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Weird Wings - De Havilland DH.108

Enlarge image (will open in a new window)Britain's DH.108 was built to an Air Ministry specification E 18/45, originally to investigate the behaviour of swept wings at low, medium and high subsonic speeds. It supported the DH.106 Comet and DH.110 programmes. Work began in October 1945, three prototypes being ordered.

The first prototype, TG283, consisted of a DH.100 Vampire fuselage married to new swept wing surfaces attached to existing pick-up points. The wings, like the fuselage, were of wooden construction, and had a span of 39 ft. 0 in. (11.887 m.) and an area of 328 sq. ft. (30,472 m²), 15% greater than the Vampire. The wings swept 43° at the leading edge, and carried elevons outboard of split trailing-edge flaps, used in conjunction with the rudder.

Enlarge image (will open in a new window)The first prototype carried anti-spin parachutes in wing-tip containers, and Handley-Page leading-edge slots. It first flew on May 15th, 1946, under the control of Geoffrey de Havilland. It flew a number of trials before crashing near Hartley Wintney, Hants. on May 1, 1950.

This first prototype, powered by the Vampire's 3,000 lb. st. DH Goblin DGn.2 turbojet, was essentially a low-speed aircraft, capable of a maximum speed of 280 mph (451 km/h).

Enlarge image (will open in a new window)The second prototype, TG306, was intended for research at higher speeds. Wing sweepback was increased to 45°. Leading edge slots were automatic and lockable by the pilot, and powered flying controls were provided. The Goblin 3 turbojet increased available power to 3,300 lb. st (1497 kgp). Full recording equipment was installed. Length was reduced from TG283's 25 ft. 10 in (7.874 m.) to 24 ft 6 in (7.467 m.). This aircraft first flew in June 1946, and was intended to better the current air speed record of 616 mph (991 km/h).

During a practice flight on 27th September, 1946, the aircraft's structure failed at around Mach. 0.9, and it broke up, falling into Egypt Bay, near Gravesend, Kent. The pilot, Geoffrey de Havilland, died in the accident.

Enlarge image (will open in a new window)The third prototype, VW120, powered by a DH Goblin 4 engine of 3,750 lb. st (1700 kgp), did not fly until 24th July, 1947. The pilot's seat had been lowered for the fitting of a low-drag canopy, and a pointed nose fitted, increasing overall length to 26 ft. 9½ in. (8.165 m). On April 12, 1948, the aircraft set a new 100 km (62.1 mile) closed circuit speed record of 605.23 mph (974 km/h), flown by John Derry, and it was certain that it could better the top speed of the preceding aircraft.

On September 9, 1948, again flown by John Derry, the aircraft reached Mach 1.0 in a dive between 40,000 and 30,000 ft. (12192 m to 9144 m) without any buffetting or instability, only some tightening of controls. It thus became the first British aircraft to exceed Mach 1.0. Fifteen weeks later, a Russian Lavochkin La-176 broke Mach 1.0, these two claiming to be the first turbojets to break the sound barrier, although that speed had previously been exceeded by both the rocket-powered Bell X-1 (Mach 1.46) and the mixed power Douglas Skyrocket.

The third DH.108 ended its career on February 15th, 1950, in a fatal crash near Birkhill, Bucks.


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