Editing Fat Man (section)

{{Short description|U.S. atomic bomb type used at Nagasaki, 1945}}
{{about|the World War II nuclear weapon}}
{{pp|small=yes}}
{{good article}}
{{Use dmy dates|date=July 2024}}{{Use American English|date=July 2018}}
{{Infobox weapon
| name               = Fat Man
| image              = [[File:Fat Man (replica of nuclear bomb).jpg|300px]]
| caption            = Replica of the original Fat Man bomb
| type               = [[Nuclear weapon|Nuclear]] [[nuclear fission|fission]] [[gravity bomb]]
<!--Type selection-->| designer           = [[Los Alamos Laboratory]]
| number             = 120
<!--General specifications-->
<!--Note on units: Wikipedia policy is to use as the primary values the original units system and provide conversions from that to the other unit system. Changing the natively English units' values to metric as the base unit violates Wikipedia policy, as does removing them entirely.-->| length             = {{convert|128|in|m|1}}
| width              = 
| height             = 
| diameter           = {{convert|60|in|m}}
<!--Explosive specifications-->| origin             = United States
| is_explosive       = yes
<!--Production history-->| design_date        = 
| manufacturer       = 
| unit_cost          = 
| production_date    = 1945–1949
| weight             = {{convert|10300|lb|-1}}
| part_length        = 
| filling            = [[Plutonium]]
| filling_weight     = 6.2&nbsp;kg{{sfn|Coster-Mullen|2012|p=57}}
| detonation         = 
| yield              = {{cvt|21|kt(TNT)|TJ|lk=in}}
}}

"'''Fat Man'''" (also known as '''Mark III''') was the design of the [[nuclear weapon]] the United States used for seven of the first eight nuclear weapons ever detonated in history. It is also the most powerful design to ever be used in warfare.

A Fat Man device was [[Atomic bombings of Hiroshima and Nagasaki#Bombing of Nagasaki|detonated over the Japanese city of Nagasaki]] on 9 August 1945. It was the second and largest of the only two nuclear weapons ever used in warfare.  It was dropped from the [[Boeing B-29 Superfortress]] ''[[Bockscar]]'' piloted by Major [[Charles Sweeney]]. Its detonation marked the third nuclear explosion in history. The name Fat Man refers to the wide, round shape. Fat Man was an [[implosion-type nuclear weapon]] with a solid plutonium [[Nuclear reactor core|core]], and later with improved cores.

The first Fat Man to be detonated was the gadget in the [[Trinity (nuclear test)|Trinity nuclear test]] less than a month earlier on 16 July at the [[Holloman Air Force Base|Alamogordo Bombing and Gunnery Range]] in [[New Mexico]].  It was built by scientists and engineers at [[Los Alamos Laboratory]] using [[plutonium]] manufactured at the [[Hanford Site]]. The second nuclear explosion, and the first used in warfare, was [[Little Boy]], a different device based on [[uranium]]. Two more Fat Mans were detonated during the [[Operation Crossroads]] nuclear tests at [[Bikini Atoll]] in 1946. The three tests in the next series, [[Operation Sandstone]] in 1948, used Fat Man devices with improved cores.  Fat Man was finally superseded by the [[Mark 4 nuclear bomb]] in the [[Operation Ranger]] tests.