by Dr. Marshall Michel
86th Airlift Wing historian
***image1***With the defeat of the Luftwaffe in its Battle of Britain daylight raids, the Germans turned to night bombing to cut losses yet still continue their attacks. As the scale of the night raids increased and the day raids dropped to nothing the RAF, which had mainly ignored night fighting since the German air raids in 1918, was forced into action.
In early1941, the British were countering with night fighters which were nothing more than black painted day fighters, usually Hawker Hurricanes, with dampers over their engine exhausts to keep the flame from destroying the pilot’s night vision. This proved inadequate and they were replaced by radar-equipped night fighters, but aircraft radar was its infancy and had a very long minimum detection range. This meant that while the radar could detect an enemy aircraft, as the night fighter approached the target would disappear off the radar at a range that was too great to allow it to be seen by the unaided eye. To attack, the fighter required some form of illumination.
The RAF reverted to a system it had considered in World War I – aircraft mounted searchlights. The first airborne searchlight conversions were of a twin-engine American-supplied light bomber, the Douglas Havoc, designated A-20 by the USAAF. Called “Turbinelights,” over 40 Havocs were fitted with a 2,700 million candle power Helmore/GEC searchlight in the nose of the aircraft, flanked by airborne radar antennas. The idea was that a single Havoc would lead a formation of two Hurricanes, one on each wing, and the Havoc would find the German aircraft by seeing them in ground searchlights, by vectors from ground radar, or with their own primitive radar. The Havoc would approach and turn on its searchlight, which threw out a sausage-shaped beam about a mile in front of the aircraft, and illuminate the bomber for the Hurricanes to attack. To allow the Hurricanes to stay in formation, the Havoc had fluorescent tape on its sides and on the top of its wings.
The Turbinelight/Hurricane combination was part of ten-night fighter units for ten months, from May 1941 to January 1942, and the many historians claim the idea was unsuccessful, since the combination only shot down one German bomber during this period. However, during the time the Germans made very few bombing raids on England since their bombers were occupied with the invasion of Russia, and it seems that the Turbinelight idea was widely accepted in the RAF as a valid night fighting technology. In 1942, one of the first of the RAF’s newest fighters, the immortal twin-engine De Havilland Mosquito, was modified to accept a Turbinelight, and a late as the fall of 1942 a four- cannon Turbinelight Mosquito was proposed. The modified Turbinelight Mosquito flew trials with the RAF’s 151 Squadron, but the drag from the flat searchlight drastically cut its performance and the arrival of more efficient air-to-air radar ended the Turbinelight’s development.
But the Turbinelight concept did play a very significant part on World War II in an entirety different theater – the Battle of the Atlantic against German U-boats. Radar equipped Coastal Command anti-submarine aircraft could detect German submarines on the surface at night, but the radar was still not precise enough for a blind attack. RAF Humphry de Verde Leigh, working on the Turbinelight principle, developed a forward pointing searchlight mounted on the wing of the aircraft to illuminate the U-boat for an attack. The eponymous “Leigh Light” was extremely effective and even today can be found on coast patrol aircraft.
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