So, who wants to win 1 million Euro?

[Noldi400]

It is a complicated maneuver in 3-D. The inertia force of the space ship is applied in one direction, Moon gravity pulls in another direction (I assume the trajectorey is already curved due to Moon gravity) and then you apply a third force - the brake force - in a third, particular direction while losing 10 800 kg mass in the SM ... that you keep steady all the time? If the brake force is not in the direction of travel, it will evidently also change the direction.

It's not all THAT complicated. If a spacecraft is traveling on a course that passes 96 km from the moon and it slows down to 1500 m/s, it's going into orbit - it's unavoidable. There's no need to do anything special to "curve into orbit".

[Andromeda]

It has been repeatedly demonstrated how Apollo went to the Moon and back.

Yes, it has in several reports that I use as reference - see link in post #1. I evidently do not believe these reports and therefore we have this friendly discussion. Let's keep it that way.

See, e.g. my post #786. Can you really show by engineering calculations that you can slow down a 43.5 ton space ship from 2 400 to 1 500 m/s speed in space by burning 10.8 ton fuel at 30 kg/s producing a 97 400 N force?

Expending that fuel gives a delta v of 1018 m/s, so also on the money. Where's my million?

[Abaddon]

Let me after about 785 posts remind you about topic, i.e. my Challenge about safety of space travel and associated fuel consumption. You have to demonstrate how to travel to the Moon and back to win the prize (€1M). It is not easy.

Say that your space ship has mass 32 676 kg excluding fuel and that you must slow down from 2 400 to 1 500 m/s velocity to insert into Moon orbit. Your space ship has a P-22 KS rocket engine with 97 400 N thrust (at full blast). How much fuel do you require to carry out the braking maneuver?

If you suggest, e.g. 10 898 kg, you must support your answer with proper calculations to win the prize (€1M). I have a feeling you need >80 000 kg.

OK, let's work through that. This will be simple math as - once again - I'm not an engineer and my math skills aren't that deep. Despite your comments, Tsiolkovsky gives us all we need.

BTW, without a time frame thrust is pretty much irrelevant - since we're talking about Apollo, I'm going to assume a P22K AJ10-137   rocket engine with an exhaust velocity of 3079 m/s.

So. The Rocket Equation:

Delta-V = EV * ln(m₀/m₁)

Where m₀ = Total mass before the burn
          m₁ = mass after the burn
          ln = natural logarithm
          EV = exhaust velocity

So, let's plug in the figures and solve for the difference between m₁ and m₀, which will be the fuel used to produce the desired change in velocity.

Delta-V = 2400 - 1500 = 900 m/s change in velocity.

900 m/s = 3079 m/s *  ln(m₀/32676)   ; divide both sides by 3079 (units cancel out)

0.2923 =  ln(m₀/32676)                       ; take the inverse ln of each side

1.3395 = m₀/32676                             ; multiply both sides by 32676

43769.5 = m₀                                      ; which gives us the mass before the burn...

43769.5 - 32676 = 11093.5                                   ; subtract the mass of the spacecraft and voila!
                                                                           ; we get the amount of mass expended.

And there's your answer, arrived at using the figures you provided and some ninth grade math.

Some of you professional number-crunchers want to check my work, please?

It's all good. Three way split on the million?

[Jason Thompson]

To get into Moon orbit you must, apart from slowing down, change course from a straight one into an elliptical/circular one around the Moon and Moon gravity will assist.

Gravity will not 'assist'. Gravity will do it anyway even if the spacecraft is unpowered. The way Apollo 11 was headed as it passed the Moon, the lunar gravity would have pulled it right round and sent it off on a heading back to Earth. This was the free return trajectory designed into the early missions as a safety factor. If the astronauts did nothing at this point they would still come home safely.

There is then quite a number of factors to keep an eye on. Just how to keep the space ship stable in one - the right - direction during 6 minutes braking/turning, while you loose 10 800 kg mass (30 kg/s) is complicated. Imagine if the space ship tips over and goes away in the wrong direction ... and you have no fuel left or means to correct it.

And so we add intertia and stability to the things you know nothing about. The spacecraft when pointing in any given direction will mainitain that attitude regardless of what direction it is travelling. When the engine was buring, keeping the ship stable was the job of the RCS system, those little rocket nozzles you were shown right near the beginning of this thread. The inertial guidance system had a continuous eye on the spacecraft attitide measured against the gyroscopically stabilised guidance platform contained the the spacecraft. If the spacecraft started to turn in one direction it would fire the relevant thrusters to comensate and keep the ship pointed the same way. That was a tried and tested technology by the time of Apollo. The astronauts didn't need to do anything except point their craft the right way and fire the engine. The computer did the rest, for the most part.

And a spacecraft in space doesn't randomly tip over and point the wrong way. That's another bit of inertia for you.

[ka9q]

Yes, it has in several reports that I use as reference - see link in post #1. I evidently do not believe these reports and therefore we have this friendly discussion. Let's keep it that way.

That you "evidently do not believe those reports" is your problem, not ours. You have to show good cause for not "believing" them. That does not include "I don't want to believe them simply because I'd have to concede that I'm wrong".

See, e.g. my post #786. Can you really show by engineering calculations that you can slow down a 43.5 ton space ship from 2 400 to 1 500 m/s speed in space by burning 10.8 ton fuel at 30 kg/s producing a 97 400 N force?

Yes, as several people have already shown.

I note, however, that your figures do not match the actual Apollo 11 mission. The SPS thrust is only 91 kN, not 97.4 kN. The figures you provide, specifically 97.4 kN of thrust and 30 kg/s mass flow rate implies an exhaust velocity of 3247 m/s and an I_sp of 331 seconds, greater than the actual performance of the Apollo SPS engine (314 sec). Yet that engine was perfectly capable of placing the Apollo stack into lunar orbit, just as I showed several days ago. Why have you ignored it?

[Abaddon]

43769.5 - 32676 = 11093.5                                   ; subtract the mass of the spacecraft and voila!
                                                                           ; we get the amount of mass expended.

And there's your answer, arrived at using the figures you provided and some ninth grade math.

Some of you professional number-crunchers want to check my work, please?

Looks right to me for the specific numbers provided. Note that they're not the actual figures for the Apollo 11 mission.

Please wire me my share of the prize money.

Yes, but the numbers are close enough to give a good approximation:

I used

Thrust = 91000 N
Isp=314.6 s
Burn = 357.53 s
M0=38418 Kg

[Jason Thompson]

Yes, it has in several reports that I use as reference - see link in post #1. I evidently do not believe these reports and therefore we have this friendly discussion. Let's keep it that way.

Ah, an acknowledgement that the data you said did not exist does in fact exist? You don't believe them because you don't understand how they are actually right.

See, e.g. my post #786. Can you really show by engineering calculations that you can slow down a 43.5 ton space ship from 2 400 to 1 500 m/s speed in space by burning 10.8 ton fuel at 30 kg/s producing a 97 400 N force?

No, because the Apollo SPS was NOT a 97,400 N engine. You don't believe the reports with the data you need in them, and yet you hold up that one simplified 9and incorrect) schematic as gospel truth every single time. When you get back from your seven day ban perhaps you will deign to answer the question I have repeatedly asked you about why you insist on using that spec when there is NOT ONE supporting spec for that designation of the SPS engine.

Or that a 5.6 ton module of thin plates/stiffeners arriving into Earth's atmosphere at 11 200 m/s speed is slowed down by friction turbulence to 100 m/s speed during 18 minutes without heating up the inside at all? A few centimeters away the air is glowing hot, the heat shield is at 1600°C and inside - 20°C!

That is also a well-known science. Have you never seen those demonstrations of heat shield material where someone puts a blowtorch on one side and their hand on the other side?

You know nothing about the subject you are trying to draw conclusions about. You simply dismiss everything that shows you to be wrong, and assume you must be right. That's a very worrying personality trait, and one I would not want from a safety consultant.

[Noldi400]

43769.5 - 32676 = 11093.5                                   ; subtract the mass of the spacecraft and voila!
                                                                           ; we get the amount of mass expended.

And there's your answer, arrived at using the figures you provided and some ninth grade math.

Some of you professional number-crunchers want to check my work, please?

Looks right to me for the specific numbers provided. Note that they're not the actual figures for the Apollo 11 mission.

I know. I used his figures deliberately so he couldn't call shenannigans.

Please wire me my share of the prize money.

Sure thing. I'll let you know when "the check's in the mail".

You know, despite it looking like a "video game", Dr. Schweiger's Orbiter really provides an excellent learning experience.

[ka9q]

When the engine was buring, keeping the ship stable was the job of the RCS system, those little rocket nozzles you were shown right near the beginning of this thread.

And the gimbals on the SPS nozzle. During a burn they could control attitude in pitch and yaw (but not roll) but I believe they were actually used only to ensure that the SPS thrust vector acted through the center of mass of the entire spacecraft. That minimized the work that the RCS pitch and yaw jets had to do. (Jay can probably check me on this.)

The inertial guidance system had a continuous eye on the spacecraft attitide measured against the gyroscopically stabilised guidance platform contained the the spacecraft. If the spacecraft started to turn in one direction it would fire the relevant thrusters to comensate and keep the ship pointed the same way. That was a tried and tested technology by the time of Apollo. The astronauts didn't need to do anything except point their craft the right way and fire the engine. The computer did the rest, for the most part.

Correct. The computer did start and stop the engine but the astronauts, being astronauts, watched over it like hawks. They had their finger on the manual stop button just in case the computer didn't stop at the right time. They may have pushed the button a few times but I don't think it was ever actually necessary.

The SPS gimbals were a major electrical load that could actually exceed the power output of the three fuel cells. They required the CM entry batteries to provide the extra power, and they had to be recharged after each burn.

[sts60]

Did Apollo 11 push a cushion or shockwave of air in front of it while trying to keep the trim angle right while flying up/down in the atmosphere? And only this cushion of air heats up and turns into ionized gas/plasma.

Yes, as did alll the other manned Apollo missions, and a couple of unmanned ones, and many other spacecraft as well.  That's what people have been trying to tell you, except that if you had been paying attention, you would also know that as a blunt lifting body, the Apollo CM is both actively steered and aerodynamically stable.  Real engineers - not pretend ones like you - have known this all along.

Have this strange phenomenom been tested in a laboratory or air tunnel test installation? Pls provide some evidence. I have a feeling you are just making it up SF style.

I can only conclude that you are deliberately lying, as this has been shown to you already:
raven noted many results from the NASA Technical Reports Server. and reminded you the formulation is not "secret", as you wrongly claimed.  So did Jason Thompson and JayUtah and nomuse.  So did I when I pointed out that a simple Google search returned a report discussing the heat shield in detail.

But just to rub your nose in it:
NASA TN-D-7564, Apollo Experience Report - Thermal Protection Subsystem
NASA CR-130827, Apollo heat shield test plan
NASA TN-D-3329, Heat-shield ablation measurements using radioisotope techniques
NASA TN-D-3028, Heat-transfer rate and pressure measurements obtained during Apollo orbital entries
Convective and radiative heat transfer during reentry and advanced techniques for their simulation
NASA CR-155280, Apollo Ablative Materials Study

There are many more; that's just a sample of some of the documentation related to Apollo.  The Apollo CM heat shield is far from the only application for ablative techniques.  In my office, for example, we have hundreds of design, test, and analysis reports about ablative heat shielding for heat sources, dating back more than half a century. 

It's one thing to be as ignorant as you are regarding the existence and use of ablative shielding and aerobraking.  That just means, well, you have no idea what you're talking about.  But to pretend the question hasn't already been answered for you - that means you're a liar. 

1. You have lied about your challenge; you don't have a million Euros to offer, and have no intention of acknowledging correct answers anyway - as you have repeatedly shown here.

2. You are still, unbelievably, unable and/or unwilling to acknowledge the very basic error in your clumsy attempt at an energy balance, despite the efforts of real engineers and educated laymen to educate you.

3. You have no idea what you're talking about - you have made an amazing series of laughably ignorant claims and continue to pretend that correct data hasn't been provided to you.   That's not just ignorance; it's willful denial.

Strike two.  The bit-bucket beckons.

[Jason Thompson]

And the gimbals on the SPS nozzle.

Ah yes, I forgot the SPS engine was gimballed. Thanks.

[Jason Thompson]

I wonder if Heiwa thinks aircraft have to aim downwards to land, if gravity is only 'assisting' during the landing phase as it changes from level flight to a curve downwards to land...

[Nowhere Man]

What was the Arthur C. Clarke short story about a race involving solar yachts?  I just re-read it a week ago, but I don't have that collection handy right now...

The Wind From The Sun? I don't remember the author right this second; it was in the collection The Science Fictional Olympics ed. by Issac Asimov.

The Wind from the Sun and Sunjammer are the same story, about racing solar-sail yachts, by Arthur C. Clarke.

Fred

[Abaddon]

I wonder if Heiwa thinks aircraft have to aim downwards to land, if gravity is only 'assisting' during the landing phase as it changes from level flight to a curve downwards to land...

It would certainly make for some interesting landings in heiwa world.
But it is a good earthbound example of how your velocity is not necessarily where you are pointing. "Kai Tak extreme landing" is a good search term on Youtube for this. Such as https://www.google.ie/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDgQtwIwAQ&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DpMOCAfSMnqQ&ei=RGroUKvNAtOzhAfO5IDwBA&usg=AFQjCNHEn8LT1S4k60PIZy404A1kSK9pKA&sig2=jUpy9v4Kx9SzmAiTeUVDMw&bvm=bv.1355534169,d.ZG4

Even better http://www.youtube.com/watch?v=9PdUdaXDHm4

[Sus_pilot]

What actually happens is that the re-entering body pushes a cushion/shockwave of air, which heats due to compression, turning into ionized gas/plasma. The majority of the energy of re-entry is spent heating atmospheric air. The purpose of the heat shield is to prevent this superheated envelope from destroying the spacecraft.

Did Apollo 11 push a cushion or shockwave of air in front of it while trying to keep the trim angle right while flying up/down in the atmosphere? And only this cushion of air heats up and turns into ionized gas/plasma.
Have this strange phenomenom been tested in a laboratory or air tunnel test installation? Pls provide some evidence. I have a feeling you are just making it up SF style.

I believe so. Then it was tested by launching dummy warheads in the late 50's. Eisenhower conducted a speech from the Oval Office with a test article that had been successfully launched and returned sitting next to him.