Aircraft interception radar, or AI radar for short,[1] is a British term for radar systems used to equip aircraft with the means to find and track other flying aircraft.[2] These radars are used primarily by Royal Air Force (RAF) and Fleet Air Arm night fighters and interceptors for locating and tracking other aircraft, although most AI radars could also be used in a number of secondary roles as well. The term was sometimes used generically for similar radars used in other countries, notably the US.[3] AI radar stands in contrast with ASV radar, whose goal is to detect ships and other sea-suface vessels, rather than aircraft; both AI and ASV are often designed for airborne use.[4]
The term was first used circa 1936, when a group at the Bawdsey Manor research center began considering how to fit a radar system into an aircraft. This work led to the AI Mk. IV radar, the first production air-to-air radar system. Mk. IV entered service in July 1940 and reached widespread availability on the Bristol Beaufighter by early 1941. The Mk. IV helped end the Blitz, the Luftwaffe's night bombing campaign of late 1940 and early 1941.
Starting with the AI Mk. VII, AI moved to microwave frequencies using the cavity magnetron, greatly improving performance while reducing size and weight. This gave the UK an enormous lead over their counterparts in the Luftwaffe, an advantage that was to exist for the remainder of World War II. By the end of the war, over a dozen AI models had been experimented with, and at least five units widely used in service. This included several US-built models, especially for the Fleet Air Arm.
The AI naming convention was used in the post-war era as well, but these generally dropped the "Mk." when written in short form and used numbers instead of Roman numerals. A good example is the AI.24 radar of the Tornado ADV. These radars were often given common names as well, and generally better known by these; the AI.24 is almost universally referred to as "Foxhunter". Other widely used post-war examples include the AI.18 used on the de Havilland Sea Vixen, and the AI.23 Airpass on the English Electric Lightning. This article will use Mk. or AI. depending on which is most commonly used in available references.
- ^ AP1093D: An Introduction Survey of Radar, Part II (PDF). Air Ministry. 1946. p. 6.
- ^ Guerlac, Henry E. (1987). Radar in World War II, Volume 2. Tomash Publishers, American Institute of Physics. p. 1123. ISBN 0-88318-486-9.
AI: Aircraft interception. Radar to detect and trace aircraft from another airplane.
- ^ Joint Chiefs of Staff. "U.S. Radar: Operational Characteristics of Radar Classified by Tactical Application". U.S. Navy. Archived from the original on 26 November 2007.
[Chapter heading:] AI — Aircraft Interception Sets
- ^ Hanbury Brown, R.; Minnett, H.C.; White, F.W.G. (November 1992). "Edward George Bowen: 14 January 1911–12 August 1991". Biographical Memoirs of Fellows of the Royal Society. 38: 47.
The airborne radar group now had two major projects, the detection of ships, (ASV, Air to Surface Vessels) and the interception of aircraft (AI, Aircraft Interception).