The Norden bombsight

The Norden bombsight was a bombsight used by the United States Army Air Force during World War II, the Korean War, and the Vietnam War. Its existence should have been one of the most closely guarded secrets of World War II, but Nazi agents managed to get hold of its blueprints even before hostilities started and Germany developed a counterpart, the Lofte-7K bombsight.

The Norden sight was originally designed for use on U.S. Navy aircraft by Carl Norden, a Dutch engineer educated in Switzerland who emigrated to the U.S. in 1904 and worked on bombsights at the Sperry Corporation. The Norden was built at the Air Force's Rome Laboratory in New York state. The device used a mechanical analog computer comprised of motors, gyros, mirrors, levels, gears, and a small telescope.

The bombardier would input the necessary information (airspeed, altitude, etc.) and the bombsight would calculate the trajectory of the bomb being dropped. Near the target the aircraft would fly on autopilot to the precise position calculated by the bombsight and release the ordnance. Using this device, bombardiers could, in theory, drop their bombs within a 100-foot circle from an altitude of well over 20,000 feet. The accuracy varied in combat conditions.