Boeing B-29 Superfortress at the National Museum of the U.S. Air Force

DAYTON - APRIL 5: In this handout footage provided by U.S. Department of Defense, 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. (Footage by U.S. Department of Defense/Milmotion via Getty Images)