The Boeing B-29 SuperFortress is an American four-engine propeller-driven heavy bomber designed by Boeing and flown primarily by the United states during World War 2 and the Korean War.Named in allusion to its predecessor, the B-17 Flying fortress, the Superfortress was designed for high-altitude strategic bombing but also excelled in low-altitude night incendiary bombing and dropping naval mines to blockade Japan.B-29s also dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki, and Also dropped a nuclear bomb, codenamed Able.Able is a nuclear bomb used in the nuclear test codenamed Operation Crossroads, And then the B-29 Superfortress became the only aircraft that has ever used nuclear weapons in combat.