SHORAN

SHORAN is an acronym for SHOrt RAnge Navigation, a type of electronic navigation and bombing system with a precision radar beacon used in the B-26 and B-29 bomber aircraft during the Korean War.

In 1938 RCA engineer Stuart William Seeley, while attempting to remove "ghost" signals from an experimental television system, realized that he could measure distances by time differences in radio reception. In summer 1940, Seeley proposed building SHORAN for the Army Air Force. Contract was awarded 9 months later, and SHORAN given its first military flight tests in August 1942. First procurement was spring 1944, with initial combat operations in northern Italy on December 11, 1944.

During the system's development, Seeley and an RCA manager flew to England to describe the system to American and British air force personnel. There they observed the Oboe, which could guide only a single aircraft, unlike Shoran which could guide multiple. On the return flight, nearly all information on Shoran was lost in a plane crash, and Seeley was forced to recreate the records from his own memory. He received a Magellanic award for his work in 1960.

SHORAN, which operates at 300 MHz, requires an airborne AN/APN-3 set and two AN/CPN-2 or 2A ground stations. The equipment on board the aircraft includes a transmitter, a receiver, an operator's console and a K-1A model bombing computer. The transmitter sends pulses to one of the ground stations and the system calculates the range in statute miles by clocking the elapsed time between transmitter pulse and the returned signal. The system was intended for use in navigation, but it became obvious that it would work well for blind targeting during bombing runs in poor visibility. The setup made up of the K-1A bombing computer combined with the navigation system was the first SHORAN. The SHORAN system is designed so that as the aircraft faces the target, the low-frequency station should be on the left, and the high-frequency station is on the right. This allows the computer to triangulate the two stations and the target.

The limitations of SHORAN included:

Little new top-of-the-line technology was used in Korea, but SHORAN was an exception. B-26 planes were first equipped with the system in January, 1951, and first carried it into battle the following month.

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