It would appear that the B-19 lost out to the B-36, an even bigger and longer ranged bomber that was based, like Howard Hughes ‘Spruce Goose’ on UK loss to Germany. 230ft wingspan, 6 piston engines (initially) and a 10,000 mile range, it went into service for the USAF / SAC in 1949. The boast / gripe was that it only landed to reenlist the aircrew. The Jimmy Stewart movie “Strategic Air Command” (1955) was almost a documentary about this amazing US Bomber.