The sleek Spitfire was not, however, the result of a moment of inspiration, rather it was the culmination of many years of dedicated work on high-speed, single-seat aircraft projects, firstly dedicated racers and subsequently fighter projects. For Supermarine’s family of Government funded racers, the S5, S6 and S6b, destined to compete in and win the Schneider Trophy, Mitchell’s team were fortuitous to be able to work with the experts at the National Physical Laboratory and the Royal Aircraft Establishment from 1925 to 1931 and had had unparalleled access to Britain’s best wind tunnel facilities. Designing their racing aircraft in close association with the engine suppliers, first Napier and subsequently Rolls-Royce, enabled them to build World-beating racers. Through this racing and record-breaking programme they had garnered a wealth of invaluable data on all aspects of high-speed flight and aircraft construction leaving the team well positioned to move on to consider designs for fast interceptor fighters.
Mitchell’s first attempts at fighter design were, however, quite conventional, partly as a result of the undemanding requirements of the Air Ministry specifications to which he was responding, and partly through his cautious approach to designing a class of aircraft with which he and his team were unfamiliar. By 1931, however, more radical ideas began to appear and Supermarine’s tender to specification F.7/30, the Type 224, was regarded as the best submitted to the Air Ministry. There were high hopes that the company would produce a winner, but these were soon dashed as it failed to meet expectations; plagued by an unreliable engine, over-complex cooling system and excessive drag. At this point, the spring of 1934, Mitchell was galvanised into action, initiating a high-priority private venture programme to address all the shortcomings of the Type 224, drawing inspiration from the work on the racers and incorporating the latest ideas in aerodynamic refinement. Through progressive refinements the Type 224 evolved into the Type 300, which by the autumn of 1934 was of sufficient potential for the Ministry to agree to fund the project as an experimental high-speed fighter. By mid-1935 the team’s work resulted in the definitive Spitfire, a fighter nearly 40mph faster than its direct competitor, the Hawker Hurricane.
These images show how Mitchell’s ideas developed over an eight-year period, from a rather conventional biplane in 1927 through the Type 224 in 1932 and finally the Spitfire in 1935.
By Ralph Pegram