460lb vehicle, and, yes, this does take it outside the designated envelope.
Why don't they pay attention to the additional rollover possibilities that occur with one astronaut?
these bits of film and video either show clear evidence of low gravity and vacuum or else are part of longer pieces of footage that show clear evidence of same even if the rover footage itself is not so clear on those points.
f you want to see what low gravity would really looks like, then have a look at the most valid test they did on the rovers (starts at 2.04):
https://www.youtube.com/watch?feature=player_detailpage&v=FVMfjPXwRO4#t=124s
Look at it bouncing around even at very low speeds and a relatively smooth test bed, look at what a farce the test is and how they have to take a run up to even get over the test bed, look at how once they lose a bit of steering they can't regain control.
But hey, on the moon, with bumpier terrain, at higher speeds, and even in an unbalanced vehicle with only one astronaut on board they had no problems.
What a joke.
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Anywho, why are you ignoring the questions put to you?
I don't think you believe the things you are saying. You keep making handwaving "arguments" that show nothing, and launch insults to boot. Clearly you neither know nor care about how the LRV worked, you just feel like being contrary. Please, get a better hobby.
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What a joke.
I would agree with if you can prove it. I would like to follow your workings out, that is me starting from scratch and learning something as I am new to this. At the moment my gut feeling still says your gut feeling is wrong.
So, over to you. My money is on you not proving it.
BTW How are the motor calculations coming on?
You said
Power:
The rovers would appear to be massively underpowered, they have 4 x 1/4hp motors giving a grand total of 1hp to drive a 1,500lb vehicle. One horsepower is low powered even for a mobility scooter, imagine putting seven big blokes on a low powered mobility scooter and seeing what performance you get out of it, yet on the moon they hooned around no problems at all.
Your first post. I started to look at this but held back waiting for input from you. Looks interesting.
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You are even more likely to end up sideways if you are driving around over slippery, uneven terrain, in an unbalanced vehicle.
Once again, anywho, more likely than what?
You keep making comparative statements without any numbers that are relevant to anything to do with the comparison. You have already been told that astronauts driving the rover reported that when they could feel the back wheels slipping out they were capable of steering to correct before they ended up sideways.
And, yes, it is unbalanced with a 400lb astronaut sitting on one side of a 460lb vehicle, and, yes, this does take it outside the designated envelope.
Designated for what? Once again you have ignored the painstakingly reiterated point that there is a difference between 'this vehicle's performance is degraded outside these parameters' and 'this vehicle cannot be operated outside these parameters'.
Why don't they pay attention to the additional rollover possibilities that occur with one astronaut?
Why don't you prove they have not done adequate testing by demonstrating some knowledge of engineering rogor and procedure? It is not inadequate simply because you say it is.
If you want to see what low gravity would really looks like, then have a look at the most valid test they did on the rovers (starts at 2.04):
That does not answer my question, and I do not accept your assertion that the test is the 'most valid'. Especially as it is plainly only 'most valid' in your eyes because it appears to you to support your predetermined conclusion: exactly the opposite of sound reasoning.
Look at it bouncing around even at very low speeds and a relatively smooth test bed,
The test bed is not 'smooth'. It is liberally peppered with small rocks, and the suspension system does exactly what it is supposed to, with the wheels responding to the rocks and the chassis not bouncing around violently at all.
look at what a farce the test is
Since you do not know the purpose and full extent of that test you may not dismiss it as a farce based on a few seconds of film.
and how they have to take a run up to even get over the test bed
Who says they 'have' to take a run up to get over the test bed? What is the test actually testing? Unless it is specifically intended to test the characteristics of the rover from a standing start, why would they not take a run up? If the test is intended to examine only the handling characteristics at 'steady state' then having them do the run up before entering the test bed is a perfectly sound piece of testing protocol.
You also assume it is a test of the rover, whereas the narration states it is actually a training aid for the astronauts to get them used to the feel of driving it in a reduced gravity environment. In that case you cannot describe it as a 'valid' test of the rover, because it is not actually any test of the rover at all, and more than the LLRV is a test of the LM.
look at how once they lose a bit of steering they can't regain control.
Show me the section where they lose control, and support your assertion. You have already told us you have no sound on your computer, so without that, what information do you actually have on the aims and outcomes of those few seconds of footage?
But hey, on the moon, with bumpier terrain, at higher speeds, and even in an unbalanced vehicle with only one astronaut on board they had no problems.
What a joke.
The joke is you and your continuing inability to demonstrate even the merest hint of an understanding of the way to discuss an engineering issue. Give us numbers and we'll have a decent discussion. Until then you will simply find your arguments dismissed as the handwaving rubbish they really are.
Now answer my question: what do you propose is actually being shown in the footage of the rover being driven on the Moon?
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they went well outside the recommended CoG and well outside the speed limits, on the moon where any failure could be disastrous,
Please support your assertion that failure of the rover would be disastrous. Rolling over at low speed into loose regolith while wearing a spacesuit in a vehicle that both astronauts could lift between them hardly seems a disaster, compared to things like landing the LM on the Moon. Never done before, and crashing the LM was not survivable. And yet people willingly did it.
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This will be my last post until I am out of moderation, it is just too difficult.
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What a joke.
Yes it is. You're still just waving your hands and begging the question, and proving that you really don't read the material before you shoot your mouth off.
You're not an engineer. You're wrong. Get over it.
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How can you use film of the rover driving around with one occupant to claim that it couldn't drive around with one occupant?
Easy, actually. Remember, like any hoaxer his basic premise was that it was all faked. So whenever you confront him with evidence that refutes his beliefs, he can claim it's fake and simply wave it away. No justification is necessary.
Remember, NASA is all powerful. They have secret technology, including but not limited to CGI far beyond anything Hollywood has even today. They can violate the laws of nature at will. They know everything, including the future, and they can do anything. Except land humans on the moon, of course.
Of course, that won't stop him from using information from NASA or anyone else when he thinks it can be used to his advantage.
Basically, in the fantasy universe of the hoaxer you can "prove" whatever you want by picking and choosing -- and modifying or ignoring -- evidence any way you like. The rest of us, who have to accept empirical evidence unless we can show a good reason not to, are at a significant disadvantage.
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Anywho, why are you ignoring the questions put to you?
I, too am curious why you can't answer this question, any...you post "what a joke", but the only humor I'm getting out of this thread is the that you still have not provided a lick of evidence for your claim that the rover was faked.
Well...here's a few related question for ya anywho...
How do you account for the 16mm video taken during the traverses between stations? (I'm specifically referring to A16) ...how was that faked?
Also, we can match "Lunar"marks (like landmarks :) ) seen in the traverses videos, to recent images taken from orbit.
How exactly was all that faked?
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f you want to see what low gravity would really looks like, then have a look at the most valid test they did on the rovers
Care to tell us what you expertise ins in this type of testing and design that allows you to call this "the most valid test?"
You seem to have a knack for criticizing others work in an area in which you have demonstrated no knowledge. Your lame analogies and after the fact inclusion of information brought to you in rebuttals is a pretty good indication that you haven't done any original work on the subject. This has shown you to be yet another internet crank.
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Yep lol, the one time they specifically acknowledge one astronaut is when the rover is static, not moving, parked.
Changing horses. You questioned whether any design work had been done for the vehicle under different loadout conditions. It had been -- the evidence for it is in a document you imply, by citing it, that you've read. Other evidence is in documents you were previously unaware of, yet you insisted on drawing a conclusion without that evidence, all the while insinuating that your cursory survey of the available information and your knowledge of the attendant sciences were adequate. You don't get to rationally move on to the next handwaving conspiracy claim without conceding that you were wrong about the first.
Consider that point the next time you insinuate that just because you haven't come across something yet, it must therefore not exist.
No they don't, not fully anyhow, they evaluated it for fully loaded only.
This rejoinder fails on three points. First, it is an argument from silence. You may not infer from the absence of some specific, arbitrary result from this particular document that the information was not known. Second, it is a begged question -- and one you consistently beg despite all requests to the contrary. You may not decide based on your layman's belief and supposition that certain information is of utmost importance and then hold professionals responsible for providing it. Third, describe how you would draw a graph consistent with those in this document, that would relate all the relevant variables.
A tripped rollover is the most common cause of rollovers...
In what environment?
And, yes, it is unbalanced with a 400lb astronaut sitting on one side of a 460lb vehicle...
Asked and answered.
...and, yes, this does take it outside the designated envelope.
You don't know what is meant by "envelope" and you keep changing your wording to dance around the fact of your ignorance.
Why don't they pay attention to the additional rollover possibilities that occur with one astronaut?
Argument from silence, along with question-begging.
If you want to see what low gravity would really looks like, then have a look at the most valid test they did on the rovers (starts at 2.04):
Dodges the question. Are you able to explain the Grand Prix video or not, in the context of your hoax hypothesis?
Look at it bouncing around even at very low speeds and a relatively smooth test bed...
What is your evidence that this is unacceptable or out-of-tolerance behavior?
...look at what a farce the test is...
I do not accept you as an authority on engineering test methods or automotive engineering, so I do not accept your judgment about the fidelity or validity of the test. Please make a more rigorous and/or documented argument.
...and how they have to take a run up to even get over the test bed...
Why does this matter?
look at how once they lose a bit of steering they can't regain control.
"Cannot regain control" over what time interval, and for what definition of "control?"
But hey, on the moon, with bumpier terrain, at higher speeds, and even in an unbalanced vehicle with only one astronaut on board they had no problems.
You have not quantified or discussed "bumpier terrain," nor dealt with the rebuttal to your assumption.
You have not addressed the rebuttal to your "higher speeds" claim.
You have not described "unbalanced" qualitatively, nor provided a correct quantitative assessment for your "unbalanced" claim, nor dealt with the fact that you were provided all long with stability factors based on displacement of the nominal c.g.
Since you're just repeating the same unsubstantiated claims over and over, I have little else but to believe you have absolutely no interest in learning about this subject or responding to the criticism of your hypothesis.
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This will be my last post until I am out of moderation, it is just too difficult.
You have to earn getting onto the moderation list, and you have to earn getting off of it. If you think threatening not to post will get you off moderation faster then you obviously don't know me very well.
If you prove to me that you can have a proper two-way discussion without insulting people I will take you off the moderation list.
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This will be my last post until I am out of moderation, it is just too difficult.
I see Anywho has put another post onto the Naked Scientist thread linked above, including a link to the Earth-based counter-weight test of the Rover.
Anywho, consider that you've had your interpretation of the physics of driving a car on the Moon contradicted on three separate forums, two of which have plenty of scientists and engineers on them (and I assume the NS one does too). You might like to consider that it's your version of the science that's wrong, not everyone else's.
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You have to earn getting onto the moderation list, and you have to earn getting off of it. If you think threatening not to post will get you off moderation faster then you obviously don't know me very well.
I'll see how long I can put up with the added frustration for.
If you want to see what low gravity would really looks like, then have a look at the most valid test they did on the rovers (starts at 2.04):
That does not answer my question, and I do not accept your assertion that the test is the 'most valid'. Especially as it is plainly only 'most valid' in your eyes because it appears to you to support your predetermined conclusion: exactly the opposite of sound reasoning.
This is untrue, I nominated the skid car type test as the most valid before trebor (many thanks) posted that footage, so I had nominated that as the "most valid" before I saw that the results supported my conclusion. Here is what I wrote:
...they used a scale model for testing.
A scale model reduces the mass as well as the weight so it will only test if a lightweight rover will work on earth, not 1/6g. The best testing would probably be something like a skidcar where the weight is reduced but the mass is the same, but it would be hard to make an off road version.
(https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTsS2vjcAlxOl_jwltPnbc4q4-fkuJQDdTHoHMjchvNOHhZGGng)
Anywho, consider that you've had your interpretation of the physics of driving a car on the Moon contradicted on three separate forums, two of which have plenty of scientists and engineers on them (and I assume the NS one does too). You might like to consider that it's your version of the science that's wrong, not everyone else's.
"My interpretation" is based on the physics, not some blind belief that they couldn't fake it.
The most valid experimental test results back up that 4WDrivng, on a loose surface, on the moon is nigh on impossible.
The numbers back up that a loose surface, combined with 1/6g, will be about as slippery as ice (here's a link to another set of numbers, to be dutifully ignored, that shows a gravel and dirt road having a CoF of .35 and ice as .1, so this set shows it would be worse than ice on the moon. .35/6 = .06)
http://www.nzta.govt.nz/resources/surface-friction-conference-2005/8/docs/frictional-characteristics-roadside-grass-types.pdf
It is important to note that although the astronauts pay lip service to the slippery conditions, what we see in the actual footage is very good traction with virtually no slipping and sliding to represent treacherous conditions. Traction-wise it doesn't look any different to what would be expected on earth.
What defense will be put up against both the test and the numbers (and common sense) coinciding to tell us that 4WDiving will be virtually impossible on the moon?
I expect to be told that the lunar surface is not a loose surface but is in fact very cohesive, yet what we see in all the footage is a very loose surface moving freely beneath the astronauts feet. So Peter B, do I believe what I see with my own eyes, or do I believe what I am told to believe? Is it a loose surface or not?
I expect to be told there is something almost magical about the design of the tires, yet they have no deep tread, and have a relatively smooth shallow chevron covering 50% of the surface area. It does looks fancy though, so do we just ignore that it absolutely flies in the face of conventional design and pretend as though it holds some hidden secret to overcoming the massive traction loss under 1/6g?
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Its a game.
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Hey, I just realized:
The astronauts are trying to walk around in 1/6 g. Not only do they still have their Earthly mass, they are wearing extremely heavy packs that make them even more unbalanced. Their boots have no more contact area than my tennis shoes, but at 1/6 g get only 1/6 the traction. It should have been impossible for them to move. They would have slid across the landscape like a kid on his first day at the skating pond, then toppled over with all that extra mass.
So all the EVAs are fake.
First of all, their boots had much bigger contact area than any tennis shoe you could buy - probably about 4 times the area. Secondly, the tread had big deep grooves, to improve the traction. Third, they pushed into the surface with their boots. Fourth, you confuse mass and weight (hint: the PLSS weren't heavy in lunar gravity).
Edit: Aldrin's boot prints were 13x6 inches - about 511 cm2.
Never a truer word said in jest by nomuse, which is why it got the bite it did.
Funny how a deep tread becomes important for traction when it suits.
You are dead set right nomuse, it would be a nightmare for traction when you are top heavy, on a loose surface, and only have 1/6th the traction. It's funny how popular sci-fi takes precedence over the laws of physics in all of the lunar footage.
In popular sci-fi on the moon you just have 1/6th the weight so you are free to skip around all you want, it's all good fun.
The laws of physics say you have the same mass, and once you start moving you will have the same momentum as on earth, so having 30kgs of weight on the ground when you are trying to control 180kgs would be a nightmare.
But hey, all these problems will not make for good tv, so we'll just go with the popular sci-fi version.
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I'll see how long I can put up with the added frustration for.
No-one really cares how long you can put up with it for. You are moderated for a reason. You want to stop being moderated, start acting decently and answering questions put to you without resorting to childishness.
This is untrue, I nominated the skid car type test as the most valid before trebor (many thanks) posted that footage, so I had nominated that as the "most valid" before I saw that the results supported my conclusion. Here is what I wrote:
You also wrote that you have no sound on your computer, and you also took that one test with no idea what it was actually testing and hung your entire conclusion from it. You have yet to prive that the run up to the test bed is suspect. You have yet to prove they 'lost control'. You have yet to prive that the boundcing around is inapprorpriate or problematic.
"My interpretation" is based on the physics, not some blind belief that they couldn't fake it.
No, your interpretation is based on your limted understanding of physics, which so far seems to go to high school level at most. You are talking to people who do this stuff for a living. Why do you think all of them are wrong and your limited understanding must be right? What arrogance you must have.
The most valid experimental test
In your view. Back that up. You don't even know what that test in the footage was actually testing, or even if it was testing anything rather than, as the narration of the clip that you never heard actually states, a training aid for the astronauts to get the feel of driving the thing.
What defense will be put up against both the test and the numbers (and common sense) coinciding to tell us that 4WDiving will be virtually impossible on the moon?
You have had it explained to you repeatedly. What good would be served by going over it again? Anyone who disagrees with you is dismissed.
I expect to be told that the lunar surface is not a loose surface but is in fact very cohesive, yet what we see in all the footage is a very loose surface moving freely beneath the astronauts feet.
No, what we see is a top layer of loose surface with a layer of compacted, cohesive regolith under it. Kicking off some loose dust from the top to expose a decent surface underneath is what we see.
I expect to be told there is something almost magical about the design of the tires, yet they have no deep tread, and have a relatively smooth shallow chevron covering 50% of the surface area. It does looks fancy though, so do we just ignore that it absolutely flies in the face of conventional design and pretend as though it holds some hidden secret to overcoming the massive traction loss under 1/6g?
We pretend nothing. We look at the design history for that tyre, which did not actually start with the development of the rover.
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Hey, I just realized:
The astronauts are trying to walk around in 1/6 g. Not only do they still have their Earthly mass, they are wearing extremely heavy packs that make them even more unbalanced. Their boots have no more contact area than my tennis shoes, but at 1/6 g get only 1/6 the traction. It should have been impossible for them to move. They would have slid across the landscape like a kid on his first day at the skating pond, then toppled over with all that extra mass.
So all the EVAs are fake.
First of all, their boots had much bigger contact area than any tennis shoe you could buy - probably about 4 times the area. Secondly, the tread had big deep grooves, to improve the traction. Third, they pushed into the surface with their boots. Fourth, you confuse mass and weight (hint: the PLSS weren't heavy in lunar gravity).
Edit: Aldrin's boot prints were 13x6 inches - about 511 cm2.
Never a truer word said in jest by nomuse, which is why it got the bite it did.
Funny how a deep tread becomes important for traction when it suits.
You are dead set right nomuse, it would be a nightmare for traction when you are top heavy, on a loose surface, and only have 1/6th the traction. It's funny how popular sci-fi takes precedence over the laws of physics in all of the lunar footage.
In popular sci-fi on the moon you just have 1/6th the weight so you are free to skip around all you want, it's all good fun.
The laws of physics say you have the same mass, and once you start moving you will have the same momentum as on earth, so having 30kgs of weight on the ground when you are trying to control 180kgs would be a nightmare.
But hey, all these problems will not make for good tv, so we'll just go with the popular sci-fi version.
And yet they didn't move as described or depicted in any previous science fiction. The closest I can think of is Tintin -- and the two-legged hop developed by Captain Haddock as he experimented with lunar locomotion is perhaps as due to his peculiar character and the inherent physical comedy as any understanding of the relevant physics.
(Nor has any FOLLOWING science fiction film managed to depict the lunar gait. Most do not even bother to try).
Your argument is invalid. There was no bounding across the surface, no great leaps. The actual lunar experience was -- yes! -- careful, sliding motions, aware of stability and the interaction of mass and weight, and a few falls as well. It was not like any popular depiction then....or since.
(In fact, to most of your companions-in-arms, the lunar motions look wrong because they AREN'T what they credulously expected from men on the Moon. Over and over again, in fact, other hoaxies ask "Where are the giant leaps?")
Incidentally, physics is not a magic word. It is a process. You can't just say "physics proves it." Physics doesn't do ANYTHING by itself. It just sits there. You have to USE physics to prove something...and you do so by doing, and showing, the work. Which is mathematical. This is the strength of the tool; that you can show by calculation that which may go against intuition.
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"My interpretation" is based on the physics, not some blind belief that they couldn't fake it.
Until you show your work, your interpretation is solely based on your personal belief as far as everyone else is concerned. Quit pretending! Show us your calculations and answer the questions such as how the Lunar Grand Prix was filmed.
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"My interpretation" is based on the physics, not some blind belief that they couldn't fake it.
Until you show your work, your interpretation is solely based on your personal belief as far as everyone else is concerned. Quit pretending! Show us your calculations and answer the questions such as how the Lunar Grand Prix was filmed.
Seconded, come on Anywho lets cut the crap about 'slippery as ice lunar surfaces', the obvious ease in which a vehicle will overturn in 1/6 gravity and how much a single astronaut would destroy the stability of the LR.
Why not Prove that you are right with the appropriate engineering/design calculations to show the lack of stability of the LR .....and whilst you are at it can you show with the appropriate geological evidence that the lunar surface is as 'slippery as ice'...... and then seeing as you beleive the whole thing was faked...you must have some relevant insight into how it was faked...just how did they film it on Earth? Becuase if it was faked I and many many others really would like to know how it was done.
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Moreover, if it's so easy as all that to prove it was fake, why hasn't every auto manufacturer in the world called them out on it? Every tire manufacturer? Every auto racer? Every off-road enthusiast? The fact that pretty much all of them accept the footage as shown should prove something, right?
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It's funny how popular sci-fi takes precedence over the laws of physics in all of the lunar footage.
Is this supposed to be evidence for something?
When will you be presenting evidence that the rovers were faked?
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Why not Prove that you are right...
...or at least make an attempt to prove...
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What defense will be put up against both the test and the numbers (and common sense) coinciding to tell us that 4WDiving will be virtually impossible on the moon?
Defense?....against what?
As has been stated too many times, your interpretation is not evidenced. If you expect anyone to take you seriously, you need to stop "declaring victory", and start providing actual evidence to "back up" the claims you have made.
...but I'm not holding my breath until I turn blue waiting for that to happen.
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A friend of mine points out that if Jupiter had a solid surface, you could drive on it. Presumably, your car wouldn't tip over or slide around all the time. But since Earth has much less surface gravity, then obviously driving HERE is impossible!
The point being, picking Earthlike conditions as some sort of norm is silly. The physics don't say, "How far are we off from 1g?" They say, "What is the calculated tipping moment for the conditions under discussion?"
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I'll see how long I can put up with the added frustration for.
You're being indulged, not indulgent. Your frustration is entirely of your own devising. You're making an engineering argument without doing any engineering. Your failure to convince practicing engineers properly frustrates you.
"My interpretation" is based on the physics...
Nonsense. You patently don't understand the physics, and just about the only thing you've been doing for the past several pages is to state and restate your belief repeatedly and beg us to "all agree on it." People are telling you why they don't accept your claims and they're telling you what it would take for them to accept them. You're simply not listening, or else uninterested in discussion beyond browbeating.
...not some blind belief that they couldn't fake it.
My rejection of your claim is based on decades of experience as a professional engineer. Your claim is laughably naive. Don't pretend your argument is so evidently strong that disbelief in it can only be the product of naivete or pig-headedness. You fail to convince because you can't do more than state a belief.
The numbers back up that a loose surface, combined with 1/6g, will be about as slippery as ice...
Asked and answered. Don't repeat yourself.
...what we see in the actual footage is very good traction with virtually no slipping and sliding to represent treacherous conditions.
Asked and answered. The purpose and parameters of the Grand Prix were explained to you, along with a refutory analysis. You have failed to address any of it.
What defense will be put up against both the test...
Asked and answered. Your layman's expectations for what the test should depict are not a valid yardstick.
...and the numbers...
Asked and answered. Your make-it-up-as-you-go analytical methods are not valid. You will not explain why you refuse to use industry-standard models. Also, you were caught asking questions that were answered in your own sources. You are unprepared to support your claims.
...(and common sense)...
Irrelevant. Science and engineering exist precisely because "common sense" (i.e., uninformed intuition) is so often wrong. You are being asked to supply an appropriately rigorous support for your claims, which contradict the conclusions of the entire engineering world. You will have to do more than "common sense."
I expect to be told that the lunar surface is not a loose surface but is in fact very cohesive, yet what we see in all the footage is a very loose surface moving freely beneath the astronauts feet.
Asked and answered. You were directed to the studies of matrixing and cementation, but have declined to comment. In spite of all available knowledge, you simply resort to your subjective lay interpretation of video. Sorry, you are not the guru of lunar regolith. Others are, because they studied it. I will accept their findings over your idle speculation.
You have no knowledge of the lunar surface characteristics, so you simply assume it must be like something you're already familiar with. No, the problem will not be dumbed down to your level. If you want to be believed, you will need to rise to the level of the professionals who study this.
I expect to be told there is something almost magical about the design of the tires, yet they have no deep tread, and have a relatively smooth shallow chevron covering 50% of the surface area.
And if you knew anything about the soil mechanics of the lunar surface, you'd realize why a 50% occlusion works better than a "deep tread." The surface of the chevrons was not the frictive interface, it was the weight-bearing portion. Further, please enlighten us with your learned conclusions on why rubber pneumatic tires are the safest thing to use on a lunar roving vehicle.
...so do we just ignore that it absolutely flies in the face of conventional design
You aren't an expert on tire design, conventional or otherwise. Keep the magic to yourself. You're asking us to believe that you, a layman, have magically come up with the smoking gun that negates five decades of informed belief by the engineering community.
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The point being, picking Earthlike conditions as some sort of norm is silly. The physics don't say, "How far are we off from 1g?" They say, "What is the calculated tipping moment for the conditions under discussion?"
You could certainly make a case for 1g being the norm for biological entities which evolved on earth, but I don't think the rover falls into that category. Earth cars are engineered for earth, moon buggies are engineered for the moon.
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I'll see how long I can put up with the added frustration for.
You wouldn't tell a mathematician they they have the solution to a quadratic equation wrong if you didn't even understand how to do quadratic equations.
You wouldn't tell football player the he had broken the rules if you didn't even understand what the rules of football were.
You wouldn't tell an English teacher that they had spelled some words incorrectly if you didn't actually yourself know how they were spelled.
Yet, you are quite willing to tell highly experienced engineers they are wrong, when you clearly do not understand the engineering yourself. You substitute your own flawed intuition in place of sound, calculable, engineering principles.
As long as you stay your current course, you will continue to be frustrated. You might be able to get away with making unsubstantiated, unproven and false statements on CT websites, but you will find that this approach does not work here, because people like Lunar Orbit, ka9q and JayUtah will call your bluff every time. You will continue to be pressed for your calculations to prove your assertions correct until you either provide them, or become so frustrated with not being taken seriously, that you no longer post here.
This is the reason why you'll never see ignorant fools like Jarrah White and Bart Sibrel here, because they cannot control the posts to suppress those posters who understand the engineering, physics and maths involved. If any of them posted here with their preposterous theories, guys like the ones I mentioned above would tear their arguments to ribbons; and they know it.
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I expect to be told that the lunar surface is not a loose surface but is in fact very cohesive, yet what we see in all the footage is a very loose surface moving freely beneath the astronauts feet.
Asked and answered. You were directed to the studies of matrixing and cementation, but have declined to comment. In spite of all available knowledge, you simply resort to your subjective lay interpretation of video. Sorry, you are not the guru of lunar regolith. Others are, because they studied it. I will accept their findings over your idle speculation.
So I should study matrixing and cementation to tell me that the lunar surface is, contrary to the visual evidence presented as the lunar surface, not a loose surface?
The sad thing is that most here will probably agree with you that the lunar regolith does not fit into the category of a loose surface, in spite of what they can see with their own eyes, namely the dirt moving freely and easily when disturbed, along with deep footprints etc.
I am being very honest and very objective when I characterise the lunar surface as "loose", any numbers can be fudged but the visual evidence is very clear, the surface, as presented, is loose.
It is impossible for me to independently test the coefficient of friction for lunar soil and the rover tires, but I can still clearly see that it is a loose surface, and a loose surface with 1/6g equals a very low CoF. Using basic numbers available the lunar surface ends up about as slippery as ice.
I expect to be told there is something almost magical about the design of the tires, yet they have no deep tread, and have a relatively smooth shallow chevron covering 50% of the surface area.
And if you knew anything about the soil mechanics of the lunar surface, you'd realize why a 50% occlusion works better than a "deep tread." The surface of the chevrons was not the frictive interface, it was the weight-bearing portion.
Actually, I'm pretty sure read somewhere that the chevrons are there to stop the tires filling up with dirt, either way they both restrict the frictive surface to 50%, and, bizarrely, recess the all important frictive surface as well, but no matter how nonsensical this design is, we must have faith that they overcame both the loose surface and 1/6g to give us 4WDriving on the moon with traction that looks remarkably similar to a loose surface on earth.
You wouldn't tell a mathematician they they have the solution to a quadratic equation wrong if you didn't even understand how to do quadratic equations.
The little boy in the story of the emperor has no clothes was completely wrong to state the obvious?
So even when it is obvious for all to see that the moon has a loose surface everyone should just agree that, although we can see the dirt moving very freely with our own eyes, because the learnered kings men have said it is not loose you should not believe what you see with your own eyes?
This is like pulling teeth, can one of you please agree that the surface of the moon, as presented in the apollo footage, is a loose surface.
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Irrelevant. Science and engineering exist precisely because "common sense" (i.e., uninformed intuition) is so often wrong.
It's amazing how often we get appeals to "common sense". If "common sense" were all that we humans needed, we wouldn't have to waste 12 years (and often 4, 5, 6 or more) of our lives getting educated instead of producing. We wouldn't have to waste a significant chunk of our tax dollars on schools and teachers -- something even most conservatives think is so important that it should be provided free to everyone as a socialistic government service.
If "common sense" were all we humans needed, we'd still be living as we have for most of our 200,000 - 300,000 year existence: as small bands of hunter-gatherers in the tropics. It wasn't until a few of us set their "common sense" aside and designed an effective system to discover how the world really works that we made real progress.
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It's amazing how often we get appeals to "common sense". If "common sense" were all that we humans needed,
Casinos would go out of business.
Relevant:
http://en.wikipedia.org/wiki/List_of_cognitive_biases
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So I should study matrixing and cementation to tell me that the lunar surface is, contrary to the visual evidence presented as the lunar surface, not a loose surface?
"Visual evidence" is simply you watching videos and trying to draw quantitative conclusions from it. So yes, you should study actual quantitative assessments rather than guessing.
I am being very honest and very objective when I characterise the lunar surface as "loose"...
You're just repeatedly begging the question.
Actually, I'm pretty sure read somewhere that the chevrons are there to stop the tires filling up with dirt...
No, but you're close.
...and, bizarrely, recess the all important frictive surface as well...
Why is that bizarre? Again, if you understood cementation and matrixing you'd understand where the traction comes from. And no, it's not a simple surface-shearing-on-surface model.
...but no matter how nonsensical this design is...
Your layman's judgment for what is "nonsensical" is irrelevant. You simply don't understand the design, so you assume it must be wrong. That will always fail to impress.
...we must have faith that they overcame both the loose surface and 1/6g to give us 4WDriving on the moon with traction that looks remarkably similar to a loose surface on earth.
Exactly the opposite. There is no faith required in engineering, but you do have to understand it. The design principles are well established here. The models are well understood, although they are not the simple ones you guess they are. The testing is well established. And generations of engineers subsequently offer their informed acceptance of it.
You're the one asking for faith. You demand belief, but you fail to provide rigor. You argue strictly from analogy you demand and assume must be relevant. You allude to science, but do no homework. You ask us to take on faith your interpretation of a few seconds of video as indicative of a quantitative condition.
The little boy in the story of the emperor has no clothes was completely wrong to state the obvious?
Your conclusions are not self-evident no matter how fervently you wish them to be.
This is like pulling teeth, can one of you please agree that the surface of the moon, as presented in the apollo footage, is a loose surface.
Your frustration is irrelevant, and it is entirely of your own devising. This is obviously the first time you've had to make any sort of formal argument, and any sort of argument involving engineering and engineering rationale. Until you come up with a more objective and supported claim than "Because I say so," and until your statements rise above "Will someone please just agree that I'm right," you will make zero headway here -- properly so.
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...can one of you please agree that the surface of the moon, as presented in the apollo footage, is a loose surface.
So you have stooped to "begging' for someone to agree with you?
Delicious...:)
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So I should study matrixing and cementation to tell me that the lunar surface is, contrary to the visual evidence presented as the lunar surface, not a loose surface?
Yes. That is how actual science and engineering is done. You don't get to look at something and conclude its physical properties simply on the basis of a bit of film footage.
The sad thing is that most here will probably agree with you that the lunar regolith does not fit into the category of a loose surface, in spite of what they can see with their own eyes, namely the dirt moving freely and easily when disturbed, along with deep footprints etc.
And what of the stuff that is uncovered by the removal of loose surface material? how does the cohesive nature of the regolith change with depth? How does it react when compressed? When I go walking on a sandy beach I kick up a lot of sand. I do not have trouble walking on it, despite leaving deep footprints and kicking up loose surface material.
I am being very honest and very objective when I characterise the lunar surface as "loose",
Rubbish. You are being entirely subjective. it looks loose to you therefore you have decided that is the sole characteristic worth mentioning and using in your argument.
any numbers can be fudged but the visual evidence is very clear
I wondered when we'd get to the attempt to dismiss the entire area of quantitiative analysis in order to bolster your argument. Again, the exact oposite of actual science and engineering.
Using basic numbers available the lunar surface ends up about as slippery as ice.
Correction: using inappropriate numbers that have no bearing on the surface or vehicle design actually involved on the Moon. You don't just get to apply a set of numbers from something you googled up to the moon and expect a bunch of professional engineers to agree with you.
Let me restate that: professional engineers.
we must have faith
No, we must have the actual engineering data and understanding. This is NOT a matter of faith. This is a matter of actual engineering expertise. You have none, patently. Others here do, and have plenty of it.
The little boy in the story of the emperor has no clothes was completely wrong to state the obvious?
Don't try and pass yourself off as some lone voice of reason among a crowd of people deluded or deliberately avoiding the obvious. You have NO relevant understanding of the engineering required in design and construction of a lunar rover.
And we still await your explanation for what exactly is being seen in the film of the rover being operated. Clearly that vehicle CAN be sat on by one astronaut and driven around on a 'loose' surface.
So even when it is obvious for all to see that the moon has a loose surface everyone should just agree that, although we can see the dirt moving very freely with our own eyes, because the learnered kings men have said it is not loose you should not believe what you see with your own eyes?
Whenh what you can see with your own eyes on some low res video is a decent substitute for a proper analysis of the characteristics of lunar regolith including cohesiveness, compaction, response to pressure etc. then we'll give you a call.
This is like pulling teeth, can one of you please agree that the surface of the moon, as presented in the apollo footage, is a loose surface.
No. I can agree that it has a loose top layer. What happens when the movement of the wheel shifts that lose material and it begins to get a grip with the stuff under it?
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The sad thing is that most here will probably agree with you that the lunar regolith does not fit into the category of a loose surface, in spite of what they can see with their own eyes, namely the dirt moving freely and easily when disturbed, along with deep footprints etc.
Your own eyes?
You have demonstrated no "skill set" that would allow you to make such a determination...as you have been told numerous times.
I am being very honest and very objective when I characterise the lunar surface as "loose"...
How is what "you" think, relevant?...so you are "honestly" mistaken...so what?
...any numbers can be fudged but the visual evidence is very clear, the surface, as presented, is loose.
Ok...now we are getting somewhere. Since YOU brought it up, please show where the numbers have been changed in order to fake a Moon mission.
...and if you don't provide those numbers, post haste then it will only be further evidence that you're just "blowing smoke" at us.
It is impossible for me to independently test the coefficient of friction for lunar soil and the rover tires, but I can still clearly see that it is a loose surface, and a loose surface with 1/6g equals a very low CoF. Using basic numbers available the lunar surface ends up about as slippery as ice.
More unsupported claims...still no evidence for those claims...typical hoax believer "tactics".
...no matter how nonsensical this design is...
Perhaps to ignorant people...those who have studied Apollo understand why things were done the way they were done.
...we must have faith that they overcame both the loose surface and 1/6g to give us 4WDriving on the moon with traction that looks remarkably similar to a loose surface on earth.
No "faith" necessary...we have evidence that the landings happened. When will you be providing evidence that they did not??
The little boy in the story of the emperor has no clothes was completely wrong to state the obvious?
Once again...this is evidence of what exactly??
So even when it is obvious for all to see that the moon has a loose surface everyone should just agree that, although we can see the dirt moving very freely with our own eyes, because the learnered kings men have said it is not loose you should not believe what you see with your own eyes?
This isn't evidence of anything except your own failings.
Will you stop "proclaiming" yourself correct, and start proving yourself correct??
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I am just looking at a paper on the testing of the wheels now:
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
They simulated 57lbs of weight on the wheels, and for measuring drawbar pull the "two horizontal sensor bars have a maximum capacity of approximately 150lbs each", this would seem to be inadequate because a wheel with 57lbs weight the moon has to be able to move 342lbs.
Interestingly, they have a pull coefficient of approx 0.5 to 0.6 before slip becomes so bad it will immobilise the vehicle (1), now I read that as meaning with 57lbs weight the wheel can pull 85lbs to 92lbs before slip is too problematic, yet it has to pull 342lbs to move the rover.
Am I reading it wrong or does this test show that the lrv wheels could not possibly operate on the moon?
(1) fig. A12. graph entitled "comparisons of relations off pull coefficients to slip obtained by three different recording methods", it is the last graph, third page from the bottom.
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The wonderful thing about math is that it doesn't rely on anyone's personal experience. You plug in the right numbers to the right formula, and you get the right answer. (Probably. But if you don't, that is the fault of neither the numbers nor the formula!) It is, as has been stated, the exact opposite of faith. "Looks like" is pretty well meaningless in science, because the human eye is easily fooled, especially in situations--such as the Moon--out of our usual expectations.
And I mean, heck, the eye is fooled all the time even by situations that we should be accustomed to; I can't tell you how many times around here people assume that the ground is solid and safe to walk across when in fact it's boggy. You can tell get across it, probably, but it's slick and oozing. But to the eye, it's fine!
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Heh, I had an experience like that. Fell hip deep in murky 'water' that looked just like ground.
Fun times, especially when it's your only pair of pants you got with you.
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Am I reading it wrong or does this test show that the lrv wheels could not possibly operate on the moon?
Seriously, which do you think is more likely? Given that untold thousands of people have read it before you have. Given that professional engineers have read it before you have and still believe that the LRV was performing as expected. Given all the facts you've been ignoring thus far, what do you think the odds are that you're the one who is right and everyone else ever is wrong?
Add this to the list of "really simple questions you should answer now, please."
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Anywho, what exactly is your claim here?
If you are trying to argue that the Apollo missions were faked -- that no one ever went to the Moon -- then you can't use the visual record as evidence of the lunar surface characteristics, "loose" or otherwise.
On the other hand, if you don't dispute that the lunar landings occurred, then that same visual record clearly shows that the LRV worked as claimed.
Suppose the visual evidence itself was faked somehow, either via then-nonexistent CGI or some physical means (an exact LRV lookalike operating in some earthly environment). In either of those cases, you can't use the visual evidence to support any claims about the lunar surface. If CGI, the surface could have been made to look any way they chose, so why would they have built in evidence that (you claim) suggests that the LRV was inoperable? If physical, the LRV is operating in a real environment that you're claiming (based on that very evidence) that it can't.
So which of the above are you actually claiming, and how do you explain the fact that, either way, the evidence shows a functional LRV?
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Am I reading it wrong or does this test show that the lrv wheels could not possibly operate on the moon?
Hmm, let's think which is more likely, shall we? Either a whole bunch of professional engineers over five decades have misread that report and assumed they could go ahead and build a rover using those wheels and have it work on the moon, or someone who has demonstrated no grasp of the mathematics, physics or engineering princicples beyond high school level has misunderstood it. It's a toughie...
Anywho, for the umpteenth time, if it was all faked what is going on in the film of the rover working?
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Heh, I had an experience like that. Fell hip deep in murky 'water' that looked just like ground.
Fun times, especially when it's your only pair of pants you got with you.
I came out of the plane once on a beautiful sunny day in Virginia, aimed for the lush green grass near the edge of the airfield...and realized an instant before I hit that there was an inch of standing water and thick soft mud under that grass. Being muddy myself wasn't so bad, but I made a really, really lousy PLF trying to twist and keep the 1911 I was carrying that day from going into the mud with me.
Not that this has anything to do with the Moon...
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To reiterate what Donnie B said:
According to you Anywho, they faked going to the Moon which would mean that any videos or images of the rover driving could not have been taken on the Moon.
But you use the same videos and images to show how loose and slippery the lunar surface is.
Do you not see a problem there? Please directly address this in your next post.
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The little boy in the story of the emperor has no clothes was completely wrong to state the obvious?
No, he wasn't wrong, but then it doesn't take any kind of expertise as a tailor to see that the King was naked, and besides, unlike engineers, physicists and scientists who earned their qualifications, the king became king by inheriting the title, not by spending many years competing a university degree in Clothesmaking.
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Am I reading it wrong... [?]
Yes.
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Perhaps anywho, you are incorrectly thinking that the lunar dust is as described in Arthur C. Clarke's famous SF book "A Fall of Moondust"...."an extremely fine dust, a fine powder far drier than the contents of a terrestrial desert and which almost flows like water" and you cannot see how the wheels of a vehicle can possibly grip this surface.
Well its not like that. Lunar soil becomes very dense beneath the top layer of regolith, in much the same way that sand on a dry beach becomes compacted below the top surface though the action of water and tides. Its why I can drive my 4WD quad bike on a totally dry stretch of my local beach without any difficulty at all.
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I am just looking at a paper on the testing of the wheels now:
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
They simulated 57lbs of weight on the wheels, and for measuring drawbar pull the "two horizontal sensor bars have a maximum capacity of approximately 150lbs each", this would seem to be inadequate because a wheel with 57lbs weight the moon has to be able to move 342lbs.
Well, it's no secret that physics is not my strong subject, and that report is so far over my head it threatened to give me a nosebleed, but even I can spot the flaw in that statement. 57 lbs represents the weight on each wheel on the moon. The LRV wasn't designed to operate in the Earth environment; there would be no reason to test the wheels with the earth weight of the loaded rover.
Heh, I had an experience like that. Fell hip deep in murky 'water' that looked just like ground.
Fun times, especially when it's your only pair of pants you got with you.
I came out of the plane once on a beautiful sunny day in Virginia, aimed for the lush green grass near the edge of the airfield...and realized an instant before I hit that there was an inch of standing water and thick soft mud under that grass. Being muddy myself wasn't so bad, but I made a really, really lousy PLF trying to twist and keep the 1911 I was carrying that day from going into the mud with me.
Not that this has anything to do with the Moon...
"Hey, Gene, would you go over and help Twinkletoes, please?” comes to mind.
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Anywho, what exactly is your claim here?
If you are trying to argue that the Apollo missions were faked -- that no one ever went to the Moon -- then you can't use the visual record as evidence of the lunar surface characteristics, "loose" or otherwise.
On the other hand, if you don't dispute that the lunar landings occurred, then that same visual record clearly shows that the LRV worked as claimed.
Suppose the visual evidence itself was faked somehow, either via then-nonexistent CGI or some physical means (an exact LRV lookalike operating in some earthly environment). In either of those cases, you can't use the visual evidence to support any claims about the lunar surface. If CGI, the surface could have been made to look any way they chose, so why would they have built in evidence that (you claim) suggests that the LRV was inoperable? If physical, the LRV is operating in a real environment that you're claiming (based on that very evidence) that it can't.
So which of the above are you actually claiming, and how do you explain the fact that, either way, the evidence shows a functional LRV?
I guess we left behind the HBs contradiction thread. But by Anywho claiming the rovers were fake while citing the footage of them in operation on the moon as evidence to support the soil characteristics of the moon certainly qualifies for an entry.
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To reiterate what Donnie B said:
According to you Anywho, they faked going to the Moon which would mean that any videos or images of the rover driving could not have been taken on the Moon.
But you use the same videos and images to show how loose and slippery the lunar surface is.
Do you not see a problem there? Please directly address this in your next post.
I am saying 4WDrivng, as presented n the appolo footage is faked, and part of the evidence is that the surface of the moon, as presented in the apollo footage, is loose and therefore combined with 1/6g presents an unassailable traction problem for the rovers, as presented.
There is no contradiction in using apollo footage, as presented, to prove the apollo footage, as presented, is fake.
Does this really have to be explained? This message board invites people to put hoax theories forward so it should not make your head explode that proponents of the hoax theory use the apollo footage to support their claims.
Well, it's no secret that physics is not my strong subject, and that report is so far over my head it threatened to give me a nosebleed, but even I can spot the flaw in that statement. 57 lbs represents the weight on each wheel on the moon. The LRV wasn't designed to operate in the Earth environment; there would be no reason to test the wheels with the earth weight of the loaded rover.
The wheel with 57lbs of weight on the moon has to move the equivalent of 342lbs of mass horizontally on the moon, and the testing shows it can't be done.
I am not saying they should have put 342lbs of weight on the wheels, I m saying the wheels have to get enough traction to be able to pull 342lbs horizontally in order for the rovers to move on the moon, and not only does the testing show that the wheels slip well before that, but the equipment is not even sufficient to test it fully.
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
The weight is 1/6 on the moon, but the mass that has to be propelled horizontally is the same as on earth. This is where the traction problems are.
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Perhaps anywho, you are incorrectly thinking that the lunar dust is as described in Arthur C. Clarke's famous SF book "A Fall of Moondust"...."an extremely fine dust, a fine powder far drier than the contents of a terrestrial desert and which almost flows like water" and you cannot see how the wheels of a vehicle can possibly grip this surface.
Well its not like that. Lunar soil becomes very dense beneath the top layer of regolith, in much the same way that sand on a dry beach becomes compacted below the top surface though the action of water and tides. Its why I can drive my 4WD quad bike on a totally dry stretch of my local beach without any difficulty at all.
Or you can walk in deserts at all. Beaches might be a bad example as there is things start getting wet not far down. Incidentally, despite been published in 1961, A Fall of Moondust 'predicts' the 'no stars' claim, a television crew mentioning how many viewers find a lack of visible stars to 'look wrong' and the technowizardry they required to get them visible in the same scene as a correctly exposed lunar surface.
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the human eye is easily fooled, especially in situations--such as the Moon--out of our usual expectations.
And I mean, heck, the eye is fooled all the time even by situations that we should be accustomed to; I can't tell you how many times around here people assume that the ground is solid and safe to walk across when in fact it's boggy. You can tell get across it, probably, but it's slick and oozing. But to the eye, it's fine!
And when you see someone sink into it, is that not then satisfactory to "see" that the ground is boggy?
Therefore, when I or anyone else who cares to look can see the surface of the moon* is easily disturbed and freely moving under the feet of the astronauts*, is that not then satisfactory to "see" by eye that the surface is loose*?
*As presented by the apollo footage... (do I really have to keep explaining this?)
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someone who has demonstrated no grasp of the mathematics, physics or engineering princicples beyond high school level has misunderstood it.
Hey, don't knock high school physics and math. If he understood them at even that level we'd be well ahead.
A lot of people would be better off if they'd actually learned and retained high school physics and math.
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the human eye is easily fooled, especially in situations--such as the Moon--out of our usual expectations.
And I mean, heck, the eye is fooled all the time even by situations that we should be accustomed to; I can't tell you how many times around here people assume that the ground is solid and safe to walk across when in fact it's boggy. You can tell get across it, probably, but it's slick and oozing. But to the eye, it's fine!
And when you see someone sink into it, is that not then satisfactory to "see" that the ground is boggy?
Therefore, when I or anyone else who cares to look can see the surface of the moon* is easily disturbed and freely moving under the feet of the astronauts*, is that not then satisfactory to "see" by eye that the surface is loose*?
*As presented by the apollo footage... (do I really have to keep explaining this?)
I want you to explain why you think the missions were faked, yet you also claim to know everything there is to know about the surface of the moon from the Apollo films of it.
The rover is clearly shown moving well on the surface you claim it cannot move on. How do you resolve this contradiction? It looks to me like you are simply ignoring it.
Why have you consistently refused to acknowledge the people who point out the differences between the uppermost layer of regolith and the layers below it?
Please also explain why you think your clear ignorance of engineering and physics should be taken more seriously than the work of experienced engineers.
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And when you see someone sink into it, is that not then satisfactory to "see" that the ground is boggy?
And when you have seen that, does that give you enough information to devise a machine to move across it?
Therefore, when I or anyone else who cares to look can see the surface of the moon* is easily disturbed and freely moving under the feet of the astronauts*, is that not then satisfactory to "see" by eye that the surface is loose*?
*As presented by the apollo footage... (do I really have to keep explaining this?)
What you really have to explain is why you are using the Apollo footage at all to bolster your argument that the rover could not operate on the surface. Can you really not grasp the fact that you are using footage of the rover actually moving over that loose surface to try and tell us it couldn't move over such a loose surface?
There is footage of a rover being sat on and operated at decent speeds over what you claim is obviously a loose surface. The vehicle on the film footage manifestly can operate on that surface, so how can you possibly claim it can't?
You have been asked this many times now, anywho. Please will you do us the courtesy of actually answering that question. What is going on in that footage if not a rover being operated by one astronaut on a loose surface: something you claim is impossible?
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I am not saying they should have put 342lbs of weight on the wheels, I m saying the wheels have to get enough traction to be able to pull 342lbs horizontally in order for the rovers to move on the moon, and not only does the testing show that the wheels slip well before that, but the equipment is not even sufficient to test it fully.
How much of a horizontal force do you need? Unless you expect 1 g acceleration or the ability to climb a really steep slope, things that most cars cannot manage, the horizontal force is less than the vehicle weight.
You really are not thinking this traction business through. You claim that the vehicle would tip over, but this will only happen if the wheels exert a lot of sideways force. You simultaneously claim that the wheels don't have much traction, so can't exert such force. You are refuting your own argument.
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I am saying 4WDrivng, as presented n the appolo footage is faked, and part of the evidence is that the surface of the moon, as presented in the apollo footage, is loose and therefore combined with 1/6g presents an unassailable traction problem for the rovers, as presented.
There is no contradiction in using apollo footage, as presented, to prove the apollo footage, as presented, is fake.
There is a contradiction.
If that footage is fake then it is not on the Moon and therefore you cannot use it to judge the properties of the lunar surface. The rover in the footage clearly is not having difficulty with that surface.
In order to use that footage to describe what the lunar surface is like you are implicitly agreeing that it actually does show the lunar surface, therefore is not faked. The rover in the footage clearly can drive over that surface.
Does this really have to be explained? This message board invites people to put hoax theories forward so it should not make your head explode that proponents of the hoax theory use the apollo footage to support their claims.
The problem is the way you are trying to use it. If that footage does not show the lunar surface, you cannot use it to support your argument that the rover could not operate on the Moon by using the footage of that non-lunar surface.
As presented, that rover has no difficulty with that surface.
The wheel with 57lbs of weight on the moon has to move the equivalent of 342lbs of mass horizontally on the moon, and the testing shows it can't be done.
There's the flaw in your logic. Shifting a given mass horizontally requires overcoming the inertia of the system. That is not the same as exerting a force greater than the weight of the object. I can push a car along a flat surface provided the brakes are off and it is in neutral. I cannot lift it. I can't lift it because I cannot exert a greater upward force than the weight of the car. I don't have to do that in order to make it move laterally, however. I can move a piano around a concert hall, rolling it on its castors. I can't lift it.
The weight is 1/6 on the moon, but the mass that has to be propelled horizontally is the same as on earth. This is where the traction problems are.
No, this is where you misunderstanding is. To overcome the inertia of a given mass does not require overcoming its weight unless you are trying to lift it.
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Therefore, when I or anyone else who cares to look can see the surface of the moon* is easily disturbed and freely moving under the feet of the astronauts*, is that not then satisfactory to "see" by eye that the surface is loose*?
You're trying to infer traction parameters from a few seconds' casual inspection of surface being aggressively disturbed. That's not good enough if you're going to challenge every engineer on the planet.
No rigor, no credibility. Got it?
*As presented by the apollo footage... (do I really have to keep explaining this?)
Yes you do. And more. And please look up what "begging the question" means.
First you have to tell us what magical faculties you possess that allow you to infer specific parameters as you claim to have done. "Easy to see" and "common sense" are cop-outs. Especially when I've mentioned what surprises the physical sciences discovered. But hey, if you're uninterested in the science then there are plenty of late night crackpot radio shows that will indulge you while the rest of us continue engineering.
Second you have to address the gaping logical flaw in your argument. That's the dichotomy of claiming that the rovers were faked (meaning that film allegedly depicting them operating on the lunar surface cannot be what it claims to be), while at the same time you're using this allegedly faked footage to infer properties of the real lunar surface.
If you spend less time complaining about having no credibility, and more time listening to people tell you why you're non-credible, you'd make more headway.
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There is no contradiction in using apollo footage, as presented, to prove the apollo footage, as presented, is fake.
Well, you go right on believing that....won't change the reality of the Apollo missions, or the fact that you "say" a lot, but have proven NOTHING.
Does this really have to be explained?
Listen fella....your have NOTHING to "teach" us...you only bring ignorance, and irrelevant personal opinion to this board.
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...by Anywho claiming the rovers were fake while citing the footage of them in operation on the moon as evidence to support the soil characteristics of the moon certainly qualifies for an entry.
I'll say....and the sad thing is...his denial of that obvious contradiction.
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There should be a wooden spoon award for stirrer of the year.
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This message board invites people to put hoax theories forward...
Yes....this board also expects those who promote hoax "theories" to back -up those theories WITH TESTABLE, CREDIBLE EVIDENCE.
When will you be getting around to doing that?
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^^^^
That has been the ask from page one. The reply is a dodge, always a dodge in its many forms.
He/she also claimed the motors were not up to it and there is no reply to that yet. Page one. I think it is ahuge chain yank to see how long he/she can keep going.
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Oh well, if nothing else there is the education value, though not in the way Anywho intended.
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^^^^
That has been the ask from page one. The reply is a dodge, always a dodge in its many forms.
He/she also claimed the motors were not up to it and there is no reply to that yet. Page one. I think it is ahuge chain yank to see how long he/she can keep going.
That is a possibility. But its also possible that Anywho really believes this. Either way, the question dodging is getting old. Anywho has had an opportunity to make a point and failed to do so. It is becoming the time when he should be held to an elevated standard of responsiveness.
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And when you see someone sink into it, is that not then satisfactory to "see" that the ground is boggy?
Well, you do get to watch them sink, but unless you know how much they weigh, you can't know how much it takes to sink.
Therefore, when I or anyone else who cares to look can see the surface of the moon* is easily disturbed and freely moving under the feet of the astronauts*, is that not then satisfactory to "see" by eye that the surface is loose*?
But they don't sink, do they? Which makes it obvious that it's only the very top layer that moves easily. They move aside the stuff that moves easily, and they, the rover, and the LM are all fine.
*As presented by the apollo footage... (do I really have to keep explaining this?)
Well, you could start by explaining why, if it's so obvious, people who deal in traction for a living don't have a problem with it. Why your "common sense" about Apollo beats their in some cases decades of expertise. Why the only people who ever seem to deny Apollo are ignorant in all the relevant issues. You might explain what you think happened, how you think the footage was filmed, something using actual evidence. Not "this is what it looks like to me," because your eye is wrong.
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the human eye is easily fooled, especially in situations--such as the Moon--out of our usual expectations.
And I mean, heck, the eye is fooled all the time even by situations that we should be accustomed to; I can't tell you how many times around here people assume that the ground is solid and safe to walk across when in fact it's boggy. You can tell get across it, probably, but it's slick and oozing. But to the eye, it's fine!
And when you see someone sink into it, is that not then satisfactory to "see" that the ground is boggy?
Therefore, when I or anyone else who cares to look can see the surface of the moon* is easily disturbed and freely moving under the feet of the astronauts*, is that not then satisfactory to "see" by eye that the surface is loose*?
*As presented by the apollo footage... (do I really have to keep explaining this?)
Is an inch of standing water a lake? If you can't see down into it, you don't know how deep it is.
Yes, the lunar SURFACE is loose, fine, easily disturbed. But you can't tell from that how far down solid surface is.
Oh, except by minor clues such as these; the LM didn't sink in. The bootprints around a cm deep. When using the penetrometer, or when setting up the flag, the astronauts had to use hammers after the first few cm into the soil.
Ah, but here we get REALLY interesting. You are using imagery from the lunar surface to describe what you think the lunar surface is like and why you think that does not support the narrative of the landings.
Do you not see the conflict here?
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^^^^
That has been the ask from page one. The reply is a dodge, always a dodge in its many forms.
He/she also claimed the motors were not up to it and there is no reply to that yet. Page one. I think it is ahuge chain yank to see how long he/she can keep going.
That is a possibility. But its also possible that Anywho really believes this. Either way, the question dodging is getting old. Anywho has had an opportunity to make a point and failed to do so. It is becoming the time when he should be held to an elevated standard of responsiveness.
It's a fishing expedition. The only thing he is interested in doing here is keeping conversation going...because he is gleaning it for technical-sounding terms he can then take to a different board and show off with.
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^^^^
That has been the ask from page one. The reply is a dodge, always a dodge in its many forms.
He/she also claimed the motors were not up to it and there is no reply to that yet. Page one. I think it is ahuge chain yank to see how long he/she can keep going.
That is a possibility. But its also possible that Anywho really believes this. Either way, the question dodging is getting old. Anywho has had an opportunity to make a point and failed to do so. It is becoming the time when he should be held to an elevated standard of responsiveness.
Whether he/she believes it or not, I think there has been enough prompting, information and certainly a challenge to the idea that should have produced the info that backs up the claim. The entity known as anywho side steps all the time. For example the lack of info and avoiding the motor power. That way has some requirement to produce the figures that can be checked where as wafty replies can dance around tyre performance. So motors are off the agenda. But I do not have the goal posts anywho does, we shall see.
For what it is worth I have once again gained more knowledge by the replies to the questions, none has been gained from anywho directly.
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Bah. I need to move to the East Coast or start working graveyard shift. If I didn't hit "reply" before reading all of the existing posts, I'd never post at all.
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To reiterate what Donnie B said:
According to you Anywho, they faked going to the Moon which would mean that any videos or images of the rover driving could not have been taken on the Moon.
But you use the same videos and images to show how loose and slippery the lunar surface is.
Do you not see a problem there? Please directly address this in your next post.
I am saying 4WDrivng, as presented n the appolo footage is faked, and part of the evidence is that the surface of the moon, as presented in the apollo footage, is loose and therefore combined with 1/6g presents an unassailable traction problem for the rovers, as presented.
There is no contradiction in using apollo footage, as presented, to prove the apollo footage, as presented, is fake.
Does this really have to be explained? This message board invites people to put hoax theories forward so it should not make your head explode that proponents of the hoax theory use the apollo footage to support their claims.
I've grown dizzy from watching all the spinning you've been doing. Your dancing, waffling and resistance to proper addressing of your logical inconsistancies now prompts me to ask these questions:
Do you believe any of the Apollo lunar footage is real? Yes or no!
If so, then do you accept that Apollo missions did land men on the Moon? Yes or no!
If not, then (one more time) how do you reconcile using any of the footage, including footsteps, as an example of actual lunar ground conditions?
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I am saying 4WDrivng, as presented n the appolo footage is faked, and part of the evidence is that the surface of the moon, as presented in the apollo footage, is loose and therefore combined with 1/6g presents an unassailable traction problem for the rovers, as presented.
I will attempt to show you your contradiction.
1. The LRV footage is fake.
2. This is demonstrated by the behaviour of the LRV on the faked Moon surface.
3. There is no way due to the behaviour of the LRV, that this was on the Moon.
4. Therefore, your conclusion on how the Moon surface actually works is based on a fake video.
5. Given that, you have no idea what the Moon surface is really like, and have further no idea how it may or may not react to anything.
6. So how do you know how the surface of the Moon operates? Your only evidence is videos you claim were faked on Earth. If true, then you can make no claim as to the behaviour of the Lunar surface, since your claim of fakery means that these videos happened on Earth.
There is no contradiction in using apollo footage, as presented, to prove the apollo footage, as presented, is fake.
Oh yes there is. See above.
Does this really have to be explained? This message board invites people to put hoax theories forward so it should not make your head explode that proponents of the hoax theory use the apollo footage to support their claims.
There really is a comprehension issue here. If the videos are evidence of how the Lunar surface behaves, then they are equally evidence of the Rover on the Lunar surface. OTOH, if the videos are fake, then the surface is also fake and you have nothing.
The wheel with 57lbs of weight on the moon has to move the equivalent of 342lbs of mass horizontally on the moon, and the testing shows it can't be done.
I am not saying they should have put 342lbs of weight on the wheels, I m saying the wheels have to get enough traction to be able to pull 342lbs horizontally in order for the rovers to move on the moon, and not only does the testing show that the wheels slip well before that, but the equipment is not even sufficient to test it fully.
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
The weight is 1/6 on the moon, but the mass that has to be propelled horizontally is the same as on earth. This is where the traction problems are.
It is pointless to go here. You have already demonstrated that you don't do physics. Deal with the contradiction first, please.
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There is no contradiction in using apollo footage, as presented, to prove the apollo footage, as presented, is fake.
I disagree with Jason Thomson here
I think you are right in that using something that is fake to prove its fake is valid (e.g. you look at a candidate counterfeit banknote, and point out that it is missing its watermark; you have used an aspect of the candidate fake item to prove that it is in fact a fake)
However, your problem lies in the conclusions you draw. What you are doing is using the claimed fake video to ascertain aspects, not about the video itself, but about the conditions under which the video was filmed, then using those conditions to prove the video was faked.
You claim that the video was faked, therefore, you must also claim that the video was not filmed on the moon, therefore, you cannot deduce anything about the lunar surface from the way the surface in the video behaves.
If you claim that the way the surface behaves shows that it is the lunar surface, then you cannot claim that the video was not filmed on the moon, ergo, it was not faked.
You can't have it both ways... choose one!!!
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Another point that occurred to me: anywho is claiming that the (real) Moon surface is "as slippery as ice". If this is true, why aren't the astronauts themselves sliding around? Their boots are no more effective at traction on ice than the LRV's wheels.
ETA: At least, I would expect them to be as effective as the LRV's wheels on ice. They have treads, yes, but so do the LRV wheels; I would expect the wire mesh in the wheels to act like the grooves in the boot treads.
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Anywho, I know the logic you're attempting to use in this thread. If the lunar conditions were as shown in the footage you claim was faked, then driving in 1/6g would have been impossible, thereby proving that the footage was faked. This is the crux of your rationale, right?
The problem is that you have failed miserably in your attempt to convince any of us that it would have been impossible. Your appeal to common sense and visual interpretation is inadequate and your conclusions have been shown to be flawed regarding mass, inertia and weight (see Posts #411 and #412 and there are many other answers you have not addressed).
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Indeed this may be one of the more incoherent arguments we've had. What then are we watching if not some kind of vehicle operating in some kind of environment?
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Yeah, as pointed out - and s/he doesn't properly address this - s/he's basically saying "this video showing the LRV driving on the Moon shows that the LRV can't drive on the Moon." Basic internal contradiction.
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Some hoaxers believe that they used a set completely filled with an artificial dust\mixture. It can all be somed up in three words. "MAGIC SAND!"
Also, known as moon sand.
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It can all be somed up in three words. "MAGIC SAND!"
Is this supposed to be some sort of a joke?...or can't you count?
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The wheel with 57lbs of weight on the moon has to move the equivalent of 342lbs of mass horizontally on the moon, and the testing shows it can't be done.
I am not saying they should have put 342lbs of weight on the wheels, I m saying the wheels have to get enough traction to be able to pull 342lbs horizontally in order for the rovers to move on the moon, and not only does the testing show that the wheels slip well before that, but the equipment is not even sufficient to test it fully.
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
I missed this earlier, so let me address it now.
This, more than anything else you have posted, shows that
a) you have little if any understanding of the principles of force, weight and mass.
b) you have a propensity to read a technical/engineering document and draw totally incorrect conclusions from it.
My car is a Subaru Impreza SW; it has a dry weight of about 3000 lbs. If I lean on it with all my weight, I can apply a force of about 40lb; sufficient to move the car on level ground. Why is this? Simply because its not the mass of the car that I have to overcome to get it moving, its overcoming friction that is the issue. You simply do not need 3000 lbs of force to move a 3000 lb vehicle horizontally. That friction can be down to a number of things. If mass is a constant, then the type of surface and the size of the wheels are the biggest issues.
I struggle to push a 3000 lb car along a road, but a 3000 lb loaded two-wheeled horse cart is easy to move and maneuvre because its wheels are four and a half feet in diameter
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A theme that keeps repeating in Anywho's posts seems to be that while he has a superficial understanding of the difference between weight and mass, he doesn't understand how that difference affects things in the real world.
Reminds me of Heiwa and the Magic Disappearing Propellant.
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Ever see those strong men competition programs where they pull lorries? Then there is one fella that pulls an aircraft. Just looked up the record, some guy has dragged a Globemaster.
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The wheel with 57lbs of weight on the moon has to move the equivalent of 342lbs of mass horizontally on the moon, and the testing shows it can't be done.
I am not saying they should have put 342lbs of weight on the wheels, I m saying the wheels have to get enough traction to be able to pull 342lbs horizontally in order for the rovers to move on the moon, and not only does the testing show that the wheels slip well before that, but the equipment is not even sufficient to test it fully.
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
My car is a Subaru Impreza SW; it has a dry weight of about 3000 lbs. If I lean on it with all my weight, I can apply a force of about 40lb; sufficient to move the car on level ground. Why is this? Simply because its not the mass of the car that I have to overcome to get it moving, its overcoming friction that is the issue. You simply do not need 3000 lbs of force to move a 3000 lb vehicle horizontally.
I never said that the wheels had to apply 342lbs of force, I said they have to pull (a) 342lbs (mass) horizontally. I included the extra words to make my point clearer.
The testing shows a drawbar pull (pull/weight) of .5 to .6 before slipping becomes too problematic, this means that the rover wheel can pull it's own weight plus 50 to 60% more.
This would be fine on earth, but on the moon the wheel needs to pull an additional 500% above and beyond the weight it has on it.
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We'll add graph reading to the list of things you don't know how to do properly.
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... on the moon the wheel needs to pull an additional 500% above and beyond the weight it has on it.
Please show us the numbers you "crunched" to arrive at that 500% figure.
If you can't/won't provide that, then your most recent claim is just like the other claims you have made...just a lot of "smoke-blowing".
Still awaiting the evidenced that the Landings were faked....what is taking you so long?
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To expand on my earlier comment, they are looking at slip on increasing slope angles and at constant speed. Their level surface test is testing a system that has already overcome the inertia of the vehicle and brought it to speed. The wheels don't have to 'pull' the mass of the vehicle any more. It's already moving and will keep moving according to Newton's first law. On a slope the wheels constantly have to pull the vehicle against its own weight, which is pulling it back down the slope, against the direction the wheels are trying to move it in. That's what is being tested. What anywho has called the 'drawbar pull' of 0.5 - 0.6 is actually the force acting to oppose the wheels in their efforts to drive the rover up a slope: the proportion of the weight acting to retard the motion. And that really is weight, not mass.
The test says nothing about the ability of the wheel to get the vehicle moving from a standing start and overcome the inertia of the static rover through controlled acceleration.
You have to identify what the test is actually testing before you can make sense of the results.
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This would be fine on earth, but on the moon the wheel needs to pull an additional 500% above and beyond the weight it has on it.
Wrong.
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This would be fine on earth, but on the moon the wheel needs to pull an additional 500% above and beyond the weight it has on it.
Like others, I would like to know how you determined this.
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The testing shows a drawbar pull (pull/weight) of .5 to .6 before slipping becomes too problematic, this means that the rover wheel can pull it's own weight plus 50 to 60% more.
This would be fine on earth, but on the moon the wheel needs to pull an additional 500% above and beyond the weight it has on it.
I'd be interested to see the force - mass - friction - -inertia calculations you carried out to arrive at that figure, because it sounds like utter BS to me.
You are still not understanding the difference between weight and mass. You obviously do know that an object in a 1G field with a mass of 100kg has a weight of 100kg, while that same object in a 1/6th G field, while only weighing 16kg, nevertheless still has a mass of 100kg. However, you are drawing all the wrong conclusions from this and failing to understand its implications.
Try this thought experiment, and give me an answer
You place a perfectly smooth 100kg block on a perfectly level 100% friction-free surface*. You place this arrangement in a vacuum chamber on the Earth.
It will take "x" amount of force to move the block one metre.
If you now set up an identical arrangement on the moon, how much force will it take to move the block one metre?
CLUE: you won't need engineering calculations to work this out.
*PS: I know there is no such thing as 100% friction free, but humour me!
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Why is it so hard to understand that a properly-designed wheeled vehicle (even a top-heavy one) can drive in a controlled manner under complete control at 10-15kph on a surface with a very low friction co-efficient?
Video proof (http://www.youtube.com/watch?v=vVkJbvv3pHg)
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Why is it so hard to understand that a properly-designed wheeled vehicle (even a top-heavy one) can drive in a controlled manner under complete control at 10-15kph on a surface with a very low friction co-efficient?
Video proof (http://www.youtube.com/watch?v=vVkJbvv3pHg)
Did you hear the one about the Irish Zamboni driver?
He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.
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On a slope the wheels constantly have to pull the vehicle against its own weight, which is pulling it back down the slope, against the direction the wheels are trying to move it in. That's what is being tested. What anywho has called the 'drawbar pull' of 0.5 - 0.6 is actually the force acting to oppose the wheels in their efforts to drive the rover up a slope: the proportion of the weight acting to retard the motion. And that really is weight, not mass.
They are measuring the drawbar pull on a level surface and extrapolating those figures to estimate the slope climbing abilities
"All the wheel performance plots shown herein reflect the assumption that the pull coefficient measured at a given slip on a level surface with a slngle wheel is roughly equivalent to the tangent of the slope that a vehicle equipped with similar wheels can climb"
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
This would be fine on earth, but on the moon the wheel needs to pull an additional 500% above and beyond the weight it has on it.
Like others, I would like to know how you determined this.
For simplicities sake we will use a 600lb vehicle, and all measurements in lbs, and ignore rolling
resistance.
A 600lb vehicle on earth weighs 600lbs and has a mass of 600lbs, on the moon it weighs 100lbs but still has a mass of 600lbs. Each wheel on earth has 150lbs of weight on it, and on the moon each wheel has 25lbs of weight on it.
In both cases the same mass has to be moved horizontally, and the forces needed to accelerate the vehicle horizontally are the same in both cases ("x" for smartcooky), but relative to the weight on the wheels it is not the same.
On earth the wheel has 150lbs of weight on it an has to move 150lbs horizontally so it does not need any drawbar pull to move (it only has to move the weight on it).
On the moon that same vehicle wheel has only 25lbs of weight on it, but it still has to move 150lbs horizontally, so if you base the drawbar pull on the weight on the wheel (which they clearly did in the test) then you need to be able to pull an additional 125lbs on top of the weight of 25lbs, or 500% more.
In the test they lost usable traction at 50 to 60% over what it takes to drive the weight of the wheel, but on the moon the need enough traction to pull an additional 500% more than the weight of the wheel, or a "pull coefficient" of 5, not .5 like they got.
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Once again, anywho, look at the graph and the testing regime. At 0% slip they have defined a 0% pull coefficient. They are NOT testing the ability of the wheel to get the mass of the rover moving, they are testing the abilities of the wheel once steady state has been reached, i.e. at a constant speed over a level surface, and making it slip deliberately to see what it could do on a slope where it does have to pull its weight (not mass) against gravity. At this point the rover does not have to pull its mass in the way you are describing.
The only thing that test tells us about the rovers ability to get moving is that if you started to spin the wheels at that speed the rover would likely slip and not make a clean start in its motion. Well so what? Cars do the same thing. You get round that by using a slow initial acceleration to give the wheels a chance to grip and get the mass of the vehicle moving.
You're taking a test that is designed to assess one aspect of performance and applying it to the one you think it should be testing, just as you did with the footage of the rover going over the test bed.
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In both cases the same mass has to be moved horizontally, and the forces needed to accelerate the vehicle horizontally are the same in both cases ("x" for smartcooky), but relative to the weight on the wheels it is not the same.
On earth the wheel has 150lbs of weight on it an has to move 150lbs horizontally so it does not need any drawbar pull to move (it only has to move the weight on it).
On the moon that same vehicle wheel has only 25lbs of weight on it, but it still has to move 150lbs horizontally, so if you base the drawbar pull on the weight on the wheel (which they clearly did in the test) then you need to be able to pull an additional 125lbs on top of the weight of 25lbs, or 500% more.
In the test they lost usable traction at 50 to 60% over what it takes to drive the weight of the wheel, but on the moon the need enough traction to pull an additional 500% more than the weight of the wheel, or a "pull coefficient" of 5, not .5 like they got.
Wait, what?
You seem to have proven that ion engines are impossible.
What do I mean? I mean that acceleration = force/mass. Always. In most real-world situation, there are addition forces to consider; friction force, air resistance, rolling resistance, etc.
But at the very basics, it does not matter how large the mass is. ANY force will produce an acceleration. And ANY acceleration over time produces velocity.
Which is how ion engines work. Or how solar sails might work. The force is very small. The acceleration is very small. But it is not zero.
IF the bearings in the LRV were perfect, and the wheels infinite in size relative to impeding terrain features (another way of saying, if the surface were perfectly flat), then the beating of a gnat's wings would be sufficient to put the LRV in motion. And if continued for a long enough interval, to reach any desired velocity.
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Once again, anywho, look at the graph and the testing regime. At 0% slip they have defined a 0% pull coefficient. They are NOT testing the ability of the wheel to get the mass of the rover moving, they are testing the abilities of the wheel once steady state has been reached, i.e. at a constant speed over a level surface, and making it slip deliberately to see what it could do on a slope where it does have to pull its weight (not mass) against gravity. At this point the rover does not have to pull its mass in the way you are describing.
The only thing that test tells us about the rovers ability to get moving is that if you started to spin the wheels at that speed the rover would likely slip and not make a clean start in its motion. Well so what? Cars do the same thing. You get round that by using a slow initial acceleration to give the wheels a chance to grip and get the mass of the vehicle moving.
You're taking a test that is designed to assess one aspect of performance and applying it to the one you think it should be testing, just as you did with the footage of the rover going over the test bed.
Heh. He's saying that since I could burn rubber in second gear in my old Mustang (boy, I miss that car!) it is obviously impossible for me to drive. Especially since I was already "losing" traction in the most perfect conditions (according to him); no slope to speak of, and essentially no forward velocity either. Heck, and not the slightest hint of turning forces either (I never left donuts. They are for the uncultured).
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For simplicities sake we will use a 600lb vehicle, and all measurements in lbs, and ignore rolling
resistance.
A 600lb vehicle on earth weighs 600lbs and has a mass of 600lbs, on the moon it weighs 100lbs but still has a mass of 600lbs. Each wheel on earth has 150lbs of weight on it, and on the moon each wheel has 25lbs of weight on it.
In both cases the same mass has to be moved horizontally, and the forces needed to accelerate the vehicle horizontally are the same in both cases ("x" for smartcooky), but relative to the weight on the wheels it is not the same.
Aha!! I think I see what you are trying to say, and where you are making your mistake.
Are you saying that the 25lbs of weight on each wheel is not enough weight to give it the friction it needs to gain traction to move 150 kg of mass horizontally?
If you are, then you are making a fundamental error and approaching the issue too simplistically. Weight on the wheel is not the only thing involved in this process, There are other factors, such as the composition and texture of the surface, the shape, texture and composition of the wheel surfaces, contaminants at the interface of the surface and the wheel, and the relative motion of loose components of the tractive surfaces.
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A 600lb vehicle on earth weighs 600lbs and has a mass of 600lbs, on the moon it weighs 100lbs but still has a mass of 600lbs. Each wheel on earth has 150lbs of weight on it, and on the moon each wheel has 25lbs of weight on it.
So for a given surface, you only have one sixth of the traction force on the moon that you have on earth. All that means is that the maximum acceleration you can get on the moon is one sixth you can get on earth. So you have a low-acceleration vehicle, but you aren't trying to do high-speed manoeuvres or heavy breaking, so why does it matter?
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A 600lb vehicle on earth weighs 600lbs and has a mass of 600lbs, on the moon it weighs 100lbs but still has a mass of 600lbs. Each wheel on earth has 150lbs of weight on it, and on the moon each wheel has 25lbs of weight on it.
So for a given surface, you only have one sixth of the traction force on the moon that you have on earth. All that means is that the maximum acceleration you can get on the moon is one sixth you can get on earth. So you have a low-acceleration vehicle, but you aren't trying to do high-speed manoeuvres or heavy breaking, so why does it matter?
I believe anywho mistakenly believes that the lack of traction will cause the vehicle's wheels to spin continuously and the vehicle to remain stationary, and if so, then that is his mistake.
Even if his 600lb vehicle had smooth steel wheels and the lunar surface was perfectly flat ice, there would still be some traction and therefore, some acceleration.
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In both cases the same mass has to be moved horizontally, and the forces needed to accelerate the vehicle horizontally are the same in both cases
No. Any force can accelerate any mass. If you want to accelerate the mass at the same rate on both Earth and the Moon you need the same force, but nowhere is that requirement specified.
In the test they lost usable traction at 50 to 60% over what it takes to drive the weight of the wheel, but on the moon the need enough traction to pull an additional 500% more than the weight of the wheel, or a "pull coefficient" of 5, not .5 like they got.
Check out this page:
http://en.wikipedia.org/wiki/Pushback
Note the section where it says a typical tractor used to move an airliner has a weight of about 120,000 lb and a drawbar pull of about 75,000 lb. Now explain how a vehicle with those specifications is able to move an airliner weighing in excess of 200,000 lb in addition to itself, using the same 'logic' you just applied to the rover wheel test.
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Once again, anywho, look at the graph and the testing regime. At 0% slip they have defined a 0% pull coefficient. They are NOT testing the ability of the wheel to get the mass of the rover moving, they are testing the abilities of the wheel once steady state has been reached, i.e. at a constant speed over a level surface, and making it slip deliberately to see what it could do on a slope where it does have to pull its weight (not mass) against gravity. At this point the rover does not have to pull its mass in the way you are describing.
The only thing that test tells us about the rovers ability to get moving is that if you started to spin the wheels at that speed the rover would likely slip and not make a clean start in its motion. Well so what? Cars do the same thing. You get round that by using a slow initial acceleration to give the wheels a chance to grip and get the mass of the vehicle moving.
0% slip and 0% pull coefficient just means that the wheel is driving the weight on it (and no more) without slip
II will have a more comprehensive answer to this post in a day or two when I have time to muddle through the testing they dd in more detail, but one thing I will say now is in relation to the comment "The only thing that test tells us about the rovers ability to get moving is that if you started to spin the wheels at that speed the rover would likely slip and not make a clean start in its motion."
The tests performed got nowhere near showing that the rovers could operate on the moon at all, the wheel failed way before it reached the necessary drawbar pull. That test was done at 2.5 ft/s or a very leisurely walking pace, they gradually added the load and the traction started failing too much at about .5 drawbar pull.
http://en.wikipedia.org/wiki/Pushback
Note the section where it says a typical tractor used to move an airliner has a weight of about 120,000 lb and a drawbar pull of about 75,000 lb. Now explain how a vehicle with those specifications is able to move an airliner weighing in excess of 200,000 lb in addition to itself, using the same 'logic' you just applied to the rover wheel test.
That drawbar pull will certainly be pertaining to power and not traction, it is worked out on a set speed, so as long as they go slow enough and have enough traction they can do it.
From your source:
For sufficient traction, the tractor must be heavy, and most models can have extra ballast added.
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Aha!! I think I see what you are trying to say, and where you are making your mistake.
Are you saying that the 25lbs of weight on each wheel is not enough weight to give it the friction it needs to gain traction to move 150 kg of mass horizontally?
If you are, then you are making a fundamental error and approaching the issue too simplistically. Weight on the wheel is not the only thing involved in this process, There are other factors, such as the composition and texture of the surface, the shape, texture and composition of the wheel surfaces, contaminants at the interface of the surface and the wheel, and the relative motion of loose components of the tractive surfaces.
Every "factor" you raise was dealt with in the test, they used the same wheels and a simulated soil.
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Even if his 600lb vehicle had smooth steel wheels and the lunar surface was perfectly flat ice, there would still be some traction and therefore, some acceleration.
Good luck :)
In the test they say:
Pull/load increased rapidly with increasing slip to a near maximum at 15 to 25% slip for all wheels, then increased slowly with Increasing wheel slip to 100% sllp. This behavior suggests that the operation of a vehicle at slips higher than 25% for protracted periods would result in immobilizing the vehlcle,
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
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Anywho, you still haven't shown us how you resolve your contradiction.
You say that the videos prove that the rover could not move, based on the way the lunar soil looks when the rover moves on it. Can you not see the problem with that?
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0% slip and 0% pull coefficient just means that the wheel is driving the weight on it (and no more) without slip
So according to your interpretation of that graph the pull of the vehicle goes up with increasing slip?!
The numbers for 'pull coefficient' on the y-axis of that graph, as I have already pointed out, represent the proportion of the weight of the vehicle that is acting downslope at those angles, also on the y-axis, i.e. that would be acting to actively oppose the forward motion of the vehicle.
The tests performed got nowhere near showing that the rovers could operate on the moon at all, the wheel failed way before it reached the necessary drawbar pull.
No, it did not.
That drawbar pull will certainly be pertaining to power and not traction, it is worked out on a set speed, so as long as they go slow enough and have enough traction they can do it.
From your source:
For sufficient traction, the tractor must be heavy, and most models can have extra ballast added.
[/quote]
Doesn't matter. The drawbar pull/weight ratio of the tractor is 75,000/120,000, which is about 0.34. That, according to you, means that vehicle can pull its own mass plus 34% more. An airliner is waaaaay above that, so according to you it should not be able to pull that airliner.
You're not even being consistent with your own arguments.
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The tests performed got nowhere near showing that the rovers could operate on the moon at all, the wheel failed way before it reached the necessary drawbar pull.
Are you saying that NASA performed tests that proved that it was impossible for the rovers to operate on the Moon?
If not, what does the above quote mean??
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The tests performed got nowhere near showing that the rovers could operate on the moon at all,
Then why do you think that physicist and engineers have not detailed this lack of performance before, over the past 40+ years? If some have please provide the results of your lit search. Why has it been left to you Anywho, some anonymous guy on the internet who dodges questions that are basic to establishing a case?
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So according to your interpretation of that graph the pull of the vehicle goes up with increasing slip?!
It's not just my interpretation, it is the interpretation of the authors also, although you do seem to have put the cart before the horse.
The slip increases with increased load, they both go up happily together until the slip gets to around 25% at which point the slip increases dramatically for very little rise in load.
Pull/load increased rapidly with increasing slip to a near maximum at 15 to 25% slip for all wheels, then increased slowly with Increasing wheel slip to 100% sllp. This behavior suggests that the operation of a vehicle at slips higher than 25% for protracted periods would result in immobilizing the vehlcle,
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
Doesn't matter. The drawbar pull/weight ratio of the tractor is 75,000/120,000, which is about 0.34. That, according to you, means that vehicle can pull its own mass plus 34% more. An airliner is waaaaay above that, so according to you it should not be able to pull that airliner.
You're not even being consistent with your own arguments.
Or .625
It's apples and oranges, that drawbar pull relates to power, not traction.
The tests performed got nowhere near showing that the rovers could operate on the moon at all, the wheel failed way before it reached the necessary drawbar pull.
Are you saying that NASA performed tests that proved that it was impossible for the rovers to operate on the Moon?
If not, what does the above quote mean??
Yes, although technically the army conducted the test, for NASA.
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It's apples and oranges, that drawbar pull relates to power, not traction.
Prove it. Calculation of drawbar pull requires the use of the coefficient of traction between the wheels and the surface. You can't ignore it because the whole point of drawbar pull is how much it can pull forward, and to do that it has to move its wheels, and to move it forward they have to have traction. How much traction they get determines the drawbar pull. Since the operation of that vehicle is restricted to one type of surface, why would that number not be valid for the traction it gets in its normal operating environment?
With a drawbar pull of 75,000 lb, a tractor like that can pull an airliner with a mass well above that. In fact you'll find various sources that tell you drawbar pull is a fraction of the maximum load the vehicle can pull, because any mass can be accelerated with any force. A vehicle does not have to be able to exert a force greater than the weight of the load it is pulling in order to move it, unless it is moving it upwards.
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Or .625
Quite right, I stand corrected. However, the vehicle can still clearly pull itself and a great deal more than that.
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Think of a Railway Locomotive.
For example a British Rail Standard 9F steam loco.
It had a total weight of about 150 tons
It had 10 coupled wheels (5 each side) It's axle weight was 15 tons on each wheel
It was capable of pulling up to 1000 tons.
They pulled coal trains of this weight up a 1 in 40 incline from the Riverside on the Tyne up to the high level main lines every day.
Accorfing to your 'calculations' it shouldn't have been able to move at all.
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May that's why Wrexham and Shropshire failed. Their loco hauled trains violated the laws of physics.
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I'm just catching up on this thread and I was hoping someone would mention railroading, locomotives, and tractive effort. Anywho, you're really in over your head on this topic. If you want to change tack and humbly ask for help, I'm sure we would be able to provide it. But as long as you're just going to arrogantly stumble through a wrong-headed misconception of basic physics and call the world's engineering community liars, I think laughter is probably all you're going to get.
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And I'm getting kinda tired of being ignored.
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Think of a Railway Locomotive.
For example a British Rail Standard 9F steam loco.
It had a total weight of about 150 tons
It had 10 coupled wheels (5 each side) It's axle weight was 15 tons on each wheel
It was capable of pulling up to 1000 tons.
They pulled coal trains of this weight up a 1 in 40 incline from the Riverside on the Tyne up to the high level main lines every day.
Accorfing to your 'calculations' it shouldn't have been able to move at all.
....and as per anywho's assertion, each wheel is pulling 115 tons (760% if its borne weight), and its doing so up a 1:40 incline with steel wheels on steel rails!!!!
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And I'm getting kinda tired of being ignored.
It seems to come with the territory.
What never ceases to amaze - although not surprise - me is the way most of the HB crowd finds consistency to be a reason for suspicion.
If an HB poses a question, and I happen to be the one who answers it, as often as not the response is something like "Boy, you NASA shills really got yur script memorized. That's the same answer I got form Able on another video and even some PAN over on cosmokwest. Why don't u open yr eyes and stop being a sheeple, retard"
It doesn't seem to matter whether it's the missing stars, or RADIATION, or slow-motion lunar gravity, they mostly just ask the same old tired questions. I guess they're hoping for just one 'Apollogist' to agree with them so they can bray "i wuz rite! AH AH AH AH!"
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"i wuz rite! AH AH AH AH!"
I see you met expattafy1 on youtube. That's his signature.
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Think of a Railway Locomotive.
For example a British Rail Standard 9F steam loco.
It had a total weight of about 150 tons
It had 10 coupled wheels (5 each side) It's axle weight was 15 tons on each wheel
It was capable of pulling up to 1000 tons.
They pulled coal trains of this weight up a 1 in 40 incline from the Riverside on the Tyne up to the high level main lines every day.
Accorfing to your 'calculations' it shouldn't have been able to move at all.
....and as per anywho's assertion, each wheel is pulling 115 tons (760% if its borne weight), and its doing so up a 1:40 incline with steel wheels on steel rails!!!!
More to the point the 9F has 10 driving wheels to spread the load and lower the axle weight so it doesn't damage the track. A single axle would have 75 tons on each wheel. At the same time as lowering the weight on each wheel it increases the contact area the loco has with the rails to stop them slipping when trying to pull away.
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I presume that anywho's position is that the videos show the rovers actually working under Earth gravity (despite being described as not able to do so), while the disturbed dust ... operates under Moon gravity in its behaviour. Neat trick, that.
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"i wuz rite! AH AH AH AH!"
I see you met expattafy1 on youtube. That's his signature.
Oh, yeah. Known of him for a while.
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You are still not understanding the difference between weight and mass. You obviously do know that an object in a 1G field with a mass of 100kg has a weight of 100kg, while that same object in a 1/6th G field, while only weighing 16kg, nevertheless still has a mass of 100kg.
I've pointed this out before. Kilogram is a unit of mass, never a unit of weight. In SI, weight is newtons, and the weight of a mass depends on the gravity field in which it's measured.
On Earth, 100 kg weighs about 981 N. On the Moon, it weighs about 162 newtons.
A mistake like yours could cost you a grade in physics class.
Fred
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A 600lb vehicle on earth weighs 600lbs and has a mass of 600lbs, on the moon it weighs 100lbs but still has a mass of 600lbs.
Same problem as my last post. Now it's in English units and weights.
The English unit of mass is the slug. 1 slug is 14.6 kg. You can take it from there.
Fred
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And I'm getting kinda tired of being ignored.
What?
But seriously, the simpler the question, the less likely he is to answer it.
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Yes, although technically the army conducted the test, for NASA.
So NASA had the Army conduct tests that showed the landings were faked, and you're the first person to "figure it out"??
Is that the reason for the "tude"...you believe yourself superiour to those who disagree with you??
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You are still not understanding the difference between weight and mass. You obviously do know that an object in a 1G field with a mass of 100kg has a weight of 100kg, while that same object in a 1/6th G field, while only weighing 16kg, nevertheless still has a mass of 100kg.
I've pointed this out before. Kilogram is a unit of mass, never a unit of weight. In SI, weight is newtons, and the weight of a mass depends on the gravity field in which it's measured.
On Earth, 100 kg weighs about 981 N. On the Moon, it weighs about 162 newtons.
A mistake like yours could cost you a grade in physics class.
Fred
Actually, the Newton is a measure of force not a measure of weight (F = ma)
For simplicity's sake, using kg as weight will suffice for nomenclature.
Besides, I have yet to find a set of bathroom scales, a set of kitchen scales, or a laboratory balance kit with its weights calibrated or marked in "Newtons"!!
When someone asks me how much I weigh, I never answer 747.56 newtons!!
The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
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The English unit of mass is the slug. 1 slug is 14.6 kg. You can take it from there.
This is often claimed to be so, but is not correct. The pound is a unit of mass...exactly 0.45359237 kg. When force and mass need to be distinguished, pound-force and pound-mass are used, the former being equal to a 1 lb mass and an acceleration of 9.80665 m/s^2.
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Think of a Railway Locomotive.
I was hoping someone would mention railroading, locomotives, and tractive effort.
Why?
What relevance does a locomotive, on tracks in 1g, have to a 4WD on a loose surface in 1/6g ?
In quoting the army test I am not using something abstract to show the rovers could not operate in 1/6g, it is the test of an actual rover wheel in a simulated lunar soil, so when it fails it fails, it not then okay to suggest it should still work well above and beyond the fail point because a train can pull x amount.
They conducted those traction tests at 2.5 ft/s which is approx 2.7kph, or a very leisurely stroll. They then gradually added a pull load and the wheel lost practical traction when it had a drawbar pull of 0.5, nowhere near the approximate 5.0 needed to operate on the moon.
What a train can pull, or a tractor at an airport, is irrelevant to the failure point in the test.
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Fine. Let's stick with SI, then.
But I suppose it doesn't matter, because anywho isn't making any sense or headway.
Fred
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Why?
What relevance does a locomotive, on tracks in 1g, have to a 4WD on a loose surface in 1/6g ?
And therin lies one of your greatest problems; your inability to extrapolate across variations of the same problem, and it IS the same problem...the relationships between force, mass, inertia, gravity and traction are the same everywhere throughout the universe.
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Why?
Because if you understood the first thing about tractive effort you'd realize just how woefully ignorant your "analysis" is. But you don't.
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Why?
What relevance does a locomotive, on tracks in 1g, have to a 4WD on a loose surface in 1/6g ?
Because it shows you the same thing we've been trying to tell you: drawbar pull is simply not the value you think it is.
In quoting the army test I am not using something abstract to show the rovers could not operate in 1/6g, it is the test of an actual rover wheel in a simulated lunar soil, so when it fails it fails, it not then okay to suggest it should still work well above and beyond the fail point because a train can pull x amount.
It is not saying it should work above the fail point, it is illustrating that the 'fail point' is not what you think it is.
They conducted those traction tests at 2.5 ft/s which is approx 2.7kph, or a very leisurely stroll. They then gradually added a pull load and the wheel lost practical traction when it had a drawbar pull of 0.5, nowhere near the approximate 5.0 needed to operate on the moon.
Your continuing failure to understand what value drawbar pull actually has is the problem here. You don't need a drawbar pull of, say, 600 lb to move a 600 lb load. The examples given here illustrate that, and the same thing applies on Earth as the Moon. If a tractor with a drawbar pull of 75,000 lb can move an airliner with a weight of 200,000, why can't a rover move itself on the Moon?
We still await your explanation for what you think is actually going on in the rover film footage, by the way. Is it the real lunar surface (in which case the rover clearly works) or not (in which case you can't argue properties of the lunar surface from it). Clearly there is a vehicle that can be operated on that surface.
What a train can pull, or a tractor at an airport, is irrelevant to the failure point in the test.
[/quote]
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I'm just catching up on this thread and I was hoping someone would mention railroading, locomotives, and tractive effort.
Probably should have been me, given the nature of one of my vocations.
Anywho - it really is the same problem. Do you really think we put 13,000 tons of tractive effort on a coal train? We'd probably tear the drawbars out of the cars if we did. But that's what you're implying with your calculations for the LRV.
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Why?
What relevance does a locomotive, on tracks in 1g, have to a 4WD on a loose surface in 1/6g ?
And therin lies one of your greatest problems; your inability to extrapolate across variations of the same problem, and it IS the same problem..
So we should take the test results, that are specific to the lunar rover and lunar soil, then extrapolate those results to a locomotive, then extrapolate back to the lunar rover and declare that the rover can therefore far exceed what the tests show the limits are?
If you do a simulated test you do not have to extrapolate the results away from the rover and then back to it, you only have to look at the results directly.
Your continuing failure to understand what value drawbar pull actually has is the problem here. You don't need a drawbar pull of, say, 600 lb to move a 600 lb load. The examples given here illustrate that, and the same thing applies on Earth as the Moon. If a tractor with a drawbar pull of 75,000 lb can move an airliner with a weight of 200,000, why can't a rover move itself on the Moon?
That tractor has a rated drawbar pull, it is not a maximum, it is based on a set standard (I believe it is what the tractor can pull over 1 meter in 1 second). The 'test' on the tarmac proves it can pull more, if they tried continuously loading it until it could not function satisfactorily due to traction loss then that would be it's physical functional limit.
The test of continuously loading the rover found its functonal drawbar limit, and it is way off what is needed for it to operate on the moon. It is not a rating or a limit set by the manufacturer that can be exceeded, it is a test designed to find the operational limits of the rover wheel and they kept increasing load until they found those physical limits.
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I'm just catching up on this thread and I was hoping someone would mention railroading, locomotives, and tractive effort.
Probably should have been me, given the nature of one of my vocations.
Anywho - it really is the same problem. Do you really think we put 13,000 tons of tractive effort on a coal train? We'd probably tear the drawbars out of the cars if we did. But that's what you're implying with your calculations for the LRV.
No, and they are not my calculations, drawbar pull is not the amount of force being applied, it is the additional mass the vehicle can pull above and beyond it's own weight, and the army tests show a drawbar pull of about 0.5 or 0.6 before the rover reaches it's functional limit.
The weight on the wheel in the test is 57lbs, but on the moon the mass it has to pull is 228lbs (total), so a drawbar pull of only 0.5 or 0.6 based on a 57lb wheel weight, means it can only pull 90lbs (total) before traction becomes too problematic.
Extrapolate all you want, that is a huge deficit.
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The test of continuously loading the rover found its functonal drawbar limit, and it is way off what is needed for it to operate on the moon. It is not a rating or a limit set by the manufacturer that can be exceeded, it is a test designed to find the operational limits of the rover wheel and they kept increasing load until they found those physical limits.
Now please reconcile that with your earlier statement that you knew the rover did not have to exert a force equal to or greater than its mass to move it.
How many different sources do you need to be shown that the value for drawbar pull is NOT the maximum mass it can pull but the amount of force it can exert. Any force can accelerate any mass. Do you even understand that principle? That is why a tractor exerting 75,000 lb of pull can shift an airliner weighing many times that. That is why I, a human male with a mass of about 180-200 lb can push a car weighing over 3,000 lb. Do you think I am exerting a force of 3,000 lb to do that? I am not working against the vehicle's weight but its inertia.
As I have said at least three times now, the testing of the rover wheel applies to a situation where its weight is acting directly to oppose the forward motion of the wheel. On a horizontal surface the rover could move with a drawbar pull rating of 0.5 lb, it just couldn't accelerate very quickly. Driving up a slope it has to counteract the acceleration due to gravity that is trying to pull it back down the slope before it can even move the rover forward. Only on an upward slope does the rover actually have to pull against its own weight.
Basic principle: F=ma.
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No, and they are not my calculations, drawbar pull is not the amount of force being applied, it is the additional mass the vehicle can pull above and beyond it's own weight,
No
It
Is
Not.
If that were true the locomotive and tractor and human examples you have been given would not be possible. Drawbar pull IS a force measurement. I challenge you to show us a source that defines drawbar pull in the manner you have defined it. Support your assertions. We've given you our sources. You show us yours.
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No, and they are not my calculations, drawbar pull is not the amount of force being applied, it is the additional mass the vehicle can pull above and beyond it's own weight,
So how does my 150 ton loco pull 1000 tons? Shouldn't it's wheels just spin? they only have a weight of 15 tons over each of them?
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Then how can a 300 lb man pull a 200.000 lb jet airliner? Strong man contest?
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No, and they are not my calculations, drawbar pull is not the amount of force being applied, it is the additional mass the vehicle can pull above and beyond it's own weight,
No
It
Is
Not.
If that were true the locomotive and tractor and human examples you have been given would not be possible. Drawbar pull IS a force measurement. I challenge you to show us a source that defines drawbar pull in the manner you have defined it. Support your assertions. We've given you our sources. You show us yours.
Okay, a quick look around shows it is generally a force, so I apologise for the obstinance and confusion. I don't know if the method I was adamant about is archaic, or if there was different criteria among different sectors.
However, the way in which I am describing drawbar pull is correct for the subject at hand which is the army test for the rover wheels.
The pull coefficient of 0.5 or 0.6 is certainly related to the mass the vehicle can pull and the weight on the wheel, the formula they use to get the coefficient is P/W or drawbar pull/wheel load, this proves that the coefficient is based on the mass the wheel can pull and not the force needed to pull it.
If the drawbar pull was a measure of force they would have to divide it by the force needed to drive the weighted wheel, not the weight on the wheel, to get the coefficient.
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The pull coefficient of 0.5 or 0.6 is certainly related to the mass the vehicle can pull and the weight on the wheel, the formula they use to get the coefficient is P/W or drawbar pull/wheel load, this proves that the coefficient is based on the mass the wheel can pull and not the force needed to pull it.
And the reasons for that have been explained. I'll try one more time.
The testing regime is operating on steady state propulsion. The wheel is not pulling the mass of the vehicle. The mass of the vehicle is not offering any resistance. On a flat, level surface once it is moving it will stay moving unless additional force is applied. That's basic physics, yes? All the wheel has to do is overcome the rolling resistance of the surface.
So why are they applying a load? Because once it starts climbing a slope (which is what they are applying their conclusions on the rover's behaviour to), the weight of the vehicle is resisting the forward motion. The lunar gravity is providing an acceleration opposing the motion of the vehicle. As the incline increases, the portion of the rover's weight it now does have to pull as a resisting load increases. That's what those ratios are. The portion of its weight now acting to resist its motion is determined by cosine (90 - incline in degrees). So at 25 degrees, the rover has to effectively exert a force of cos(90-25) = 0.42 x its weight all the time just to keep moving forward at a constant speed. Not its mass, its weight.
It is only when dealing with a motor trying to pull a load up an incline that drawbar pull becomes a limiting force that has to exceed the portion of the weight of the vehicle acting to resist the forward motion in order to allow the vehicle to pull the load. That's why I can shove a 3,000 lb car along a flat road but can't push it up an incline without assistance.
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Okay, a quick look around shows it is generally a force, so I apologise for the obstinance and confusion.
Thank you.
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And by the way I hope my reasoning is correct. I'm sure someone will correct me if I'm wrong, since I'm not an engineer.
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So why are they applying a load? Because once it starts climbing a slope (which is what they are applying their conclusions on the rover's behaviour to), the weight of the vehicle is resisting the forward motion.
They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?
Either way, if you want to only relate it to a slope then the results are still impossible for the rovers to operate on the moon, the results clearly show it could not start on or climb even the mildest of slopes.
Even if you get a rover going on a downslope and use momentum to keep it going over a flat area, once even a slight incline is needed to be driven up under the power of the rover (not momentum) then the test show the rover traction will fail.
If a pull coefficient of 5 is needed to drive the vehicle along the flat (ignoring momentum) then on even a mild slope it will be greater, and the test show the rovers can only sustain traction at around 0.5 or 0.6
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So we should take the test results, that are specific to the lunar rover and lunar soil, then extrapolate those results to a locomotive...
No, you should have looked at how the comparable results are obtained and reported for locomotives, to help you arrive at your belated realization that you didn't know what the heck you're talking about. You have a substantial lack of qualitative understanding about how to measure vehicle performance, stemming from a fundamental ignorance of basic physical principles.
You may want to revisit your claim that every engineer in the world is wrong and that you, decades later, seem to be the only one that has discovered the alleged impossibility of the LRV.
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They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?
To accelerate at what rate?
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They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?
Once again, the wheels are operating at a constant speed. The vehicle does NOT require a pull coefficient of 5 to accelerate. It can accelerate with any force and whatever speed it likes. F = ma. On a level surface it does NOT have to pull with a force equal to or greater than its weight or mass. You even said that yourself in an earlier post. Why are you now insisting otherwise?
Either way, if you want to only relate it to a slope then the results are still impossible for the rovers to operate on the moon, the results clearly show it could not start on or climb even the mildest of slopes.
No, the results show that it can't run at that speed up slopes of about 25 degrees without slipping too much.
If a pull coefficient of 5 is needed to drive the vehicle along the flat
Which it isn't, for reasons gone over so many times now I have to wonder if you're just being argumentative for the sake of it.
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Did you hear the one about the Irish Zamboni driver?
He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.
^^Nice line in racism. What's for your encore? Pointing out that women are weaker than men? That all Muslims are terrorists?
An apology for making out that a nation's people are stupid and backward just because they happened to be born in a certain geography would be welcome. Especially as The Learning Curve report places the Irish education system ahead of Denmark, Australia, Poland, Germany, Belgium and the US (amongst others).
http://thelearningcurve.pearson.com/the-report
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So we should take the test results, that are specific to the lunar rover and lunar soil, then extrapolate those results to a locomotive, then extrapolate back to the lunar rover and declare that the rover can therefore far exceed what the tests show the limits are?
If you do a simulated test you do not have to extrapolate the results away from the rover and then back to it, you only have to look at the results directly.
...
No.
It's called a sanity check.
You test your method against a known quantity. If it returns nonsense -- in this case, if your method tells you a locomotive can't work -- then you know there are problems with the method.
It is exactly the same as testing a tester, or calibrating a measuring device. Before you trust it to tell you about an unknown, you check to see if it returns data in agreement with a known.
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They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?
To accelerate at what rate?
Any rate. a (traction) pull coefficient of 5 is the minimum needed, the faster you want to accelerate the higher that will go.
Please note that when I am talking about pull coefficient or drawbar pull I am talking about the formula in the army test, so it is not a measurement of force, it is a measurement of the mass the wheel can pull before traction is useless.
The wheel has a 57lb load on it, on the moon it needs enough traction to pull 342lbs to accelerate, or 6 times the wheel load, which equates to a drawbar pull of 5.
They could also extrapolate the results to acceleration rather than a slope if they wanted. How would they get a vehicle that requires pull coefficient of 5 to accellerate when all their testing shows traction failing at about 0.5?
Once again, the wheels are operating at a constant speed. The vehicle does NOT require a pull coefficient of 5 to accelerate. It can accelerate with any force and whatever speed it likes. F = ma. On a level surface it does NOT have to pull with a force equal to or greater than its weight or mass. You even said that yourself in an earlier post. Why are you now insisting otherwise?
Once again for clarity, in the army test the pull coefficient is the amount of mass the wheel can pull (above and beyond it's own load) before traction becomes useless, it is not a force.
So yes, the wheel does not have to be able to pull with a force anywhere near its own weight to move, but it does have to be able to get enough traction to pull 6 times its weight. This equates to, using the army testing method, a pull coefficient of 5.
On earth the wheel only needs enough traction to pull it's own weight.
Either way, if you want to only relate it to a slope then the results are still impossible for the rovers to operate on the moon, the results clearly show it could not start on or climb even the mildest of slopes.
No, the results show that it can't run at that speed up slopes of about 25 degrees without slipping too much.
No the results show the wheel has enough reserve traction to go up a 25 degree slope on earth only.
When the testing shows a pull coefficient of 0.5 before traction is too problematic, it is saying the wheel has enough traction to drive the weight on it plus 50% more (which is enough to get it up a 25 degree slope here on earth).
But on the moon it needs enough traction to drive/pull the weight on it, plus 500% more.
Do you see what i am saying?
A wheel on earth with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 228lbs.
On the moon a wheel with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 1368lbs.
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I don't know if the method I was adamant about is archaic, or if there was different criteria among different sectors.
Have you ever, here or elsewhere, just considered the possibility that you might be wrong? This is not intended to be an insult. It is a serious and legitimate question. Have you ever, anywhere along the proceedings, considered the possibility of your own error? If not, why not?
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Any rate.
Nope.
...a (traction) pull coefficient of 5 is the minimum needed...
Nope.
Please note that when I am talking about pull coefficient or drawbar pull I am talking about...
No, do not redefine things to make it seem like you were still right.
Do you see what i am saying?
I see what you're trying to say. I also see a lot of patient people, including myself, trying to explain exactly how your understanding is in error. But what I don't see is any indication from you that you've considered that you may be wrong on a fundamental level. And I don't see any interest from you in determining whether your understanding is correct.
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Funny how Anywho has focused on Jason...
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Any rate.
Wrong.
a (traction) pull coefficient of 5 is the minimum needed, the faster you want to accelerate the higher that will go.
Wrong.
F = ma. How many times do i have to write that formula down for you? Since F = ma, it follows that a = F/m
If I have a 100 kg mass I can accelerate it with any force whatsoever. If I apply 1 Newton force I can accelerate it at 1/100 m/s^2. If I apply 10 N of force I can accelerate it at 1/10 m/s^2. If I shove it with 1,000,000 Newtons it will accelerate at 10,000 m/s^2. There is NO 'minimum force' required to accelerate any given mass, ignoring all other factors such as friction, rolling resistance etc. The thing that determines minimum force is any force that acts directly to oppose the motion the wheel is trying to impart. Since the wheel is trying to move the vehicle forward, the limiting force has to be one that acts 'backwards'. Weight does not do that on the level surface. Weight acts straight down. There is NO lateral component of weight that opposes forward motion. Therefore, weight is NOT directly a limiting factor in accelerating a vehicle forwards at any rate. It does of course affect things like traction and static friction, but you certainly do not need to exert a force equivalent to its weight just to get the vehicle moving. Hence I can push a car.
Please note that when I am talking about pull coefficient or drawbar pull I am talking about the formula in the army test, so it is not a measurement of force, it is a measurement of the mass the wheel can pull before traction is useless.
No, it really is not. That is YOUR erroneous conclusion. I have already explained, twice, what those numbers actually represent and how that test applies to reality.
Drawbar pull, anywhere, is the force available to pull a load after the vehicle has moved itself. That's what it is in all cases, INLCUDING this test. You can keep on saying it means something else here, but the authors of that paper would not agree with you.
The wheel has a 57lb load on it, on the moon it needs enough traction to pull 342lbs to accelerate, or 6 times the wheel load, which equates to a drawbar pull of 5.
No it does not.
Once again for clarity, in the army test the pull coefficient is the amount of mass the wheel can pull (above and beyond it's own load) before traction becomes useless, it is not a force.
Which bit of what I have written about what those numbers actually represent is not clear to you?
So yes, the wheel does not have to be able to pull with a force anywhere near its own weight to move, but it does have to be able to get enough traction to pull 6 times its weight.
No it does not. It ONLY has to pull against its own weight when the rover goes up a slope and its weight, which is an acceleration itself, is acting against the force the wheel is applying to move the rover forward.
No the results show the wheel has enough reserve traction to go up a 25 degree slope on earth only.
No, they don't.
When the testing shows a pull coefficient of 0.5 before traction is too problematic, it is saying the wheel has enough traction to drive the weight on it plus 50% more (which is enough to get it up a 25 degree slope here on earth).
But on the moon it needs enough traction to drive/pull the weight on it, plus 500% more.
No, it does not.
Do you see what i am saying?
Yes, but that does not make you any more right.
A wheel on earth with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 228lbs.
On the moon a wheel with 57lbs of weight on it has to have enough traction to drive 1/4 of a vehicle weighing 1368lbs.
And how much traction is required to drive that?
Stop trying to redefine already well-defined parameters to make your argument fit your conclusion. drawbar pull is a measure of force, FULL STOP. That force does not have to exceed the weight of the vehicle to move it along the surface, ever. That's why I can push a car, a tractor can tow an airliner and a train can tow several carriages.
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Did you hear the one about the Irish Zamboni driver?
He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.
^^Nice line in racism. What's for your encore? Pointing out that women are weaker than men? That all Muslims are terrorists?
An apology for making out that a nation's people are stupid and backward just because they happened to be born in a certain geography would be welcome. Especially as The Learning Curve report places the Irish education system ahead of Denmark, Australia, Poland, Germany, Belgium and the US (amongst others).
http://thelearningcurve.pearson.com/the-report
OK, I'll apologise to myself then?
No! Wait! That would be only a half apology, since I'm only half-Irish (mother's side, Kerry born and bred!!)
Sometimes a joke is just a joke.
(PM on the way)
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Did you hear the one about the Irish Zamboni driver?
He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.
^^Nice line in racism. What's for your encore? Pointing out that women are weaker than men? That all Muslims are terrorists?
An apology for making out that a nation's people are stupid and backward just because they happened to be born in a certain geography would be welcome. Especially as The Learning Curve report places the Irish education system ahead of Denmark, Australia, Poland, Germany, Belgium and the US (amongst others).
http://thelearningcurve.pearson.com/the-report
I am Irish. I take no offence at it.
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Funny how Anywho has focused on Jason...
What's your problem? You did as well! LOL
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Back to the topic at hand, I await Anywho's explanation for the contradiction in his claims. Where exactly was the LRV footage filmed, if not on the moon?
Either it was filmed on Earth, and the LRV was able to perform under Earth gravity, or...
It was faked on the Moon somehow under 1/6 gravity, or...
Something else.
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Funny how Anywho has focused on Jason...
What's your problem? You did as well! LOL
I think she's allowed to. In fact I'd be disappointed if she didn't...
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Anywho, take a look at these pages:
http://en.wikipedia.org/wiki/Tractive_force
http://en.wikipedia.org/wiki/2-10-10-2
Pay particular attention to the specs of the locomotive and the difference between its weight and its tractive effort. The other page gives its starting tractive effort, which is also significantly less than its own weight. And yet, somehow, that thing moves....
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Funny how Anywho has focused on Jason...
Especially because it's usually Jay. Maybe we should get Jason to ask our questions for us.
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Um, guys? What's a pull coefficient? What is drawbar pull?
I read looked at the report being discussed and was totally lost. Just too many variables and unfamiliar terms to remember, and I couldn't get a picture in my head of how the test was being done.
Lil help? :-[
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Did you hear the one about the Irish Zamboni driver?
He wanted to take the Zamboni on a hill-climb, but he abandoned the idea when he couldn't find an Ice Hockey rink on a hillside.
^^Nice line in racism. What's for your encore? Pointing out that women are weaker than men? That all Muslims are terrorists?
An apology for making out that a nation's people are stupid and backward just because they happened to be born in a certain geography would be welcome. Especially as The Learning Curve report places the Irish education system ahead of Denmark, Australia, Poland, Germany, Belgium and the US (amongst others).
http://thelearningcurve.pearson.com/the-report
OK, I'll apologise to myself then?
No! Wait! That would be only a half apology, since I'm only half-Irish (mother's side, Kerry born and bred!!)
Sometimes a joke is just a joke.
(PM on the way)
And you've got one back.
My last post on this as I do not want to create a thread drift.
You might find "jokes" about race funny or humorous. It might even be acceptable in certain backwaters of the world. But it's not acceptable everywhere, and it has no place in a thread about Apollo (read the Forum Rules if you need clarification).
I'm pretty sure that there are places in the Deep South that find "jokes" based on race hilarious. But I'm sure if you starting posting them then there might be a justified backlash.
Over and out.
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Back to the topic at hand, I await Anywho's explanation for the contradiction in his claims. Where exactly was the LRV footage filmed, if not on the moon?
Either it was filmed on Earth, and the LRV was able to perform under Earth gravity, or...
It was faked on the Moon somehow under 1/6 gravity, or...
Something else.
I suppose that one could try to argue that:
1. The hoaxers deliberately described the LRV as frail, because they wanted to provide evidence of how they were engineering for low gravity.
2. They then build a much more rugged LRV, and filmed it in Earth gravity, because the original would not work on Earth.
3. They published the tests that anywho claims prove it could not work on the Moon, because ... um, because they're just stupid?
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I suppose that one could try to argue that:
1. The hoaxers deliberately described the LRV as frail, because they wanted to provide evidence of how they were engineering for low gravity.
2. They then build a much more rugged LRV, and filmed it in Earth gravity, because the original would not work on Earth.
3. They published the tests that anywho claims prove it could not work on the Moon, because ... um, because they're just stupid?
4. In 40+ years, no engineers anywhere in the world have ever cottoned onto this stupidity, proves that all engineers everywhere in the the world are just NASA shills.
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Funny how Anywho has focused on Jason...
Better him than me. ;D
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Funny how Anywho has focused on Jason...
Better him than me. ;D
Quitter. ;D
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Funny how Anywho has focused on Jason...
Better him than me. ;D
Quitter. ;D
Careful, you could be characterising engineers as "quitters". ::)
Frankly. I think anywho probably knows who Jay is (by reputation) and probably understands that he will be even more over his head if he were to take him on. "Bringing a knife to a gunfight" springs to mind.
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Another example for Anywho:
(http://i1336.photobucket.com/albums/o657/Andromeda_Apollo/4DF5C21C-26BE-4C37-9FE2-E570737EC072-498-000000CFF3802C2D_zps53d1f551.jpg)
Hmm, does water count as a "loose surface"?! ;)
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Back to the topic at hand, I await Anywho's explanation for the contradiction in his claims. Where exactly was the LRV footage filmed, if not on the moon?
Either it was filmed on Earth, and the LRV was able to perform under Earth gravity, or...
It was faked on the Moon somehow under 1/6 gravity, or...
Something else.
I suppose that one could try to argue that:
1. The hoaxers deliberately described the LRV as frail, because they wanted to provide evidence of how they were engineering for low gravity.
2. They then build a much more rugged LRV, and filmed it in Earth gravity, because the original would not work on Earth.
3. They published the tests that anywho claims prove it could not work on the Moon, because ... um, because they're just stupid?
I've been thinking for a while that anywho would present this as an explanation. I'm surprised he hasn't yet. Of course, it still means that he can't use the characteristics of the Lunar surface in the video as an argument.
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The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
I think it's reasonable to say that a bathroom scale measures mass in kilograms as long as one remembers how it works and the limitations of that method: by measuring the force of gravity and converting that to kilograms, implicitly assuming an acceleration of 9.8... m/s^2. I.e., it's a mass-measuring device with a mechanism of operation that works fine on earth as long as the minor variations in gravity from place to place are below your accuracy requirements, as they usually are. Any precise mass-measuring instrument of this type would have to be calibrated for local gravity to give correct results.
So I think it's simply wrong (as well as extremely confusing and error-prone) to say that an object that's 100 kg on earth becomes only 16.7 kg on the moon. It's still 100 kg on the moon, as it would be measured by a scale properly calibrated to the local gravity. It's just 6 times easier to pick up.
Suppose the bathroom-type scale had never been invented. Suppose we still measured things with the balance scale, matching the pull of gravity on our test mass with that on a set of calibrated masses. Then, without any changes, an object weighing 100 kg on earth would still weigh 100 kg on the moon, or anywhere that had a non-negligible gravity field. So would a bathroom-type scale with a built-in accelerometer to compensate for local gravity variations. I.e., the notion of the kilogram as a unit of gravity force depends not only on a specific local gravity field, but on the use of a specific type of device to measure it. That's silly.
SI carefully distinguishes between mass and force, something largely unknown to those who measure all forces and masses in pounds. It's a bit like the notion of grammatical gender in many non-English languages, only it actually makes very real sense. Just as English speakers can't impose their rules on other peoples' languages, they should not introduce their confusion between mass and force into other measurement systems.
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The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
I think it's reasonable to say that a bathroom scale measures mass in kilograms as long as one remembers how it works and the limitations of that method: by measuring the force of gravity and converting that to kilograms, implicitly assuming an acceleration of 9.8... m/s^2. I.e., it's a mass-measuring device with a mechanism of operation that works fine on earth as long as the minor variations in gravity from place to place are below your accuracy requirements, as they usually are. Any precise mass-measuring instrument of this type would have to be calibrated for local gravity to give correct results.
Unless, of course, you're Anders Björkman.*
* For anyone not familiar with the reference, Anders (also known as Heiwa) famously claimed on JREF that a bathroom scale measured only weight, not force, and that if a person jumped on a scale from a height of 3.7 meters, it would read the same as if he just stepped upon it.
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and its doing so up a 1:40 incline with steel wheels on steel rails!!!!
I know steel wheels on steel rails give less traction than rubber tires on asphalt or concrete, as well as less rolling resistance. Anybody have some typical figures?
I often hear it claimed that trains are dramatically more energy efficient than trucks and cars because they run steel wheels on steel rails. I think that's incorrect; even on a highway, aerodynamic drag almost always exceeds rolling resistance, so further decreases in rolling resistance provide diminishing returns. I think trains are so energy-efficient because they're so long. Only the the locomotive (or lead car) has to push the air out of the way for all the other cars. It's like they're all drafting each other, something I've personally seen work surprisingly well on the highway (and extremely dangerously).
Of course, many trains (especially freight trains) run much slower than highway speeds, thus reducing aerodynamic drag considerably. But the differences are large even at comparable speeds.
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The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
I think it's reasonable to say that a bathroom scale measures mass in kilograms as long as one remembers how it works and the limitations of that method: by measuring the force of gravity and converting that to kilograms, implicitly assuming an acceleration of 9.8... m/s^2. I.e., it's a mass-measuring device with a mechanism of operation that works fine on earth as long as the minor variations in gravity from place to place are below your accuracy requirements, as they usually are. Any precise mass-measuring instrument of this type would have to be calibrated for local gravity to give correct results.
So I think it's simply wrong (as well as extremely confusing and error-prone) to say that an object that's 100 kg on earth becomes only 16.7 kg on the moon. It's still 100 kg on the moon, as it would be measured by a scale properly calibrated to the local gravity. It's just 6 times easier to pick up.
Suppose the bathroom-type scale had never been invented. Suppose we still measured things with the balance scale, matching the pull of gravity on our test mass with that on a set of calibrated masses. Then, without any changes, an object weighing 100 kg on earth would still weigh 100 kg on the moon, or anywhere that had a non-negligible gravity field. So would a bathroom-type scale with a built-in accelerometer to compensate for local gravity variations. I.e., the notion of the kilogram as a unit of gravity force depends not only on a specific local gravity field, but on the use of a specific type of device to measure it. That's silly.
SI carefully distinguishes between mass and force, something largely unknown to those who measure all forces and masses in pounds. It's a bit like the notion of grammatical gender in many non-English languages, only it actually makes very real sense. Just as English speakers can't impose their rules on other peoples' languages, they should not introduce their confusion between mass and force into other measurement systems.
Ok, strictly speaking you are right, but I have found that when I start talking to non-scientific minded people about the moon and Apollo, they understand when I tell them that a 60 kg object only weighs 10 kg on the moon because the moon's gravity is only 1/6th that of earth, and that is why the astronauts walked funny on the moon.
However, when I start launching into explanations about how 1G is actually 9.81 m/s2, and I start using terms like "newtons" or "joules" which are not in everyday use, I find their eyes begin to glaze over, and at that point, I know I am on the way to losing them.
As I said, using kg for mass and weight might not be scientifically correct, but the lay public can understand them better because these are terms that are familiar to them.
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As I said, using kg for mass and weight might not be scientifically correct, but the lay public can understand them better because these are terms that are familiar to them.
Why not just say that 100 kg on the earth is still 100 kg on the moon, but it's 6 times easier to pick up because of the lower gravity?
These explanations usually go on to say how mass is still present in low gravity or even in weightlessness, which is why astronauts on the ISS or performing EVAs in orbit have to be careful when maneuvering themselves or heavy (massive) objects. So you can't avoid the distinction between mass and weight at some point.
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If I have a 100 kg mass I can accelerate it with any force whatsoever. If I apply 1 Newton force I can accelerate it at 1/100 m/s^2. If I apply 10 N of force I can accelerate it at 1/10 m/s^2. If I shove it with 1,000,000 Newtons it will accelerate at 10,000 m/s^2. There is NO 'minimum force' required to accelerate any given mass, ignoring all other factors such as friction, rolling resistance etc.
Does anyone happen to know the coefficient of rolling friction for the LRV's tires? It would be good to know before we dismiss it as small compared to the inertial forces and gravity slope forces.
On earth, at least, rolling resistance can be characterized by a dimensionless coefficient that relates the tractive force required to overcome it to the vehicle weight. E.g., if the RR coefficient is 0.1, then a vehicle with a weight (gravitational force) of 100 N would require a horizontal tractive force of 10 N to keep it moving (at any speed above zero) on a level surface. This energy goes into flexing and heating the tires, crunching up a soft roadbed, etc. This is why it takes a minimum tractive force to budge a car, train or airplane even on a level surface.
Because the tractive force needed to overcome rolling resistance is proportional to weight, it is also proportional to the local gravity field. All other things equal, a rover that takes, say, 100 N of tractive force to budge on earth would take only 16.7 N of tractive force on the moon.
Because the rolling resistance is a fixed force, and energy is force times distance, the power needed to overcome it increases linearly with velocity. This sets a maximum velocity that a rover could achieve on a level surface with a given amount of motor power. Can we work out what that is for the LRV?
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How about we just say that an object exerts a force due to gravity in kilos on the Moon that is one sixth of that force in kilos that it would exert on the Earth, and be done with it?
Yes, I know that force is measured in newtons, but the balances I used in physics class weighed objects in kilos.
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How about we just say that an object exerts a force due to gravity in kilos on the Moon that is one sixth of that force in kilos that it would exert on the Earth, and be done with it?
Not unless that's kiloNewtons. The kilogram is a unit of mass, not force.
Yes, I know that force is measured in newtons, but the balances I used in physics class weighed objects in kilos.
If they were classic balances with reference masses, either a set you manually added and removed or a set you slide along beams, they measured the objects' masses, and those are represented in kilograms. They used gravity to do it but they were not sensitive to the actual gravitational acceleration; they'd give the same answers on the moon.
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Yes, I know that force is measured in newtons, but the balances I used in physics class weighed objects in kilos.
To my knowledge, the commercial world measures force in kgf and the USA/etc measures mass in lbm. But we are having an engineering discussion, where mass and force should be dealt with more rigorously.
Most scales measure force, while a balance measures mass. A laboratory electronic balance technically measures force, but since it is calibrated before use with reference masses, the readout is calibrated directly to mass and measured in kg. In the USA, some engineering disciplines (including mine) still use inconsistent systems of units in which lbm is the unit of mass, lbf is the unit of force, and a conversion factor of ~32.2 must be used for f to equal m*a. HVAC is more than a little behind the times in that regard (grains per lbm, anyone)?
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"Bringing a knife to a gunfight" springs to mind.
Doesn't matter what weapons anyone brings; if you get to referee your own fight, who will the winner be?
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Please note that when I am talking about pull coefficient or drawbar pull I am talking about the formula in the army test, so it is not a measurement of force, it is a measurement of the mass the wheel can pull before traction is useless.
No, it really is not. That is YOUR erroneous conclusion. I have already explained, twice, what those numbers actually represent and how that test applies to reality.
Drawbar pull, anywhere, is the force available to pull a load after the vehicle has moved itself. That's what it is in all cases, INLCUDING this test. You can keep on saying it means something else here, but the authors of that paper would not agree with you.
My bold:
This is incorrect and gets to the heart of the confusion, in the army test they are certainly testing the weight/mass that can be pulled. I don't know why it differs from modern formulas but the most obvious reasons are that it is because of the specific nature of the soil/wheel interaction testing, or that it is simply how drawbar pull was measured in the 60's and 70's (how much extra weight the vehicle can tow).
They are not clear about the meaning of "drawbar pull" as they just list it as "lb", so this could be either a weight or a horizontal force. BUT, what they are very clear about is that to get the "pull coefficient" they divide "drawbar pull" by the "wheel load; weight, lb", this makes it very clear that the drawbar pull in the paper is also a weight and not a horizontal force.
If the drawbar pull was a force in the paper, they would have to divide it by the force needed to drive the wheel load to get the coefficient, not the wheel load itself.
I stand by the claim that the test show that the rover can only pull approx 50% more than its own weight before traction is too problematic.
Funny how Anywho has focused on Jason...
Better him than me. ;D
You can't discuss anything with someone who just goes "nope" all the time.
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To everyone who wants to use a locomotive, or a tugboat, or an airport tractor, please consider that none of these can get bogged, none of these are indented into the surface before they even try moving (apart from the tug lol). This, along with the low traction of a loose surface, is why a loose surface is such an easy one to get stuck on, as most of us have probably experienced.
I have towed a truck that was stuck on a loose surface with a 4wd, but that was with the truck using whatever traction it could muster as well, if the truck was in neutral forget it, it was also a very good surface which is why the driver though he could make it.
Do you really think a 4wd on a loose surface can act like a locomotive and pull many other 4wds?
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To everyone who wants to use a locomotive, or a tugboat, or an airport tractor, please consider that none of these can get bogged, none of these are indented into the surface before they even try moving (apart from the tug lol). This, along with the low traction of a loose surface, is why a loose surface is such an easy one to get stuck on, as most of us have probably experienced.
I have towed a truck that was stuck on a loose surface with a 4wd, but that was with the truck using whatever traction it could muster as well, if the truck was in neutral forget it, it was also a very good surface which is why the driver though he could make it.
Do you really think a 4wd on a loose surface can act like a locomotive and pull many other 4wds?
And your evidence that the lunar surface is loose and incapable of providing traction is...?
Hint: It's video from the lunar surface.
If you're insisting that no-one drove on the lunar surface, you have no evidence that it can't be driven on by the LRV.
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This is incorrect and gets to the heart of the confusion, in the army test they are certainly testing the weight/mass that can be pulled.
Yes, and I'll say it again: in a regime where the vehicle is already moving and has to pull its own weight up a hill. In a regime where the weight of the vehicle is actively opposing the forward motion.
I don't know why it differs from modern formulas but the most obvious reasons are that it is because of the specific nature of the soil/wheel interaction testing, or that it is simply how drawbar pull was measured in the 60's and 70's (how much extra weight the vehicle can tow).
No, it's simply that you are consistently misunderstanding the test.
I stand by the claim that the test show that the rover can only pull approx 50% more than its own weight before traction is too problematic.
And the rest of the engineering world for over four decades disagrees with you. It does not have to 'pull' it's own weight on a level surface. It has to overcome the rolling resistance of the surface.
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To everyone who wants to use a locomotive, or a tugboat, or an airport tractor, please consider that none of these can get bogged, none of these are indented into the surface before they even try moving (apart from the tug lol).
It really doesn't matter. The point still stands that not one of these has a drawbar pull that is higher than the mass it can pull. You keep insisting that this one example is somehow different from every other counter-example, but that is only because it has to be if your argument is correct. Unfortunately your argument is very very wrong, as has been explained to you time and time again.
Drwabar pull is drawbar pull, and vehicles do not have to exert a force greater than the mass or weight of the load they pull in order to move that mass, here or on the moon.
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You can't discuss anything with someone who just goes "nope" all the time.
You could start by answering her questions.
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This is incorrect and gets to the heart of the confusion, in the army test they are certainly testing the weight/mass that can be pulled.
Yes, and I'll say it again: in a regime where the vehicle is already moving and has to pull its own weight up a hill. In a regime where the weight of the vehicle is actively opposing the forward motion.
So, just to be clear, you agree it is weight represented by the drawbar pull lb?
Earlier you said it was a force, there is a world of difference between a wheel being able to pull 30lbs in a test, and being able to exert a 30lb force.
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This is incorrect and gets to the heart of the confusion, in the army test they are certainly testing the weight/mass that can be pulled.
Which one do you claim it is, weight or mass?
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So, just to be clear, you agree it is weight represented by the drawbar pull lb?
Earlier you said it was a force, there is a world of difference between a wheel being able to pull 30lbs in a test, and being able to exert a 30lb force.
A weight is a force. It is the downward force exerted by a mass in a gravitational field. I know there is a difference between being able to pull 30 lb and being able to exert a force of 30 lb. The ability to pull a weight of 30 lb does not require a 30 lb force for one thing, unless you pull it upwards.
However (and this is the point you seem to be consistently missing), the amount of force needed to pull 30 lb increases depending on the angle you wish to pull it at relative to the horizontal/vertical. It varies according to the cosine of the angle to the perpendicular. If I want to hold a 30 lb weight up against gravity I have to exert a 30 lb force straight upwards. To lift it I have to exert a force in excess of 30 lb. To stop a 30 lb object rolling down a 45 degree slope I have to exert a force of 30 * cos 45 degrees, which is 30 * 0.707 = 21.2 lb. That's just to stop it rolling downhill. To lift it up the slope I have to exert a force greater than that, but it can be any little bit greater and I'll still be able to move it up the hill against its weight.
On the flat I don't have to exert any force to stop it moving because its weight won't make it move anyway. I can therefore apply any force to it and still move it, provided I can overcome the friction or rolling resistance. That resistance is related to its weight but is not equal to it. It is some fraction of its weight. If the force resisting its motion is 5 lb, I can move the object provided I can exert a force greater than 5 lb, no matter what the object weighs.
This is why I can move a car with its brakes off in neutral along a flat road, but I can't move it up an incline or when its brakes are on. On the flat I can exceed the resistance to its motion caused by rolling resistance and friction of the internal moving parts. When the brakes are on I cannot exceed the force provided by the friction of the wheels with the surface. On the incline I cannot exceed the portion of its weight making it accelerate down the hill, though I might be able to stop it rolling down the hill. On a steeper hill I would not be able to stop it rolling over me. The amount of force I can exert does not change. The conditions I have to overcome to make it move do.
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This is incorrect and gets to the heart of the confusion, in the army test they are certainly testing the weight/mass that can be pulled.
Which one do you claim it is, weight or mass?
Good question, I'm really not too sure, the difference being the rolling resistance, for some reason i thought it was weight with the same rolling resistance as the wheel but I can't recall why.
If I get time later I will try to figure it out if I can, it will depend on how they set the carriage up which I don't think they elaborate enough about.
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Um, guys? What's a pull coefficient? What is drawbar pull?
I read looked at the report being discussed and was totally lost. Just too many variables and unfamiliar terms to remember, and I couldn't get a picture in my head of how the test was being done.
Lil help? :-[
Sorry, missed this earlier.
The setup is a rover wheel in a dynamometer carriage. The wheel is resting on a bed of simulated lunar soil, and a load of 57 lb is applied to it to make it 'dig in' and get some traction. The wheel is running at a rate that would move the carriage forward at about 2.5 fps if it was allowed to roll freely. The wheel speed is kept constant.
The carriage, however, is moved independently, and it is moved along the test bed at speeds ranging from 0 to about 3 fps. At 0 fps the wheel is spinning without moving, a condition of 100% slip. At 2.5 fps the wheel is rolling along the surface with no slip. In between the amount of slip varies with the speed of the carriage.
As the wheel slips it digs into the soil and is 'trying' to move the carriage forward. It is exerting a pulling force that is measured by force gauges in the carriage. You can also, however, consider this force to be the force the carriage is applying to the wheel to make it slip: in other words the amount of force opposing the forward motion of the wheel that is required to induce that level of slip.
Applying that result to reality, as long as the wheel can overcome that force without slipping the rover can be driven. On a flat, that force is the rolling resistance of the surface. On a hill, the rover's weight acts against it, trying to pull it backwards down the hill. The portion of the weight acting opposite the rover's motion is the force it has to overcome without slipping. The 'pull coefficient' they are describing in the paper is that portion of weight.
Drawbar pull is the force left over when the vehicle has moved itself along a flat surface. An engine exerts a force. Some of that force goes to moving the vehicle itself. The leftover force is what can be used to pull an additional load. That additional load can be a trailer or it can be the extra effort required to move the vehicle up a hill due to the additional effect of the vehicle's own weight trying to make it roll back down the hill.
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This is incorrect and gets to the heart of the confusion, in the army test they are certainly testing the weight/mass that can be pulled.
Which one do you claim it is, weight or mass?
Good question, I'm really not too sure, the difference being the rolling resistance, for some reason i thought it was weight with the same rolling resistance as the wheel but I can't recall why.
If I get time later I will try to figure it out if I can, it will depend on how they set the carriage up which I don't think they elaborate enough about.
It would probably be a good idea for you to understand the basic concepts prior drawing your conclusions (let alone accusing others of making mistakes).
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To everyone who wants to use a locomotive, or a tugboat, or an airport tractor, please consider that none of these can get bogged, none of these are indented into the surface before they even try moving (apart from the tug lol). This, along with the low traction of a loose surface, is why a loose surface is such an easy one to get stuck on, as most of us have probably experienced.
I have towed a truck that was stuck on a loose surface with a 4wd, but that was with the truck using whatever traction it could muster as well, if the truck was in neutral forget it, it was also a very good surface which is why the driver though he could make it.
Do you really think a 4wd on a loose surface can act like a locomotive and pull many other 4wds?
A locomotive's wheels are indented into the surface. The rail is deflected downward by the weight on the axle.
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and its doing so up a 1:40 incline with steel wheels on steel rails!!!!
I know steel wheels on steel rails give less traction than rubber tires on asphalt or concrete, as well as less rolling resistance. Anybody have some typical figures?
I often hear it claimed that trains are dramatically more energy efficient than trucks and cars because they run steel wheels on steel rails. I think that's incorrect; even on a highway, aerodynamic drag almost always exceeds rolling resistance, so further decreases in rolling resistance provide diminishing returns. I think trains are so energy-efficient because they're so long. Only the the locomotive (or lead car) has to push the air out of the way for all the other cars. It's like they're all drafting each other, something I've personally seen work surprisingly well on the highway (and extremely dangerously).
Of course, many trains (especially freight trains) run much slower than highway speeds, thus reducing aerodynamic drag considerably. But the differences are large even at comparable speeds.
I don't have the numbers, but it's mainly the fact that the overall rolling resistance of the cars (carriages to you outside North America) is far less than the equivalent tonnage of highway vehicles. Aerodynamic drag is important, but nearly as much as the rolling resistance; locomotive engineers ("drivers" - sigh) can tell the difference in train handling when there are empty auto racks in the train, given the same overall length and tonnage. Empty unit coal trains have higher aerodynamic drag coefficients than loaded ones because of the air swirling around in the cars.
The biggest source of drag, though, are crosswinds, which push the wheel flanges up against the rail. That's huge, because, if your track structure is properly engineered and maintained, the flanges shouldn't touch the rail, at least ideally (the wheels are slightly conical - the flanges come more into play in turnouts, sharp curves at low speeds, or at very low speed on super-elevated curves, etc.).
Don't get me wrong, though. For the amount of fuel we use, we are looking at aerodynamic drag - we always have. One source of pain are double-stacked container trains. Having, effectively, a flat plate sticking up behind the locomotives and moving it upwards 70 MPH is significant. See this article for more: http://www.marcgunther.com/the-power-of-one-union-pacific/
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Better him than me. ;D
You can't discuss anything with someone who just goes "nope" all the time.
That's the first time I've ever seen anyone complain that Jay's responses are too short. Be careful what you wish for, anywho. ;)
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The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
I think it's reasonable to say that a bathroom scale measures mass in kilograms as long as one remembers how it works and the limitations of that method: by measuring the force of gravity and converting that to kilograms, implicitly assuming an acceleration of 9.8... m/s^2. I.e., it's a mass-measuring device with a mechanism of operation that works fine on earth as long as the minor variations in gravity from place to place are below your accuracy requirements, as they usually are. Any precise mass-measuring instrument of this type would have to be calibrated for local gravity to give correct results.
Unless, of course, you're Anders Björkman.*
* For anyone not familiar with the reference, Anders (also known as Heiwa) famously claimed on JREF that a bathroom scale measured only weight, not force, and that if a person jumped on a scale from a height of 3.7 meters, it would read the same as if he just stepped upon it.
Funnily enough I have to spend a fair amount of time explaining to construction workers why their fall arrest anchorages must be 'strong' enough to withstand a dynamic shock loading of at least 1.2 Tonnes even if they weigh less than 100Kg. And on a 'rat run' lifeline the anchorage at each end must be even 'stronger' than this (cant remember the exact figure off the top of my head but 144% rings a bell).
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This is incorrect and gets to the heart of the confusion, in the army test they are certainly testing the weight/mass that can be pulled.
Which one do you claim it is, weight or mass?
Good question, I'm really not too sure, the difference being the rolling resistance, for some reason i thought it was weight with the same rolling resistance as the wheel but I can't recall why.
We all know why. You got a preconceived notion that the rovers were faked, and now you're attempting to "fit" the evidence to "match" those preconceptions.
....and, hopefully, you are beginning to realize that just doesn't "work".
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You can't discuss anything with someone who just goes "nope" all the time.
No, you don't get to play that card. I wrote you several lengthy responses earlier in the thread and you ignored those too. You're still fumbling with the concepts of weight versus mass, like a beginning high school physics student. This, among other things, is leading you to misunderstand and misrepresent industry tests.
Let's be plain. You're standing firmly in the realm of my professional activity and you don't know what you're talking about. No, not even a little.
Many of your claims are based on allegations of fact you claim as premises to your physical model. A number of these assertions are just plain wrong. Those naked assertions are what's being called out and dismissed with "Nope." When a professional engineer tells you you're wrong on a point of engineering, and minces no words in the telling, you ignore it at your peril. And yes, that's what my staff engineers get. If I red-line some assertion or assumption in their analysis and write the single word "Incorrect" and send it back to them for revision, they know what to fix. You don't.
In your case you keep plodding along with the same misconceptions, unwilling to be corrected. Hence why I don't waste much more time on your foolishness. You have no interest in the right answer. Fix the "Nopes" first, then you can be taken more seriously.
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To everyone who wants to use a locomotive, or a tugboat, or an airport tractor, please consider...
No, all those putative objections have their proper analogues in the problem you're purporting to study and thus do not render the counter examples irrelevant. You're trying to come up with feeble excuses for why your home-grown physics model doesn't predict the behavior of any other vehicle in the solar system but is somehow still accurate for the LRV. But the answer is that your model is wrong, not that there's some nitpicky detail being left out. As has already been belabored, you've omitted the important sanity-check of your purported analysis method.
You don't know how properly to interpret drawbar tension or tractive effort. These counter-examples have been provided to you in the hope they will help you realize the qualitative nature of your error. That hope is dwindling. Over the past 30-odd pages you've advanced and abandoned half a dozen different ad hoc hypothesis and demonstrated a consistent inability to read and understand the technical literature. You can't discuss any of these concepts competently. What do you think the odds are that allegedly discrepant drawbar pull is really a smoking gun? Or is it more likely that it's just the latest in a long line of arguments you don't understand and will eventually abandon as soon as you trump up something else?
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The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
I think it's reasonable to say that a bathroom scale measures mass in kilograms as long as one remembers how it works and the limitations of that method: by measuring the force of gravity and converting that to kilograms, implicitly assuming an acceleration of 9.8... m/s^2. I.e., it's a mass-measuring device with a mechanism of operation that works fine on earth as long as the minor variations in gravity from place to place are below your accuracy requirements, as they usually are. Any precise mass-measuring instrument of this type would have to be calibrated for local gravity to give correct results.
Unless, of course, you're Anders Björkman.*
* For anyone not familiar with the reference, Anders (also known as Heiwa) famously claimed on JREF that a bathroom scale measured only weight, not force, and that if a person jumped on a scale from a height of 3.7 meters, it would read the same as if he just stepped upon it.
Funnily enough I have to spend a fair amount of time explaining to construction workers why their fall arrest anchorages must be 'strong' enough to withstand a dynamic shock loading of at least 1.2 Tonnes even if they weigh less than 100Kg. And on a 'rat run' lifeline the anchorage at each end must be even 'stronger' than this (cant remember the exact figure off the top of my head but 144% rings a bell).
Probably why climbing gear is rated in kilo-newtons. But practically, most only know if it is rated for a fall factor of 2 (worst-case lead fall). Learning how to build an anchor that can hold that, though..! And far too many still set the so-called "American Death Triangle"; a loop of webbing run between two anchors in such a way as to nearly double the load on them.
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The fact is that an object of 100 kg mass, weighs 100 kg on the Earth because it is in a 1G field
W = mg ... 100 x 1 = 100
and in the lunar gravity its weight is 16.7 kg
W = mg ... 100 x 0.167 = 16.7 (disregarding mascons of course!!)
I think it's reasonable to say that a bathroom scale measures mass in kilograms as long as one remembers how it works and the limitations of that method: by measuring the force of gravity and converting that to kilograms, implicitly assuming an acceleration of 9.8... m/s^2. I.e., it's a mass-measuring device with a mechanism of operation that works fine on earth as long as the minor variations in gravity from place to place are below your accuracy requirements, as they usually are. Any precise mass-measuring instrument of this type would have to be calibrated for local gravity to give correct results.
Unless, of course, you're Anders Björkman.*
* For anyone not familiar with the reference, Anders (also known as Heiwa) famously claimed on JREF that a bathroom scale measured only weight, not force, and that if a person jumped on a scale from a height of 3.7 meters, it would read the same as if he just stepped upon it.
Funnily enough I have to spend a fair amount of time explaining to construction workers why their fall arrest anchorages must be 'strong' enough to withstand a dynamic shock loading of at least 1.2 Tonnes even if they weigh less than 100Kg. And on a 'rat run' lifeline the anchorage at each end must be even 'stronger' than this (cant remember the exact figure off the top of my head but 144% rings a bell).
Probably why climbing gear is rated in kilo-newtons. But practically, most only know if it is rated for a fall factor of 2 (worst-case lead fall). Learning how to build an anchor that can hold that, though..! And far too many still set the so-called "American Death Triangle"; a loop of webbing run between two anchors in such a way as to nearly double the load on them.
As is so for Construction Fall Arrest Equipment (in fact some of the modern equipment is dual marked with EN Numbers applicable for both the workplace and the Rock face) At the Risk of sounding 'superior' I don't want to be explaining kN to East European bricklayers and carpenters...Keep It Simple Stupid.
To be fair they understand the principle of shock loading... they just cant quite understand why, if they weigh 100Kg, they need an anchor sling with a far higher capacity. I don't allow double anchors on my sites, but that usually falls in line with manufacturers specs so I just use that as my decision factor as far as the workforce are concerned.
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To everyone who wants to use a locomotive, or a tugboat, or an airport tractor, please consider that none of these can get bogged, none of these are indented into the surface before they even try moving (apart from the tug lol). This, along with the low traction of a loose surface, is why a loose surface is such an easy one to get stuck on, as most of us have probably experienced.
I have towed a truck that was stuck on a loose surface with a 4wd, but that was with the truck using whatever traction it could muster as well, if the truck was in neutral forget it, it was also a very good surface which is why the driver though he could make it.
Do you really think a 4wd on a loose surface can act like a locomotive and pull many other 4wds?
A locomotive's wheels are indented into the surface. The rail is deflected downward by the weight on the axle.
And - needless to say - a boat indents the surface it is on, and has to overcome the drag caused by trying to move horizontally in that indent.
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To be fair they understand the principle of shock loading... they just cant quite understand why, if they weigh 100Kg, they need an anchor sling with a far higher capacity.
To compute the shock loading, don't you also have to know something about the spring constant of the line and its hardware, not to mention that of your body? If there's no elasticity in the system then the peak force when you fall could be arbitrarily high, and even if your line can withstand it this shock could also hurt you.
I suppose you could say that there's no point in having a line with a load rating higher than the maximum force your body could withstand so it might as well break. But somehow that doesn't seem right.
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On the flat I don't have to exert any force to stop it moving because its weight won't make it move anyway. I can therefore apply any force to it and still move it, provided I can overcome the friction or rolling resistance.
Just to be rigorously complete, because the rolling resistance depends on weight (the downward force of gravity), it too depends on the slope. While the tractive force required to overcome gravity on a slope varies with the sine of the slope (from horizontal), the rolling resistance varies as the cosine of the slope because that sets the force of gravity normal to the ground.
Because the coefficient of rolling resistance is usually much less than 1, and because the sine of a small angle increases much more rapidly than its cosine decreases this is usually a small effect, but I mention it for completeness. 'anywho' may not have any rigor whatsoever in his analyses, but it's still good for us...
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...when I start talking to non-scientific minded people about the moon and Apollo, they understand when I tell them that a 60 kg object only weighs 10 kg on the moon because the moon's gravity is only 1/6th that of earth, and that is why the astronauts walked funny on the moon.
Actually, this is not correct. My son weighs 1/6th what I do (yes, I need to lose weight), but our walking-gait is essentially the same. This is because the kinesthetics of the gait is dictated by the downward acceleration, not by weight.
When you walk, the ankle joint of your left leg is rotating forward. Your center-of-gravity is shifting forward (and gains some momentum as it does so). When it is so far forward that it is no longer over your foot, you are falling forward. Meanwhile your other leg is swinging forward. The downward pull of gravity brings your right heel into contact with the ground just as your center-of-gravity moves over it. Your CoG continues forward, over your right foot as you pick-up your left leg and let it swing forward. In 1g, your CoG will be moving forward and your legs will be swinging to stay under it so that it feels natural to move at ~2-3mph.
On the Moon, the CoG shifts forward, and you swing your leg to get your foot under it, but gravity is not pulling your heel down fast enough to make contact with the ground. Your CoG keeps moving forward over the unplanted foot and you're trying to get the other leg forward to get it underneath... and a simple walk turns into a skipping-lope. That is why the astronauts "walk funny".
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When you walk, the ankle joint of your left leg is rotating forward. Your center-of-gravity is shifting forward (and gains some momentum as it does so). When it is so far forward that it is no longer over your foot, you are falling forward. Meanwhile your other leg is swinging forward. The downward pull of gravity brings your right heel into contact with the ground just as your center-of-gravity moves over it.
I think the term is "inverted pendulum", and like any pendulum its natural period depends on length and the acceleration of gravity.
and a simple walk turns into a skipping-lope. That is why the astronauts "walk funny".
Here's how I like to think about it. Because a bipedal walker is an inverted pendulum, and every pendulum has a natural rate, there's a natural speed limit on how fast we can walk.
Above that limit, we can no longer keep a foot on the ground at all times because we simply can't fall fast enough. So we transition to running, defined as no longer having at least one foot on the ground at all times. The much lower gravity on the moon forces this walk-to-run transition to happen at an unusually slow speed, well below the speed you'd often like to move and which your metabolic rate can easily support.
So the totally natural thing to do is to "run" at walking speed -- and that's exactly what the loping stride we see in Apollo lunar EVAs really is.
Everyone who has done it says it's totally natural, even people who have only experienced lunar gravity on an airplane without much time to think or adapt. At the end of my favorite segment of that wonderful Mythbusters episode on the Apollo hoax, Adam Savage said that the 1/6g Apollo lope instantly felt totally natural to him.
We humans are extremely familiar with walking, and because it is so profoundly affected by gravity it is virtually impossible to convincingly fake lunar walking in 1g. If I had to pick a single compelling argument for the Apollo lunar EVA footage being real, this would be it.
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To be fair they understand the principle of shock loading... they just cant quite understand why, if they weigh 100Kg, they need an anchor sling with a far higher capacity.
To compute the shock loading, don't you also have to know something about the spring constant of the line and its hardware, not to mention that of your body? If there's no elasticity in the system then the peak force when you fall could be arbitrarily high, and even if your line can withstand it this shock could also hurt you.
I suppose you could say that there's no point in having a line with a load rating higher than the maximum force your body could withstand so it might as well break. But somehow that doesn't seem right.
Under EN (European Standards) Fall Arrest Harnesses must limit the force on the body to a maximum of 600kgf. For Fall arrest you must have a shock absorber, usually a webbing or rope line with a compact concertina of webbing straps stitched in a pouch with strategic stitches so that it deploys 'in sequence'.
This shock absorber needs more than 200kgf to deploy and before use,with its webbing or rope line, can be no longer than 2m in length from anchorage point to where it is connected on the harness (between the shoulder blades- 'dorsal' or over the chest- 'breast') although in practice this can be lengthened slightly if an anchor sling is used between the shock absorber line and the anchorage (not specified as long as you be sensible about it).
Currently in Europe harnesses shock absorber lines and anchorages are tested to 15kN but many components are far stronger (some karabiners for example can be rated to 45kN, and some slings as high as 70kN). The regulations are being looked at to increase this to 22kN. If you use proprietary equipment the only thing you need to ensure is that your anchorage point is strong enough, Currently 12kN for fall arrest, 15kN for rope access work (the nutters (my personal opinion ;D) who abseil down the sides of buildings whilst at work!)
What this all means is that in a Factor 2 fall, usually where your anchor point is at foot level, you can fall the length of your connector rope from anchorage to where it is connected on your harness (maximum of 2m) and then the full length of the connector (maximum 2m) then you have to fall a further 1.2-1.5m as the shock absorber deploys, you will exert maximum force on the system.... the shock absorber, stretch in lines and harness, and the design of the harness mean that the force on your body is progressively reduced and you should not receive more than 600kgf (which should be spread fairly evenly across the thighs waist and torso).
However much the maximum loading experienced overall is, obviously you want your anchor point to be stronger than the potential maximum loading, which the systems designers currently rate at 1200kgf in a classic fall from height at work. (sorry everyone for being so off topic!)
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To compute the shock loading, don't you also have to know something about the spring constant of the line and its hardware, not to mention that of your body? If there's no elasticity in the system then the peak force when you fall could be arbitrarily high, and even if your line can withstand it this shock could also hurt you.
I suppose you could say that there's no point in having a line with a load rating higher than the maximum force your body could withstand so it might as well break. But somehow that doesn't seem right.
Not could hurt you, but would definitely hurt you. IIRC, a fall stopped by an arrest system missing a shock absorbing device is fatal from a shorter height than an unarrested fall.
...However much the maximum loading experienced overall is, obviously you want your anchor point to be stronger than the potential maximum loading, which the systems designers currently rate at 1200kgf in a classic fall from height at work. (sorry everyone for being so off topic!)
At my work in the USA, we design "generic" (can be installed as required) fall arrest anchorages for 5000 lb static load - pretty similar to your 1200kgf rating. Application-specific designs that get field verified individually have lower safety factors, but its not my department and I couldn't tell you how much lower.
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In Larry Niven & Jerry Pournelle's sci-fi Novel "The mote in God's eye", human walking is described as a 'controlled fall', which I always liked. Kind of apt here.
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In Larry Niven & Jerry Pournelle's sci-fi Novel "The mote in God's eye", human walking is described as a 'controlled fall', which I always liked. Kind of apt here.
I never read that one, but the same authors used that same description in "Footfall".
The description was from the POV of alien invaders who were built very much like Terran elephants and for whom watching human locomotion was unsettling and a little queasy-making.
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In Larry Niven & Jerry Pournelle's sci-fi Novel "The mote in God's eye", human walking is described as a 'controlled fall', which I always liked. Kind of apt here.
I never read that one, but the same authors used that same description in "Footfall".
The description was from the POV of alien invaders who were built very much like Terran elephants and for whom watching human locomotion was unsettling and a little queasy-making.
Aah that's the one - apologies. I couldn't remember the title, googled and 'Mote..' was the one I recognised.
Both good reads :)
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To everyone who wants to use a locomotive, or a tugboat, or an airport tractor, please consider...
No, all those putative objections have their proper analogues in the problem you're purporting to study ...
No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
What a train on tracks , and a tugboat can pull (news flash, tugboats don't have wheels), does nothing to prove a 4wd on a loose surface can tow 5 times its own weight.
If only someone would do an actual test with a rover wheel and a simulated soil so we could look at those results instead of relying on trains and tugboats and pushbacks.
However (and this is the point you seem to be consistently missing), the amount of force needed to pull 30 lb increases depending on the angle you wish to pull it at relative to the horizontal/vertical.
The drawbar pull required to drive up the hill is roughly equvalent to the tangent of the slope
All the wheel performance plots shown herein reflect the assumption that the pull coefficient measured at a given slip on a level surface with a slngle wheel is roughly equivalent to the tangent of the angle of the slope that a vehicle equipped with similar wheels can climb.
http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt1.pdf
Accordingly, on this basis the maximum slope climbing capability of the 50 percent chevron covered wire-mesh GM wheel is estimated to be of the order of 20 deg.
So we have the rover wheel that is tested in a simulated lunar soil and it can only muster enough traction to drive up a 20 degree slope before traction becomes too problematic. That means traction is at its designated limit when the wheel has to sustain a pull of a little more than 1/3 of its own weight, there is a safety margin in that figure so lets round it up to a 27 degree slope where it has to pull 50% more than its own weight.
So a sustained pull of 0.5 times the weight on the wheel is the traction limit. Don't forget, these tests were done on a level pit and then extrapolated to find the slope climbing ability, therefore the pull limits are based on a level pull.
To accelerate the rover has to find enough traction to sustain a pull of 5 times its own weight, and that is undeniable.
The test shows a 50% drawbar pull coefficient is possible with the available traction, basic physics say a 500% coefficient is needed for acceleration.
BTW, the silence is deafening wrt anyone claiming the army test proves the rover could operate on the moon, it seems like the best tactic is to shift the discussion away from the test to tug boats lol.
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To accelerate the rover has to find enough traction to sustain a pull of 5 times its own weight, and that is undeniable.
So when my car is on black ice, where the friction coefficient is around 0.01, it cannot move? My car weight 1700 kilos, and according to you, it has to be able exert a pulling force of 6.5 tonnes? Is that right?
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Anywho, you have been shown, multiple times, how to apply the physics you spout using a number of examples - and given reasons for those examples. You have also been shown your errors. Your only response is to refuse to accept facts as presented to you.
I still want to know how you can claim that a video showing the rover moving well on the lunar surface somehow disproves that the rover could do so.
If only someone would do an actual test with a rover wheel and a simulated soil so we could look at those results instead of relying on trains and tugboats and pushbacks.
Or.... they could drive it on the moon. As the video you linked to shows them doing!
There is no need to rely on any other proof using "simulated" anything. The rover is clearly seen working on the moon.
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If only someone would do an actual test with a rover wheel and a simulated soil so we could look at those results instead of relying on trains and tugboats and pushbacks.
No need for further testing, as the rovers performed fine on the Moon.
If you believe differently, then present actual evidence that the rovers were faked...this "Army report garbage" combined with your woeful lack of physics knowledge leads you to the wrong conclusions...and as evidence, it is not convincing.
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No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
So the Army test "proved" the rovers could not operate on the Moon, and in the over 40+ years since that test, you are the very first person to "see" it?
Is that really what you are saying?, because if you are, then there is no need to debunk you...you've debunked yourself.
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No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
Wrong. When other examples that DO NOT support your conclusions are given they are issues YOU have to deal with. You don't get to dismiss them as diversions. Physics is universal. If it doesn't work on one thing it won't work on another.
So we have the rover wheel that is tested in a simulated lunar soil and it can only muster enough traction to drive up a 20 degree slope before traction becomes too problematic.
Yes, because at this point it has to effectively cancel out the rearward acceleration of its own weight due to the slope before it can move forward at all: something that it does NOT have to do on the flat. Which bit of that is not clear?
To accelerate the rover has to find enough traction to sustain a pull of 5 times its own weight, and that is undeniable.
No, it does not. It has to provide enough force to move itself, starting from a speed of zero and slowly building up the speed. It can do this with ANY force. F = ma.
The test shows a 50% drawbar pull coefficient is possible with the available traction, basic physics say a 500% coefficient is needed for acceleration.
No, your total lack of understanding of basic physics makes you assert that repeatedly without any actual basis in reality.
BTW, the silence is deafening wrt anyone claiming the army test proves the rover could operate on the moon, it seems like the best tactic is to shift the discussion away from the test to tug boats lol.
It is not our burden of proof. It is yours. and so far all you have done is failed to meet it.
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So we have the rover wheel that is tested in a simulated lunar soil and it can only muster enough traction to drive up a 20 degree slope before traction becomes too problematic. That means traction is at its designated limit when the wheel has to sustain a pull of a little more than 1/3 of its own weight, there is a safety margin in that figure so lets round it up to a 27 degree slope where it has to pull 50% more than its own weight.
You might want to look at how they derived that lunar simulant there.
Please can you also give us your sources of information as to the nature of the slopes on which the LRV would be driving, and which slopes it actually did drive on that were greater than the stated capabilities of it, and also your sources showing that the surface material would be incapable of providing traction.
I did ask this before, but the silence was deafening.
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No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
No, they are an attempt to show you how you are misinterpreting the test. Since you have utterly failed to interpret practically anything correctly in this discussion, kindly stop for a moment and consider that we're trying to get you to realize something that everyone else in the engineering world sees already. Your knee-jerk reaction is simply to dismiss the counterexamples on a pretext.
BTW, the silence is deafening wrt anyone claiming the army test proves the rover could operate on the moon...
Fishing for straw men is not an argument, nor is shifting the burden of proof.
...it seems like the best tactic is to shift the discussion away from the test to tug boats lol.
Oh, please. You've been trying to argue by irrelevant analogy for weeks. It's a poor time now to start trying to tar others with a similar brush.
Your understanding of the physics principles is wrong. Hence the model of vehicle dynamics you're using to "prove" the LRV is impractical, is commensurately wrong. Your wrong-headed model would nevertheless apply to other vehicles. Hence if it were true and probative for the LRV, it would have to be equally true and probative for other tractive vehicles. It is provably not, therefore your homegrown yardstick is discarded.
You evidently realize this, which is why you're desperately trying to trump up reasons why we shouldn't attempt to validate your model.
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No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
OK, page one, post one, by you. You want to get back on topic then Your claim the motors are not capable, please show your workings out, I don't know but I reckon I could follow your examples if you paste them in here. Going to dodge this again after so many pages?
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Anywho, perhaps you'd go through some 'basic physics' with us, to show where we're going wrong, according to you?
1: Do you agree that F = ma?
2: Do you agree that it follows from that that a = F/m, and that therefore if I have a mass of, say 100 kg, I can accelerate it with any force at all, and all that will change is the rate of acceleration? So if I apply a force of 1 N it will accelerate at 1/100 ms^-2, a force of 10 N will accelerate it at 1/10 ms^-2, a force of 100 N at 1 ms^-2, and so on?
Let's start there.
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To accelerate the rover has to find enough traction to sustain a pull of 5 times its own weight, and that is undeniable.
So when my car is on black ice, where the friction coefficient is around 0.01, it cannot move? My car weight 1700 kilos, and according to you, it has to be able exert a pulling force of 6.5 tonnes? Is that right?
On the moon f your car weighs 1700kgs then it has a mass of 10,200 kgs, so it has to find enough traction to pull 8,500kgs on top of the weght (this is not a force of 8500kgs, it is just an additional mass it has to tow)
On the moon your car would weigh only 283kgs but would still have to get enough traction to pull the 1700kgs along the black ice.
Anywho, perhaps you'd go through some 'basic physics' with us, to show where we're going wrong, according to you?
1: Do you agree that F = ma?
2: Do you agree that it follows from that that a = F/m, and that therefore if I have a mass of, say 100 kg, I can accelerate it with any force at all, and all that will change is the rate of acceleration?
1. Yes
2. No, not when a vehicle is on a loose surface, you have to get enough traction to overcome the rolling resistance and that can not only be significant but can also be very complicated to work out due to issues like the wheel sinking into the surface (both before and in addition to any wheel spinnage).
It can sometimes be impossible to apply the force needed to accelerate the vehicle, or do you believe it is impossible to get stuck on a loose surface as long as you just go slow enough? even towing multiple trailers with your 4x4 on a loose surface?
To overcome the complexities inherent n a loose surface you could do some very complicated modelling, or you could conduct some tests. If those tests show you can only accelerate at x rate pulling a maximum of 50% before slippage is too problematic, then it's a no-brainer that you will get bogged f you try to pull 500%.
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2. No, not when...
Do not complicate the basic physics. Get the basic physics right first, then add the real-world complicating factors. This is where you habitually go wrong. You try to fumble your way through secondary factors as a substitute for understanding the basics qualitatively.
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No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
Perhaps this should have been addressed more unambiguously earlier then - the report does not say that.
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On the moon f your car weighs 1700kgs then it has a mass of 10,200 kgs, so it has to find enough traction to pull 8,500kgs on top of the weght (this is not a force of 8500kgs, it is just an additional mass it has to tow)
Do you understand rolling resistance? I just explained it here a few days ago. This is the force needed to keep a wheeled vehicle going at a constant speed on a level surface. It is independent of speed but varies linearly with weight, so if the vehicle is transported to the moon and operated on a comparable surface the rolling resistance is only 1/6 of that on earth. That means only 1/6 as much motor power is needed to keep the vehicle moving at a constant speed.
The only force that doesn't vary with gravity is that needed to accelerate the vehicle, because inertial acceleration is the one place where mass really matters. Here you are limited by the fact that the static friction of the wheels, i.e., the maximum torque they can take without slipping, is also reduced to 1/6 of its earth value. So you simply can't accelerate or brake as rapidly on the moon as you can on earth, at least if you don't want the tires to slip. But kinetic friction, while often lower than static friction, isn't always so, and if you don't care if the wheels slip a little and/or if the coefficient of kinetic friction is close to that of static friction, this isn't a serious problem.
Besides, drivers usually spend far more time cruising than accelerating. Since the LRV's top speed on the moon for a given motor power is at least 6x that on the earth, it simply means the astronauts couldn't do much drag racing on the moon. It hardly means they couldn't drive around prospecting.
You complained that 1 hp was "obviously" insufficient for the LRV. But the LRV operated in a vacuum where aerodynamic drag is totally absent, in a 1/6 g gravity field where rolling resistance is only 1/6 of its earth value, and is limited in peak acceleration because of the decrease in maximum allowable traction force, at least if you care about wheel slippage. In other words, the LRV didn't need a bigger motor, and it probably couldn't have used one anyway.
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2. No, not when a vehicle is on a loose surface,
I didn't ask about the surface. We'll deal with the details later. Answer the question. Do you agree that acceleration is proportional to force?
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No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
Explain why the Army (or the report), did not reach the same conclusion.
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No, the are just an attempt to divert away from the subject matter, which is an army test which shows the rover cannot get enough traction to operate in 1/6g.
That is your interpretation of the test. The test report itself does not say that. So we are left with the possibility that your interpretation is wrong and are asking you to examine that possibility, which you have steadfastly refused to do.
If the rover could not operate on the moon, how is it that we have video of a vehicle that is indistinguishable from the lunar rover operating in an environment that is indistinguishable from the lunar surface?
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If the Army tests really proved that the traction was insufficient, why didn't they just redesign the wheels with, say, spikes?
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If the Army tests really proved that the traction was insufficient, why didn't they just redesign the wheels with, say, spikes?
Or snow chains! ;D
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If the Army tests really proved that the traction was insufficient, why didn't they just redesign the wheels with, say, spikes?
Well, that's pretty much the bottom line, isn't it? If the test had determined that the tire/weight/motor combination was not able to meet the desired parameters, they would have gone back to the drawing board and made changes until they had a combination that worked.
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If the Army tests really proved that the traction was insufficient, why didn't they just redesign the wheels with, say, spikes?
Indeed, that's a popular solution here in Alaska...from October to May anyway. But they aren't strictly necessary, though. I get by year-round with a quality set of all-season tires in spite of living on the foot of a mountain and seeing virtually no asphalt for months at a time. Since moving into our house more than 8 years ago, there were only two occasions when I really needed studs: when the streets really were sheets of glare ice, which is in no way comparable to lunar regolith.
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To accelerate the rover has to find enough traction to sustain a pull of 5 times its own weight, and that is undeniable.
So when my car is on black ice, where the friction coefficient is around 0.01, it cannot move? My car weight 1700 kilos, and according to you, it has to be able exert a pulling force of 6.5 tonnes? Is that right?
On the moon f your car weighs 1700kgs then it has a mass of 10,200 kgs, so it has to find enough traction to pull 8,500kgs on top of the weght (this is not a force of 8500kgs, it is just an additional mass it has to tow)
On the moon your car would weigh only 283kgs but would still have to get enough traction to pull the 1700kgs along the black ice.
That makes no sense whatsoever.
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Well, that's pretty much the bottom line, isn't it? If the test had determined that the tire/weight/motor combination was not able to meet the desired parameters, they would have gone back to the drawing board and made changes until they had a combination that worked.
Or, at least, if we assume for a moment it was faked, why would they run tests that would prove the fake wouldn't work, leave them in the public domain, and not make at least cosmetic changes that would look like they had addressed the issue?
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Right. If the tests showed the LRV couldn't work, they'd fix the LRV. If there was a giant conspiracy, then they'd falsify the results. Or just not do the test (or tell anyone what they found.)
So what we have is yet another bit of Cunning Dude, er. The person with native wits and a quick read-up who manages to see what no-one, including those people actually conducting the test, managed to notice. Good thing the Dude didn't accidentally get himself any engineering training! That might have gotten in the way of his common sense and left him similarly unable to see the obvious.
Of course, the TEST is a bit of a Crimson Clupeidae here. The design of the wheel isn't a state secret. Nor is the nature of lunar soil. Anyone is capable of making a similar empirical test, or estimating the results using long-tested engineering approximations. And thus if there was a conspiracy, why would they tell ANYONE what the design of the wheels looked like? Every detail you put out there makes it more likely someone will catch you up.
I mean, lets have some perspective here. When there's a bit of wrong history in a movie or bad science in a book people don't just skip it and move on. They tell others. They point fingers and laugh. They make entire blog posts and reviews and videos pointing out the stupidity of the mistake. And it isn't like the space program gets less attention than the latest blockbuster. Well....certainly not during the time of Apollo!
You seriously think NASA could make basic mistakes, put the information out for public consumption, and no-one would bother to take a more than cursory look at it?
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Right. If the tests showed the LRV couldn't work, they'd fix the LRV. If there was a giant conspiracy, then they'd falsify the results. Or just not do the test (or tell anyone what they found.)
So what we have is yet another bit of Cunning Dude, er. The person with native wits and a quick read-up who manages to see what no-one, including those people actually conducting the test, managed to notice. Good thing the Dude didn't accidentally get himself any engineering training! That might have gotten in the way of his common sense and left him similarly unable to see the obvious.
Of course, the TEST is a bit of a Crimson Clupeidae here. The design of the wheel isn't a state secret. Nor is the nature of lunar soil. Anyone is capable of making a similar empirical test, or estimating the results using long-tested engineering approximations. And thus if there was a conspiracy, why would they tell ANYONE what the design of the wheels looked like? Every detail you put out there makes it more likely someone will catch you up.
I mean, lets have some perspective here. When there's a bit of wrong history in a movie or bad science in a book people don't just skip it and move on. They tell others. They point fingers and laugh. They make entire blog posts and reviews and videos pointing out the stupidity of the mistake. And it isn't like the space program gets less attention than the latest blockbuster. Well....certainly not during the time of Apollo!
You seriously think NASA could make basic mistakes, put the information out for public consumption, and no-one would bother to take a more than cursory look at it?
The excuse Hunchbacked gives is that the engineers were making deliberate mistakes so that self important 'geniuses' like him could pick up on them and blow the whistle...
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Has there EVER been a case of scientific or engineering whistleblowing of this nature? Hiding evidence in public documents or film, and letting it sit around for decades until an intrepid investigator discovers it?
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Right. If the tests showed the LRV couldn't work, they'd fix the LRV. If there was a giant conspiracy, then they'd falsify the results. Or just not do the test (or tell anyone what they found.)
So what we have is yet another bit of Cunning Dude, er. The person with native wits and a quick read-up who manages to see what no-one, including those people actually conducting the test, managed to notice. Good thing the Dude didn't accidentally get himself any engineering training! That might have gotten in the way of his common sense and left him similarly unable to see the obvious.
Of course, the TEST is a bit of a Crimson Clupeidae here. The design of the wheel isn't a state secret. Nor is the nature of lunar soil. Anyone is capable of making a similar empirical test, or estimating the results using long-tested engineering approximations. And thus if there was a conspiracy, why would they tell ANYONE what the design of the wheels looked like? Every detail you put out there makes it more likely someone will catch you up.
I mean, lets have some perspective here. When there's a bit of wrong history in a movie or bad science in a book people don't just skip it and move on. They tell others. They point fingers and laugh. They make entire blog posts and reviews and videos pointing out the stupidity of the mistake. And it isn't like the space program gets less attention than the latest blockbuster. Well....certainly not during the time of Apollo!
You seriously think NASA could make basic mistakes, put the information out for public consumption, and no-one would bother to take a more than cursory look at it?
The excuse Hunchbacked gives is that the engineers were making deliberate mistakes so that self important 'geniuses' like him could pick up on them and blow the whistle...
It's been my experience so far that, at least with the moon hoax CT, if you follow their chain of... well, logic might not be the right word, but we'll let that pass... chain of logic, it always seems to lead into wilder and wilder absurdities.
Back-room US-USSR pacts to keep each other's hoaxes secret - the Cold War was all a giant hoax anyway.
Reflectors were placed on the moon and almost half a ton of samples brought back by robot probes. Ignore the fact that probes with this level of capability have never been seen, before or since.
The 'hoax' was known to only a handful of people because information was kept tightly compartmentalized.
Aliens. Illuminati. And the genius who pointed out that if they took heavy digging equipment to Antarctica, it wouldn't have taken them long to dig up 850 pounds of moon rocks. :o
Anyway. Similar to what nomuse said, IMHO, when you consider the amount of technical documentation, transcripts, video & photographic records, personal accounts, interviews, speeches, books written by central participants... all of it consistent within the usual limits of human error, just the sheer volume of data all pointing to the reality of the Apollo program should be convincing in itself.
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If the Army tests really proved that the traction was insufficient, why didn't they just redesign the wheels with, say, spikes?
They did look at using spikes, why they didn't go with them is anyones guess, perhaps they didn't look good enough, perhaps they would raise too many questions about traction on the moon and why the astronauts don't need crampons.
When it's all a sham they can choose style over substance, and lets be honest, the rover tyres make no sense at all, they are an absolute triumph of style over substance.
They have a mesh which is supposed to be the frictive surface, then they cover 50% of it with a smooth chevron, the chevron is thin so provides no notable tread, it is smooth so provides limited traction, it covers 50% of the mesh and recesses the other 50% ???
Worlds dumbest tyre design ever.
Well, that's pretty much the bottom line, isn't it? If the test had determined that the tire/weight/motor combination was not able to meet the desired parameters, they would have gone back to the drawing board and made changes until they had a combination that worked.
It may be impossible to make a vehicle with weight restrictions that would work on the moon, also they didn't have time for delays, also IT WAS ALL A SHAM, so why not go with a cool looking design they can hoon around in rather than something clumsy looking like a tracked vehicle?
Or, at least, if we assume for a moment it was faked, why would they run tests that would prove the fake wouldn't work, leave them in the public domain, and not make at least cosmetic changes that would look like they had addressed the issue?
These are army tests, they were told to test the wheels with the expected weight the would have on the moon, in a simulated lunar soil, and that is what they did. Simple as that.
It is entirely possible that they did not consider the implications of 1/6g above and beyond the weight difference at all, especially as it was not in their brief to go beyond testing the wheel/soil interaction.
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The excuse Hunchbacked gives is that the engineers were making deliberate mistakes so that self important 'geniuses' like him could pick up on them and blow the whistle...
Which is strongly reminiscent of Dr. John Nash's delusion that the Russians were sending him secret messages encoded in newspapers and magazines.
This is why, despite the entirely reasonable objections often made about diagnosing mental illness from a distance, I'm personally convinced that hunchbacked is just batshit insane. The main difference between him and John Nash is that Nash actually did good work before he became ill.
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When it's all a sham they can choose style over substance
Do you think you just might be able to take some time away from repeating, ad infinitum, your bare assertion that it was all faked and actually answer some questions from the people here?
Like andromeda's excellent but repeatedly ignored question to you, to wit:
What exactly are we seeing in the films and videos of the LRV operating on the moon? Do you not see the contradiction between your claim that it could not withstand operation in 1g and your claim that the films and videos were shot on the earth, not the moon?
Her questions are dozens of pages back, yet you have never given her the courtesy of a reply. Why?
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It may be impossible to make a vehicle with weight restrictions that would work on the moon, also they didn't have time for delays, also IT WAS ALL A SHAM, so why not go with a cool looking design they can hoon around in rather than something clumsy looking like a tracked vehicle?
So they were insistent on the LRV having a "cool looking design" but they didn't care if the LM looked like taped-together cardboard? More inconsistencies in the hoax theory.
And why haven't you answered Andromeda's question?
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Like andromeda's excellent but repeatedly ignored question to you, to wit:
What exactly are we seeing in the films and videos of the LRV operating on the moon? Do you not see the contradiction between your claim that it could not withstand operation in 1g and your claim that the films and videos were shot on the earth, not the moon?
Her questions are dozens of pages back, yet you have never given her the courtesy of a reply. Why?
The question is not worthy of a reply, maybe you all need a sticky where the mods can explain to you that someone who thinks the apollo landings were a hoax implicitly believes the footage is faked.
As I have already sad, there is no contradiction in using the fake apollo footage, as presented, to demonstrate the apollo landng could not have taken place, as presented.
It is not me who claimed the rovers could not operate or even be sat on in 1g, it is NASA, and that is a big contradiction from NASA (not me) because the forces experienced when hitting moguls on the moon will be very similar to earth.
I am happy to say that at least one of you can figure out the bleeding obvious:
What is your alternative scenario to 'the rovers were operated on the Moon as described'?
I imagine something along the lines of the Rover in the film not being built to the Specs put out by NASA and the footage is somewhere on Earth.
This is a message board that invites people to put hoax theories forward, do you all really need it explained that a hoax believer is someone who thinks it was all faked?
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It is also a board where you are requested and required to use proper physics, mathematics and engineering principles to back those claims up. And answer the questions posed to you.
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When it's all a sham they can choose style over substance, and lets be honest, the rover tyres make no sense at all, they are an absolute triumph of style over substance.
They have a mesh which is supposed to be the frictive surface, then they cover 50% of it with a smooth chevron, the chevron is thin so provides no notable tread, it is smooth so provides limited traction, it covers 50% of the mesh and recesses the other 50%
If you'd read the report properly you'd have understood that it was comparing a range of options, and the chevron design (and the edges of the chevrons will provide traction, as will the chevrons themselves - prove otherwise) providing the right balance between grip and not accumulating debris inside the mesh.
You may think the answer is beneath you, but can you enlighten us poor savages by telling us how they derived the properties for the lunar simulant, and what evidence you have that the lunar soil would not provide enough traction and the slopes were too steep.
3rd time of asking.
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Anywho, it seems to me that you thought that the Rover did produce a noticeable tread. Remember "Tracks of a Moon Rover?"
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Anywho, can you please explain what's going on in this video? A 2 wheel drive vehicle getting traction (and not sinking!) in water.
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The question is not worthy of a reply
Wrong. A reply is common courtesy, and everyone is worthy of that.
maybe you all need a sticky where the mods can explain to you that someone who thinks the apollo landings were a hoax implicitly believes the footage is faked.
So if the footage is faked how do you justify using it to judge the properties of the real lunar surface? What you see there is a vehicle with the 'dumbest tire design ever' manifestly not having trouble on a loose surface, and some pretty good indications of vacuum and low gravity. So how was that shot produced?
Now you will answer my question: do you agree that if you accept F = ma you must also accept that a = F/m? Forget the details, we're talking about the basics here. Do you agree that the acceleration of any mass is proportional to the net force on it?
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Anywho, can you please explain what's going on in this video? A 2 wheel drive vehicle getting traction (and not sinking!) in water.
Well patently this was not shot anywhere on the Earth, because we all know that a vehicle such as a quad-bike is designed to operate on LAND will not get any traction on water.
Perhaps it was faked on a planet where there are oceans of sodium hydroxide (has twice the density of water)
Don't agree? Well my suggestion certainly makes as much sense as anything anywho has contributed so far.
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Anywho, if you know physics, you can make you own calculation and see than on the moon the rover could reach 10-11km/h with maximum load - very rough estimate i made a couple of minutes ago. And around 15-16 km/h with one person load.
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The question is not worthy of a reply, maybe you all need a sticky where the mods can explain to you that someone who thinks the apollo landings were a hoax implicitly believes the footage is faked.
As I have already sad, there is no contradiction in using the fake apollo footage, as presented, to demonstrate the apollo landng could not have taken place, as presented.
I think it is. You propose something you have not backed up. The alternative to actually doing it will need some explaining. Of course if you are unable to do that then your stance is in error.
Still waiting to follow your claims on page one.
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The question is not worthy of a reply,
Because you cannot answer it? Or maybe you think I am unworthy of reply?
maybe you all need a sticky where the mods can explain to you that someone who thinks the apollo landings were a hoax implicitly believes the footage is faked.
We are well acquainted with what HBs think. What we want to know is how you think it was done. Maybe you need a sticky to explain to you what "burden of proof" means.
As I have already sad, there is no contradiction in using the fake apollo footage, as presented, to demonstrate the apollo landng could not have taken place, as presented.
Except there is - in fact, there are three.
Contradiction 1: You say that rover could not be sat on in Earth gravity. You also say that the rover didn't go to the moon. The video clearly shows the rover driving around. That means, in your mind, that the film could not have been made on Earth or the moon! Where do you claim it was filmed, and how?
Contradiction 2: You claim the video shows the surface is too loose to move on based on your interpretation of the way it moves under the rover. How do you resolve the contradiction that the rover is clearly moving on a surface you declare it cannot move on?
Contradiction 3: You claim that the "lunar surface" has particular features, based on that film. But wait! You don't think the rover went to the moon at all! So how can you declare what the lunar surface is like by using what you believe to be a fake video to back you up?
This is a message board that invites people to put hoax theories forward, do you all really need it explained that a hoax believer is someone who thinks it was all faked?
We also expect contributors to explain how they think the "hoax" was done. Out position here is that the Apollo missions happened in accordance with the historical record. We are not here to bat about silly ideas about a hoax with no basis in physics, engineering, political plausibility or indeed any basis in reality. Do you really need that explained? If so read this The goal of the website is to use factual information to counter the claims that the Apollo moon landings were faked
from www.apollohoax.net
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As I have already sad, there is no contradiction in using the fake apollo footage, as presented, to demonstrate the apollo landng could not have taken place, as presented.
Early in this thread you were using the video to hypothesize the properties of the lunar surface. Then using the hypothesized properties to support the idea that the rover could not drive on the moon. That is a contradiction because if the video was made somewhere else then the properties of the surface could not be attributed to the moon.
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Anywho, I don't think that you have answered or explained as to what is actually happening in the videos of the LRV*
Clearly something that looks like the LRV IS being driven on a surface that looks a lot like the Moon. And there are lots of clues that this took place in a low gravity vacuum. So what exactly is happening?
No need to strain at maths and physics that you clearly have a weak grasp on. Just tell us what you think is happening in the videos and how you came to the conclusions.
That'd be super. Thanks in advance.
*along with a load of other questions...
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The question is not worthy of a reply, maybe you all need a sticky where the mods can explain to you that someone who thinks the apollo landings were a hoax implicitly believes the footage is faked.
Well Andromeda, you got your answer. Pesky and persistent questions that require an alternative scenario that is consistent with a hoax theory are too difficult to answer and must be ignored.
So once again this proves that Anywho is just another anonymous beggar of questions that is trapped in the underperforming logic of his argument.
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As I have already sad, there is no contradiction in using the fake apollo footage, as presented, to demonstrate the apollo landng could not have taken place, as presented.
Except there is - in fact, there are three.
Contradiction 1: You say that rover could not be sat on in Earth gravity. You also say that the rover didn't go to the moon. The video clearly shows the rover driving around. That means, in your mind, that the film could not have been made on Earth or the moon! Where do you claim it was filmed, and how?
I did not say the rover could not be sat on in earth gravity, NASA did, I say that if you make a vehicle so weak it cannot be sat on then it cannot be driven over a bumpy surface on either the moon or the earth ERGO, IT IS NOT THE COMPLETE BS SUPERLIGHT SUPERWEAK ROVER SEEN ON THE VIDEO, THEY MADE A STRONGER VERSION SO THE MOST OBVIOUS ANSWER TO YOUR INANE QUESTION IS THAT THE USED A STRONGER VERSION HERE ON EARTH
Contradiction 2: You claim the video shows the surface is too loose to move on based on your interpretation of the way it moves under the rover. How do you resolve the contradiction that the rover is clearly moving on a surface you declare it cannot move on?
IT IS NOT MOVING ON A LOOSE SURFACE IN 1/6g, BECAUSE IT WAS NOT FILMED ON THE MOON, ERGO IT WAS FILMED ON EARTH SOMEWHERE
Contradiction 3: You claim that the "lunar surface" has particular features, based on that film. But wait! You don't think the rover went to the moon at all! So how can you declare what the lunar surface is like by using what you believe to be a fake video to back you up?[/b]
I DON'T KNOW WHAT THE MOON SURFACE IS LIKE, THERE COULD BE A 2M LAYER OF DUST FOR ALL I KNOW, BUT EVEN USING THE FAKE SURFACE PRESENTED IN THE FAKE APOLLO FOOTAGE IT CAN BE DEMONSTRATED THAT 4WDRIVNG ON A LOOSE SURFACE IN 1/6G WITH THE WORLDS DUMBEST TYRES IS IMPOSSIBLE.
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IT IS NOT THE COMPLETE BS SUPERLIGHT SUPERWEAK ROVER SEEN ON THE VIDEO, THEY MADE A STRONGER VERSION SO THE MOST OBVIOUS ANSWER TO YOUR INANE QUESTION IS THAT THE USED A STRONGER VERSION HERE ON EARTH
Leave the shouting and the insults at home. All you had to do was say that outright at the start when you were first asked. Don't start shouting at us after days of refusing to answer our questions simply.
I DON'T KNOW WHAT THE MOON SURFACE IS LIKE
Then you can't use that video to judge the properties of the lunar surface, as you have done.
THERE COULD BE A 2M LAYER OF DUST FOR ALL I KNOW, BUT EVEN USING THE FAKE SURFACE PRESENTED IN THE FAKE APOLLO FOOTAGE IT CAN BE DEMONSTRATED THAT 4WDRIVNG ON A LOOSE SURFACE IN 1/6G WITH THE WORLDS DUMBEST TYRES IS IMPOSSIBLE.
No, it can't. If that thing can drive on that surface on Earth it can drive on that surface on the Moon. Your inability to grasp the physics of that is the problem.
Now, how about answering my question about the physics: is acceleration of a mass proportional to the net force on it?
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This is a message board that invites people to put hoax theories forward, do you all really need it explained that a hoax believer is someone who thinks it was all faked?
That's all well and good, but you can't simply handwave away the video and 16mm film documentation of the rover in operation...in what to all appearances is a gravity field 1/6th of Earth's...as well as what to all appearances is a vacuum...in what appears to be broad daylight, with a black sky...with some of the continuous 16mm footage demonstrating the rover covering relatively long distances. You'll have to explain how all the environmental and physical things we see in the footage could be faked, and faked using the technology available in the early 1970s.
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Don't insult me, and do not shout at me. That behaviour is not tolerated here.
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http://www.hq.nasa.gov/alsj/PerfBoeingLRVWheelsRpt2.pdf
This is the second set of tests the army did, I apologise that it is nothing to do with locomotves, tugboats, and hydroplaning quads. All it represents is an actual physical test of the laughable rover wheel together with a simulated soil based on the previous fake apollo missions.
What it shows is that on page 21 (Fig. 8. influence of wheel speed on pull coefficient) there are results showing the drawbar pull at different acceleration rates with 20% slip (20% slip is their safe limit), these show that the rover wheel accelerating in a lunar soil can only muster a drawbar pull coefficient of approx 0.4
Once again, to accelerate the rover wheel needs enough traction to pull 6 times the weight on it in total (a drawbar coeffciient of 5), so how would this thing accelerate n 1/6g on such a loose surface if the most it can safely accelerate with the available traction is just 40% more than its weight?
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I DON'T KNOW WHAT THE MOON SURFACE IS LIKE, THERE COULD BE A 2M LAYER OF DUST FOR ALL I KNOW
That's all we needed.
You have no idea what the surface is like. The only idea of what the lunar surface is like that you have is the Apollo photos and film footage you claim wasn't shot there. If we have no evidence as to what it is like because we didn't go, then you have no evidence that it is impossible to drive on.
Your argument is totally contradictory.
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I DON'T KNOW WHAT THE MOON SURFACE IS LIKE
Then you can't use that video to judge the properties of the lunar surface, as you have done.
OMG, slowly...
I can use it to judge the lunar surface as presented by NASA
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So then how do you account for the fact that the rover is shown driving on the surface you claim it cannot be driven on?
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I DON'T KNOW WHAT THE MOON SURFACE IS LIKE
Then you can't use that video to judge the properties of the lunar surface, as you have done.
OMG, slowly...
I can use it to judge the lunar surface as presented by NASA
Then you are saying it couldn't be driven on that surface on the Moon?
Then you are simply wrong. Sorry.
Now, do you plan to answer my question?
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I DON'T KNOW WHAT THE MOON SURFACE IS LIKE
Then you can't use that video to judge the properties of the lunar surface, as you have done.
OMG, slowly...
I can use it to judge the lunar surface as presented by NASA
Well, you are proceeding "as expected". First, you become frustrated that no one here agrees with you, then, you start being unreasonably sarcastic, as in the quoted post...
...if you continue along these lines, as I know you will, your posts will become more and more insulting to other posters, until you get yourself banned.
Sad and predictable...
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...lets be honest, the rover tyres make no sense at all...
No one here cares that they make no sense to you. In the future, please don't make assumptions regarding others opinions, particularly, when those assumptions are in error...no one here agrees with you.
Worlds dumbest tyre design ever.
Your uninformed opinion is not evidence...when will you present evidence that the rovers were faked....soon?
It may be impossible to make a vehicle with weight restrictions that would work on the moon, also they didn't have time for delays, also IT WAS ALL A SHAM, so why not go with a cool looking design they can hoon around in rather than something clumsy looking like a tracked vehicle?
Is this how you will be proceeding? ...no evidence , just you shouting IT WAS FAKE?
Once again....not evidence...
These are army tests, they were told to test the wheels with the expected weight the would have on the moon, in a simulated lunar soil, and that is what they did. Simple as that.
...and apparently passed those tests, OR THEY WOULD HAVE "FIXED" THE ROVER UNTIL IT DID WORK.
It is entirely possible that they did not consider the implications of 1/6g above and beyond the weight difference at all, especially as it was not in their brief to go beyond testing the wheel/soil interaction.
So you make the unsupported assumption that the scientists were pretty stupid.
Sorry, but no foundation for you to make such a determination.
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The question is not worthy of a reply...
You are mistaken. See, we have the "advantage" of knowing that Apollo was not faked. People here are showing you a "courtesy" by even responding to any of your posts.
As I posted earlier, this sort of attitude will only bring you trouble.
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...THEY MADE A STRONGER VERSION...
You do realize that there were 1G version rovers used for Earth training, right?
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All it represents is an actual physical test of the laughable rover wheel together with a simulated soil based on the previous fake apollo missions.
So do you believe that the TV camera from Surveyor 3 that the crew of A12 returned to Earth was a fake.
Were all Lunar missions, even the unmanned ones, faked? Just how far are you willing to go with this "lunacy". :)
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I DON'T KNOW WHAT THE MOON SURFACE IS LIKE...
Well, that's the thing, isn't it...because you see, we do know what the Moon's surface is like from the unmanned landers.
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Once again, to accelerate the rover wheel needs enough traction to pull 6 times the weight on it in total (a drawbar coeffciient of 5), so how would this thing accelerate n 1/6g on such a loose surface if the most it can safely accelerate with the available traction is just 40% more than its weight?
It doesn't matter how many times you say this, it won't make it right. Drawbar pull is a measure of force. The coefficient as measured in these tests is the drawbar pull divided by the weight of the vehicle, and is relevant in slope tests because on upward gradients the rover DOES have to pull against its own weight (not its mass). On the flat it does not. This number does NOT have to match or exceed the weight or mass of the vehicle in order to move it on a level. If that were so none of the counter examples you dismiss would actually work at all.
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On the moon f your car weighs 1700kgs then it has a mass of 10,200 kgs, so it has to find enough traction to pull 8,500kgs on top of the weght (this is not a force of 8500kgs, it is just an additional mass it has to tow)
(emphasis mine)
So what is that extra force? How much extra force is needed to move that extra mass?
You keep talking about the 'pull coefficient' on the test. It's a ratio of force to weight. A pull coefficient of 0.5 means it is exerting a force equal to half the weight of the vehicle. Not the mass, the weight. So, a vehicle of 1000 lb with a pull coefficient of 0.5 is able to exert a force of 500 lb. A vehicle of the same weight with a pull coefficient of 5 is able to exert a 5000 lb force. In this post you claim the force does not have to equal the additional mass, but in your others you say it has to. You say the rover needs a pull coefficient of 5, so it has to be able to exert a force equal to five times its own weight. In other words, a force equal to the extra mass of the vehicle.
So which is it?
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I suspect that anywho is not a Canadian, and has never driven on ice. Even if the dust surface was "ice like" (which it was not, but he has said up front he doesn't want to be told about how the lunar particles act differently than, say, dust on a dirt road), it's still possible to drive on it. Slowly and carefully, yes, but possible.
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When it's all a sham they can choose style over substance...
...says the non-engineer.
...and lets be honest
Yes, let's. Where did you get your engineering degree, for starters? What actual engineering designs have you worked on?
...the rover tyres make no sense at all, they are an absolute triumph of style over substance.
No, you just don't understand what properly constitutes "substance" in this design. Your lack of understanding has been the overarching problem since Day One. Until you get an actual clue, you aren't worth much attention. You still don't know the difference among weight, mass, and force.
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Once again, to accelerate the rover wheel needs enough traction to pull 6 times the weight on it in total...
No. This is a wrong assumption. How many times do the professionals need to tell you it's wrong before you finally get a clue?
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All it represents is an actual physical test of the laughable rover wheel together with a simulated soil based on the previous fake apollo missions.
Please answer this: Was the entire Apollo program a hoax? If not, what missions were real?
Part of proper scientific method is to look objectively at evidence against one's hypothesis. You ignore most of the evidence against yours. It's time you start showing proof of faked missions instead of clinging to your misunderstanding of physics principles. It appears we've seen the best of what you have and it's lame, to put it bluntly.
You have used common sense as part of your belief in NASA fakery. Does your common sense tell you how they could possibly keep that fakery secret for 40+ years with thousands of professional physicists, engineers, launch control personnel, tracking station workers, system subcontract workers etc. etc. having to be in on the hoax or at least suspect it and yet remain totally quiet for all this time? My common sense (and direct knowledge of 1960's space program development) tells me that making rovers which could and did drive on the Moon would have been a snap compared to the difficulty in successfully hoaxing even just the LRV portion of the Apollo program.
I worked in the space program in the 1960's so if I seem to show a lack of respect for your inept hoax belief, it's because I find it personally insulting that someone with mediocre knowledge and research tries to demean what is considered to be the finest technological achievement in history.
You should be totally ashamed of your presentation here. Perhaps some day you will be.
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Once again, to accelerate the rover wheel needs enough traction to pull 6 times the weight on it
No it doesn't.
I weigh about 170 lb, yet I can easily push my 1982 Honda CB750 (weight about 500 lb) along a flat and level road.
Please explain how this is possible, and show your working.
You should be totally ashamed of your presentation here. Perhaps some day you will be.
Don't hold your breath!!
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Anywho, have you considered the possibility that thousands, probably tens of thousands, of experts who have a different opinion from yours are right and you are wrong?
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Anywho, have you considered the possibility that thousands, probably tens of thousands, of experts who have a different opinion from yours are right and you are wrong?
For that matter, do any of the HBs believe they might possibly be wrong?
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anywho, you have two very important rebuttals by Jason Thompson to your physics assumption you need to address and you have been asked repeatedly to do so. They are at the crux of your accusation of fakery:
1.
Now you will answer my question: do you agree that if you accept F = ma you must also accept that a = F/m? Forget the details, we're talking about the basics here. Do you agree that the acceleration of any mass is proportional to the net force on it?
2.
On the moon f your car weighs 1700kgs then it has a mass of 10,200 kgs, so it has to find enough traction to pull 8,500kgs on top of the weght (this is not a force of 8500kgs, it is just an additional mass it has to tow)
(emphasis mine)
So what is that extra force? How much extra force is needed to move that extra mass?
You keep talking about the 'pull coefficient' on the test. It's a ratio of force to weight. A pull coefficient of 0.5 means it is exerting a force equal to half the weight of the vehicle. Not the mass, the weight. So, a vehicle of 1000 lb with a pull coefficient of 0.5 is able to exert a force of 500 lb. A vehicle of the same weight with a pull coefficient of 5 is able to exert a 5000 lb force. In this post you claim the force does not have to equal the additional mass, but in your others you say it has to. You say the rover needs a pull coefficient of 5, so it has to be able to exert a force equal to five times its own weight. In other words, a force equal to the extra mass of the vehicle.
So which is it?
If you continue to misapply basic physics and ignore corrections and questions, it can only be assumed that you don't understand your own argument and/or refuse to consider any possibility that you may be wrong. Is that where we are or will you actually engage in a basic physics discussion?
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When it's all a sham they can choose style over substance, and lets be honest, the rover tyres make no sense at all, they are an absolute triumph of style over substance.
Anywho, I'd like to make an observation and ask you a sincere question based on that observation. I'd like you to take a deep breath and address it honestly and candidly, as I do not ask it as a means of provocation or antagonism. I'm genuinely curious about your thought processes and the underlying motivation behind your posts.
In this forum there are multiple professionals who work in fields directly related to the sciences which governed the Apollo program, and space flight in general. I have read these posts. They are ALL telling you that your claims have little or no merit, and that your understanding of said science is lacking. Despite this, you continue to insist that your positions are factual, while theirs are faulty.
1) Is it your belief that the professionals in this forum are trying to deceive you by intentionally posting information they know to be false?
2) If "no", then is it your belief that your knowledge of the topic is somehow superior to theirs and others with similar expertise?
3) If you answered "no" to both questions, can you explain why you continue to dispute their points, and moreover, why you continue to favor the possibility of a hoax, given your newly gained knowledge?
I thank you in advance for your timely response to these questions.
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anywho, let's recap:
You started with The motors were too small.
You failed to support that assumption (it was shown that they weren't too small).
So you went to The rover wasn't strong enough to support two astronauts' weight in 1G.
You failed to support that assumption (they made a 1G rover for training.... and photos).
So you went to The Moon is slippery as ice so the rover wouldn't have worked.
You failed to support that assumption (you admit no knowledge of lunar surface conditions).
So you went to The rover had to pull over 5 times it's weight, which it couldn't do.
You failed to support that assumption (a = F/m).
So you now have gone to The tire chevrons were chosen to look cool instead of assisting operation.
You have yet to support that assumption (and how would that help prove fakery?).
So what's next? Let me help.... The paint is the wrong color causing the rover to melt in direct sunlight?
Or maybe.... The rover electronics would have fried from cosmic rays within the first 10 minutes?
Both of those make at least as much sense as what you've presented so far.
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THEY MADE A STRONGER VERSION SO THE MOST OBVIOUS ANSWER TO YOUR INANE QUESTION IS THAT THE USED A STRONGER VERSION HERE ON EARTH
There actually is a "1-g trainer" version of the LRV that, as the name suggests, could be driven on earth and there are many pictures of it in the Apollo archives. It is now in storage at the Smithsonian. All the differences between it and the lunar version are highlighted in this detailed manual:
http://www.hq.nasa.gov/alsj/LRV_OpsNAS8-25145.pdf
The most obvious difference was the use of pneumatic tires to support the 6x greater weight. These are clearly visible in the training photos. So are numerous support people not wearing pressure suits; grass, trees, buildings, cars, roads, sidewalks, etc in the background; atmospheric haze and a blue sky and clouds overhead; and plenty of other subtle indications to the astute observer that the scene was on earth, not the moon. Since you claim the alleged lunar pictures were really taken on the earth, perhaps you could point out to us some of these giveaway clues that we must have missed.
And perhaps you can also explain to us why the LRV was too fragile to operate in 1/6 g on the moon when the 1-g version obviously worked well on earth without any obvious structural differences other than the tires.
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Anywho, can you please explain what's going on in this video? A 2 wheel drive vehicle getting traction (and not sinking!) in water.
Wow, I had no idea that was possible! The Mythbusters had great difficulty doing this with a car some time back, but I think they ultimately succeeded over a much shorter stretch of water. Here the weight-to-tire-area ratio is probably a lot lower too.
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Wow, I had no idea that was possible! The Mythbusters had great difficulty doing this with a car some time back, but I think they ultimately succeeded over a much shorter stretch of water. Here the weight-to-tire-area ratio is probably a lot lower too.
You don't even need 4 wheels. Heres Pastrana doing it on a motocrosser.
Of course, this must be faked as a wheel cannot gain traction on a slippery surface..... ::)
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So then how do you account for the fact that the rover is shown driving on the surface you claim it cannot be driven on?
In anywho's defense, there's a logically consistent answer that I'm surprised he hasn't given yet:
The film does not depict an event that is physically possible on either the earth or the moon. I.e., it was synthesized somehow, in all or in part.
Of course that would open him up to several lines of perfectly reasonable questioning:
Exactly what are we seeing that's physically impossible on both the earth and the moon? (Since the conclusion is based on quantitative arguments like "the rover couldn't have withstood the applied forces" this would necessarily include detailed engineering physics calculations with the actual properties of all materials available around 1970.)
Exactly how was the film faked so realistically? (Since this is arguably impossible even today, we would need complete details of how it was done with 1970 technology.)
If it was based at least in part on real live footage, exactly where was it shot? ("Area 51" is not an acceptable answer unless you have actual evidence it was shot there. If you can't narrow it down to a specific location, provide a list of candidate sites with surface characteristics identical to what we see, or close enough to be modified into what we see with 1970 film/video technology. Low gravity and/or a vacuum atmosphere is a definite plus.)
Exactly who created this footage? (Names, titles and actual evidence of their actions.)
Why did they create it as an alternative to doing what they claimed to have done? (Given the difficulty of creating a convincing fake, plus the enormous risks of being found out, wouldn't it have been easier to just go to the moon for real?)
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So what's next? Let me help.... The paint is the wrong color causing the rover to melt in direct sunlight?
That would somewhat make sense, but in the other direction. The problem was the LRV getting too cold. Mission rules allowed it to be parked in shade for only up to two hours, otherwise it would get too cold to function properly. The coatings on the instrument cluster etc. were to provide the proper absoprtion. Incidentally this is also why certain portions of the LM are black and/or otherwise differently coated: the hypergolic fuel likes to be kept at around 70 F and needs a certain amount of solar influx to maintain that.
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That would somewhat make sense, but in the other direction. The problem was the LRV getting too cold. Mission rules allowed it to be parked in shade for only up to two hours, otherwise it would get too cold to function properly. The coatings on the instrument cluster etc. were to provide the proper absoprtion. Incidentally this is also why certain portions of the LM are black and/or otherwise differently coated: the hypergolic fuel likes to be kept at around 70 F and needs a certain amount of solar influx to maintain that.
That reminds me of a debate I had on another forum, with a guy who claimed that Apollo was fake because the LRV couldn't operate at night on the Moon, with lots of sarcastic comments about putting it in a garage. I pointed out to him that the lunar day lasted two weeks so the astronauts were long gone before that became an issue.
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So what's next? Let me help.... The paint is the wrong color causing the rover to melt in direct sunlight?
Or maybe.... The rover electronics would have fried from cosmic rays within the first 10 minutes?
You realize he now has all the ammo he needs for a new 43-page thread.
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anywho, let's recap:
So you went to The rover wasn't strong enough to support two astronauts' weight in 1G.
You failed to support that assumption (they made a 1G rover for training.... and photos).
For the 100th time, it was not me who said that the rover could not support the rovers weight in 1g, it is NASA, all I am saying is that it makes no sense for them them to say that the lunar rovers were too weak to support the astronauts weight but then they can take it to the moon and slam it into craters at 10kph.
anywho, let's recap:
So you went to The Moon is slippery as ice so the rover wouldn't have worked.
You failed to support that assumption (you admit no knowledge of lunar surface conditions).
So you went to The rover had to pull over 5 times it's weight, which it couldn't do.
You failed to support that assumption (a = F/m).
I admit I was wrong about the drawbar pull coefficient needing to be 5 to accelerate (longer post coming when I have time, which will show that traction on the moon is indeed comparable to ice on earth), but it is still true that the rovers need power and traction to pull the entire mass of the vehicle, which on the moon is 6 times the weight. That is irrefutable.
So you now have gone to The tire chevrons were chosen to look cool instead of assisting operation.
You have yet to support that assumption (and how would that help prove fakery?).
I didn't just say the were a triumph of style over substance, I gave my reasons, the chevrons cover 50% of the fictive surface, they recess the reamaining 50%, they are smooth and they are thin so provide very little by way of tread.
They're just plain dumb, an elegant solution might have been to put the chevrons on the inside of the mesh but when it's all a farce, why bother?
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anywho, let's recap:
You started with The motors were too small.
You failed to support that assumption (it was shown that they weren't too small).
It was never "shown that they weren't too small", not only are the motors ridiculously small for such a large mass but the wheels are ridiculously large, I have (admittedly) belatedly done some calculations.
1/4hp @ 125rpm = torque 10.5 lb.ft, tyre radius 15inch, mass fully loaded 400lbs.
F = 10.5/1.25= 8.4
8.4/400 = 0.021
0.021*32.18 = 0.68 ft/s/s or 0.2m/s/s (more than 13s to make it to 10kph)
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I can't really follow that calculation, but it seems you have forgotten that each wheel had 1/4 horsepower. Also, the mass of the LRV is too low, and you have forgotten to add the
weight mass of the astronauts.
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anywho, let's recap:
So you went to The rover wasn't strong enough to support two astronauts' weight in 1G.
You failed to support that assumption (they made a 1G rover for training.... and photos).
For the 100th time, it was not me who said that the rover could not support the rovers weight in 1g, it is NASA, all I am saying is that it makes no sense for them them to say that the lunar rovers were too weak to support the astronauts weight but then they can take it to the moon and slam it into craters at 10kph.
No, they didn't say that, you did.
anywho, let's recap:
So you went to The Moon is slippery as ice so the rover wouldn't have worked.
You failed to support that assumption (you admit no knowledge of lunar surface conditions).
So you went to The rover had to pull over 5 times it's weight, which it couldn't do.
You failed to support that assumption (a = F/m).
I admit I was wrong about the drawbar pull coefficient needing to be 5 to accelerate (longer post coming when I have time, which will show that traction on the moon is indeed comparable to ice on earth), but it is still true that the rovers need power and traction to pull the entire mass of the vehicle, which on the moon is 6 times the weight. That is irrefutable.
Once again, with feeling, what evidence will you be using to demonstrate that the lunar surface exhibits the qualities you so desperately want it to have? How on Earth (no pun intended) do you draw the conclusion that a surface composed of jagged particles and rocks has absolutely no friction? Sources pelase, links, whatever.
Secondly, the mass may be 6 times the weight, but can you please remind us again by how much, proportionately, the resistance to moving that mass provided by gravity is compared with Earth?
So you now have gone to The tire chevrons were chosen to look cool instead of assisting operation.
You have yet to support that assumption (and how would that help prove fakery?).
I didn't just say the were a triumph of style over substance, I gave my reasons, the chevrons cover 50% of the fictive surface, they recess the remaining 50%, they are smooth and they are thin so provide very little by way of tread.
They're just plain dumb, an elegant solution might have been to put the chevrons on the inside of the mesh but when it's all a farce, why bother?
Do please provide us with a manufacturing method that would allow the chevrons to be placed inside the mesh.
e2a: Let's be honest here. it wouldn't matter which tyre they'd chosen, it wouldn't matter what tractive capabilities the LRV possessed, you'd still be arguing that it was incapable of doing it. If they'd gone for the straight mesh, you'd be saying that the LRV would have sunk in to the ground.
You just plain old don't believe it, and this is the thing you've latched on to as your big 'a-haa' moment.
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I can't really follow that calculation, but it seems you have forgotten that each wheel had 1/4 horsepower. Also, the mass of the LRV is too low, and you have forgotten to add the weight mass of the astronauts.
The mass I used is 1/4 the total, the rover is 1600lbs total fully loaded.
I worked it out on 1 wheel with 1/4hp having to accelerate 400lbs, instead of 1hp having to accelerate 1600lbs.
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anywho, let's recap:
You started with The motors were too small.
You failed to support that assumption (it was shown that they weren't too small).
It was never "shown that they weren't too small", not only are the motors ridiculously small for such a large mass but the wheels are ridiculously large, I have (admittedly) belatedly done some calculations.
1/4hp @ 125rpm = torque 10.5 lb.ft, tyre radius 15inch, mass fully loaded 400lbs.
F = 10.5/1.25= 8.4
8.4/400 = 0.021
0.021*32.18 = 0.68 ft/s/s or 0.2m/s/s (more than 13s to make it to 10kph)
You last line is the most egregious. You have multiplied an acceleration by an acceleration, yielding units of ft2/s4 which is pretty meaningless.
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For the 100th time, it was not me who said that the rover could not support the rovers weight in 1g, it is NASA, all I am saying is that it makes no sense for them them to say that the lunar rovers were too weak to support the astronauts weight but then they can take it to the moon and slam it into craters at 10kph.
But you never bothered to find out why the lunar rover could not support the astronauts on earth, did you?
If you had, you would have discovered the reason was the tires. You want your tires to normally deflect a certain amount, so because of the lower lunar gravity they had to be made softer. This also made them subject to bottoming out and damage if the astronauts sat on the rover in 1-g on earth.
The fact that the rest of the rover was quite strong is proved by the existence of the 1-g training rover, which is largely identical to the lunar model and has no special structural reinforcements. The differences between it and the lunar version were primarily the tires (ordinary pneumatics designed for 1-g) and differences in equipment for environmental and operational reasons (the training rover operated in air and had a much longer service life).
So this is all really very simple, but you didn't bother to find any of it out.
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For the 100th time, it was not me who said that the rover could not support the rovers weight in 1g, it is NASA,
But you didn't bother to find out why they said that, did you? You didn't go off and figure out what it was about the rover design that made it unable to be sat on here on Earth, and why that would not necessarily be a problem on the Moon, did you?
Why?
I admit I was wrong about the drawbar pull coefficient needing to be 5 to accelerate
Hurrah! It's only taken days of us constantly battering you with counter-examples and explanations and so on...
but it is still true that the rovers need power and traction to pull the entire mass of the vehicle, which on the moon is 6 times the weight. That is irrefutable.
Yes, they need to accelerate the mass, but as we have repeatedly said, if the traction is there the mass can be accelerated by any force.
They're just plain dumb,
Since that opinion is clearly based on no engineering or physics expertise of any significant level, I think we can safely discount it.
Once again, there is film of that tyre design working very nicely. Why do you dismiss it as dumb when it clearly works?
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I have (admittedly) belatedly done some calculations.
Now do them again and show all your work. You've got numbers in there with no explanation of what they are or how you obtained them. Your presentation would be ignored by any competent scientist or engineer for that reason. Show your work. All of it.
(more than 13s to make it to 10kph)
So what? The rover wasn't a drag racer.
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It was never "shown that they weren't too small", not only are the motors ridiculously small for such a large mass but the wheels are ridiculously large, I have (admittedly) belatedly done some calculations.
1/4hp @ 125rpm = torque 10.5 lb.ft, tyre radius 15inch, mass fully loaded 400lbs.
So the torque is worked out from the 10,000rpm of the motor via a 80:1 harmonic drive.
T = 5252 x HP / rpm
F = 10.5/1.25= 8.4
OK, with you so far. This is the Linear Force equation and 1.25 is the radius in feet(15 inches).
8.4/400 = 0.021
So this is supposed to be acceleration=linear force/mass.
0.021*32.18 = 0.68 ft/s/s or 0.2m/s/s (more than 13s to make it to 10kph)
Now I'm lost. 0.021ft per second * 32.18 feet per second. You appear to be multiplying the acceleration of one wheel on the LRV by the gravitational acceleration on Earth.
Is that right and why? What is this 32.18 figure if not the gravity of Earth?
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But you never bothered to find out why the lunar rover could not support the astronauts on earth, did you?
If you had, you would have discovered the reason was the tires.
The fact that the rest of the rover was quite strong is proved by the existence of the 1-g training rover, which is largely identical to the lunar model and has no special structural reinforcements. The differences between it and the lunar version were primarily the tires (ordinary pneumatics designed for 1-g) and differences in equipment for environmental and operational reasons (the training rover operated in air and had a much longer service life).
So this is all really very simple, but you didn't bother to find any of it out.
Do you have a reference for any of this?
I have never read any document that specifies the wheels as the problem, and the two NASA quotes I supplied suggest that the structural problems go beyond the wheels
It is often said that if astronauts could not even sit on a Lunar Rover here on Earth because the Rovers were built of such lightweight construction that they "would have collapsed in 1 g if the crew sat on it." (1), and that the " The vehicle could support its own weight on earth, but no more" (2).
(1) http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/docs/ApolloCat/Part1/LRV.htm
(2) http://www.hq.nasa.gov/office/pao/History/SP-4204/ch23-3.html
And why would the wheels be damaged by astronauts sitting on the rover in 1g anyhow? If they can withstand being driven into crater walls at 10kph with the same mass then they too should be able to be sat on.
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It was never "shown that they weren't too small", not only are the motors ridiculously small for such a large mass but the wheels are ridiculously large, I have (admittedly) belatedly done some calculations.
1/4hp @ 125rpm = torque 10.5 lb.ft, tyre radius 15inch, mass fully loaded 400lbs.
So the torque is worked out from the 10,000rpm of the motor via a 80:1 harmonic drive.
T = 5252 x HP / rpm
F = 10.5/1.25= 8.4
OK, with you so far. This is the Linear Force equation and 1.25 is the radius in inches.
8.4/400 = 0.021
So this is supposed to be acceleration=linear force/mass.
0.021*32.18 = 0.68 ft/s/s or 0.2m/s/s (more than 13s to make it to 10kph)
Now I'm lost. 0.021ft per second * 32.18 feet per second. You appear to be multiplying the acceleration of one wheel on the LRV by the gravitational acceleration on Earth.
Is that right and why? What is this 32.18 figure if not the gravity of Earth?
It's a fraction of G, I will probably describe it wrong so I will give a demonstration instead.
If the force equalled 400lb and the mass to be accelerated was also 400lbs then it would be 400/400 = 1, then to convert 1g to ft/s/s you would multiply it by 32.18.
Or, if F/m was 200/400, it would equal 0.5, then 0.5*32.18 equals 16.09 ft/s/s (or 0.5g)
This formula is not restricted to earths gravity, it is still a=F/m, it's just what you have to do when using lbs.
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And why would the wheels be damaged by astronauts sitting on the rover in 1g anyhow? If they can withstand being driven into crater walls at 10kph with the same mass then they too should be able to be sat on.
And you still don't get the difference between a short sharp load that allows the wheels to deform and then spring back elastically and a sustained load that leads to plastic deformation, do you?
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If the force equalled 400lb and the mass to be accelerated was also 400lbs then it would be 400/400 = 1, then to convert 1g to ft/s/s you would multiply it by 32.18.
And your reason for leaving the unit 'g' off in your original post was what, then?
Your presentation of equations is sloppy to say the least.
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but it is still true that the rovers need power and traction to pull the entire mass of the vehicle, which on the moon is 6 times the weight. That is irrefutable.
Anywho, have you ever looked a powered trailer dollies? Using a 1.5 HP motor they can move 11K lbs trailers. The smallest of the ones I've seen have 1/4 HP motors and are used to move small boat or RV trailers. All on earth. There is simply no argument by analogy that can hold in claiming that the LRV was underpowered. We await your belated analysis.
For your Reference (http://www.parkit360.ca/shop/p360xl-11000lbs-4989kgs)
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The mass I used is 1/4 the total, the rover is 1600lbs total fully loaded.
When was it fully loaded? The figures on wiki come in at 1543lbs total.
But so what, with the only visible speed evidence on the Moon being the LRV Apollo 16 grand prix, we have one astronaut on board, 200lbs mass per wheel and 6.5 seconds to get up to 10kps.
And? What was your point?
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It's a fraction of G, I will probably describe it wrong so I will give a demonstration instead.
Oh, dear. You just really don't know the physics on this at all, do you? You've learned an equation or two; well done. But you don't know how to apply them or what they mean, do you?
And for the umpteenth time, why do you assume that you're right? When engineers from around the world, including countries hostile to the US, disagree with you, why do you assume that you're right and they're wrong?
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It was never "shown that they weren't too small", not only are the motors ridiculously small for such a large mass but the wheels are ridiculously large, I have (admittedly) belatedly done some calculations.
1/4hp @ 125rpm = torque 10.5 lb.ft, tyre radius 15inch, mass fully loaded 400lbs.
So the torque is worked out from the 10,000rpm of the motor via a 80:1 harmonic drive.
T = 5252 x HP / rpm
F = 10.5/1.25= 8.4
OK, with you so far. This is the Linear Force equation and 1.25 is the radius in inches.
8.4/400 = 0.021
So this is supposed to be acceleration=linear force/mass.
0.021*32.18 = 0.68 ft/s/s or 0.2m/s/s (more than 13s to make it to 10kph)
Now I'm lost. 0.021ft per second * 32.18 feet per second. You appear to be multiplying the acceleration of one wheel on the LRV by the gravitational acceleration on Earth.
Is that right and why? What is this 32.18 figure if not the gravity of Earth?
It's a fraction of G, I will probably describe it wrong so I will give a demonstration instead.
If the force equalled 400lb and the mass to be accelerated was also 400lbs then it would be 400/400 = 1, then to convert 1g to ft/s/s you would multiply it by 32.18.
Fail. Force/mass=acceleration, not some dimensionless number.
Or, if F/m was 200/400, it would equal 0.5, then 0.5*32.18 equals 16.09 ft/s/s (or 0.5g)
At last you admit that the last line is acceleration multiplied by acceleration. Can you see that the result of such a multiplication cannot be another acceleration?
This formula is not restricted to earths gravity, it is still a=F/m, it's just what you have to do when using lbs.
Which renders your calculation invalid. What you have done is multiply ft/s/s by ft/s/s and goten ft/s/s as a result. Surely you can see how wrong this is?
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And your reason for leaving the unit 'g' off in your original post was what, then?
Your presentation of equations is sloppy to say the least.
I second the motion for terribly sloppy presentation. Here is why:
It was never "shown that they weren't too small", not only are the motors ridiculously small for such a large mass but the wheels are ridiculously large, I have (admittedly) belatedly done some calculations.
1/4hp @ 125rpm = torque 10.5 lb.ft, tyre radius 15inch, mass fully loaded 400lbs.
No Back-up for the figures.
F = 10.5/1.25= 8.4
Formula used not identified, units used not identified, "1.25" number not identified. Now I could figure out which formula was used and where "1.25" came from from the context, but I am willing to bet not everyone could.
8.4/400 = 0.021
A number divided by a number equals a number. Again, no formula, no units. Again, I could figure those out from the context, but not necessarily everyone could.
0.021*32.18 = 0.68 ft/s/s or 0.2m/s/s (more than 13s to make it to 10kph)
and again, your result is in the meaningless terms of ft2/s4, the square of acceleration.
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Oh dear anywho.
I leave this thread alone for the weekend, and come back to find that you are STILL insisting that you are right and hundreds of professional, qualified aerospace engineers with many years of experience behind them, are wrong.
Do you truly believe that your argument from incredulity carries more weight than the combined physics and engineering expertise of the last fifty years?
You finally come up with some figures, but they don't prove your point. What they prove is what others here have been saying all along; that you lack any understanding of basic high-school physics. You have been told over and over, by people who are far more qualified than you appear to be, that YOU ARE WRONG. What will it take for you to accept this fact?
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0.021*32.18 = 0.68 ft/s/s or 0.2m/s/s (more than 13s to make it to 10kph)
and again, your result is in the meaningless terms of ft2/s4, the square of acceleration.
Not good, but he arrived at the correct result. The 32.18 should have been applied to the 400lb(mg) in the f=ma (ie. 1/32 of a slug) -
8.4/(400/32.18) rather than multiplied against the acceleration.
Still pointless though, we now have figures that show the LRV accelerates to 10kph in 6.5 seconds with one astronaut onboard and just under 13 seconds fully laden. But as has already been stated, so what.
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It's a fraction of G, I will probably describe it wrong
Welcome back to the discussion, Anywho.
Would you kindly address my question(s) from a few pages back? It appears you may have missed the original post, as I do not yet see a reply.
http://www.apollohoax.net/forum/index.php?topic=393.msg14505#msg14505
Thanks.
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If the force equalled 400lb and the mass to be accelerated was also 400lbs then it would be 400/400 = 1, then to convert 1g to ft/s/s you would multiply it by 32.18.
Or, if F/m was 200/400, it would equal 0.5, then 0.5*32.18 equals 16.09 ft/s/s (or 0.5g)
This formula is not restricted to earths gravity, it is still a=F/m, it's just what you have to do when using lbs.
Can we please, please, please use SI units? This confusion between pounds of mass and pounds of force is an excellent example of why the customary English system of units ought to have no place in modern science and engineering.
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Do you have a reference for any of this?
I certainly do:
NASA TM X-66816, LRV Operations Handbook Appendix A (Performance Data)
Figure 2-8 on page A-11 (pdf page 20) graphs the radial deflection of the tire as a function of applied load. The nominal deflection is 1.75 inches (4.45 cm) at a radial load of 63 lbf (280 N). The bump stop is at a deflection of 3.25 inches (8.26 cm) with an applied load of 135 lbf (600 N).
Given that the rover's mass is 210 kg and could carry a payload of up to 490 kg (including two suited astronauts with a mass of 96.2 kg for each suit and perhaps 80 kg for their bodies) it should be obvious to anyone with your vast engineering knowledge that such tires on earth would nearly bottom out under the rover's own weight, and would most definitely bottom out if even one unsuited adult human sat on it. And while hitting the bump stop occasionally won't immediately destroy the wheel, it is something you definitely want to avoid doing unnecessarily. Especially with flight hardware on earth before launch. (Obviously you have never worked in aerospace, so you cannot appreciate the care -- approaching obsessive-compulsive paranoia -- with which people handle hardware intended to go into space.)
I have never read any document that specifies the wheels as the problem, and the two NASA quotes I supplied suggest that the structural problems go beyond the wheels
Again, someone with your vast engineering knowledge should not need explicit, formal statements from NASA public relations persons. You claim to be able to do your own computations, so do them.
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By the way, this same document (NASA TM X 66816), as you might expect from its subtitle (Performance Data) contains page after page of specifications and graphs showing the performance and limitations of the vehicle in its intended operational environment: the moon.
It even includes graphs showing exactly how much force is needed to move the control handle a certain distance.
Of special interest are the many graphs showing the allowable c.g. locations, the maximum slopes on which the rover will remain stable under various loading conditions, the limits to dynamic stability in sharp turns, etc, etc, etc.
Even a non-engineer can appreciate that an awful lot of work went into this thing. And since these documents have been made public, doesn't it seem likely that if they were phony some engineer would have already discovered it by now? And that his discoveries would be quickly confirmed by his peers?
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If the force equalled 400lb and the mass to be accelerated was also 400lbs then it would be 400/400 = 1, then to convert 1g to ft/s/s you would multiply it by 32.18.
Or, if F/m was 200/400, it would equal 0.5, then 0.5*32.18 equals 16.09 ft/s/s (or 0.5g)
This formula is not restricted to earths gravity, it is still a=F/m, it's just what you have to do when using lbs.
Can we please, please, please use SI units? This confusion between pounds of mass and pounds of force is an excellent example of why the customary English system of units ought to have no place in modern science and engineering.
This is a clear indication that anywho doesn't know a lot about physics. S/he is completely oblivious to the notion of units, and having them work out to give you the concept (force, acceleration, velocity) that you are looking for. If the units don't cancel out correctly, you haven't done the math correctly. So, when s/he uses pounds for both weight and mass, it indicates a basic lack of understanding.
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Not good, but he arrived at the correct result. The 32.18 should have been applied to the 400lb(mg) in the f=ma (ie. 1/32 of a slug) -
8.4/(400/32.18) rather than multiplied against the acceleration.
Still pointless though, we now have figures that show the LRV accelerates to 10kph in 6.5 seconds with one astronaut onboard and just under 13 seconds fully laden. But as has already been stated, so what.
Those ridiculously slow figures don't even allow for rolling resistance, frictional losses, slopes, or uneven terrain where the weight might not be evenly distributed.
It's a bit of a joke really.
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What's the difference between rolling resistance and frictional losses? How much loss?
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It's a bit of a joke really.
Maybe that's part of your problem. If you took this subject more seriously, you might actually learn something.
Once again, you smugly dismiss rebuttals with generalized remarks that prove nothing.
Now I'll ask you once again:
Was the entire Apollo program a hoax? If not, what missions were real?
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Well, learned more on the motors from this recent bit. You got around to it anywho, digesting the replies to see that I did things wrong as well, just like yourself.
I shall start from the beginning on a clean sheet when time allows to see what mine looks like then.
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This is a clear indication that anywho doesn't know a lot about physics. S/he is completely oblivious to the notion of units, and having them work out to give you the concept (force, acceleration, velocity) that you are looking for. If the units don't cancel out correctly, you haven't done the math correctly. So, when s/he uses pounds for both weight and mass, it indicates a basic lack of understanding.
Well, to be perfectly fair anyone (including me) can easily foul up the units when we're forced to work with the English system. So let's see anywho redo everything in SI. If s/he still gets it wrong, then we can confidently conclude that s/he hasn't a clue. :-)
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Please don't call it the "English system". We use SI!
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Please don't call it the "English system". We use SI!
Système Impérial?
Seriously I thought you still used some Imperial units even though you're far closer to SI than the US.
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Please don't call it the "English system". We use SI!
But we got it from you!
Sort of like we use the Arabic numeral system when the Arabs don't.
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Please don't call it the "English system". We use SI!
Système Impérial?
Seriously I thought you still used some Imperial units even though you're far closer to SI than the US.
Le Système international d'unités
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Please don't call it the "English system". We use SI!
Système Impérial?
Seriously I thought you still used some Imperial units even though you're far closer to SI than the US.
Le Système international d'unités
It was a joke...
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Please don't call it the "English system". We use SI!
Système Impérial?
Seriously I thought you still used some Imperial units even though you're far closer to SI than the US.
To make matters worse, imperial units were not always the same as domestic U.S units. An imperial gallon in Canada was about one fifth more volume than U.S. gallon.
Now if the U.S. could just convert to SI and be done with it. I know it would not be easy for people of my generation, but it would make life easier for our posterity. My kids have had a good grounding in SI from their education and it would be much easier for them.
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Please don't call it the "English system". We use SI!
Système Impérial?
Seriously I thought you still used some Imperial units even though you're far closer to SI than the US.
Le Système international d'unités
It was a joke...
It was funny...
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Now if the U.S. could just convert to SI and be done with it. I know it would not be easy for people of my generation, but it would make life easier for our posterity. My kids have had a good grounding in SI from their education and it would be much easier for them.
Yeah, I remember my high school physics teacher insisting that we do everything in SI because it was going to be a matter of law in the US in just a few years.
That was about 1973.
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Please don't call it the "English system". We use SI!
Système Impérial?
Seriously I thought you still used some Imperial units even though you're far closer to SI than the US.
Nope. The only time you see imperial units these days is on road signs and some people insist on using it to measure things like vegetables (although that has got people in trouble!) or rooms in houses. SI has been used in science and academia for years and years!
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Please don't call it the "English system". We use SI!
Système Impérial?
Seriously I thought you still used some Imperial units even though you're far closer to SI than the US.
Nope. The only time you see imperial units these days is on road signs and some people insist on using it to measure things like vegetables (although that has got people in trouble!) or rooms in houses. SI has been used in science and academia for years and years!
And those imperial units we do use are legally defined in terms of their equivalent SI units, not by any independent standards.
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Please don't call it the "English system". We use SI!
Its offiicial name is EES, for English Engineering System. Sorry. As with SI, it is a subset of (previously) English units according to which a consistent system of measurement is derived. The problem with EES is not that it is unwieldy or inconsistent, but rather that the wrong units of mass are commonly used. EES requires g0 to equate its unit of mass with its unit of force, as does SI. g0 has a different value in each system, but is required in both systems in order to render them "consistent." ("Consistent" has special meaning in engineering measurement systems.)
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Nope. The only time you see imperial units these days is on road signs and some people insist on using it to measure things like vegetables (although that has got people in trouble!) or rooms in houses. SI has been used in science and academia for years and years!
Don't forget that there are still legacy imperial-unit aircraft and other vehicles in use in the UK, and any engineering support they require is still in those units. I was effectively bi-lingual in SI and imperial for my entire professional life.
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Its offiicial name is EES, for English Engineering System.
Haven't finished my 2nd cup of coffee, and already I've learned something I did not previously know.
That's why I like "hanging out" with you, Jay...because I'm always going to learn something new. :)
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SI and "the metric system" are not equivalent, just as EES and "those bass-ackwards Americans" are not equivalent. SI is a subset of available metric units -- or more specifically, magnitude prefixes. EES, for example, does not use gallons for a measurement of volume, but rather cubic feet. SI does not use hectograms, which is a common and convenient way to sell meats and vegatables on the Continent -- SI uses grams or kilograms or milligrams. One goes from millimeters to meters to kilometers. Centimeters are convenient for common metric measurements, but strictly speaking are not allowed in SI.
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Don't forget that there are still legacy imperial-unit aircraft and other vehicles in use in the UK, and any engineering support they require is still in those units. I was effectively bi-lingual in SI and imperial for my entire professional life.
This is why the U.S. will require EES proficiency for the foreseeable future. As the chief engineering officer for my organization I can stamp my feet all I want and require SI. But the fact is that I still have to order cable by the foot. If my engineers habitually have to design in SI and then convert to EES for ordering, that adds time and effort and incurs a greater risk of error.
My city is laid out according to the City of God design devised by Mormon founder Joseph Smith and implemented throughout the intermountain West by Brigham Young and the Mormon settlers. Blocks are exactly 660 feet square (1/8 mile) and enclose exactly 10 acres. A mere half block from my executive offices, buried in a vault under the sidewalk near the courthouse, is the standard "rod" for the city. That was, is, and likely forever will be the standard for anything done in downtown Salt Lake City. Yes, 660 feet is agonizingly close to -- but just shy enough to be engineeringly significant, of -- 200 meters.
As long as life remains non-pretty, measurement will remain annoying.
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I don't see what any of that has to so with us not switching to km/h speed limits. It's not a European integrationist thing because not just Europe uses it, but the entire world except the UK and USA.
The Commonwealth uses it. The Eastern tigers use it. Ireland uses it. There's a motorway junction in the Republic where part of a sliproad crosses the border into Northern Ireland. For the distance of a few hundred metres, you have to switch to a speed limit in mph before returning to the Republic if you're heading South.
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In trying to work things out from the Apollo records, it also doesn't help that they're pretty much all in EES units.
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Well, I like knots myself, and its fun to be different.
(Runs from room snickering)
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"So I was flying at 130 knots per hour..." (runs in the other direction)
I'm reasonably comfortable working in either EES or IS. The problem is that there are two systems. It's the number of the systems that bothers me, not the alleged superiority of one system over the other. Decimal inches is not any more difficult for me to think in that decimal feet or decimal meters.
I remember a European engineer telling me how silly we must all feel using feet, inches, and carpenters' subdivisions (i.e., 3-3/8 inch). He was quite surprised to learn that EES uses either feet or inches as a linear measurement for a single problem, with consistent units built around each -- e.g., "foot-pounds" or "inch-pounds" for torque, but never both in the same design. And the base units are decimalized, just as SI. So a spacecraft velocity could be given as "32,543.3 feet per second." Boeing for decades engineered all their aircraft in decimal inches. Many people are unaware how engineers use EES, just as many people grow up learning the metric system without learning the special engineering SI usage.
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Well, I like knots myself, and its fun to be different.
The nautical mile at least has a basis in (true) geometry, being defined as a specific fraction of the Earth's circumference at the equator.
The English survey units are what most people think of when the refer to the crapulence of the English/Commonwealth/Imperial units. Salt Lake City still has to deal with acres and rods and statute miles because that's the way it was laid out, and it makes little sense to measure it in SI, or even in less uncommon English units.
The base blocks is here https://familysearch.org/learn/wiki/en/images/e/e9/Salt_Lake_Base_and_Meridian_2.JPG at Temple Square. The meridian obelisk is one of the original USGS survey marks and sits precisely at 111 W 54 00 according to the old datum. (Your GPS will differ.) All the blocks are laid out on a grid with this as its origin, each 10-acre block receiving a 100-unit address block east, west, north, or south from this location. Salt Lake City addresses are simply the coordinates of the location according to that obelisk. (Drives visitors nuts, but it's an incredibly logical plan. Say what you want about Mormon politics and religion -- their civil engineering was 50 years ahead of its time.)
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"So I was flying at 130 knots per hour..." (runs in the other direction)
I'm reasonably comfortable working in either EES or IS. The problem is that there are two systems. It's the number of the systems that bothers me, not the alleged superiority of one system over the other. Decimal inches is not any more difficult for me to think in that decimal feet or decimal meters.
I remember a European engineer telling me how silly we must all feel using feet, inches, and carpenters' subdivisions (i.e., 3-3/8 inch). He was quite surprised to learn that EES uses either feet or inches as a linear measurement for a single problem, with consistent units built around each -- e.g., "foot-pounds" or "inch-pounds" for torque, but never both in the same design. And the base units are decimalized, just as SI. So a spacecraft velocity could be given as "32,543.3 feet per second." Boeing for decades engineered all their aircraft in decimal inches. Many people are unaware how engineers use EES, just as many people grow up learning the metric system without learning the special engineering SI usage.
We use carpenters' subdivisions (so that's what it's called) quite a lot. Pipe sizes and bit sizes an obvious example. On our wells, the 12 1/4" hole was cased with 9 5/8" casing. I suppose our continual talk about "the nine 'n' five eighths" is a bit more lyrical than "the two four four point four seven five".
Also, choke sizes are usually given in 64ths of an inch and irritatingly, Prosper doesn't have an option for 1/64th of an inch as a unit so I keep having to convert to a decimal to run the choke calculation. I have asked for this option.
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"So I was flying at 130 knots per hour..." (runs in the other direction)
I'm reasonably comfortable working in either EES or IS. The problem is that there are two systems. It's the number of the systems that bothers me, not the alleged superiority of one system over the other. Decimal inches is not any more difficult for me to think in that decimal feet or decimal meters.
I remember a European engineer telling me how silly we must all feel using feet, inches, and carpenters' subdivisions (i.e., 3-3/8 inch). He was quite surprised to learn that EES uses either feet or inches as a linear measurement for a single problem, with consistent units built around each -- e.g., "foot-pounds" or "inch-pounds" for torque, but never both in the same design. And the base units are decimalized, just as SI. So a spacecraft velocity could be given as "32,543.3 feet per second." Boeing for decades engineered all their aircraft in decimal inches. Many people are unaware how engineers use EES, just as many people grow up learning the metric system without learning the special engineering SI usage.
We use carpenters' subdivisions (so that's what it's called) quite a lot. Pipe sizes and bit sizes an obvious example. On our wells, the 12 1/4" hole was cased with 9 5/8" casing. I suppose our continual talk about "the nine 'n' five eighths" is a bit more lyrical than "the two four four point four seven five".
Also, choke sizes are usually given in 64ths of an inch and irritatingly, Prosper doesn't have an option for 1/64th of an inch as a unit so I keep having to convert to a decimal to run the choke calculation. I have asked for this option.
Funny you mention carpenters. Round here, nuts bolts, self tapping screws are metric, yet oddly, woodscrews are imperial. People still talk of mpg, even though it's now officially kilometers per litre, and convert to boot. In local stores, people still ask for a pint of milk, even though it is now half a litre, yet oddly, if you order a pint of beer to get an old imperial pint. Perhaps it's a cultural thing.
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"So I was flying at 130 knots per hour..." (runs in the other direction)
AACK! I hate when people say that. That's like saying "I was awake at 4:00 AM in the morning."
Anyway, the thing that really makes me crazy is doing date/time math. I find myself converting things (assuming the software doesn't have native interval functions) to decimal hours and minutes, then doing the math, then converting back into hours and minutes. Bleah.
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We use carpenters' subdivisions (so that's what it's called) quite a lot.
Yes, when I say "decimalized" I don't mean necessarily roundly decimalized. I still design with alignment holes 0.2504 in in diameter to accommodate a 0.2500-in dowel pin, because at heart a "quarter-inch dowel pin" will always be a quarter-inch dowel pin. However, we still put electronics headers on 0.1-in centers, so there.
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AACK! I hate when people say that. That's like saying "I was awake at 4:00 AM in the morning."
I know. It annoys me too, hence I knew it would antagonize you appropriately. :)
Anyway, the thing that really makes me crazy is doing date/time math. I find myself converting things (assuming the software doesn't have native interval functions)...
I always have a terminal window open to a MySQL server for that purpose :)
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Anyway, the thing that really makes me crazy is doing date/time math. I find myself converting things (assuming the software doesn't have native interval functions) to decimal hours and minutes, then doing the math, then converting back into hours and minutes. Bleah.
Now think about what you have to do to handle the calendar, leap seconds, and daylight savings time. Our time and calendar system is really quite absurdly complicated, to very little benefit.
And electronics is in a weird place where almost anything these days involves a mishmash of components measured in decimal inches and ones measured in SI. It's moving toward metric, but there's still a lot of 0.1" pitch components and connectors, and things like printed circuit board trace widths and spacing are generally specified in mils.
Like this:
http://lh5.googleusercontent.com/-eEuKlkwdxVk/TCjg_ugVfyI/AAAAAAAAAQo/_ewzRRKjMcY/s971/rf231side.jpg
0.1" pin header on the left, while the transceiver IC is a 0.5 mm pitch QFN package.
I always have a terminal window open to a MySQL server for that purpose :)
Pry (http://pryrepl.org/) here.
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"So I was flying at 130 knots per hour..." (runs in the other direction)
AACK! I hate when people say that. That's like saying "I was awake at 4:00 AM in the morning."
Just think of it as accelerating at .02 meters/sec^2 (if I got my math right). :)
Ranb
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In the photographic trade, even outside of the US, people still routinely use imperial units to describe photographic sizing; 6x4, 7x5, 8x6 etc. Some of us even still use the old descriptions; 4R, 5R, 6R, 4S etc. People come into my shop and ask for a 7x5 frame, not an 18x13 or 180x130 frame
Also, while centimeters are not used generally in engineering, they are used in radar. Equipment operating around 10 GHz (X band), such as airborne primary weather radars, are generally known as "3cm radar", those operating around 3 GHz (S band), such as ground based surveillance radar, are known as "10cm radar".
Show me a piece of waveguide, and I could tell you what band it operates in and what probably what the radar was used for.
PS: and you know that little screw hole on the bottom of your camera that allows you to attach a tripod? Well, that screw hole has a ¼" British Standard Whitworth thread.
Even today, the latest digital cameras on the market made in Japan, China, Taiwan or Korea, are all equipped with the same ¼ BSW threaded hole that the 1950's 35mm film camera had.
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"So I was flying at 130 knots per hour..." (runs in the other direction)
AACK! I hate when people say that. That's like saying "I was awake at 4:00 AM in the morning."
"degrees Kelvin" is my cringe.
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Australia went metric in 1974, when I was in Year 2. I have a vague memory of being taught a lot that year about weights and measures, including one experiment where I tested my ability to drink successively 10 ml, 100 ml and 1000 ml of water. Not surprisingly, I succeeded with the first two amounts and failed with the third. Our heights were also recorded, and I remember being 121 cm tall, one of the shorter kids in class.
Yet despite being officially metric now for nearly 40 years, there are still some strange Imperial holdouts. While hospitals record baby birth weights in kilos, newpaper notices and informal discussions still often refer to pounds (when talking to people about the birth of our daughter, I always gave her birth weight in kilos, but made sure I knew what it was in pounds for those who looked confused). Milk is sold in 1, 2 and 3 litre bottles, but smaller cartons come in 600 ml and 300 ml, which are close to the pint and half-pint. And TVs are advertised with their screen sizes specified in inches.
I've always been comfortable thinking in Imperial distances, but for some reason I've never been able to sort out Imperial weights. A little more obscurely, I can work reasonably well with pounds, shillings and pence.
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Well, I like knots myself, and its fun to be different.
(Runs from room snickering)
Since I don't have a stake in the "units" race, can I complain about the apostrophe error?
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Well, I like knots myself, and its fun to be different.
(Runs from room snickering)
Since I don't have a stake in the "units" race, can I complain about the apostrophe error?
Now your just being silly.
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Well, I like knots myself, and its fun to be different.
(Runs from room snickering)
Since I don't have a stake in the "units" race, can I complain about the apostrophe error?
Sure, why not (no pun). It's what I get for posting from an iPhone.
Fortunately, at the e-newsletter and "slick" magazine where I have to fill space all the time (Lord, how I hate deadlines!), I've got a really good editor to keep me in line...
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Draught beer can only legally be sold as a pint, half a pint or a third.
Cars still use MPH and road distance is still in miles.
Beer is a cultural hang over and the road distances was sn economic one. It was going to cost a lot of money to change all the road signs so they didn't bother.
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Draught beer can only legally be sold as a pint, half a pint or a third.
Cars still use MPH and road distance is still in miles.
Beer is a cultural hang over and the road distances was sn economic one. It was going to cost a lot of money to change all the road signs so they didn't bother.
I suppose I can understand the reasons, but presumably the signs will have to be changed in due course as they age. Are they going to be replaced with more signs in miles?
In Australia's case the changeover was complete within a few years, as far as I can remember. For road distances, the signs were at the time mostly concrete marker posts (triangular prisms) with a letter and a number. The letter was the first letter of the next town's name and the number pretty obvious. They were replaced with simple signposts saying the same thing, only in kilometres, and only at 5 km intervals. At greater intervals there are bigger signs listing the distances to the next few towns and cities. I think the old concrete posts were left in place, but soon disappeared as souvenirs. Presumably part of the difference is the comparative density of populations in the UK and Australia (the UK's is nearly 100 times greater than Oz).
As for beer, measurements are in mls, but they're odd fractions of a litre, thanks to direct conversions of old Imperial measurements: http://en.wikipedia.org/wiki/Australian_beer#Beer_glasses
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Draught beer can only legally be sold as a pint, half a pint or a third.
Cars still use MPH and road distance is still in miles.
Beer is a cultural hang over and the road distances was sn economic one. It was going to cost a lot of money to change all the road signs so they didn't bother.
Hell matey, you've obviously never been to Australia!
Depending on which state you're in (as in "territory" not "condition"), and sometimes even which town in that state, you can buy beer in a variety of different containers.
You can order a...
Jug
Pint
Half
Handle
Minny
Middy
Schooner
Seven
Pony
Pot
Five
Butcher
Ten
Bobbie
Shetland
Six
Glass
Small Glass
Eight
Here a complete guide to confuse assist you should you ever wish to undertake a journey to the "Land of the Bouncing Rat"
(https://dl.dropboxusercontent.com/u/98915197/Beer.png)
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Now think about what you have to do to handle the calendar, leap seconds, and daylight savings time. Our time and calendar system is really quite absurdly complicated, to very little benefit.
Partially unavoidable, since the only 2 natural units of time we commonly use are based on the average rotation and revolution rates of the earth, which have little to do with each other, and all the rest are arbitrary derivations thereof. I've sometimes wondered, if an when we colonize Mars, how long it will be before terracentric time units are abandoned for Mars-centric by the colonists. I know operators of Mars probes already work shifts based on Martian time.
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Draught beer can only legally be sold as a pint, half a pint or a third.
Cars still use MPH and road distance is still in miles.
Beer is a cultural hang over and the road distances was sn economic one. It was going to cost a lot of money to change all the road signs so they didn't bother.
In Ireland, it pretty much happened overnight. From mph to kph, all signs changed. There was a pre-change campaign, telling everyone about it. Beer is still in pints though.
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Re signage in the UK. There has been enough of a fuss over metric weights and measures in the UK that I think they will not try it for a while. That and the touchy subject of the EU. But one or two vans we have are km on the digital milage.... km...counter but obviously both on the speedo.
I still get a pound of sausages but weighed out in kilos etc. Awkward sod that I am.
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Back in the 1980s a few places in the U.S. appended kilometer measurements to their milepost signs, but the practice was short-lived. Not surprising to me, because the addenda were panels bolted to the right edges of the signs in slap-dash fashion -- sloppy.
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Speaking of Hunchbacked, I see that he's posted a new YT vid with his critique of the "technical aberrations" of the "lunatic lunar rover". I wonder if he's been lurking this thread for ideas.
Being willing to take one for the team, I'll go watch all 26:42 of it and see whether he has any new ideas. :P
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It's doubtful, but I am grateful for you taking the time and effort. :)
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Well, the good news is that, like many of the HB posters here, I usually end up doing some interesting research as a result of his lunacy.
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OK, this is me asking for a little help in dealing with some HB foolishness...
Is there anyone around who has either actually had the opportunity to look first hand at the controls of an LRV? I've read all the documentation I can locate and there's something (probably obvious) that I'm having trouble grasping.
Heres a diagram of the T-Bar hand controller...
(http://i627.photobucket.com/albums/tt353/jarvisn/LRV-TBar_zpsa0d18c95.jpg)
Now. To go forward, you pivot the controller forward - like a joystick [green arror on the diagram]. The farther you push it, the faster the LRV goes. Pivot it back and and you slow down.
Now here's where I'm running into trouble. The LRV Handbook says:
"With the reverse inhibit switch in the down position, the hand controller can be pivoted forward only, thereby preventing inadvertently placing the vehicle in reverse."
So far, so good. But then under Braking Control, it says:
"Braking is initiated in either forward or reverse by pivoting the hand controller rearward about the brake pivot point."
I seem to be missing something. How do you pivot the controller backward to brake if the controller can only be pivoted forward? Are there two different pivot points? How does the driver control which one he pivots the controller around?
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I seem to be missing something. How do you pivot the controller backward to brake if the controller can only be pivoted forward? Are there two different pivot points? How does the driver control which one he pivots the controller around?
I think the difference is that you tilt the controller handle back to drive the motors in reverse, and you "translate" (slide) the entire handle backward without tilting it to engage the brakes.
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I seem to be missing something. How do you pivot the controller backward to brake if the controller can only be pivoted forward? Are there two different pivot points? How does the driver control which one he pivots the controller around?
I think the difference is that you tilt the controller handle back to drive the motors in reverse, and you "translate" (slide) the entire handle backward without tilting it to engage the brakes.
...and the inhibit switch stops you inadvertently selecting reverse when applying the brakes.
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Yeah. On an ordinary EV, engaging reverse while going forward would be one way to do regenerative braking. But the LRV batteries were not rechargeable, so you probably wouldn't want to do that. You'd have to dump your kinetic energy in the brakes.
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I seem to be missing something. How do you pivot the controller backward to brake if the controller can only be pivoted forward? Are there two different pivot points? How does the driver control which one he pivots the controller around?
I think the difference is that you tilt the controller handle back to drive the motors in reverse, and you "translate" (slide) the entire handle backward without tilting it to engage the brakes.
That was my tentative conclusion - see the blue arrow in the diagram - but I'd like to be sure before I start in on Hunchy.
I seem to be missing something. How do you pivot the controller backward to brake if the controller can only be pivoted forward? Are there two different pivot points? How does the driver control which one he pivots the controller around?
I think the difference is that you tilt the controller handle back to drive the motors in reverse, and you "translate" (slide) the entire handle backward without tilting it to engage the brakes.
...and the inhibit switch stops you inadvertently selecting reverse when applying the brakes.
Must make driving in reverse and braking an interesting exercise in coordination. Of course, they were pretty much all Naval aviators, so it can't have been that challenging. I think it's interesting that NASA classes the LRV as a spacecraft, which I guess it technically is, even though it can't lift off (well, not very far) from the surface.
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Not making a direct comparison but when I first towed a trailer is was completely new and you had to think about reversing (pivot point and which way will it go etc). Also the hitch was braked so that could cause issues so reversing up slopes was fun. They sent me to the far side of the yard and said "practice".
I just saw it as a new set of skills and got quite handy slotting the trailer into the bays allocated etc.
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The first trailer tow I did was a small RV, which I had to back into a slot that was behind my corner garage. After entertaining the neighbors for some time, one of them offered to guide me. That didn't work either so I asked him to do it. He hit it the first time. At the next opportunity, I took the trailer to a parking lot and spent hours practicing turning and backing around buckets. It is a nice skill to have and the confidence really makes a difference on the road. I also learned to pay attention when parking for a way out of the spot. Every trailer is different and short ones are particularly difficult because they jack knife so easily.
As you said, Tedward, it is not a direct comparison, but an example of how new experiences will lead one to appreciate the unsuspected difficulty in doing something new, even when it is a familiar activity that others do every day. Now put that into novel activity in a completely different environment and it is no wonder that NASA completely misunderstood what was needed to do orbital rendezvous and EVA requirements on the first try.
My new RV (when it arrives) is the same length as the old one but is lighter and we widened the driveway so that the backing path is now fully paved. Parking should now be a breeze.
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Not making a direct comparison but when I first towed a trailer is was completely new and you had to think about reversing (pivot point and which way will it go etc). Also the hitch was braked so that could cause issues so reversing up slopes was fun. They sent me to the far side of the yard and said "practice".
I just saw it as a new set of skills and got quite handy slotting the trailer into the bays allocated etc.
I finally learned the skill by holding the steering wheel at the bottom - then the direction I moved my hand was the direction the rear of the trailer took.
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That is the only way I can do it. A misplacement of the hand, even on the side of the steering wheel, makes for a disaster. Or at least more entertaining for those watching.
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I think it's interesting that NASA classes the LRV as a spacecraft, which I guess it technically is, even though it can't lift off (well, not very far) from the surface.
When it comes to the engineering skills required to design it, it does qualify as a spacecraft. The communication system was functionally the same as on the LM. The thermal problems in particular were much like any spacecraft, or even worse since it had to operate not only in a vacuum but on the moon. What's unusual about it among spacecraft is that it had to operate under continuous acceleration, i.e., gravity, rather than weightlessness.
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I think it's interesting that NASA classes the LRV as a spacecraft, which I guess it technically is, even though it can't lift off (well, not very far) from the surface.
When it comes to the engineering skills required to design it, it does qualify as a spacecraft. The communication system was functionally the same as on the LM. The thermal problems in particular were much like any spacecraft, or even worse since it had to operate not only in a vacuum but on the moon. What's unusual about it among spacecraft is that it had to operate under continuous acceleration, i.e., gravity, rather than weightlessness.
The control panel was more like an aircraft than anything else: pitch, roll, range & bearing. And operated with a control stick.
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I finally learned the skill by holding the steering wheel at the bottom - then the direction I moved my hand was the direction the rear of the trailer took.
Never goes away does it. Like learning to ride one of them new fangled falling off machines.
I got a chance to have a go at a HGV (US parlance, truck and trailer? 18 wheeler or whatever?) capable 30+tons with a tractor unit and long trailer. It was off road (old runway) and we had an instructor, cones out for obstacles etc. It had been a few years since I had dealt with a trailer but get your head around the pivot point and I thought I did quite well. Only killed a few traffic cones. The cones were set out as parking bays, road corners etc to get the artic around.
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I finally learned the skill by holding the steering wheel at the bottom - then the direction I moved my hand was the direction the rear of the trailer took.
Never goes away does it. Like learning to ride one of them new fangled falling off machines.
I got a chance to have a go at a HGV (US parlance, truck and trailer? 18 wheeler or whatever?) capable 30+tons with a tractor unit and long trailer.
Usually "tractor-trailer" or "semi". "18-wheeler" is used but is more rural slang, generally. But we're a big country - there's a considerable variation in regional slang dialects.
Never tried one myself although I have a son who drove for Pepsi for a while. He also says it's similar to a car and trailer once, as you said, you figure out where the pivot point is.