The rarely seen Norden bombsight was crucial to the success of the U.S. Army Air Forces' daylight bombing campaigns during World War II, and a well-protected secret. It was developed by Carl Norden for the U.S. Navy, then the Army Air Corps acquired its first Norden bombsight in 1932. Highly classified, it gave American forces bombing accuracy unmatched by any other nation at the time. The Norden bombsight functioned as part of a whole system when connected to the Sperry C-1 Autopilot. As the bomber approached its target, the bombardier entered data about wind direction, airspeed and altitude into the bombsight's analog computer, which calculated wind drift and provided the correct aim point. An internal gyroscope provided the stability necessary for using the telescopic sight at high altitudes. This integrated system provided unprecedented accuracy. Initial slow production of the Norden bombsight forced the rapidly expanding Army Air Corp to use the less accurate Sperry S-1 bombsight. Eventually, by 1943, enough Norden bombsights had been produced, and production of the S-1 ended. This example seems to be complete, only lacking the mounting tray used in the B-17. Overall excellent condition