Very interesting. We need a TL with the model 341 going past the mockup stage. Perhaps at the expense of P-47s, since those R-2800s must come from somewhere... Is there any pictures of the mockup ?
It never went beyond the project design phase since it was overtaken by events. The slightly earlier Boeing Project 334A was advanced to mock-up internally by Boeing but I am unaware of any images being available.
The problem with R-2800 designs appears to be that they can't do the job, hence the universal decision to go to the R-3350 as the VLR engine choice.
There is a reason that the B-29 is accepted as the ultimate piston engine bomber. If one starts to remove the basic elements of the design, starting with less efficient engines, elimination of full pressurization, proper streamlining, and any of the many other innovations that litter the B-29's design the result is a faster debut of the B-29. It is the introduction of an improved B-17. While that is not in itself a bad thing, it is also not the breakthrough that the B-29 represents, it is a better 1930s bomber.
Pressurization was a critical element of the B-29 design. Pressurization allows longer flights at altitude with far less loss of crew effectiveness. It isn't a matter of comfort, it is a matter of the limitations of the human body. People routinely die at over 8,000 meters, just from being there; climbers call 8,000 meters and up the "death zone" (the human body can often adapt to the conditions, given time, but the crews of WW II bombers didn't have that time). Pressurization is what allows 12 hour flights at 30,000 feet.
The B-29 was pretty much a production miracle. The B-32 was never seen as close to the capability of the B-29, yet it was, by most measures the second most advanced bomber of the war. The Air Corps actually cancelled the program in 1943 as the aircraft was seen as obsolescent, before restarting it a month later
The United States spent vast amounts of money on the B-29. Prior to the war they had been working on the B-36 would it not have been a better idea to work on the B-36 it would not just be used in Europe for dropping a nuke but you have a big Pacific ocean that were flying planes back and forth does anyone know why that Avenue is not followed?
B-36 was not ready for prime time. Its teething problems make the issues of the B-29 and B-32 combined look like a bad paint job.
The Air Force never did figure out a way to properly cool the engines, resulting in regular engine fires (this wasn't helped by the remarkable tendency to foul plugs, both with oil and with lead, the lead a result of the, wait for it...
143 octane fuel required by the engine). The engines were such oil hogs that the bomber had a separate 100 GALLON tank for engine oil that was filled to the brim before each flight.
Had the Air Corps waited for the B-36 to be ready enter service rather than driving on with the B-29, the Home Islands would have been invaded (and the supply situation on the Home Islands would have been much better, one of the often overlooked parts of the strangulation of the Home Islands was the massive mining campaign conducted by the B-29 force).