I told you already I am reading about the development of the Lunar Module. Very unique thing as it was built to not fly in our atmosphere and would not be used to bring humans back to earth. That gave them the ability to design simply for functionality with no regard to aerodynamics. Weight was the most critical factor. I'm blown away by the attention to detail that had to be made down to every screw. During testing of the tanks they kept having problems with leaks and finally narrowed it down to just one tank, they couldn't figure out why that one tank wouldn't pass the tests. They spent months figuring out why. It was putting the moon race in jeopardy. Grumman got their top investigator on the job and they went over every piece of tracking history. Turns out when they were wiping the tanks down that was the only tank that didn't use a brand new rag. it was used. The rag had traces of detergent on it and that affected the titanium. I'm both amazed that happened and that they could figure that out, down to the rags used to wipe each piece of equipment.
Another example referred to the Redstone rockets, used on the early Mercury flights. An unmanned launch attempt lifted off the ground a few inches then settled back into the bay, luckily it didn't tip over because the escape chute did fire and they were worried the wind would catch it and bring it all crashing down. The reason the rocket aborted? A crewman at one point had filed down one prong just a little bit of a two prong plug and didn't tell anybody. This prong was ejected during liftoff. Safety mechanisms in place said that if the prongs didn't exit at the same time then something was wrong and to initiate abort.