Nuclear fission the Manhattan Project during World War II (September 1, 1939 – September 2, 1945) carried out most of the early scientific work on fission chain reactions, culminating in the three events involving fission bombs that occurred during the war. The first fission bomb, codenamed "The Gadget", was detonated during the Trinity Test in the desert of New Mexico on July 16, 1945. Two other fission bombs, codenamed "Little Boy" and "Fat Man", were used in combat against the Japanese cities of Hiroshima and Nagasaki in on August 6 and 9, 1945 respectively. Even the first fission bombs were thousands of
Mark 5 nuclear bomb have been reported. As with many early US nuclear weapon designs, the fissile material or pit could be kept separately from the bomb and assembled into it during flight. This technology is known as In Flight Insertion or IFI. The Mark 5 had an automatic IFI mechanism which could insert the pit into the center of the explosive assembly from a storage position in the bomb nose. The image here shows the doors to that nose compartment open. The Mark 5 was in service from 1952 to 1963. The W5 saw service from 1954 to 1963. Approximately 72 Mark 5