Lunar lander?

[sharksandwich]

One of the most convincing pieces of "evidence" propounded by the Lunar Landing Hoax theorists is that it would be impossible to control the Lunar Landing Module using the directional jets - in fact, on earth trials, the Lander always became uncontrollable. It has been suggested that moon gravity made it more controllable (I know there were several landers, but as far as I know they were of similar configuration).
Anyone have thoughts either way?

FLIGHT CONTROL AND THE LUNAR MODULE
Flight control involves controlling the LM trajectory (flight path) and attitude. Flight path control depends on the motion of the LM center of gravity; attitude control primarily involves rotations about the center of gravity.
In controlling the LM in its flight path, the thrust of its engines must be directed so that it produces a desired variation in either magnitude or direction to place the LM in some particular orbit, position, or attitude. The major velocity changes associated with the lunar orbit, injection, landing, and ascent phases of the mission are accomplished by either the descent propulsion section or ascent propulsion section of the Main Propulsion Subsystem (MPS). The engines can produce high thrust in specific directions in inertial space.
During the descent phase, the LM must be slowed (braked) to place it in a transfer orbit from which it can make a soft landing on the lunar surface. To accomplish braking, descent engine thrust is controllable so that the precise velocity (feet per second) necessary to alter the vehicle's trajectory can be achieved. For a soft landing on the lunar surface, the weight of the LM must be matched by an upward force so that a state of equilibrium exists, and from this point, the descent engine is shut off and the LM free falls to the lunar surface. The thrust of the descent engine provides this upward force, and since the weight of the vehicle is a variable (due to consumption of expendables) this is another reason why the magnitude of the engine thrust is controllable. In addition, the center of gravity is also variable and the thrust must be such that it is in line with the LM center of gravity. This is accomplished by gimbaling (tilting) the descent engine.
During the lunar ascent phase, the flight control portion of the GN&CS commands the ascent engine. In this phase, control of the thrust direction is not achieved by gimbaling the engine, but by attitude control, using the Reaction Control Subsystem (RCS) thrusters. This is necessary during ascent to keep the vehicle stabilized, because the center of gravity changes due to propellant depletion. The ascent engine is not throttleable, since the function of this engine is to lift the ascent stage from the lunar surface and conduct rendezvous. The proper orbit for rendezvous is achieved by means of a midcourse correction (if necessary) in which thrust is directed by attitude control, and thrust magnitude is controlled by controlling the duration of the burn.
It is apparent then for flight control, that some measure of the LM velocity vector and its position must be determined at all times for purposes of comparison with a desired (predetermined) velocity vector, at any particular instant, to generate an error signal if the two are not equal. The flight control portion of the primary guidance and navigation section then directs the thrust to reduce the error to zero. Attitude control maintains the LM body axes in a fixed relationship to the inertial reference axes. Any pitch, roll, or yaw rotations of the vehicle produce a misalignment between the LM axes and where the LM axes should be. This is called attitude error and is detected by the inertial guidance system, which, in turn, routes the errors to the computer. The computer generates on and off commands for the RCS to reduce the error to zero. Attitude control is implemented through 16 rocket engine thrusters (100 pounds thrust each) equally distributed in clusters of four around the ascent stage. Each cluster is located so that it will exert efficient torque to rotate the LM about its center of gravity. The thrusters are capable of repeated starts and very short (fraction of second) firing times. The appropriate thrusters are selected by the computer during automatic operation and manually by the astronaut during manual operation.
LM News Reference: Guidance, Navigation and Control

[sp221156]

I would guess that the RCS thrusters (effectively small rocket engines) would be far more effective in a vacuum in one-sixth gravity than on Earth simulations using the Lunar Landing Training Vehicle. The LLTV was very diffcult to fly and often unstable. (Neil Armstrong himself had to eject from one).

I've never seen the RCS controls on the Lunar Module being used by the hoax theorists as convincing evidence as to why the landing didn't take place.

One of their favourites however is why did the descent engine of the LM not leave any sort of crater under it's landing spot. There are a number of good reasons for this it seems. There are some good websites effectively shooting huge holes through the 'hoax' arguments which are worth a look at.

Steve

[sharksandwich]

It is a serious aeronautical challenge (while on earth).
Look at this video of a failed trial using 2007 computing power:YouTube - Flight of experimental Moon lander
Make one wonder how six flawless landings were performed in the 70s, while it can't be done once today. 100% accurancy is required, as there is no latitude for errors or go-arounds.

I would guess that the RCS thrusters (effectively small rocket engines) would be far more effective in a vacuum in one-sixth gravity than on Earth simulations using the Lunar Landing Training Vehicle. The LLTV was very diffcult to fly and often unstable. (Neil Armstrong himself had to eject from one).

That is the problem: DOES REDUCED GRAVITY MAKE A LANDER MORE STABLE? Somehow I doubt it.

[Rainboe]

Yes it does. It was designed for 1/6 Earth gravity. So to produce a test bed that will have enough thrust to support an experimental device in Earth gravity, you need an engine six times as powerful. The engine is gimballed for directional thrust as well as using small 'puffers' around the craft for additional control, so you have a totally different machine designed for the special circumstances of lunar gravity. If you look at the movies of the lander approaching the Command ship for docking, you have a craft in perfect stability. Look at the testing of the Harrier VTOL fighter and the instability it had at first, and the stability it had when the design was refined, and look at it today. And you say 'it can't be done'! Crazy.

Once again, we have another nutty conspiracy theory that people fervently believe, in the face of all evidence. They won't even believe it happened when they see video or photographs of the lunar craft being revisited! It will be 'faked', according to them. The important thing is not to get sucked up in this nonsense, because these people peddling this daft stuff are actually mentally disturbed. It is a mental condition to fervently believe things in the face of evidence against, but then again, I suppose that applies to all religion, and paints even the Pope as a bit 'dodgy'.

I would say, 'please stop wasting our time with this nonsense'! Yet more proof of the insanity of conspiracy theorists, do you really imagine that Big Government could maintain a big conspiracy and lie involving tens of thousands of government employees, including astronauts themselves who are extremely honest and religious, and nobody, not even drunk out of their minds, has ever admitted being part of a big 'lie'. So please give it up and take this nonsense to websites where other fruitloops congregate together, not here! A place where people can waste their lives telling each other a 757 couldn't have hit the Pentagon, that the US Government blew up the WTC (that's another real proof of total fruitloopness!). 95% of the population have had enough of this garbage- a government that can't sort out medical care and bus services is supposed to do all that? Mad! Can't you see the error of all this nonsense?

[Load Toad]

I've always believed the government, conspired with various companies and brilliant scientists and brave pilots an' such, with the aid of tax dollars...to land on the moon. And so far no one has proved they didn't.
So I'm sold.

The faking it thing; what would be the chuffing point? Wouldn't Super Communist Soviet Union have said 'You're fibbing!' and proved otherwise. Or were they in on it to just so they could celebrate coming second in the space race?

[aviate1138]

Amazing how hundreds of thousands of technicians all kept their mouths shut for nearly 40 years.

sharksandwich you naughty boy! Someone should give you a big smack!

[Load Toad]

Why don't conspiracy fruitcakes just go to the moon, go to the sites where the lunar landers are supposed to have landed - photograph the big empty spaces that have no lunar landers an' stuff on them and then come back and tell us 'bout it?

Instead of whining on like stuck pigs.

[sharksandwich]

No,no hoax theory!

It was designed for 1/6 Earth gravity. So to produce a test bed that will have enough thrust to support an experimental device in Earth gravity, you need an engine six times as powerful. The engine is gimballed for directional thrust as well as using small 'puffers' around the craft for additional control, so you have a totally different machine designed for the special circumstances of lunar gravity.

Good point, rainboe, but doesn't answer all the questions, which are likely to become more topical if the new lunar landings go ahead.
I know the hoax theories are hokem, but this one aspect is intriguing.
The lander is unstable, and even in reduced gravity is subject to Newton's Laws.
Once a touch too much puff is given (or needed), corrective efforts are as likely to increase as decrease any ocillation.
Since NASA's total computing power in 1970 was less than most of us carry round with us today in the form of cell-phones, how was it done? I mean, pilot's make errors, but here were no human errors in several landings.

[TheOptimist]

Of course reduced gravity makes it easier. It makes it about 10 times easier. If you can't see that then you don't deserve to be breathing let alone coming up with more crap conspiracy theories.

[Load Toad]

Why is it the Lunar Landing they have a problem with - is all of the other space exploration stuff and rocket technology from the V2 onwards a load of BS too?

[BOAC]

Poor old SS - I don't think he actually PUSHED any conspiracy theory, but just asked about the claims? Still, why not have a hack at him - this is PPRune, after all.

Originally Posted by SS

That is the problem: DOES REDUCED GRAVITY MAKE A LANDER MORE STABLE? Somehow I doubt it.

- I'm a bit out of touch with space mechanincs, but my vote is no. I reckon that since the mass of the module remains the same, moon or earth, 1/6th G or 1G, it will react the same. F=M x a and all that. All that changes is the main engine power needed. The C of G of the module does not change, so all the stability formulae remain the same.

Once a touch too much puff is given (or needed), corrective efforts are as likely to increase as decrease any ocillation. Since NASA's total computing power in 1970 was less than most of us carry round with us today in the form of cell-phones, how was it done? I mean, pilot's make errors, but here were no human errors in several landings. Today 12:08

- the big factor is - they were good pilots?

[dazdaz]

I'm still trying to comprehend (1969 landing) after just 24 years after the end of WWII space suits, oxygen filters where develop in such a (WWII prop a/c) short time scale., did they have them back in the 60s? With reference to submarine fleets. Could they stay below water (as take off, landing and return to earth of this 69 mission) without using the snorkel to replenish air?.How long would the scrubbers on subs operate in 69?

1969:: They never went to the moon, maybe other launches did, mid 70s. Where are the space suits of the 69 landings? They were cremated to avoid contamination. Umm

[con-pilot]

I'm still trying to comprehend

Try harder.

[sharksandwich]

I reckon that since the mass of the module remains the same, moon or earth, 1/6th G or 1G, it will react the same. F=M x a and all that. All that changes is the main engine power needed. The C of G of the module does not change, so all the stability formulae remain the same.

Thank you, BOAC,for getting to the nub of the problem!
The Moon landing craft could not be under control from Cape Canaveral (radio time lag would preclude this, plus the intricacy of the procedures) whereas it is conceivable, if not probable,the majority of the "flight" could be remotely controlled.
Since control of such an inherantly un-stable craft proved so problematic on Earth, even flown by military jet pilots, why would a decision be made to do it several times (one might think NASA would say"we got away with it once, let's call it a day!").
And having mastered it then, why is it now proving so difficult to replicate?

[dazdaz]

Technology? They never went/landed on the moon (69). All arguments asside. Who would imagine/comprehend that after (I say this again) 24 years after WWII space suite technology, systems controls, rocket technology. In my book it seems a little far fetched that they landed on the moon 69

[togsdragracing]

Just point your local conspiracy theorist at this page and ask them to explain it away...

NASA - A Second Look at Apollo 11

[wiggy]

dazdaz

"All arguments asside",..... Err no, you can't do that - the arguments are very much relevant, you can't just blow them off because you don't fit your theory.

Technology - "technology" was around well before Apollo, it didn't start with the microchip and trendy IT courses in school....

FWIW 24 years is more than long enough to scale up the rocket technology of the V2 to become the Saturn V..., especially if the V2 design team turned it's hand to the task.

Many of the fighters of the 1950's were neutrally stable at best without some sort of Stability Augmentation system..., so I reckon the early 60's design LM was in with chance of flying right side up for a while......

CO2 filters were commonplace well before Laika's flight in '1957..

I was programming at a UK University in the early 70's using a computer language that was certainly capable of handling Lunar landing style guidance equations - I'd guess NASA, with the big bucks had much better computing capability much earlier than I did.....

In my book it's entirely credible that they went to the Moon in the late 60's, the only real mystery is why the conspiracy theories continue to run well into the 21st Century - is it because it's a feat that's beyond the wit, intellect and imagination of most of the facebook generation?

[Ace Rimmer]

daz daz Well your Polaris boat circa 69 could stay down a long, long time typically a patrol would be about 4 months (limited by food and human factors). That after all was their mission go to sea hide and be ready to zap off the instant sunshine if need be...much the same as Trident boats do today. Of course that is why you need at least four two in refit one in training one on patrol (but try telling that to Broon and his cohorts)...


But back to the moon...they went out to the moon - did it twice in 69 (three times if you count Con's cousin in law's dress rehearsal) once in 70 (ok that was a wave off and rather more than the plot line for a movie) twice in 71 and twice in 72. Did it dun it and if the guvmit will stup up the cash they'll do it again...

Oh and ref the LM flying - you have to remember that every CDR was a very very very good pilot

[BOAC]

togsdrag - no doubt our resident expert will be here shortly telling us the pics have been photo-shopped?

[BKS Air Transport]

No atmosphere. That must surely make things easier.