Nagasaki Atomic Bomb Museum
The atomic bomb was developed by scientists working under the Manhattan Project. The project was granted funding on December 6, 1941, with American leaders aiming for a new invention that would serve as a wartime weapon. The decision to drop an atomic bomb on Japan had been made by 1943, and a shortlist of candidate target cities was in place in 1945. At the time, it was argued that an atomic bombing would bring about a more rapid end to the war. Hiroshima, the first target, was selected to show the power of America's new weapon. The second bombing, of Nagasaki, was intended to demonstrate that the USA had a large arsenal. At 11:02 A.M. local time on August 9, 1945, the atomic bomb, nicknamed Fat Man as its code name by Robert Serber in the United States (after Sydney Greenstreet's character in "The Maltese Falcon") was dropped on Nagasaki, forever changing the city's landscape. A mushroom cloud rose to an altitude of 45,000 feet above the city.
Contact fuze
Notable examples of air-dropped bombs that did use contact fuzes include the Fat Man atomic bomb dropped on Nagasaki. The bomb was intended for air burst detonation and was fitted with both radar height-finding and barometric fuzes. As the device was so secret, and the risk of informative fragments or plutonium being recovered after a failed drop was considered to be unacceptable, it was fitted with supplementary contact fuzes that were only intended to destroy the weapon beyond recognition. Four AN-219 piezo-electric impact fuzes were fitted to the nose of the bomb casing.