The most advanced aircraft of WWII was the B29 Superfortress. No other bomber could carry the load, nor carry it as far, as the Superfortress! The Russians interred, and reverse engineered three of them in WWII, and those planes became the core of the Russian strategic bomber force for decades after the War. This is the ONLY kind of bomber to ever deliver an atom bomb in wartime; and she did it twice!
Today, there are only two, still flight ready, B29s in the World; Fifi, and Doc, with Doc being a recent addition, salvaged and rebuilt from an aircraft boneyard!
Here is a short film of Fifi in flight:
My Father in Law was a Flight Engineer on the B29 Superforts, and so when Fifi came to town we took him to see her. She was HUGE, and Beautiful; and he got on board because he was a B29 crew member. He brought his flight manual for fun, and they almost wet their pants! Apparently, since the aircraft was so top secret, the flight engineers manual was marked top secret, and when the plane was made obsolete, they destroyed the manual so the Russians would not get a copy! They did so well, that the fliers in Fifi did NOT have one either!
He gave them his manual, and they offered him a flight. When he got on board, they set him in the flight Engineers seat! They were smart enough to film him, while he set up the aircraft for take off, and they asked a LOT of questions. He taught them for half an hour, before they even started the engines! They had been flying by their best guess, and he showed them how to get better fuel economy, and better take off lift ability; while running the engines cooler.
He got one Cadillac of a ride from these grateful people, and had the time of his life! He flew her several times more when they came to town, and did a lot of crew training. He has passed away now, but his flight manual is still on board Fifi to this day. I kind of suspect that a copy of his flight manual, may be on board Doc too, ROFLOL! The crew he trained, has, by now; trained Docs crew too.
He told me in passing, that he didn't get hazard pay, because to get hazard pay, you had to be shot down three times, and he was one shy of that! It was no big deal to him, but I was thinking that being shot down twice, was reasonably serious stuff!