Boeing B-50 Superfortress

The Boeing B-50 Superfortress is a retired American strategic bomber. A post–World War II revision of the Boeing B-29 Superfortress, it was fitted with more powerful Pratt & Whitney R-4360 radial engines, stronger structure, a taller tail fin, and other improvements. It was the last piston-engined bomber built by Boeing for the United States Air Force, and was refined into Boeing's final such design, the prototype B-54. Although not as well known as its direct predecessor, the B-50 was in USAF service for nearly 20 years.

After their primary service with Strategic Air Command (SAC) ended, B-50s were modified to serve as KB-50 aerial tankers for Tactical Air Command (TAC) and WB-50 weather reconnaissance aircraft for the Air Weather Service. These tanker and hurricane-hunter variants were retired in March 1965 after metal fatigue and corrosion were found in the wreckage of a KB-50J, 48-065, that crashed on 14 October 1964.

Design and development

thumb|The sole XB-44 Superfortress was a [[Boeing B-29 Superfortress|B-29 Superfortress converted to test the possibility of using the R-4360 radial engine.]]

Development of an improved B-29 started in 1944, with the desire to replace the unreliable Wright R-3350 Duplex-Cyclone engines with the more powerful four-row, 28-cylinder Pratt & Whitney R-4360 Wasp Major radial engines, America's largest-ever displacement aircraft piston engine in large-scale production. A B-29A-5-BN (serial number 42-93845) was modified by Pratt & Whitney as a testbed for the installation of the R-4360 in the B-29, with four R-4360-33s replacing the R-3350s. The modified aircraft, designated XB-44 Superfortress, first flew in May 1945.

The planned Wasp-Major powered bomber, the B-29D, was to incorporate considerable changes in addition to the engine installation tested in the XB-44. The use of a new alloy of aluminum, 75-S rather than the existing 24ST, gave a wing that was both stronger and lighter, while the undercarriage was strengthened to allow the aircraft to operate at weights of up to greater than the B-29. A larger vertical fin and rudder (which could fold to allow the aircraft to fit into existing hangars) and enlarged flaps were provided to deal with the increased engine power and weight, respectively.