The Boeing B-50 Superfortress strategic bomber, was a post-World War II revision of the Boeing B-29 Superfortress, fitted with more powerful Pratt & Whitney R-4360 radial engines, stronger structure, a taller fin, and other improvements. Design work began with the XB-44 Superfortress and continued when the program was re-named B-50 in 1945. The B-50 served with the United States Air Force Strategic Air Command in a number of roles, from 1947 to 1965, including- Strategic bomber, strategic reconnaissance, weather reconnaissance and in-flight refuelling tanker.
The B-50 program began life as the XB-44 Superfortress. One B-29A-5-BN (s/n 42-93845) was modified by Pratt & Whitney in 1944 to accept the larger engines; the resulting engine testbed first flew in May 1945. If the engine modification had been included in the B-29 program, the resulting model was to have been known as the B-29D. However, due to other structural changes that would also be necessary to address the increased power, weight and fuel consumption, it was decided to change its military designation to a new model. Since the B-44 program was only for the engine modification, that designation was not considered, and in December 1945 the program was named B-50 Superfortress.