USA, Consolidated B-32 Dominator
I took my inspiration from Kilomuse's excellent B-32. This was one I wanted to draw just for the challenge, since I haven't drawn a heavy bomber from scratch.
The B-32 was developed in case the B-29 turned out to be a failure, which it wasn't. Instead the B-32 had a longer development time to work out its own problems, particularly with the pressurization system and instability. At one point, a B-29 tail was used until a new tail was designed after the B-24 style twin stabilizer caused handling problems. The pressurization problem was never solved and the equipment removed on production aircraft.
114 were built in Consolidated's Fort Worth Plant during WWII, and only a handful saw actual combat before they were shelved in favor of the B-29. All examples were scrapped, and none survive today. Thankfully there a plenty of good photographs available on the interwebs to show plenty of details.