de Havilland DH 108
The de Havilland DH 108 was a experimental jet aircraft designed in October 1945.
The DH 108 featured a tailless, swept wing with a single vertical stabilizer, similar to the layout of the wartime German Messerschmitt Me 163 Komet rocket-powered point-defence interceptor. Initially designed to evaluate swept wing handling characteristics at low and high subsonic speeds for the proposed early tailless design of the Comet airliner. With the adoption of a conventional tail for the Comet, the aircraft were used instead to investigate swept wing handling up to supersonic speeds.
Using the main fuselage section and engine of the de Havilland Vampire mated to a longer fuselage with a single tailfin and swept wings, the de Havilland DH 108 was proposed in 1944 as a test for the DH 106 Comet which had initially been considered a tailless, swept-wing concept. Despite the Comet design taking on more conventional features, the value of testing the unique configuration to provide basic data for the DH.110 encouraged de Havilland to continue development of the DH 108. Selecting two airframes from the English Electric Vampire F 1 production line, the new aircraft had unmistakable similarities to its fighter origins, especially in the original forward fuselage which retained the nose, cockpit and other components of the Vampire.
The new metal wing incorporating a 43˚ sweepback was approximately 15% greater in area than the standard Vampire wing.The first DH 108 prototype, TG283, using the Vampire fuselage and a 43° swept wing, flew on 15 May 1946. Designed to investigate low-speed handling, it was capable of only 280 mph. The second, high-speed prototype, TG306, with a 45° swept wing powered by a de Havilland Goblin 3 turbojet, flew soon after in June 1946. Modifications included a more streamlined, longer nose and a smaller canopy.While being used to evaluate handling characteristics at high speed, on 27 September 1946 TG306 suffered a catastrophic structural failure in a dive from 10,000 ft at Mach 0.9 and crashed in the Thames Estuary.
Pilot, Geoffrey de Havilland Jr., was killed in the accident. Early wind tunnel testing had pointed to potentially dangerous flight behaviour, but pitch oscillation at high speed had been unexpected. The accident investigation centred on a structural failure that occurred as air built up at Mach 0.9, pitching the aircraft into a shock stall that placed tremendous loading on the fuselage and wings. The main spar cracked at the roots, causing the wings to collapse rearwards.
The DH108 established a number of "firsts" for a British aircraft: it was the first British swept-winged jet aircraft and the first British tailless jet aircraft. Sadly all three prototypes were lost in fatal crashes.
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