On 15 May 1946, the de Havilland DH.108 registered TG283 made its first flight, taking off from the RAF emergency airfield at Woodbridge. It was flown by the company’s chief test pilot Geoffrey de Havilland Jr. The flight lasted half an hour. TG 283 handled so well that de Havilland was able to fly in formation with a Dove and to pose alongside a Proctor for air to air photography.
The DH.108 was an approximately half-scale model of the projected DH.106, a multi-engined, jet-propelled tailless transport aircraft. Eventually the tailless configuration of the DH.106 was abandoned and it evolved into the famous Comet, the world’s first jet-powered airliner. Thereafter the DH.108 served as a swept-wing research aircraft.
Three DH.108 aircraft were built. TG283, the first DH.108, was intended to investigate the low-speed handling characteristics of swept wings. It incorporated a de Havilland Goblin 2 engine of 3,000 lb thrust, and was fitted with 40° swept-back wings.
After the first four sorties, TG283 was returned on 19 May to Hatfield where de Havilland completed the initial testing of the aircraft with a series of 24 flights that included air demonstrations, low-speed and low-altitude sorties, flights to and from Woodbridge, and a mock dogfight with a Mosquito.
TG 306, the second DH.108, was intended to assess the high-speed characteristics of the swept wing and was therefore fitted with strengthened wing structure. With de Havilland Jr. at the controls, it made its first flight on 23 August at Woodbridge. During its first seven flights, TG306 flew at speeds in excess of Mach .82, achieving Mach .895 at 34,000 ft during its fourth sortie and making public debut in an impressive display at the SBAC Display at Handley Page’s Radlett airfield in Hertfordshire, in September. The successful flights encouraged program managers to attempt to achieve a record speed.
On 27 September, during a practice flight for the record attempt, TG306 crashed into the Thames Estuary, and young de Havilland was killed. It was apparent that he had reached a speed of 660 mph at about 8,000 ft altitude. This was a Mach number of .88, and resulted in a divergent pitch oscillation so severe that structural wing failure occurred in a few seconds and the aircraft disintegrated. TG306 had flown 13 hours as DH.108 when it took off for its tragic flight on 27 Sep 46 for its tragic flight.
Flights continued with the first aircraft with the new Chief Test Pilot John Cunningham.
VW 120, the third DH.108, was ordered after the loss of TG306. It was powered by a Goblin 4 turbojet, rated at 3,750 lb and, unlike the first two aircraft, was equipped with an ejector seat. It was first flown at Hatfield on 24 July 1947, with John Cunningham at the controls. It took part in the SBAC show at Radlett in September, then resumed the high speed programme initiated by Geoffrey de Havilland, in flights made for pressure plotting and general investigation of stability and control by Cunningham and new company test pilot John Derry.
By the end of March 1948, de Havilland were satisfied with the maneuverability of the DH.108 and its flying characteristics, and entered it for the 100 km closed circuit speed record. Derry was named the pilot. On 12 April 1948, Derry succeeded in establishing a new Closed-Circuit Speed Record. He continued high-speed test flights throughout the summer. On 6 September 1948, VW120 made the first British supersonic flight when it exceeded Mach 1 during an uncontrolled vertical dive over South England, with Derry at the controls.
TG238 and VW120 moved to RAE Farnborough in 1948 and 1949, respectively after more than 135 contractor flights by the first and 190 by the latter. The legendary Captain Eric ‘Winkle’ Brown, Commanding Officer of Aero Flight., was charged with a programme of stability, control, and landing trials using TG 283, with other RAE pilots taking part. VW120 was used for stalling tests and to investigate high-speed longitudinal stability.
On 15 February 1950, VW120 crashed at Little Brickhill killing Squadron Leader Stuart Muller-Rowland. VW120 total flight time was 122 hours 25 min.
TG283 crashed on 1 May 1950 after going in a spin and the RAE pilot Flt Lt Eric Genders was killed. It had accumulated 135 hr 20 minutes in the air as DH.108 before taking off on its tragic flight on 1 May 1950.
© Henry Matthews 2012 (excerpted from the book The Saga of DH.108, by Henry Matthews, HPM Publications)