The B-29 program was a huge CF. The US government wanted a long range bomber so badly they approved the contract before the prototype had been built, much less flown, and ordered a couple hundred of them. All of the bugs that are normally worked out in development fell to the Army Air Force crews. There were completed bombers parked all over the US that then had to be modified, and teams of mechanics sent out to do the work, often in the wintertime, things like that. The Wright engines were nicknamed “Wrong” engines, because they had a habit of catching on fire. Magnesium engine components would be ignited due to overheating exhaust valves. They spent about $3 billion in 1940 dollars on the entire program.
The crew of Doc mentioned that magnesium problem as one of the differences between 1945 29’s and today. Pretty scary problem, burning magnesium.
My Great Uncle was on Iwo Jima late in the war being one of the guys who worked on 29’s that had to land there. He was 30, so naturally he was called “Grandpa”.