DH-106 Comet

In December 1942, Lord Brabazon formed a special committee to propose how British civil aviation could be competitive after the war. By May 1943, key aircraft types had been identified, including a high-speed transport for carrying one ton of mail and a few passengers across the Atlantic. This was known as the “Type IV”.

Flying quickly and efficiently implied travelling in thin air at high altitude; a perfect application for gas-turbine engines. De Havilland were well-qualified for this: in April 1942, they had become Britain’s second jet engine manufacturer with the successful test of the Goblin engine. They had also conducted research into “compressibility”, an aerodynamic effect that acted like a physical barrier to conventionally-shaped aircraft as they approached the speed of sound. In June 1943, de Havilland put forward a radical concept for the Type IV, with three jet engines, a swept-wing, tailless shape, and room for six passengers.

De Havilland had to fight a strong case for jets rather than turbo-props, or gas-turbine powered propellors, favoured by the Ministry. In September 1943, they began trials of their new jet fighter, the DH-100 Vampire, providing proof that the quietness and lack of vibration was ideal for passenger service.

BOAC were staunch allies in favour of jet-power, and provided the economic argument. Undoubtedly, a jet airliner would be more expensive to develop and use more fuel, but its engines would require less frequent maintenance. This meant quicker turn-around on the ground and more time in the air. Speed was the key: if the aircraft could do 500 mph, it would pay for the investment in technology.

In 1944, de Havilland began developing a more powerful jet engine, called the Ghost. This had a direct effect on payload. By February 1945, a revised proposal was made with four Ghost engines under the trailing edges of the wings, like Concorde, a wing-sweep of 40°, and 24 passengers. The all-up weight would be 75,000 lb.

Two half scale prototypes were commissioned

BAE SYSTEMS

to prove the concept. These were called the DH-108. They proved to be very fast, despite only a single Goblin engine, highly manoeuvrable, but unstable. This had tragic consequences when Geoffrey de Havilland’s son was killed on 27 September 1946. For all its advantages, the shape required reactions beyond the means of conventional controls. It was not yet suitable for an airliner, and a more conventional Comet evolved.