Two types of Leigh Light entered operational use:[6]
i) The Turret type, fitted on Wellington aircraft, was a 24-inch searchlight mounted in a retractable under-turret controlled by hydraulic motor and ram. The maximum beam intensity was 50 million candles without the spreading lens and about 20 million candelas with the lens. Total weight was 1,100 lbs.
ii) The Nacelle type, fitted on Catalinas and Liberators, was a 20-inch searchlight mounted in a nacelle 32 inches in diameter slung from the bomb lugs on the wing. The controls were electric and the maximum beam intensity was 90 million candelas without the spreading lens and about 17 million with the lens. Total weight was 870 lbs.
By June 1942, aircraft equipped with ASV radar and the Leigh Light were operating over the Bay of Biscay intercepting U-boats moving to and from their home ports on the coast of France. The first submarine to be successfully sighted was the Italian submarine Torelli, on the night of 3 June 1942,[7] and the first confirmed kill was the German submarine U-502, sunk on 5 July 1942 by a Vickers Wellington of 172 Squadron, piloted by American, Wiley B. Howell. In the five months prior not one submarine had been sunk, and six aircraft had been lost. The Leigh Light turned the tables, and by August the U-boats preferred to take their chances in daytime when they at least had some warning and could fight back.
Fairey Swordfish biplane torpedo bombers were trialled with a Leigh Light under the lower port wing. A large battery pack for it was slung under the fuselage where the torpedo would normally be carried. The armament was a rack of anti-submarine bombs carried under the other wing. With such a heavy load performance was poor with a top speed marginally above the stall speed.[8]
Wing Commander Peter Cundy was also given the Air Force Cross for his part in the development of the Leigh Light.
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