Mark 4 (nuclear weapon)
One of the earliest United States nuclear weapons, the Mark 4 was still first-generation but a production-quality, re-engineered version of the Fat Man (nuclear weapon)|Fat Man bomb that had been used on Nagasaki. An fission device|implosion device, its yield of which could be varied from 1, 3.5, 8, 14, 21, 22, and 31 kt by exchanging the plutonium pits; it also contained uranium. Mark 4 was the first weapon made on an assembly line rather than by hand. 550 were produced.[1]
Relation to later devices
It was among the design ancestors of the first deployed British nuclear weapon, the Blue Danube (nuclear weapon)|Blue Danube bomb. Mark 4 was also the basis of the first systematic engineering testing of United States of America|U.S. bombs since World War II, in the 1951 Operation Ranger a series of air drops over the Nevada (U.S. state)|Nevada desert. The test program explored variations in the Mark 4 core, and then tested the Mark 6 (nuclear weapon),[2] essentially an improved, lighter-weight Mark 4.
Accidents
The Mark 4 was the first bomb involved in an operational accident. On 10 November 1950. a B-50, in mechanical distress, jettisoned its bomb over the St. Lawrence River, approximately 300 miles northeast of Montreal, Quebec. The weapon's HE [high explosive] detonated on impact, scattering nearly 100 pounds (45 kg) of uranium. Its plutonium pit remained aboard the aircraft, which later landed safely. [3]
References
- ↑ Chart of Strategic Nuclear Bombs, StrategicAirCommand.com
- ↑ Operation Ranger: 1951, Nuclear Weapons Archive, 3 January 2005
- ↑ Broken Arrows: Nuclear Weapons Accidents, AtomicArchive