Boeing B-29 Superfortress 'Bockscar'- Interior Views at the National Museum of the USAF

The B-29 on display, Bockscar, dropped the Fat Man atomic bomb on Nagasaki on Aug. 9, 1945, three days after the atomic attack against Hiroshima. Bockscar was one of 15 specially modified "Silverplate" B-29s assigned to the 509th Composite Group. Most B-29s carried eight .50-cal. machine guns in remote controlled turrets, two .50-cal. machine guns and one 20mm cannon in a tail turret, and up to 20,000 pounds of bombs. Silverplate B-29s, however, retained only the tail turret and had their armor removed to save weight so that the heavy atomic bombs of the time could be carried over a longer distance.
Designed in 1940 as an eventual replacement for the B-17 and B-24, the first B-29 made its maiden flight on Sept. 21, 1942. In December 1943 U.S. Army Air Forces leadership committed the Superfortress to Asia, where its great range made it particularly suited for the long over-water flights against the Japanese homeland from bases in China. During the last two months of 1944, B-29s began operating against Japan from the islands of Saipan, Guam and Tinian. With the advent of the conflict in Korea in June 1950, the B-29 returned to combat. Although vulnerable to MiG-15 jet fighter attacks, the Superfortress remained effective against several types of targets throughout the Korean War.
Bockscar was flown to the museum on Sept. 26, 1961.
A "Fat Man" bomb was dropped over Nagasaki, Japan, on Aug. 9, 1945, near the end of World War II. Released by the B-29 Bockscar, the 10,000-pound weapon was detonated at an altitude of approximately 1,800 feet over the city. The bomb had an explosive force (yield) of about 20,000 tons of TNT, about the same as the bomb dropped on Hiroshima. Because of Nagasaki's hilly terrain, however, the damage was somewhat less extensive than of the relatively flat Hiroshima.
"Fat Man" was an implosion-type weapon using plutonium. A subcritical sphere of plutonium was placed in the center of a hollow sphere of high explosive (HE). Numerous detonators located on the surface of the HE were fired simultaneously to produce a powerful inward pressure on the capsule, squeezing it and increasing its density. This resulted in a supercritical condition and a nuclear explosion.