Norden Bombsight

The Norden bombsight was a tachometric bombsight used by the United States Army Air Forces (USAAF) and the United States Navy during World War II, and the United States Air Force in the Korean and the Vietnam Wars to aid the crew of bomber aircraft in dropping bombs accurately. It was known as the "Blue Ox". Key to the operation of the Norden were two features; a mechanical computer that calculated the bomb's trajectory based on current flight conditions, and a linkage to the bomber's autopilot that let it react quickly and accurately to changes in the wind or other effects. Together, they allowed for unprecedented accuracy in day bombing from high altitudes; in testing the Norden demonstrated a circular error probable (CEP) of 75 feet (23 m), an astonishing performance for the era.