Turbinlite

The Helmore/GEC Turbinlite was a 2,700 million candela (2.7 Gcd) searchlight fitted in the nose of a number of British Douglas Havoc night fighters during the early part of the Second World War and around the time of The Blitz. The Havoc was guided to enemy aircraft by ground radar and its own radar. The searchlight would then be used to illuminate attacking enemy bombers for defending fighters accompanying the Havoc to shoot down. In practice the Turbinlite was not a success and the introduction of higher performance night fighters with their own radar meant they were withdrawn from service in early 1943.

The then state-of-the-art metre-wavelength airborne interception radar, known in British parlance of the time as RDF (Radio Direction Finding) equipment, was bulky and, due to the operator workload, generally unsuited to carriage by single-engined fighters, and so required a twin-engine design. However, the early radar-equipped Bristol Blenheims lacked the necessary speed advantage over the German Heinkel 111s and Dornier Do 17 bombers then raiding the UK to be truly effective, the Blenheim being able to find the bomber, but often not being fast enough to be able to reach a position in which to shoot it down. Non-RDF equipped single-engined fighters, whilst being fast enough to catch the bombers, simply could not find the bombers to shoot them down. In addition, there was some doubt as to the best way to find, intercept and shoot down attacking bombers at night. The idea put forward that an aircraft that carried a searchlight could light up the attacking bombers for non-RDF equipped fighters to shoot them down, the single-engine fighters having a considerable performance advantage over the German twin-engine bombers.

At around this time the new Douglas Havoc then entering limited service as an "intruder" offered an alternative to the Blenheim, also having a considerable performance advantage, and it was decided to conduct experiments with these.

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