ApolloHoax.net
Apollo Discussions => The Reality of Apollo => Topic started by: Nowhere Man on April 02, 2012, 09:24:36 PM
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Just in case the Saturn V wasn't ready in time.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770078693_1977078693.pdf
Documents like these are really hard for Apollo-was-a-hoax believers to explain away except with "Obvious fake!" or "LA LA LA LA I CAN'T HEAR YOU!"
Fred
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Very cool document. It took me a bit of reading to realize what was being proposed -- launching a complete CSM-LM stack unmanned on a non-man-rated Saturn V, and doing an earth-orbit rendezvous using a whole second manned "ferry" CSM launched on a Saturn 1B. That CSM would be abandoned in orbit (or deorbited empty) after the crew transferred to the CSM-LM stack and headed for the Moon. If anything went wrong with the rendezvous they would perform an alternate earth-orbit mission and return to Earth in the ferry CM. Wowsers!
One little detail wasn't clear to me, and maybe hadn't been considered in this preliminary study. A docking drogue would be used to dock the lunar and ferry CMs nose-to-nose for the crew transfer. But which vehicle would carry the drogue? The manned CSM would require an LES (escape rocket) so you couldn't have the drogue attached to that CM's nose. The unmanned stack would be launched without an LES to increase the propellant load in the S-IVB (for longer duration in Earth orbit), so it could carry the drogue -- but that would cancel the advantage of eliminating the LES to some extent at least. Besides, their drawings show the drogue on the ferry CM, not the lunar CM.
Maybe the drogue would have been carried on top of the S-IC, and the ferry CM would pick it up -- something like the way the lunar CMs picked up the LM after TLI. Or were they actually considering launching the crew in a CM with a drogue and no LES? Somehow I don't see that as being too popular with the astronaut corps.
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Maybe the drogue would have been carried on top of the S-IC, and the ferry CM would pick it up
I would assume this to be the case, since that arrangement was eventually used for the ASTP docking adapter.
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Maybe the drogue would have been carried on top of the S-IC, and the ferry CM would pick it up -- something like the way the lunar CMs picked up the LM after TLI. Or were they actually considering launching the crew in a CM with a drogue and no LES? Somehow I don't see that as being too popular with the astronaut corps.
Not likely since the S-IC would have been dropped long before reaching orbit and the Saturn IB didn't even have a S-IC stage. I presume you meant S-IVB.
Combining the complication of Earth Orbit Rendezvous with the complication of Lunar Orbit Rendezvous is something we're pretty sure would be a mission mode now. Seems like they were thinking of it in the most wasteful way though compared to pure EOR.
And of course CM on CM action would upset certain people. Look at the trouble Gene Cernan got into for saying a naughty word.
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Maybe the drogue would have been carried on top of the S-IC, and the ferry CM would pick it up -- something like the way the lunar CMs picked up the LM after TLI. Or were they actually considering launching the crew in a CM with a drogue and no LES? Somehow I don't see that as being too popular with the astronaut corps.
Not likely since the S-IC would have been dropped long before reaching orbit and the Saturn IB didn't even have a S-IC stage. I presume you meant S-IVB.
Yes, I did. Must have been a glitch in the matrix there... :o
And of course CM on CM action would upset certain people. Look at the trouble Gene Cernan got into for saying a naughty word.
Hard core docking?
One thing this document underlines is the difficulty and criticality of achieving man-rating status. The whole concept relies on the availability of the Saturn V, fully functional but not quite reliable enough for people to ride on.
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Not to mention, if I am reading it right, the SIVb would have to be man rated, even if the first two stages weren't.
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Not to mention, if I am reading it right, the SIVb would have to be man rated, even if the first two stages weren't.
Easier to achieve. The Saturn IB was man rated for Apollo 1.
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I've heard the expression "man rated" many times but I still don't know what it really means.
Does it mean a probability of mission failure less than some threshold?
Or does it mean a probability of killing its crew that's less than some threshold?
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I've heard the expression "man rated" many times but I still don't know what it really means.
Does it mean a probability of mission failure less than some threshold?
Or does it mean a probability of killing its crew that's less than some threshold?
Well, there's this: http://nodis3.gsfc.nasa.gov/displayDir.cfm?Internal_ID=N_PR_8705_002B_
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Well, there's this: http://nodis3.gsfc.nasa.gov/displayDir.cfm?Internal_ID=N_PR_8705_002B_
Typical NASA bureaucratese - awfully verbose for what it actually says.
Most of it is circular and therefore rather meaningless: "human-rating is making a system safe for humans". The one specific requirement I do read into it is for features to protect and recover the crew even after serious failures that otherwise prevent mission completion.
For the Saturn/Apollo system, these would include a) the launch escape tower and b) the Emergency Detection System (EDS) active during first stage flight. It would also include the related operational considerations of flying a trajectory such that survivable abort options always exist were one or more engines to fail or go "hard over" (experience a steering actuator failure).
By this definition, I'd say the Shuttle never achieved a human rating, mainly because it was never designed to have one. Neither would the Aries I have been human-rated, because certain credible failures (notably a SRB breach during first stage flight) would have been unsurvivable even with an escape tower; the parachutes would have been burned up by flaming chunks of propellant.
The Saturn V also had considerably wider operating margins than most launchers. It could (and actually did) lose engines at certain points in flight and still achieve its mission. Few unmanned launchers even come close.
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Let's see...the partial failures I'm aware of during Saturn launches include:
Apollo 6 - premature shutdown of two J-2s during S-II flight, failure of S-IVB J-2 to re-ignite. Mission was still a partial success, and had it flown with a crew they would likely have been recovered.
Apollo 13 - premature shutdown of center J-2 during S-II flight. Still reached nominal cutoff targets and performed TLI.
Skylab I - second-plane separation failure (the interstage ring between the S-IC and S-II failed to jettison 30 seconds after staging). Payload still achieved nominal orbit. (Problems with micrometeroid shield and solar array were unrelated to Saturn V performance.)
I can't think of any Saturn IB failures, manned or unmanned - were there any?
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Not to mention, if I am reading it right, the SIVb would have to be man rated, even if the first two stages weren't.
Easier to achieve. The Saturn IB was man rated for Apollo 1.
Still must have been a process in itself considering it not only had to work, it had to work twice with perfect reliability or there would be no mission.
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The mission itself would have been quite a challenge. If the Saturn V were launched first, its S-IVB would have to wait some time for the the Saturn IB to bring the crew.
The S-IVB in an Apollo parking orbit had a very short life; the altitude was kept extremely low so as to avoid wasting propellant that would be better used for TLI, and the cryogenic propellants boiled off so quickly that the hydrogen had to be continually vented. In fact, the hydrogen vents were used to provide a little thrust to help compensate for the drag of the low parking orbit. Obviously it couldn't endure that for very long and still make it to the moon. Each operational lunar mission had only two opportunities for TLI, otherwise the S-IVB wouldn't have enough propellant left.
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Fascinating. This what I love about these forums, I always learn something. :)
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To illustrate why first going into a parking orbit costs energy over a direct escape trajectory, consider the following thought experiment.
Imagine that the earth, instead of being a solid/liquid sphere, consists of a thin hollow shell with the earth's diameter plus a infinitesmal black hole at the center containing the earth's entire mass. The space between the shell and the black hole is a vacuum.
Imagine strapping a rocket on your back, opening a trap door in the earth, and jumping in. You do this from the equator so you start with the earth's eastward equatorial velocity of 465.1 m/s.
About 15 minutes later you would reach periapsis with the black hole at a radius distance of a little over 11 km, moving tangentially at a little over 268 km/sec.
Now you fire the rocket on your back in a prograde direction (to boost your velocity). It's a really puny one, with a delta-V of only 233 m/sec.
As you climb away from the black hole on your return to the surface, you will of course slow down again. Assuming you have planned ahead and made arrangements for someone to open a trap door for you in the proper location, you will fly through it with a velocity of 11,186 m/sec - the earth's surface escape velocity.
You will then fly off into space, never to return.
Imagine -- escaping from the earth entirely with a delta V of only 233 m/sec. If you wanted to remain in orbit, you'd need even less.
What this really says is that the most energy-efficient way to escape the earth is on a hyperbolic trajectory with a perigee as close to the earth's center as possible. Since, sadly, the real earth is unreasonably dense even if not completely solid, you will have to fly a less energy-efficient trajectory from your surface launch site to your departure hyperbola, joining it at the first post-perigee point above the amosphere. Your subterranean perigee is then of no consequence since you won't be coming back to fly through it. But if you are required to complete one or more parking orbits before departure, then a subterranean perigee is a definite problem. You'll have to spend some of your launcher capability on raising it to a safe level -- capability you would have preferred to spend on raising your apogee.
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It's hard to imagine after 30 years of Space Shuttle that a launch vehicle could lose an engine and the missions just shrugs it off.
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It helps that it was a centre engine I imagine, correct me if I am wrong, so there was no loss of symmetry of thrust. An outer engine failure would have created some massive torque.
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It helps that it was a centre engine I imagine, correct me if I am wrong, so there was no loss of symmetry of thrust. An outer engine failure would have created some massive torque.
The S-II J2 failures on Apollo 6 were two adjacent outer engines. The ICU still managed to get the S-IVB into orbit... in a most unconventional manner. It was actually thrusting backwards at engine cutoff.
(I hope I'm remembering this correctly -- it's been a while since I read up on it.)
Though that mission was a "partial success", it was only such because it was unmanned. If it had been crewed it would certainly have ended in an abort.
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What this really says is that the most energy-efficient way to escape the earth is on a hyperbolic trajectory with a perigee as close to the earth's center as possible. Since, sadly, the real earth is unreasonably dense even if not completely solid, you will have to fly a less energy-efficient trajectory from your surface launch site to your departure hyperbola, joining it at the first post-perigee point above the amosphere. Your subterranean perigee is then of no consequence since you won't be coming back to fly through it. But if you are required to complete one or more parking orbits before departure, then a subterranean perigee is a definite problem. You'll have to spend some of your launcher capability on raising it to a safe level -- capability you would have preferred to spend on raising your apogee.
Clearly, the solution is to convert yourself into neutrinos, and launch yourself right though the Earth.
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The mission itself would have been quite a challenge. If the Saturn V were launched first, its S-IVB would have to wait some time for the the Saturn IB to bring the crew.
This was addressed in the backup plan proposal. By removing the LES, the S-V could carry extra cryogenics. This increased the endurance to 10 hours in orbit.
That's still a tight timeline, though, which suggests that they might have chosen to launch the crew ferry mission first. That had some extra mission risk -- if you launch the lunar stack first and it fails, you don't launch the crew at all. Of course, if you launch the crew first and then lose the S-V you can still do an orbital mission of some kind; and if the S-V launch succeeds your timing requirements are more relaxed.
It's a wild thought, though -- imagine a manned liftoff from one pad while the big Saturn was already sitting on a nearby pad, all set to go (or vice versa). Shades of (dare I say it) Armageddon!
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Clearly, the solution is to convert yourself into neutrinos, and launch yourself right though the Earth.
Sounds good at first, but it won't really work even though, as far as we know, at least some neutrinos have rest mass and are subject to gravity. My model put all the earth's mass at its center so that you could fall down an enormous gravity well, pick up a large velocity, and then exploit the Oberth effect with a puny rocket. What seems to be "something for nothing" really comes from having carried a chunk of propellant deep into a gravity hole and dropping it there so I don't have to carry it back out. I get its released gravitational potential energy.
But the real earth distributes its mass throughout its interior. If the mass were uniformly distributed, gravity would fall linearly as you approach the center instead of increasing with the inverse square of your distance to a hypothetical black hole at the center.
In reality the earth's density is not uniform; it has liquid and solid iron cores that are even denser than iron on the surface because they're under extreme compression. So gravity actually reaches a peak at the surface of the outer core of 10.62 m/s^2 (about 1.08g) before dropping to zero at the center. But this still wouldn't give the dramatic effect of my black hole at the center.
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It's a wild thought, though -- imagine a manned liftoff from one pad while the big Saturn was already sitting on a nearby pad, all set to go (or vice versa). Shades of (dare I say it) Armageddon!
Or Skylab...?
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It helps that it was a centre engine I imagine, correct me if I am wrong, so there was no loss of symmetry of thrust. An outer engine failure would have created some massive torque.
As long as the remaining engines can generate net thrust through the center of gravity, there's no problem. That means having gimbals that go far enough. This would increase the angle of attack, and that might be a problem during atmospheric flight but not in vacuum.
As I recall, at least some of the Saturn V launches canted the four outer F-1 engines outward slightly after tower clear to improve the IU's ability to compensate were one of the engines to fail. Since liftoff acceleration was barely greater than 1 g I don't think the Saturn could tolerate an engine failure immediately after liftoff, but if it happened later when acceleration had increased and less burn time would be lost on the failed engine, it might well have been able to compensate. I don't know what the angle of attack would be, this is absolutely critical in the max-Q region but you get out of that as quickly as you enter.
Edit to add: Remember the IU deliberately shut down the inboard engine before the four outboard engines. I'm sure the IU was programmed so that if an engine had already failed, the IU would not shut down another one, and this would probably compensate for much of the lost performance. Maybe even completely compensate if the engine failure happens late enough.
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Clearly, the solution is to convert yourself into neutrinos, and launch yourself right though the Earth.
... But this still wouldn't give the dramatic effect of my black hole at the center.
Spoilsport. I guess I'll have to find a different application for my Reversible Neutrinoizer.
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Thanks everyone for the replies on my statement. I learned another bit of Apollo history. Thanks!
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It's a wild thought, though -- imagine a manned liftoff from one pad while the big Saturn was already sitting on a nearby pad, all set to go (or vice versa). Shades of (dare I say it) Armageddon!
Or Skylab...?
Thank you. And Skylab had the sense to not put the two space vehicles right next to each other.
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In reality the earth's density is not uniform; it has liquid and solid iron cores that are even denser than iron on the surface because they're under extreme compression. So gravity actually reaches a peak at the surface of the outer core of 10.62 m/s^2 (about 1.08g) before dropping to zero at the center. But this still wouldn't give the dramatic effect of my black hole at the center.
Where did you find that 10.62 m/s2 number? A couple years ago I modelled Earth's interior to estimate gravity versus depth and I arrived at a number very close to that right at the surface of the outer iron core. I didn't expect such a result when I started, so it's good to see data that appears to confirm my numbers.
(http://www.braeunig.us/pics/EarthGravity2.gif)
Here's the original thread in which this was discussed:
http://apollohoax.proboards.com/index.cgi?board=theories&action=display&thread=2964&page=3
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Where did you find that 10.62 m/s2 number?
Via Google, of course. I didn't hang onto the link, so if you published it on the web, your result might have been the one that I found. So don't use it as confirmation. :-)
I do remember the person did a fairly straightforward if brute-force numerical integration, working through the earth as a series of concentric shells, each shell having a uniform composition that changed with depth. I had remembered seeing something like this result a while ago, but I wasn't sure of the actual acceleration value.
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The ICU still managed to get the S-IVB into orbit... in a most unconventional manner. It was actually thrusting backwards at engine cutoff.
Are you sure about that? It's hard for me to conceive of a reason why the IU would flip the stack around. That would only happen if there had been an overspeed, but this was an underspeed.
I do remember reading that in the LM guidance equations it was possible for the LM to invert during descent if one of the phases (probably the braking phase) had been carried too far, because it was targeted for a specific point in space and normally switched to the next program (probably the approach phase) before actually reaching it. Remember, computers (like many humans) lack any notion of common sense.
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The ICU still managed to get the S-IVB into orbit... in a most unconventional manner. It was actually thrusting backwards at engine cutoff.
Are you sure about that? It's hard for me to conceive of a reason why the IU would flip the stack around. That would only happen if there had been an overspeed, but this was an underspeed.
You made me go and look it up!
This is regarding Apollo 6, the second all-up unmanned test of a Saturn V. The quote is taken from Apollo: The Race To the Moon by Murray and Cox, one of my favorite references -- it's more focused on the flight controller side of things than the astronauts', and has an excellent chapter on A13 (among many other things).
After the two [S-II] engines had gone out, the vehicle had maintained a pitched-up attitude known as "chi-freeze" for far longer than it would have under ordinary circumstances. "Well, the S-IVB lit up," [FIDO Jay] Greene recalled, "and the first thing it said was, 'Omigod, I've got too much altitude.' And so it pointed its nose straight at the center of the earth." This battle between the guidance system and the gimbal limits on the engine continued for about eighty seconds, with Greene getting closer and closer to calling an abort of his own. When the S-IVB finally gave up trying to get to the altitude it wanted, it had a flight-path angle that was unacceptably low. "So then the little devil said, 'Well, this is bad, I've got to pick up the flight-path angle,' so it started pitching up, and as it started pitching up it said, 'Now I'm overspeed,' so it actually went into orbit thrusting backward."
Nothing like a little IU anthropomorphizing to brighten a FIDO's day.
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I do remember the person did a fairly straightforward if brute-force numerical integration, working through the earth as a series of concentric shells, each shell having a uniform composition that changed with depth. I had remembered seeing something like this result a while ago, but I wasn't sure of the actual acceleration value.
That sounds very similar to what I did, but I don't recall ever giving an actual number for the maximum acceleration - I just plotted and presented the graph. If someone gave a specific number of 10.62 m/s2, then they likely calculated it independently from me.
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I never knew that about Apollo 6 - now I have to go back and re-read the mission and especially the Saturn V reports!
The LVDC (Launch Vehicle Digital Computer) on the Saturn V was impressive for its day (with triple redundancy!) but it was an ant-brain by today's standards. That it could deal at all with a non-nominal condition without blowing up is itself remarkable.