By Jenn Jett, Museum Specialist
Content Warning: This article contains graphic images and video that may be upsetting to some readers.
Author’s Note: The contents of this article are the author’s personal views/positions and do not represent the views or positions of the Center of Military History, the Department of the Army, or the United States Government. Links to external websites are provided for context and do not imply endorsement.
After the first plutonium bomb was tested at Trinity Site on 16 July 1945, the next available weapon was the Little Boy, a uranium gun-type atomic bomb. Little Boy was dropped on the Japanese city of Hiroshima on 6 August 1945 by the Enola Gay, piloted by Lieutenant Colonel Paul W. Tibbets. Fat Man was the only other atomic weapon used in history. It was dropped from Bockscar (sometimes spelled Bock’s Car), a modified B-29 Superfortress bomber commanded by Major Charles W. Sweeney, on Nagasaki, Japan, 9 August 1945.
| Name: | Fat Man |
| Type: | Plutonium implosion-type atomic bomb, Mark III |
| Model: | Model Y-1561 |
| Guidance: | None |
| Core: | 13.6 pounds (6.19 kilograms) Plutonium-239 |
| Fusing: | Timing, barometric, radar, impact |
| Yield: | 18-25 kilotons TNT |
| Length: | 10.6 feet (3.2 meters) |
| Diameter: | 5 feet (1.5 meters) |
| Weight: | 10,300 pounds (4,672 kilograms) |
| First test: | 16 July 1945 |
| First use: | 9 August 1945 |
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