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"Fat Man" Atomic Bomb

DAYTON, Ohio -- "Fat Man" atomic bomb at the National Museum of the United States Air Force. (U.S. Air Force photo)

DAYTON, Ohio -- "Fat Man" atomic bomb at the National Museum of the United States Air Force. (U.S. Air Force photo)

A "Fat Man" bomb was dropped over Nagasaki, Japan, on Aug. 9, 1945, near the end of World War II. Released by the B-29 Bockscar, the 10,000-pound weapon was detonated at an altitude of approximately 1,800 feet over the city. The bomb had an explosive force (yield) of about 20,000 tons of TNT, about the same as the bomb dropped on Hiroshima. Because of Nagasaki's hilly terrain, however, the damage was somewhat less extensive than of the relatively flat Hiroshima.

"Fat Man" was an implosion-type weapon using plutonium. A subcritical sphere of plutonium was placed in the center of a hollow sphere of high explosive (HE). Numerous detonators located on the surface of the HE were fired simultaneously to produce a powerful inward pressure on the capsule, squeezing it and increasing its density. This resulted in a supercritical condition and a nuclear explosion. 

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Mask Policy:
In accordance with the updated guidance released by the Center for Disease Control and Prevention (CDC), the Department of Defense (DoD) and Wright-Patterson Air Force Base, the National Museum of the U.S. Air Force will require all visitors to wear face masks indoors effective July 30, 2021 until further notice.

Visitors ages three and up will be required to wear masks while indoors at the museum. This policy applies to all visitors, staff and volunteers regardless of vaccination status. Visitors may wear their own masks or a free paper mask will be provided. Cloth masks will also be available for purchase in the Museum Store.
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Please note Springfield Street, the road that leads to the museum’s entrance, is undergoing construction through the beginning of September. Expect lane reductions and some delays. Please follow the signs and instructions provided by the road crews.

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