The Boeing B-50 Superfortress was a post-World War II revision of the wartime United States B-29 Superfortress with larger Pratt & Whitney R-4360 radial engines, a taller vertical stabilizer, and other improvements. 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.
Boeing built 371 of the various B-50 models and variants between 1947 and 1953, some serving until 1965. The B-50 was the last member of the B-29 family and was one of the last piston-engined bombers built. The B-50 was retired from its main role as atomic bomber in 1955. A number were converted into KB-50 tankers and lasted long enough to be deployed to Southeast Asia in support of tactical operations. A reconnaissance variant, the RB-50B (a B-50B conversion) existed and played an important role in Cold War espionage.
In 1949, The Lucky Lady II, commanded by Captain James Gallagher, became the first airplane to circle the world nonstop. This was achieved by refueling the plane in flight.