The Supermarine Type 224 was an inverted gull-wing monoplane fighter aircraft designed by

R.J. Mitchell Reginald Joseph Mitchell (20 May 189511 June 1937) was a British aeronautical engineering, aircraft designer who worked for the Southampton aviation company Supermarine from 1916 until 1936. He is best remembered for designing racing seaplan ...

Supermarine Supermarine was a British aircraft manufacturer that is most famous for producing the Spitfire fighter plane during World War II as well as a range of seaplanes and flying boats, and a series of jet-powered fighter aircraft after World War II ...

in response to Air Ministry Specification F.7/30, which sought a fighter for introduction to succeed the

Gloster Gauntlet The Gloster Gauntlet was a single-seat biplane fighter designed and produced by the British aeroplane manufacturer Gloster Aircraft in the 1930s. It was the last fighter to be operated by the Royal Air Force (RAF) to have an open cockpit, and ...

. It was powered by the

Rolls-Royce Goshawk The Rolls-Royce Goshawk was a development of the Rolls-Royce Kestrel that used evaporative or steam cooling. In line with Rolls-Royce convention of naming piston engines after birds of prey, it was named after the goshawk. The engine first ...

engine, which used an experimental

evaporative cooling An evaporative cooler (also known as evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning s ...

system, and problems with this system, combined with its disappointing performance, led to it being rejected, a contract for production aircraft eventually going to the

Gloster Gladiator The Gloster Gladiator is a British biplane fighter. It was used by the Royal Air Force (RAF) and the Fleet Air Arm (FAA) (as the Sea Gladiator variant) and was exported to a number of other air forces during the late 1930s. Developed private ...

. It is nevertheless notable because R.J. Mitchell learnt lessons from its failure that were to contribute greatly to his success with the Supermarine Spitfire.

Design and development

Specification F.7/30, which was formally issued to the aircraft industry in October 1931, called for an all-metal day and night fighter armed with four machine guns, a high top speed and rate of climb, and a landing speed of less than 60 mph. The importance of a good view from the cockpit was made clear. Although the use of any power plant was permitted, the Air Ministry did express a preference for the evaporatively cooled

then being developed. Of the many proposals submitted by manufacturers, three were selected for official development as prototypes, the Supermarine 224 among them. In addition, privately funded submissions for the competition were encouraged. R. J. Mitchell, Supermarine's designer, came up with a clean-looking inverted gull-wing monoplane with a fixed undercarriage powered by the 600 hp Goshawk II. The gull wing configuration was chosen in order to shorten the undercarriage legs and so reduce drag, but since this configuration was known to be liable to produce problems with lateral stability an extensive programme of

wind-tunnel Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...

testing using models was carried out before arriving at the final design. These tests also revealed a lack of directional stability: Mitchell accordingly enlarged the fin area. The cockpit was open, and further wind-tunnel tests were also carried out on a full-size model of the cockpit area to ensure that the pilot would not be subjected to undue buffeting. The fuselage was of

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

construction, with one pair of guns mounted either side of the cockpit and the other pair in the 'trouser' fairings of the undercarriage. The wing was of unusual construction, having a single main spar, forward of which the condensers of the engine cooling system formed the entire leading edge of the wing, the combination of the two producing a 'D-box' spar of great torsional rigidity. Behind the main spar the wing was fabric-covered. The evaporative cooling system used by the Goshawk involved allowing the cooling water to reach a temperature greater than 100 °C without boiling by keeping it under pressure while circulating through the engine: this superheated water was then allowed to boil off by releasing the pressure, the resulting steam then being cooled in a condenser, collected as water and then recirculated through the engine. The system had been experimentally flown in other aircraft, but these were all biplanes, and the condensers and collector tank for the condensed water were all mounted in the upper wing. In the Type 224 the collector tanks were in the undercarriage fairings, and, as the condensed water was nearly at boiling point, it was liable to turn to steam under any slight change of pressure; this frequently occurred in the water pumps and would cause them to stop working.

Competition

The Type 224 first flew on 19 February 1934, piloted by "Mutt" Summers.Andrews and Morgan 1987, p. 206. Its performance was disappointing: maximum speed was 228 mph (367 km/h) and it took 9.5 minutes to climb to , well below the predicted performance of a 245 mph (394 km/h) speed and climb to in 6.6 min.Andrews and Morgan 1987, p. 207. The aircraft which was chosen for production, the radial-engined

, was a late entrant to the F.7/30 competition, making its first flight on 12 September 1934 and was a rapidly undertaken development of the aircraft the competition was intended to provide a replacement for. However, Mitchell was already in discussions about a number of improvements - these included a new wing,

tailplane A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyropla ...

, and engine arrangements - which would give it a top speed of 265 mph (426 km/h). The Ministry felt that, as eight rather than four guns would be needed, a wholly new aircraft, rather than a modification of the Type 224, was called for. In 1933, Supermarine had asked the Air Ministry for the name "Spitfire" to be reserved for it.Buttler p. 10 The Type 224 ended its career as a target on a firing range at

Orford Ness Orford Ness is a cuspate foreland shingle spit on the Suffolk coast in Great Britain, linked to the mainland at Aldeburgh and stretching along the coast to Orford and down to North Weir Point, opposite Shingle Street. It is divided from the m ...

, Suffolk in summer 1937.Price 1986, p. 14.

Specifications (Supermarine Type 224)

References

Bibliography

* *Buttler, T. ''British Secret Projects: fighters and bombers 1935-1955''. Midland, 2004. * *Mason, Francis K. ''The British Fighter since 1912''. London: Putnam, 1992. . *Mitchell, Gordon. ''R.J. Mitchell: Schooldays to Spitfire''. London: Tempus Publishing, 2009. . *Price, Alfred. ''The Spitfire Story: Second edition''. London: Arms and Armour Press Ltd., 1986. . *

External links