Turbinlite
Encyclopedia
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 fighter
s during the early part of the Second World War
and around the time of The Blitz
.
The Havoc was guided to the 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was not a success and the introduction of higher performance night fighters with their own radar meant they were withdrawn from service in early 1943.
Airborne Interception RDF (radar) 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 Blenheim
s 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. 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.
In September 1940, Sidney Cotton
pursued the idea of an airborne searchlight
for night-fighters, that he termed "Aerial Target Illumination" (ATI). He enlisted the help of William Helmore
, and they jointly took out patents on the techniques (GB574970 and GB575093). Helmore, a serving RAF officer, then sponsored the development of what became known as Turbinlite.
The searchlight was developed 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. Battery power for the 135 kW (1,200 Amp) searchlight was sufficient for about two minutes of operation. The Havoc's own armament was removed from the nose.
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, dipole
s. The modifications were carried out at Burtonwood Aircraft Repair Depot
and the resulting aircraft was known as the Havoc I Turbinlite.
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 Hurricane
s to find and shoot down.
, 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, Serial
W4087, was itself experimentally fitted with a Turbinlite installation.
s at night, but lost out to the competing Leigh light
.
William Helmore
Air Commodore William Helmore Ph.D., M.S., F.C.S., F.R.Ae.S., CBE was an engineer who had a varied and distinguished career in scientific research with the Air Ministry and the Ministry of Aircraft Production during the Second World War, as a broadcaster, and for two years as Member of Parliament...
/GEC
The General Electric Company plc
The General Electric Company or GEC was a major British-based industrial conglomerate, involved in consumer and defence electronics, communications and engineering. The company was once a constituent of the FTSE 100 Index. It was renamed Marconi Corporation plc in 1999 after its defence arm,...
Turbinlite was a 2,700 million candela
Candela
The candela is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function . A common candle emits light with a luminous intensity of roughly one candela...
(2.7 Gcd) searchlight
Searchlight
A searchlight is an apparatus that combines a bright light source with some form of curved reflector or other optics to project a powerful beam of light of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.-Military use:The Royal Navy used...
fitted in the nose of a number of British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
Douglas Havoc night fighter
Night fighter
A night fighter is a fighter aircraft adapted for use at night or in other times of bad visibility...
s during the early part of the Second World War
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
and around the time of The Blitz
The Blitz
The Blitz was the sustained strategic bombing of Britain by Nazi Germany between 7 September 1940 and 10 May 1941, during the Second World War. The city of London was bombed by the Luftwaffe for 76 consecutive nights and many towns and cities across the country followed...
.
The Havoc was guided to the 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.
Background
The then state-of-the-art metre-wavelengthWavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
Airborne Interception RDF (radar) 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 Blenheim
Bristol Blenheim
The Bristol Blenheim was a British light bomber aircraft designed and built by the Bristol Aeroplane Company that was used extensively in the early days of the Second World War. It was adapted as an interim long-range and night fighter, pending the availability of the Beaufighter...
s lacked the necessary performance advantage over the German
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
Heinkel 111s and Dornier Do 17
Dornier Do 17
The Dornier Do 17, sometimes referred to as the Fliegender Bleistift , was a World War II German light bomber produced by Claudius Dornier's company, Dornier Flugzeugwerke...
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. 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.
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.In September 1940, Sidney Cotton
Sidney Cotton
Frederick Sidney Cotton OBE was an Australian inventor, photographer and aviation and photography pioneer, responsible for developing and promoting an early colour film process, and largely responsible for the development of photographic reconnaissance before and during the Second World War...
pursued the idea of an airborne searchlight
Searchlight
A searchlight is an apparatus that combines a bright light source with some form of curved reflector or other optics to project a powerful beam of light of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.-Military use:The Royal Navy used...
for night-fighters, that he termed "Aerial Target Illumination" (ATI). He enlisted the help of William Helmore
William Helmore
Air Commodore William Helmore Ph.D., M.S., F.C.S., F.R.Ae.S., CBE was an engineer who had a varied and distinguished career in scientific research with the Air Ministry and the Ministry of Aircraft Production during the Second World War, as a broadcaster, and for two years as Member of Parliament...
, and they jointly took out patents on the techniques (GB574970 and GB575093). Helmore, a serving RAF officer, then sponsored the development of what became known as Turbinlite.
The searchlight was developed and built by GEC, and was fitted into the nose of the Havoc behind a flat transparent
Transparency and translucency
In the field of optics, transparency is the physical property of allowing light to pass through a material; translucency only allows light to pass through diffusely. The opposite property is opacity...
screen with power for the light coming from heavy lead-acid batteries fitted in the Havoc's bomb bay. Battery power for the 135 kW (1,200 Amp) searchlight was sufficient for about two minutes of operation. The Havoc's own armament was removed from the nose.
The radar fitted was the AI Mk.IV
History of radar
The history of radar starts with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell's seminal work on electromagnetism...
, with broad "arrow head" aerials
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
protruding from the both sides of the aircraft nose with additional side-mounted, and upper- and lower-wing mounted, dipole
Dipole antenna
A dipole antenna is a radio antenna that can be made of a simple wire, with a center-fed driven element. It consists of two metal conductors of rod or wire, oriented parallel and collinear with each other , with a small space between them. The radio frequency voltage is applied to the antenna at...
s. The modifications were carried out at Burtonwood Aircraft Repair Depot
RAF Burtonwood
RAF Burtonwood was a Royal Air Force station in England, 2 miles north-west of Warrington, Lancashire. During World War II and the Cold War it was used by the United States Air Force and was also known as USAAF station 590.- Overview :...
and the resulting aircraft was known as the Havoc I Turbinlite.
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 Hurricane
Hawker Hurricane
The Hawker Hurricane is a British single-seat fighter aircraft that was designed and predominantly built by Hawker Aircraft Ltd for the Royal Air Force...
s to find and shoot down.
Service
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. 530No. 530 Squadron RAF
No. 530 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 530 Squadron was formed at RAF Hunsdon, Hertfordshire on 8 September 1942, from No. 1451 Flight, as part of No. 11 Group RAF in Fighter Command...
, 531
No. 531 Squadron RAF
No. 531 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 531 Squadron was formed at RAF West Malling, Kent on 8 September 1942, from No. 1452 Flight, as part of No. 11 Group RAF in Fighter Command...
, 532
No. 532 Squadron RAF
No. 532 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 532 Squadron RAF was formed on 2 September 1942 from 1453 Flight, based at RAF Wittering. 1453 Turbinlite Flight had previously operated in conjunction with No....
, 533
No. 533 Squadron RAF
No. 533 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 533 Squadron was formed at RAF Charmy Down, Somerset on 8 September 1942, from No. 1454 Flight, as part of No. 10 Group RAF in Fighter Command...
, 534
No. 534 Squadron RAF
No. 534 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 534 Squadron was formed at RAF Tangmere, Sussex on 2 September 1942, from No. 1455 Flight, as part of No. 11 Group RAF in Fighter Command...
, 535
No. 535 Squadron RAF
No. 535 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 535 Squadron was formed at RAF High Ercall, Shropshire on 2 September 1942, from No. 1456 Flight, as part of No. 9 Group RAF in Fighter Command...
, 536
No. 536 Squadron RAF
No. 536 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 536 Squadron was formed at RAF Predannack, Cornwall on 8 September 1942, from No. 1457 Flight, as part of No. 10 Group RAF in Fighter Command...
, 537
No. 537 Squadron RAF
No. 537 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 537 Squadron was formed at RAF Middle Wallop, Hampshire on 8 September 1942, from No. 1458 Flight, as part of No. 10 Group RAF in Fighter Command...
, 538
No. 538 Squadron RAF
No. 538 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 538 Squadron was formed at RAF Hibaldstow, Lincolnshire on 2 September 1942, from No. 1459 Flight, as part of No. 9 Group RAF in Fighter Command...
and 539
No. 539 Squadron RAF
No. 539 Squadron RAF was one of the ten Turbinlite nightfighter squadrons of the Royal Air Force during the Second World War.-History:No. 539 Squadron was formed at RAF Acklington, Northumberland on 2 September 1942, from No. 1460 Flight, as part of No. 13 Group RAF in Fighter Command...
Squadrons during 1942-43. Many of these units had previously operated as specialised Turbinlite "Flights"
Flight (military unit)
A flight is a military unit in an air force, naval air service, or army air corps. It usually comprises three to six aircraft, with their aircrews and ground staff; or, in the case of a non-flying ground flight, no aircraft and a roughly equivalent number of support personnel. In most usages,...
. For example 1453 Turbinlite Flight, which operated in conjunction with No. 151 Squadron RAF
No. 151 Squadron RAF
-World War I:No. 151 squadron was founded at Hainault Farm in Essex on 12 June 1918, and was equipped with Sopwith Camel aircraft.During the five months in which 151 Squadron had taken part in hostilities overseas, the total number of hours flown by night was 1443 hrs 26 mins.Sixteen enemy aircraft...
and No. 486 Squadron RNZAF
No. 486 Squadron RNZAF
486 Squadron was a fighter squadron of the Royal New Zealand Air Force during the Second World War. It was formed under Article XV of the Empire Air Training Scheme and served in Europe under the operational command of the Royal Air Force.Second World War....
.
The concept behind the Turbinlite-equipped Havoc was rendered obsolete with the introduction of centimetric
Super high frequency
Super high frequency refers to radio frequencies in the range of 3 GHz and 30 GHz. This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from ten to one centimetres....
radar along with suitable high-performance night fighters such as the Bristol Beaufighter
Bristol Beaufighter
The Bristol Type 156 Beaufighter, often referred to as simply the Beau, was a British long-range heavy fighter modification of the Bristol Aeroplane Company's earlier Beaufort torpedo bomber design...
and the later de Havilland Mosquito
De Havilland Mosquito
The de Havilland DH.98 Mosquito was a British multi-role combat aircraft that served during the Second World War and the postwar era. It was known affectionately as the "Mossie" to its crews and was also nicknamed "The Wooden Wonder"...
, although one of the latter, the Mosquito II, Serial
United Kingdom military aircraft serials
In the United Kingdom to identify individual aircraft, all military aircraft are allocated and display a unique serial number. A unified serial number system, maintained by the Air Ministry , and its successor the Ministry of Defence , is used for aircraft operated by the Royal Air Force , Fleet...
W4087, was itself experimentally fitted with a Turbinlite installation.
Other use
The Turbinlite was later considered in the search for a method of illuminating surfaced enemy U-boatU-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...
s at night, but lost out to the competing Leigh light
Leigh light
The Leigh Light was a British World War II era anti-submarine device used in the Second Battle of the Atlantic.It was a powerful carbon arc searchlight of 24 inches diameter fitted to a number of the British Royal Air Force's Coastal Command patrol bombers to help them spot surfaced...
.
