When on 8 September 1936, the British Air Ministry issued Specification P.13/36 which called for a twin-engine medium bomber de Havilland was in the ideal position to be one of the competitors especially so since the ministry had indicated that it would also consider design submissions using non-strategic materials.
World War II was in full swing and the production of duralumin and steel could barely keep up with demand whilst the supply of wood was plentiful. De Havilland had a long history of producing innovative high-speed aircraft of wooden construction. Its composite wood DH.88 twin engine Comet racer and the 22 passenger DH.91 Albatross airliner stood it in good stead when it came to the design of the Mosquito.
De Havilland's initial response to the specification though was the DH.95 Flamingo an all metal design based on its Albatross airliner. However, Geoffrey de Havilland was in favour of a clean sheet design of wooden monocoque construction with minimal skin area. He argued that such a design would not only save weight but simplify production and reduce construction time as well as overcome possible shortages of duralumin and would also offer future development potential.
Powered by Merlin engines de Havilland envisaged a bomber with good manoeuvrability that would be faster than enemy fighters and could thus dispense with defensive turrets. The lack of turrets would not only reduce weight and aerodynamic drag but also eliminate the need for gunners thus reducing crew compliment to a pilot and navigator only. The saving in weight meant that it could carry a higher bomb load than conventional bombers.
However, the Air Ministry considered de Havilland's design to radical and showed very little interest. Unperturbed de Havilland's design team under the leadership of Eric Bishop on 7 October 1939 in secrecy started design work on the DH.98. Although it was initially decided to dispense with all armaments Bishop included four 20 mm cannon in the forward half of the bomb bay. On 29 December 1939 de Havilland revealed a full scale mock-up to the Air Ministry and the Royal Air Force's (RAF) operational command and they were suitable impressed and backed the project and on 1 March 1940 issued a contract for 50 bomber/ reconnaissance variants.
Construction on the first prototype started almost immediately but was stopped when it was decided by the Air Ministry that de Havilland should concentrate on its other more pressing contracting work. Work was only reinstated in July after de Havilland promised delivery of 50 aircraft by December 1941. The Mosquito first flew on 25 November 1940 only 11 months after the start of detailed design work. Geoffrey de Havilland Junior, the company's chief test pilot, was at the controls.
The first flight went well except for buffeting and the undercarriage doors that did not close completely. These problems were sorted out and during further trials held during January 1941 de Havilland's prediction came true when the Mosquito reached 392 mph (631 km/h) easily outpacing a Spitfire Mk II.
Initially the Air Ministry ordered 19 photo-reconnaissance (PR) models and 176 fighters. Deliveries to the RAF started on 15 November 1941 and by end of January 1942 contracts for a further 1,378 of all variants were awarded. In total 7,781 Mosquitos were built and de Havilland's wooden bomber went on to serve in almost all roles imaginable including doing duty as trainers, target tugs, torpedo bombers, night fighters and fighter bombers.
Mosquitos did not only serve with the RAF but were exported to Australia, Belgium, Burma, Canada, the Republic of China, Czechoslovakia, Dominican Republic, France, Israel, New Zealand, Norway, Poland, South Africa, the Soviet Union, Sweden, Turkey, Switzerland, the United States and Yugoslavia.
Sadly, only one airworthy example survives whilst approximately thirty are exhibited in Museums.
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