Operation Crossroads
There were only seven nuclear bombs in existence in July 1946. The two bombs used in the test were Fat Man plutonium implosion-type nuclear weapons of the kind dropped on Nagasaki. The "Able" bomb was stenciled with the name "Gilda" and decorated with an "Esquire" magazine photograph of Rita Hayworth, star of the 1946 movie, "Gilda". The "Baker" bomb was "Helen of Bikini." This femme-fatale theme for nuclear weapons, combining seduction and destruction, is epitomized by the use in all languages, starting in 1946, of "bikini" as the name for a woman's two-piece bathing suit.
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.