Preparing Little Boy Bomb

In essence, the Little Boy design consisted of a gun that fired one mass of uranium 235 at another mass of uranium 235, thus creating a supercritical mass. A crucial requirement was that the pieces be brought together in a time shorter than the time between spontaneous fissions. Once the two pieces of uranium are brought together, the initiator introduces a burst of neutrons and the chain reaction begins, continuing until the energy released becomes so great that the bomb simply blows itself apart.

This is a replica of the bomb that was dropped over Hiroshima, Japan on August 6, 1945.

Little Boy Specifications

Length:	120.0 inches (10 feet / 3.0 meters)
Diameter:	28.0 inches (71.1 cm)
Weight:	9,700 lbs (4,400 kg)
Yield:	15 kiltons (+/- 20%)