|Please note: This section is a 'work in progress' - at the moment only the very initial history of the Mosquito is shown...|
The First Steps...
The origins of the Mosquito can be traced to Air Ministry Specification P.13/36 issued on 24th August 1936 by Air Commodore R.H.Verney on behalf of the RAF Directorate of Technical Development (DTD). Specification P.13/36 called for a 'twin-engined medium bomber for world-wide use' and continued: 'It should be an aircraft that can exploit the alternatives between long range and very heavy bomb load which are made possible by catapult launching in heavily loaded condition. During all operations it is necessary to reduce time spent over enemy territory to a minimum. Therefore the highest possible cruising speed is necessary.'
The Specification also called for defensive armament consisting of nose and tail gun turrets, horizontal bomb stowage in tiers if needed and suitability for outdoor maintenance at home or abroad. 'It appears', it said, 'there is a possibility of combining medium-bomber, general reconnaissance and general purpose classes in one basic design,' and went on to suggest that two 18-inch torpedoes might be carried. A top speed of 275 mph was required at 15,000 feet, and a range of 3,000 miles with a 4,000-lb. Bomb load. Consideration would be given to remotely controlled guns.
De Havilland was one of the companies invited to tender for military specifications, but generally at the time preferred to build civil aircraft for the open market following experiences in the 1920's, and a wariness of government specifications. When the threat from Hitler began to appear grave however, consideration was given to Specification P.13/36 by de Havilland. The DH.91 Albatross airliner, manufactured from wood with stressed skin construction, and DH.94 Moth Minor light aircraft were the company's newest projects at the time, having flown for the first time on 20th May and 22nd June 1937 respectively.
Following experiences with the Albatross, de Havilland noted that the concepts of aerodynamic cleanliness and minimum skin area to keep drag to a minimum were equally valid for the design of a bomber as a fighter, and initially a military version of the Albatross was one time saving possibility considered to meet the specification. A twin Merlin Albatross estimate appeared in April 1938, with Hercules HE 1M and Sabre engine comparisons.
On 7th July a letter was sent to Sir Wilfred Freeman, an old friend of de Havilland's from WW1, now Air Council Member for Research and Development, discussing the specification and arguing for wood construction. De Havilland noted that except in torsion, wood's strength for weight was as great as that of duralumin or steel. The letter further suggested that should war break out without warning, the adequate supplies of suitable timber and a capable workforce in the form of labour from the furniture, coach building and other woodworking trades would aid in having the new aircraft in service rapidly. De Havilland felt however that Specification P.13/36 would produce a mediocre aircraft and suggested a different approach.
In a second letter dated 27th July, de Havilland distanced themselves still further when they concluded that the specification could not be met by two Merlins - if speed was paramount, then only half the required bomb load could be carried, if load was paramount, a larger, slower aircraft would result. A two Merlin compromise design was arrived at on 11 August, with a bomb load of 4,000 lb., a top speed of 260 mph and a range of 1,500 miles. However it was felt that to continue would have been an admission of defeat in design principles and the company soon rejected the idea.
The Munich crisis of September 1938 brought greater urgency to the preparations for hostilities. De Havilland began to consider a new, smaller aircraft with a crew of two, powered by two Merlin engines and completely sacrificing armament for speed. De Havilland and C.C Walker went to the Air Ministry early in October to make this proposal. Again they advocated wood construction, estimating a saving of a year in the prototype stage and also timesaving in aircraft production and development of subsequent variants.
The Blenheim, Whitley, Wellington and Hapden, heavily (for the time) armed bombers of metal construction, were by now in production, with the trend being towards larger four-engined machines. Not surprisingly perhaps, de Havilland's proposal was unceremoniously rejected; the Air Ministry was simply not interested in the unarmed bomber concept. Perhaps de Havilland could take on building wings for one of the other bombers instead?
More to come soon!
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