Named in allusion to its predecessor, the Boeing B Flying Fortress , the Superfortress was designed for high-altitude strategic bombing , but also excelled in low-altitude night incendiary bombing , and in dropping naval mines to blockade Japan. Bs dropped the atomic bombs on Hiroshima and Nagasaki , the only aircraft ever to drop nuclear weapons in combat. One of the largest aircraft of World War II, the B was designed with state-of-the-art technology, which included a pressurized cabin , dual-wheeled tricycle landing gear , and an analog computer -controlled fire-control system that allowed one gunner and a fire-control officer to direct four remote machine gun turrets.
The B remained in service in various roles throughout the s, being retired in the early s after 3, had been built. A few were also used as flying television transmitters by the Stratovision company.
The Royal Air Force flew the B with the service name Washington from to when the jet-powered Canberra entered service. The B was the progenitor of a series of Boeing-built bombers, transports, tankers, reconnaissance aircraft, and trainers. For example, the re-engined B Superfortress Lucky Lady II became the first aircraft to fly around the world non-stop, during a hour flight in The Boeing C Stratofreighter airlifter, which was first flown in , was followed in by its commercial airliner variant, the Boeing Model Stratocruiser.
Twenty-two Bs have survived to preservation; while the majority are on static display at museums, 2 airframes, FIFI and Doc , still fly. Boeing began work on long-range bombers in Boeing's design study for the Model was a pressurized derivative of the Boeing B Flying Fortress with nosewheel undercarriage. Although the Air Corps lacked funds to pursue the design, Boeing continued development with its own funds as a private venture. Boeing's previous private venture studies formed the starting point for its response to the Air Corps formal specification.
On 29 January , the United States Army Air Corps issued a request to five major aircraft manufacturers to submit designs for a four-engine bomber with a range of 2, miles 3, km. Douglas and Lockheed soon abandoned work on their projects, but Boeing received an order for two flying prototypes , which were given the designation XB, and an airframe for static testing on 24 August , with the order being revised to add a third flying aircraft on 14 December.
