Supermarine Type 224

The Supermarine Type 224 was a British gull-wing monoplane fighter aircraft designed by R.J. Mitchell at Supermarine in response to Air Ministry Specification F.7/30, which sought to introduce a new fighter to succeed the Gloster Gauntlet. The Type 224 was powered by a Rolls-Royce Goshawk engine, which used an experimental evaporative cooling system.

Problems with the cooling system, combined with its disappointing performance during trials, led to the Type 224 being rejected by the Air Ministry, a contract for production aircraft eventually going to the Gloster Gladiator. The type is nevertheless notable because Mitchell learnt lessons from its design that were to contribute to his success with the Supermarine Spitfire.

Air Ministry Specification F.7/30, which developed from O.R.1, was formally issued to the British aircraft industry in October 1931, called for an all-metal day and night fighter aircraft armed with four machine guns, a high maximum speed and rate of climb, and a landing speed of less than 60 miles per hour (97 km/h). The importance of good visibility from the cockpit was specified. Although the use of any suitable engine was permitted, the Air Ministry expressed a preference for the Rolls-Royce Goshawk, then still being developed. Designs tendered to the specification came from Bristol, Hawker, Westland, Blackburn and Supermarine

Of the proposals submitted by British aircraft manufacturers, three were officially selected to produce prototypes for the Air MInistry, Supermarine (the Type 224), Blackburn (Blackburn F.3), and Westland (Westland F.7/30). Hawker had both its biplane and monoplane designs rejected but built the Hawker P.V.3, as a private venture, similarly Bristol had three rejected and built both the Bristol Type 123 biplane and Bristol Type 133 (a monoplane) with its own money. Gloster had not tendered a submission as they were engaged on the Gloster Gauntlet, but later built their private venture Gloster SS.37 using Hawker construction techniques to improve their Gauntlet design.

As a result of the success of Supermarine during the Schneider Trophy contests, Supermarine's chief designer R. J. Mitchell was confident that he could design a highspeed fighter. Less than four months after receiving the specification, Supermarine tendered a monoplane design, the Type 224.

Mitchell's design for the Type 224 included an inverted gull-wing, chosen in order to shorten the undercarriage legs and so reduce drag. He chose a thick airfoil for the wing, in contrast to the type of airfoil for the Schneider Trophy racers.

The fixed landing gear were encased in large fairings. The fuselage was of monocoque construction, with one pair of guns mounted either side of the cockpit and the other pair in the 'trouser' fairings of the undercarriage, which was fixed.^{[citation needed]}

The wing had a single main spar. The engine cooling system's condensers formed the wing's entire leading edge, the combination of the two producing a 'D-box' spar that had a high torsional stiffness. Behind the main spar the wing was fabric-covered.^{[citation needed]}