Turbinlite

In 1940-41 Britain’s night defences were in a poor state with few suitable aircraft able to successfully operate at night, although Blenheim night fighters were gradually being replaced by the more powerful Beaufighters, albeit in small numbers. Airborne Interception (AI) radar was still in its infancy, so unarmed Douglas Havoc bombers were modified and fitted with a 2,700 million candle-power searchlight, developed and built by GEC, in the nose behind a flat transparent screen with power for the light coming from lead-acid batteries in the bomb bay. The aircraft was guided to enemy aircraft by a mix of ground control and its own on-board AI Mk.IV radar. As the Havoc’s own armament had been removed, the aircraft was accompanied by a pair of Hurricanes, which, when the target was illuminated, would then attack the enemy bomber and shoot it down.

These composite Turbinlite squadrons, which had been created out of desperation rather than with any real hope of success, achieved little, and, with the rapid development of AI radar and the introduction of the Mosquito night fighter, this wasteful and fruitless experiment was finally abandoned in late 1942.

Air Marshal Sholto Douglas, who had become C-in-C of Fighter Command, promoted the use of twin-engined American-made Douglas Havoc aircraft against the German night bombers:

A more promising idea upon which there was spent a great deal of money and time and effort was an extension of the use of airborne radar. Known as Turbinlite it called for the combined use of radar and an airborne searchlight … The object aimed at with Turbinlite was to place the two aircraft behind the enemy raider. The Havoc would detect it with its radar and illuminate it with its searchlight in such a way that the Hurricane could then close in for the kill.

Getting a 2,700-million candlepower searchlight to function inside a plane was difficult. Flying a Hurricane in formation with a Douglas Havoc weighted in this way, and doing it in darkness, was virtually impossible. What a pity that before Sholto Douglas ‘spent a great deal of money and time and effort’ on this idea it didn’t occur to him that if the Havoc pilot had the enemy on his radar, and in front of him, he didn’t need a friend in a nearby Hurricane. He could blow the raider out of the sky with a gun.

Night-fighter strength was increased with the decision to form specialist Flights to operate modified AI-equipped Havocs, the modification being the addition of a high-power searchlight (The Helmore searchlight). Each of these Fighter Flights was to have an establishment of 8 + 1 Turbinlite Havocs in what on paper looked like the brilliantly simple idea of taking a searchlight into the air to help turn night into day. In essence the system was simple, a Turbinlite Havoc would work as a pair with a single-seat fighter and both would initially be vectored to the target by a ground controller. Once the Havoc AI operator had acquired the target he would home it, position the fighter and when the time was right, turn on the searchlight to allow the fighter to make his attack.

No. 93 Squadron carried out initial development work, having virtually given-up its previous work with the LAM, but it was the formation of No. 1451 (Fighter) Flight at Hunsdon in May 1941 that really got the project underway. The Flight was tasked with training four other Turbinlite Flights and it was one of these, No. 1452 Flight that developed the standard tactic. On 6 November the CO, Sqn Ldr J E Marshall, submitted a progress report in which he detailed this tactic: ‘In this attack, the parasite, when given the word, dives forward so as to lose about 500 ft. The AI operator keeps the Turbinlite pilot directed on to the target, and gives the pilot the word to illuminate when he can see by his tubes that the parasite is approximately 300 yards behind the target. The parasite then sees the target illuminated slightly above him and is able to make a well-timed and effective attack.’ A follow-up report stated: ‘success in the scheme depends among other things on each member of the crew taking the correct action at the appropriate moment. As orders are passed from one to another, and as the conditions of the intercept will seldom be identical on two nights, it is clear that a complete understanding must exist between each member of the team.

The satellite pilot should always work with the same Turbinlite pilot . . . it is particularly easy in the first few seconds to miss an illuminated target.’ The original concept was for the Flight to work with single-seat squadrons, although Marshall was convinced that the fighter needed to be part of the Turbinlite unit. All ten Flights had formed by the end of the year and all were engaged with intensive training to try and make the system work; it was 1942 before they were truly part of the night-defence Order of Battle.

Havocs were the main carrier of the Turbinlite, though this was also fitted to individual aircraft of other types. It was a 2,700-million candlepower searchlight, fitted in the nose, drawing current from a large generator set in the fuselage. Its name was originally the Helmore light, after its chief proposer, Wing Commander (later Air Commodore) W. Helmore, pilot, engineer and wartime broadcaster. The idea was that the Havoc should take off, in pitch darkness, in close formation with two Hurricanes, which could see special rear-facing lights on the Havoc. The formation would be vectored on to the enemy by GCI, until the Havoc could use its AI Mk IV, which had a transmitter aerial on each side of its flat glass nose. Eventually the formation might be lucky enough to come within 1,000 feet of the target, directly astern of it. Then, instead of shooting down the enemy, the Havoc would switch on its searchlight – which might or might not score a bull. At this, the Hurricanes had to overtake the Havoc and shoot the enemy down. What happened in practice was that the target instantly jinked out of the bright beam faster than the Havoc could follow, usually by turning one way and then, when the Havoc had set up the ‘wrong’ bank, by reversing the turn. The Hurricanes got in each other’s way, and in the Havoc’s way; or they obstructed the beam, or (on several occasions) got the Havoc in their sights instead. What almost always happened was that the target got away, while a Havoc and two rather helpless Hurricanes floundered about completely lost, and with their pilots’ night-adapted vision destroyed. Only once, in 1942, was the system credited with a kill; unfortunately the victim belonged to the RAF.

The Turbinlite Flights were all operational by early 1942, which in theory boosted the night defence capability, and indeed all were upgraded to squadron status – as 530 to 539 squadrons – in September 1942. However, their operational record was poor, with plenty of flying accidents but very few successes and in January 1943 they were all disbanded. Fighter Command flew over 16,000 night sorties in 1942, including intruder operations, and claims were made for the destruction of 182 enemy aircraft (43 of those by intruder ops), with a further 43 ‘Probables’ and 137 ‘Damaged’. The Command lost 40 aircraft destroyed in night ops over the UK. The Fighter Command Diary summarised the night operations for 1942: ‘the year was largely one of consolidation and unremitting patrol work. If there were no spectacular achievements, Fighter Command’s success must be measured not by the number of aircraft shot down but by the relatively few occasions on which British towns and industries were troubled by night air attack.’

Turbinlite Flights

Flight no. Formed Airfield

1451 Flt 22 May 1941 Hunsdon

1452 Flt 7 Jul 1941 West Mailing

1453 Flt 10 Jul 1941 Wittering

1454 Flt 27 Jun 1941 Colerne

1455 Flt 7 Jul 1941 Tangmere

1456 Flt 24 Nov 1941 Honiley

1456 Flt 15 Sep 1941 Colerne

1458 Flt 6 Dec 1941 Middle Wallop

1459 Flt 20 Sep 1941 Hunsdon

1460 Flt 15 Dec 1941 Acklington

 

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