For the Apollo Lunar Vehicle did the build blueprints specify orange reflective foil to be installed as if you were a 2nd grader with the scotch tape role for the first time. How would the blueprints specify some of the odd ball foil installation that I have seen on pictures of the vehicle .
That foil was applied not only to the command module, but to the lunar module as well.
Kapton foil was explicitly developed as thermal protection, a protectant to the three astronauts inside the command module from all of the heat during their 25,000 miles an hour re-entry through our atmosphere.
Kapton is a polyimide film produced by DuPont in the late 1960s that remains stable across a wide range of temperatures, from −269 to +400 °C (−452 to 752 °F; 4 to 673 K).
The chemical name for Kapton K and HN is poly (4,4′-oxydiphenylene-pyromellitimide).
It is produced from the condensation of pyromellitic dianhydride and 4,4′-oxydiphenylamine.
Apollo 11 Lunar Module
It’s the same material and the same rationale behind the gold-colored material on the Apollo 11 lunar modules descent stage. The descent stage of the Apollo Lunar Module, and the bottom of the ascent stage surrounding the ascent engine, were covered in blankets of aluminized Kapton foil to provide thermal insulation.
Therefore, it was all about temperature management protecting the vital systems inside the lunar modules descent stage from the extreme heat of being in unfiltered sunlight and extreme cold of being away from the Sun.
Not sure about the blueprints, but the familiarization manual has this to say:
"The ascent stage thermal and micrometeoroid shield combines either a blanket of multiple
layers of aluminized polyimide sheet (Kapton H-film) and aluminized polyester sheet
(mylar) with a sandwich of inconel mesh and nickel foil or a polyimide blanket with a
single sheet of aluminum skin. The combined thermal and micrometeoroid shield is mounted
on supports (standoffs) , which keep it at least 2 inches from the main structure. The
standoffs have low thermal conductivity. Where subsystem components are mounted
external to the ascent stage basic structure, the standoffs are mounted to aluminum frames
that surround the components. The aluminum or inconel (the outermost material) serves
as a micrometeoroid bumper; the sandwich and blanket material serve as thermal
shielding. Where the blankets meet, the mating edges are sealed with mylar tape. The
blankets have vent holes. During earth prelaunch activities, various components and
areas of the ascent stage must be readily accessible. Access panels in the outer skin and
insulation provide this accessibility. "
The OP’s question about the foil being installed by a 2nd grader is important. The insulation was in many layers, and in order to work, the layers can’t touch, or at least touch as little as possible. Some multi-layer insulation blankets incorporate scrim layers to provide separation, but an alternative is to randomly crinkle each layer. They will hardly touch if loosely installed, and thus provide an effective system. Especially easy of you have a large vehicle to cover.
As to the blueprints. A lot of specialised assembly of things like this never sees blueprints. There will have been lots of experimental work done to work out the parameters of the needed insulation and how to make multiple layers that work. The people doing the work were likely trained how to do it, possibly by those who did the experimental work.
Given this technique is pretty much standard for any spacecraft there is now likely a huge body of work describing techniques and providing design guides. Even then, I bet experience and hands on training is still important.
With apologies to the OP for this thread hijack, I have a not unrelated question regarding the Apollo lander. What did they do with the helium?
https://www.youtube.com/watch?v=oX8-IXdABuc
The above links to a YouTube video showing a computer animation detailing some of the layout and construction details of the Apollo landers. I found it quite interesting, YMMV. The animation shows several tanks of helium but doesn’t explain their importance. I’m assuming it was for cooling/thermal regulation. If that’s not correct then what were their intended use?
Helium was used as a pressuriser to push fuel and propellant out of the tanks and into the rockets. Simpler and lighter than pumps, apparently.
Many thanks, that makes perfect sense and I had not considered that option. The only other thought that crossed my mind was that it was for some version of Heliox but that seemed much less likely. Rather than being simpler and lighter, I would say simpler and more reliable especially given the available power budget.
BTW, “fuel and propellant”?
Actually, I think the LM used fuel and oxidiser to create its own propellant. A real rocket scientist might explain better.
Exactly. The lunar module ascent stage engine was intended to be as light and reliable as possible, which meant no pumps and interestingly enough, an ablative composite nozzle cone as well. It was fixed thrust, non-gimballed and used hypergolic propellants. It was about as simple as a liquid fuel engine could be.
Light, reliable, simple - yeah, I get all that. But it did not merely get them off of the moon’s surface. It got them to a specific place and at a specific time, so they could rendezvous with the Command Module. That’s the part that really blows me away.
It is unquestionably an impressive bit of engineering, but, if you think about it, it would be pretty foolish to land on the moon without an ascent engine that was absolutely reliable and would instantly ignite when required and perform according to specifications. Don’t forget your $100000 guidance computer, plus independent backup computer.
It’s mentioned in Tom Kelly’s book about the LM that the ascent engine was often at the top of the notorious list of problems that could seriously delay the Apollo program. The biggest issue was combustion instability and after eventually figuring out how to eliminate it did twice as many test firings as required to have it certified for the program.
That’s more of a matter of mathematics. They know how heavy the ascent module would be, and while they couldn’t throttle it (vary the thrust), they could shut it off. And they knew how much thrust it put out.
So it becomes at that point a question of how long to burn the engine to accelerate to lunar orbital speed, at what angle to go, and when to actually blast off so that they properly rendezvous with the command module.
And don’t forget, both had the RCS engines which could fine tune things so they could dock.
How did they steer? Or am I misunderstanding the bolded word?
RCS thrusters, I assume.
This is a great contemporary video explaining how a lunar rendezvous worked…
And if any of you liked that last video check this one out about how they chose landing sites… Also, it’s a shame they don’t make films like this anymore!
