Supermarine Spitfire

Design

Supermarine Chief Designer R.J. Mitchell had won three Schneider Trophy seaplane races with his aircraft, by combining powerful Napier or Rolls Royce engines with minute attention to streamlining. These same qualities are equally useful for a fighter design, and in 1930 Mitchell produced such a plane in response to an Air Ministry request for a new and modern monoplane fighter.

Related Topics:
Supermarine - R.J. Mitchell - Schneider Trophy - Napier - Rolls Royce - Streamlining - 1930 - Air Ministry

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This first attempt at a fighter resulted in an open-cockpit monoplane with gull-wings and a large fixed spatted undercarriage. The Supermarine Type 224 did not live up to expectations; nor did any of the competing designs which were also deemed failures.

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Mitchell immediately turned his attention to an improved design as a private venture, with the backing of Supermarine owners Vickers. The new design added gear retraction, an enclosed cockpit, oxygen gear, and the much more powerful Rolls Royce PV-12 engine, later named the Merlin.

Related Topics:
Vickers - PV-12

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By 1935 the Air Ministry had seen enough advancement in the industry to try the monoplane design again. They eventually rejected the new Supermarine design on the grounds that it did

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not carry the required eight-gun load, and did not appear to have room to do so.

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Once again Mitchell was able to solve the problem. It has been suggested that by looking at various Heinkel planes he settled on the use of an elliptical planform, which had much more chord to allow for the required eight guns, while still having the low drag of the earlier, simpler wing design. Mitchell's aerodynamicist, Beverley Shenstone, however, has pointed out that Mitchell's wing was not directly copied from the Heinkel He 70, as some have claimed; the Spitfire wing was much thinner and had a completely different section. In any event, the elliptical wing was enough to sell the Air Ministry on this new Type 300, which they funded as F.10/35.

Related Topics:
Heinkel - Planform - Chord

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The prototype first flew on March 5, 1936. Performance was such that the Air Ministry immediately placed an order for 310. At the time it was still being "shaken out" by Vickers test pilots, even before the aircraft had been handed to them for their own flight testing.

Related Topics:
March 5 - 1936

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A feature of the final Spitfire design that has often been singled out by pilots is its washout feature, which was unusual at the time. The incidence of the wing is +2° at its root and −½° at its tip. This twist means that the wing roots will stall before the tips http://www.fly-imaa.org/imaa/hfarticles/const/v1-4-10.html, reducing the potentially dangerous rolling moment in the stall known as a spin. Many pilots have benefited from this feature in combat when doing tight turns close to the aircraft's limits because when the wing root stalled it made the control column shudder giving the pilot a warning that he was about to reach the limit of the aircraft`s performance.

Related Topics:
Washout - Stall

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