The Mosquito was a twin engine fast fighter bomber, with an airframe that was largely constructed in a composite of wood layers and adhesive. Its history can be related back to the de Havilland company’s earlier projects, in particular the DH 88 Comet Racer. In the early 1930s the company was gaining experience in using wooden construction methods for its aircraft; offering reduced weight with improved speeds and payload-range capabilities. A new design in the form of the Comet, with two engines and a retracting undercarriage, was offered for private individuals to purchase and enter in the MacRobertson Trophy Air Race. This was a long distance race between RAF Mildenhall and Melbourne, Australia, with defined en route stopping stages. The winning aircraft which took less than 3 days to reach Melbourne in October 1934, was one of three Comets entered. The de Havilland company was inspired to invest further in wooden construction technology. It marketed the Comet for mail delivery duties and later followed on with its DH 91 Albatross; a new streamlined 4 engine wooden transport aircraft.

In 1936 the Air Ministry issued Specification P13/36 for a twin engine medium bomber capable of ‘world wide use’ but de Havillands were not invited to tender a design. The company maintained its interest in the concept. After a number of ideas had been explored initially based on the Albatross, the company arrived at a radical solution with its Model DH 98; a fast streamlined aircraft, using two Merlin engines and no defensive armament, in view of its speed. However, provision was made in the nose volume for 20mm canons. The aircraft had a 2 man crew and its airframe format was similar to that of the Comet. It used wooden plies and composite construction wherever possible, including for the stressed skin surfaces. Steel assemblies would transfer major loads to the wooden structure, for example those from the engines, undercarriage and armaments. Other metal assemblies were utilised only where essential. In October 1938 the Air Ministry rejected the de Havilland design, being uncomfortable with a wooden bomber airframe and no defensive armament. As some sections of the Air Ministry were warming to the de Havilland design, so others were unconvinced about its rationale. However, on 1^st March 1940 a contract was awarded for one prototype and 50 production DH.98 aircraft, under Specification B.1/40. The start of war delayed aircraft development, as materials, projects and engine production became stretched. The prototype Mosquito, registration W4050, was first airborne on 25 November 1940.

Significant attention was given to the external finish of the airframe, to ensure that its wood based construction would be durable in service. This process also gave a streamlined surface finish to what was a well proportioned machine. From the outset, trials proved that the aircraft would exceed its minimum requirements in most respects, such as speed, payload and range. As the war continued it allowed the furniture industry to devote an alternative skilled workforce to produce Mosquito parts, placing less strain upon the metal industries as well as other aircraft companies that employed all metal designs. As growing engine powers and improved propeller units became available, the aircraft speed and payload capabilities became legend, prompting nicknames such as the ‘wooden wonder’ and to its crews the ‘Mossie’. In its fighter role the aircraft would typically have four 0.303in (7.7mm) Browning machine guns in the nose and four Hispano 20mm cannons in the forward fuselage underside. In its bomber role it could carry a 2000 lb (907 kg) payload and a series of specially modified aircraft carried a 4000 lb (1,814kg) bomb load.

Later Mosquito Marks could readily exceed 400 mph in level flight. It was adapted to a large range of duties as a medium bomber, fighter bomber for fast tactical strike, reconnaissance, anti-submarine warfare, night fighter work and in the Pathfinder force of the RAF strategic bombing campaign. By the end of the war almost 7000 aircraft had been produced, with some fuselages sourced from overseas, most notably from Canada. Production for export continued beyond WW2, bringing the total number produced to almost 8000.

de Havilland Mosquito NF.Mk XVII :

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© 2010 Victor K L Marshall M Sc, C Eng, M I Mech E

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