| Supermarine Type 224 | |
|---|---|
 Model of the Supermarine 224 | |
| General information | |
| Other name | Spitfire (not officially adopted) |
| Type | Fighter aircraft |
| National origin | United Kingdom |
| Manufacturer | Supermarine |
| Designer | Team led byR. J. Mitchell |
| Owners | Royal Air Force |
| Number built | 1 |
| History | |
| First flight | 19 February 1934 |
| Fate | Destroyed in 1937 (target practice) |
TheSupermarine Type 224 was a Britishgull-wing monoplanefighter aircraft designed byR.J. Mitchell atSupermarine in response toAir Ministry Specification F.7/30, which sought to introduce a new fighter to succeed theGloster Gauntlet. The Type 224 was powered by aRolls-Royce Goshawk engine, which used an experimentalevaporative cooling system.
Problems with the cooling system, combined with its disappointing performance during trials, led to the Type 224 being rejected by theAir Ministry, a contract for production aircraft eventually going to theGloster Gladiator. The type is nevertheless notable because Mitchell learnt lessons from its design that were to contribute to his success with theSupermarine Spitfire.
Air Ministry Specification F.7/30, which developed fromO.R.1,[1] was formally issued to the British aircraft industry in October 1931,[2] called for an all-metal day and nightfighter aircraft armed with four machine guns, a high maximum speed andrate of climb, and a landing speed of less than 60 miles per hour (97 km/h). The importance of good visibility from thecockpit was specified. Although the use of any suitable engine was permitted, theAir Ministry expressed a preference for theRolls-Royce Goshawk, then still being developed.[3][note 1] Designs tendered to the specification came fromBristol,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).[2] Hawker had both its biplane and monoplane designs rejected but built theHawker P.V.3, as a private venture, similarly Bristol had three rejected and built both theBristol Type 123 biplane andBristol 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 theSchneider Trophy contests, Supermarine's chief designerR. J. Mitchell was confident that he could design a highspeed fighter. Less than four months after receiving the specification, Supermarine tendered amonoplane design, the Type 224.[5]
Mitchell's design for the Type 224 included an invertedgull-wing,[6] chosen in order to shorten theundercarriage legs and so reducedrag. He chose a thick airfoil for the wing, in contrast to the type of airfoil for the Schneider Trophy racers.[7]
The fixed landing gear were encased in largefairings.[7] The fuselage was ofmonocoque construction, with one pair of guns mounted either side of the cockpit and the other pair in the 'trouser' fairings of theundercarriage, which was fixed.[citation needed]
The wing had a single main spar. The engine cooling system'scondensers formed the wing's entire leading edge,[8] the combination of the two producing a 'D-box'spar that had a high torsionalstiffness. Behind the main spar the wing was fabric-covered.[citation needed]
The Type 224 was powered by the 600 horsepower (450 kW) Goshawk II. The evaporative cooling system used by the Goshawk involved allowing the cooling water to reach a temperature greater than 100 °C (212 °F) 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.[9]
Mitchell was not a proponent of the use ofwind tunnel tests, but theVickers wind tunnel was used to test aspects of the design of the Type 224, and the results obtained indicated the superiority of a gull-wing design.[7] Wind-tunnel tests were carried out on a full-size model of the open cockpit area to ensure that the pilot would not be subjected to undue buffeting due to the design of the windscreen.[10]
Supermarine submitted information on the predicted performance of the Type 224 to the Air Ministry based on the wind-tunnel data, which suggested that the aircraft would perform well, and in response, the ministry issued a production contact for a prototype.[11] The Type 224 first flew on 19 February 1934, piloted by"Mutt" Summers.[10] Its performance was disappointing—the maximum speed was 228 miles per hour (367 km/h) and it took 9.5 minutes to climb to 15,000 ft (4,600 m), well below the predicted performance of a 245 miles per hour (394 km/h) speed and climb to 15,000 ft (4,600 m) in 6.6 minutes.[12] The wing design created issues withlateral stability, and further wind-tunnel tests were carried out before the design was finalised, when Mitchell enlarged thefin.[10]
Mitchell was in discussions about a number of improvements to the Type 224—a new wing,tailplane, and engine arrangements—which would give it a top speed of 265 miles per hour (426 km/h), but the Air Ministry decided that a new aircraft, rather than a modification of the Type 224, was called for. In 1933.[6] In January 1935, further construction was cancelled. Mitchell was disappointed in the Type 224’s under-performance, and came to doubt the reliability of the data produced by wind-tunnel tests.[11]
Gloster's private venture was ordered in mid-1935 as the Gladiator to equip the expanding RAF.
On 25 May 1937 the aircraft was transferred to theAeroplane and Armament Experimental Establishment atRAF Martlesham Heath.[13] It ended its career during the summer of 1937, when it was used as for target practice atOrford Ness,Suffolk.[14]
The failure of the Type 224, coming soon after the Schneider racer successes, did not cause Mitchell to lose faith in his ability to design a fighter. He completely redesigned the type, producing a new design with straight wings and a thinner airfoil shape.[15]
The Air Ministry quickly realized that Mitchell’s new design was a new airplane. It wanted a fighter designed by Mitchell and his team, and in January 1935 it issued Specification F.37/34, for the sole purpose of covering a new design by Supermarine.[16] The specification, essentially an addendum to specification F.7/30 mentioning Supermarines specification 425a and drawing,[17] led on to the design of theSupermarine Spitfire.[18]
Supermarine had asked the Air Ministry for the nameSpitfire to be reserved for the type.[6] The name was adopted, but Mitchell disliked it, and the use of it for the Type 224 was later dropped.[10]
Data fromSupermarine Aircraft since 1914.[19]
General characteristics
Performance
Armament
 | This sectionneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources in this section. Unsourced material may be challenged and removed.(March 2024) (Learn how and when to remove this message) |
Aircraft of comparable role, configuration, and era
