The Norden bombsight was a tachometric bombsightused by the United States Army Air Forces (USAAF) and the United States Navyduring World War II, and theUnited States Air Force in the Korean and the Vietnam Wars to aid the crew ofbomber aircraft in droppingbombs accurately. Key to the operation of the Norden were two features; an analog computer that constantly 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, these features allowed for unprecedented accuracy in day bombing from high altitudes; in testing the Norden demonstrated a circular error probable (CEP) of 23 metres (75 ft),[clarification needed] an astonishing performance for the era. This accuracy allowed direct attacks on ships, factories, and other point targets. Both the Navy and the AAF saw this as a means to achieve war aims through high-altitude bombing, without resorting to area bombing, as proposed by European forces. To achieve these aims, the Norden was granted the utmost secrecy well into the war, and was part of a then-unprecedented production effort on the same scale as the Manhattan Project. Carl L. Norden, Inc. ranked 46th among United States corporations in the value of World War II military production contracts.
In practice it was not possible to achieve this level of accuracy in combat conditions, with the average CEP in 1943 being 370 metres (1,200 ft). Both the Navy and Air Forces had to give up on the idea of pinpoint attacks during the war. The Navy turned to dive bombingand skip bombing to attack ships, while the Air Forces developed the lead bomber concept to improve accuracy. Nevertheless, the Norden’s reputation as a pin-point device lived on, due in no small part to Norden’s own advertising of the device after secrecy was reduced during the war.
The Norden saw some use in the post-World War II era, especially during the Korean War. Post-war uses were greatly reduced due to the introduction of radar-based systems, but the need for accurate daytime attacks kept it in service for some time. The last combat use of the Norden was in the US Navy’s VO-67 squadron, which used them to drop sensors onto the Ho Chi Minh Trail as late as 1967. The Norden remains one of the best known bombsights of all time.