Editing Little Boy (section)

==Bombing of Hiroshima==
{{main|Atomic bombings of Hiroshima and Nagasaki#Bombing of Hiroshima}}
[[File:Enola Gay (plane).jpg|thumb|upright=1.6|right|''Enola Gay'' after Hiroshima mission, entering [[hardstand]]. It is in its 6th Bombardment Group livery, with [[USAAF unit identification aircraft markings|victor number]] 82 visible on fuselage just forward of the tail fin]]
Parsons, the ''Enola Gay''{{'}}s weaponeer, was concerned about the possibility of an accidental detonation if the plane crashed on takeoff, so he decided not to load the four cordite powder bags into the gun breech until the aircraft was in flight. After takeoff, Parsons and his assistant, [[Second Lieutenant]] [[Morris R. Jeppson]], made their way into the bomb bay along the narrow catwalk on the port side. Jeppson held a flashlight while Parsons disconnected the primer wires, removed the breech plug, inserted the powder bags, replaced the breech plug, and reconnected the wires. Before climbing to altitude on approach to the target, Jeppson switched the three safety plugs between the electrical connectors of the internal battery and the firing mechanism from green to red. The bomb was then fully armed. Jeppson monitored the bomb's circuits.{{sfn|Coster-Mullen|2012|pp=34–35}}
[[File: Atomic cloud over Hiroshima - NARA 542192 - Edit.jpg|thumb|upright=1.2|left|The [[mushroom cloud]] over [[Hiroshima]] after the detonation of Little Boy on 6 August 1945. A separation between the upper mushroom head and the stem is visible. This photograph and its vaguely [[question mark]] appearance was used as the inspiration for the [[:File:Manhattan_District.svg|insignia of the Manhattan Engineer District]], and was widely reprinted globally within days of the attack]]

The bomb was dropped at approximately 08:15 (JST) on 6 August 1945. After falling for 44.4 seconds, the time and barometric triggers started the firing mechanism. The detonation happened at an altitude of {{convert|1968|+/-|50|ft}}. It was less powerful than the [[Fat Man]], which was dropped on [[Nagasaki]], but the damage and the number of victims at Hiroshima were much higher, as Hiroshima was on flat terrain, while the [[hypocenter]] of Nagasaki lay in a small valley. According to figures published in 1945, 66,000 people were killed as a direct result of the Hiroshima blast, and 69,000 were injured to varying degrees.<ref>{{cite web|author=The Manhattan Engineer District|date=29 June 1946|title=The Atomic Bombings of Hiroshima and Nagasaki|url=https://www.gutenberg.org/cache/epub/685/pg685.html|via=[[Project Gutenberg]] |page=3}}</ref> Later estimates put the deaths as high as 140,000 people.<ref>{{cite web|last=Wellerstein|first=Alex|authorlink=Alex Wellerstein|date=4 August 2020|title=Counting the Dead at Hiroshima and Nagasaki|url=https://thebulletin.org/2020/08/counting-the-dead-at-hiroshima-and-nagasaki/|work=[[Bulletin of the Atomic Scientists]]}}</ref> The [[United States Strategic Bombing Survey]] estimated that out of 24,158 [[Imperial Japanese Army]] soldiers in Hiroshima at the time of the bombing, 6,789 were killed or missing as a result of the bombing.{{sfn|Craven|Cate|1983|p=723}}

The exact measurement of the explosive yield of the bomb was problematic since the weapon had never been tested. [[President of the United States|President]] [[Harry S. Truman]] officially announced that the yield was {{convert|20|ktonTNT}}. This was based on Parsons's visual assessment that the blast was greater than what he had seen at the [[Trinity nuclear test]]. Since that had been estimated at {{convert|18|ktonTNT}}, speech writers rounded up to 20 kilotons. Further discussion was then suppressed, for fear of lessening the impact of the bomb on the Japanese. Data had been collected by [[Luis Walter Alvarez|Luis Alvarez]], [[Harold Agnew]], and [[Lawrence H. Johnston]] on the instrument plane, ''[[The Great Artiste]]'', but this was not used to calculate the yield at the time.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|p=393}} More rigorous estimates of the bomb yield and conventional bomb equivalent were made when more data was acquired following the end of the war. A 1985 study estimated the bomb's yield was around {{convert|15|ktonTNT}}.{{sfn|Malik|1985|p=1}} {{Further|Little boy#Conventional weapon equivalent}}