Turbinlite

The Helmore/GEC Turbinlite was a 2,700 million candela (2.7 Gcd) searchlight fitted in the nose of a number of experimental radar equipped Douglas Havoc night fighters by the British during the early part of World War II and around the time of The Blitz. The light was intended to be used to illuminate attacking enemy bombers for defending fighters accompanying the Havoc to then shoot down.

Concept

At the time, the then state-of-the-art metre-wavelength AI RDF (radar) equipment was bulky and due to the operator workload required unsuited to carriage by single-engined fighters, so it required a twin-engine design. However, the early radar-equipped Bristol Blenheims lacked the necessary performance advantage over the German Heinkel 111s and Dornier Do 17 bombers then raiding the UK to be truly effective. In addition, there was some doubt as to the best way to find, intercept and shoot down attacking bombers at night, and the idea was put forward for an aircraft that carried its own onboard searchlight that could light up the attacking bombers so that non-RDF equipped single-engined fighters could then see them to shoot down, the single-engine fighters having a considerable performance advantage over the German twin-engine bombers.

Development

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. The searchlight was based on the work of Air Commodore William Helmore and built by GEC, and was fitted into the nose of the Havoc behind a flat transparent screen with power for the light coming from heavy lead-acid batteries fitted in the Havoc's bomb bay. The radar fitted was the AI Mk.IV, with broad "arrow head" aerials protruding from the both sides of the aircraft nose with additional side-mounted, and upper- and lower-wing mounted, dipoles. The modifications were carried out at Burtonwood Aircraft Repair Depot and the resulting aircraft was known as the Havoc I Turbinlite. The aircraft itself carried no guns.

The unarmed Havoc Turbinlite was intended to find the enemy bomber using its RDF equipment and then use the Turbinlite to illuminate the target for the accompanying Hurricanes to find and shoot down. The Havoc Turbinlite was itself unarmed because the searchlight took up all the space in the nose and was powered by heavy batteries which occupied the only other space available for installing armament, i.e., the Havoc's bomb bay.

ervice

Approximately 31 Havoc I Turbinlite were so modified, using the Havoc I or Havoc L.A.M. (Long Aerial Mine), which had themselves originally been Boston II's, before the advent of the Havoc II Turbinlite, of which a further 39 were built, this time as conversions from the Havoc II. Turbinlite-Havocs served with No. 530, 531, 532, 533, 534, 535, 536, 537, 538 and 539 Squadrons during 1942-43. Many of these units had previously operated as specialised Turbinlite 'Flights'. For example 1453 Turbinlite Flight, which operated in conjunction with No. 151 Squadron RAF and No. 486 Squadron RNZAF.

The concept behind the Turbinlite-equipped Havoc was rendered obsolete with the introduction of centimetric radar along with suitable high-performance night fighters such as the Bristol Beaufighter and the later de Havilland Mosquito, although one of the latter, the Mosquito II, "W4087", was itself experimentally fitted with a Turbinlite installation.

The tactic of using single-engined non-radar-equipped fighters at night was later utilised with some success by Germany against RAF Bomber Command later in the war, the tactic being known to the Luftwaffe as "Wilde Sau" (Wild Boar), however the illumination provided by the much larger-scale fires created by the British allowed visual attacks to be carried out from much longer ranges than had been possible in 1940, rendering the additional illumination that was to have been supplied by an aircraft such as the Havoc Turbinlite superfluous.

Other use

The Turbinlite was later considered in the search for a method of illuminating surfaced enemy U-boats at night, but lost out to the competing Leigh light.

References

* Green, William. "Famous Bombers of the Second World War, 2nd Edition". London: MacDonald & Jane's,1975. ISBN 0-356-08333-0.
* [http://www.ateaseweb.com/mb/index.php?showtopic=234992711 B25 MITCHELL OVER CHANNEL (1.17)]

ee also

* Douglas DB-7
* Leigh light
*List of aircraft of the RAF

External links

* [http://www.rafweb.org/Markings/530Sqn1.jpgAn illustration of a Havoc I (Turbinlite)]
* [http://www.rafweb.org/Markings/538Sqn1.jpgA similar illustration of a Havoc II (Turbinlite)]
* [http://eddurham.tripod.com/sitebuildercontent/sitebuilderpictures/boston560.jpgA photograph of a Havoc (Turbinlite)]
* [http://www.pprune.org/forums/showthread.php?p=3078407 A forum with some pictures of Turbinlite Havocs]
* [http://www.airwarfareforum.com/viewtopic.php?p=35422&sid=9fac358aa1d9b6db247e12bc0b8259b6 Another forum with pictures of Turbinlite Havocs]