The Helmore/ GEC Turbinlite was a 2,700 million

candela The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to ...

(2.7 Gcd)

searchlight A searchlight (or spotlight) is an apparatus that combines an extremely bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a particular direc ...

fitted in the nose of a number of

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...

Douglas Havoc

night fighter A night fighter (also known as all-weather fighter or all-weather interceptor for a period of time after the Second World War) is a fighter aircraft adapted for use at night or in other times of bad visibility. Night fighters began to be used i ...

s during the early part of the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

and around the time of

The Blitz The Blitz was a German bombing campaign against the United Kingdom in 1940 and 1941, during the Second World War. The term was first used by the British press and originated from the term , the German word meaning 'lightning war'. The Germa ...

. 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was not a success and the introduction of higher performance night fighters with their own radar meant they were withdrawn from service in early 1943.

Background

The then state-of-the-art metre-

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...

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 Blenheim The Bristol Blenheim is a British light bomber aircraft designed and built by the Bristol Aeroplane Company (Bristol) which was used extensively in the first two years of the Second World War, with examples still being used as trainers until ...

s lacked the necessary speed advantage over the

German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

Heinkel 111 The Heinkel He 111 is a German airliner and bomber designed by Siegfried and Walter Günter at Heinkel Flugzeugwerke in 1934. Through development, it was described as a " wolf in sheep's clothing". Due to restrictions placed on Germany after t ...

s and

Dornier Do 17 The Dornier Do 17 is a twin-engined light bomber produced by Dornier Flugzeugwerke for the German Luftwaffe during World War II. Designed in the early 1930s as a ''Schnellbomber'' ("fast bomber") intended to be fast enough to outrun opposing a ...

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, as well as AI radar, could light up the attacking bombers after locating them 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 Frederick Sidney Cotton OBE (17 June 1894 – 13 February 1969) was an Australian inventor, photographer and aviation and photography pioneer, responsible for developing and promoting an early colour film process, and largely responsible for ...

pursued the idea of an airborne

for night-fighters, that he termed "aerial target illumination" (ATI). He enlisted the help of

William Helmore Air Commodore William Helmore CBE, PhD, MS., FCS, F.R.Ae.S. (1 March 1894 – 18 December 1964) was an engineer who had a varied and distinguished career in scientific research with the Air Ministry and the Ministry of Aircraft Production duri ...

, 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, transparence or transparent most often refer to: * Transparency (optics), the physical property of allowing the transmission of light through a material They may also refer to: Literal uses * Transparency (photography), a still, ...

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.Flight (1949) p775 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 In physics, a dipole () is an electromagnetic phenomenon which occurs in two ways: *An electric dipole deals with the separation of the positive and negative electric charges found in any electromagnetic system. A simple example of this system i ...

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 A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...

s to find and shoot down.

Service

Douglas Havoc II Turbinlite 1459 Flight RAF c1942

Approximately 31 Havoc I Turbinlites 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. 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 The Bristol Type 156 Beaufighter (often called the Beau) is a British multi-role aircraft developed during the Second World War by the Bristol Aeroplane Company. It was originally conceived as a heavy fighter variant of the Bristol Beaufort ...

and the later

de Havilland Mosquito The de Havilland DH.98 Mosquito is a British twin-engined, shoulder-winged, multirole combat aircraft, introduced during the Second World War. Unusual in that its frame was constructed mostly of wood, it was nicknamed the "Wooden Wonder", or ...

, although one of the latter, the Mosquito II, serial ''W4087'', was itself experimentally fitted with a Turbinlite installation. The tactic of using single-engined fighters unequipped with radar at night was later utilised with some success by Germany against

RAF Bomber Command RAF Bomber Command controlled the Royal Air Force's bomber forces from 1936 to 1968. Along with the United States Army Air Forces, it played the central role in the strategic bombing of Germany in World War II. From 1942 onward, the British bo ...

later in the war, the tactic being known to the ''

Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...

'' as ''

Wilde Sau ''Wilde Sau'' ( Lit. wild sow; generally known in English as "Wild Boar") was the term given by the ''Luftwaffe'' to the tactic used from 1943 to 1944 during World War II by which British night bombers were engaged by single-seat day-fighter airc ...

'' (wild boar). However, the illumination provided by the much larger-scale fires created by the British allowed visual interceptions over the bomber's target by non-radar equipped fighters to be carried out from much longer ranges than had been possible in 1940. This rendered the additional illumination that was intended to guide the fighters towards the bombers, and which was to have been supplied for the British by an aircraft such as the Havoc Turbinlite in 1940, superfluous.

Units

The following units are known to have used the Havoc I Turbinlite and Havoc II Turbinlite operationally: In September 1942 the numbered flights were incorporated with their own fighter aircraft into new squadrons Typically during operations, 1453 Flt operated in conjunction with

No. 151 Squadron RAF (Translation: "Fidelity unto duty" or "Faith for duty" or "Fidelity into duty") , colors= , colors_label= , march= , mascot= , equipment= , equipment_label= , battles= , decorations= , battle_honours= , commander1= , commander1_label= , command ...

and No. 486 Squadron RNZAF, illuminating targets for the fighters to attack, with each flight / squadron of Turbinlite Havocs being associated with fighter squadrons in their vicinity.

Other use

The Turbinlite was later considered in the search for a method of illuminating surfaced enemy

U-boat U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role ...

s at night, but lost out to the competing Leigh light.

Notes

References

*Cotton, Sidney as told to Ralph Barker. 1969. ''Aviator Extraordinary: The Sidney Cotton Story''. Chatto & Windus *Green, William. 1975. ''Famous Bombers of the Second World War, 2nd Edition''. MacDonald &

Jane's Jane's Information Group, now styled Janes, is a global open-source intelligence company specialising in military, national security, aerospace and transport topics, whose name derives from British author Fred T. Jane. History Jane's Informat ...

*Thompson, Scott. 2004. ''Douglas Havoc and Boston: The DB-7/ A-20 Series''. Crowood Press
"Research Enterprise"
''Flight'' via ''flightglobal.com'', 30 June 1949, p. 775

External links

{{Commons category, Turbinlite
B25 MITCHELL OVER CHANNEL (1.17)An illustration of a Havoc I (Turbinlite)A similar illustration of a Havoc II (Turbinlite)A forum with some pictures of Turbinlite Havocs
World War II aircraft of the United Kingdom World War II military equipment of the United Kingdom Searchlights History of the Royal Air Force during World War II 1943 disestablishments in the United Kingdom