The Supermarine Spitfire is a British single-seat fighter aircraft that was used by the Royal Air Force and many other Allied countries before, during and after the Second World War. The Spitfire was built in many variants, using several wing configurations, and was produced in greater numbers than any other British aircraft. It was also the only British fighter to be in continuous production throughout the war. The Spitfire continues to be popular among enthusiasts, with approximately 53 Spitfires being airworthy, while many more are static exhibits in aviation museums throughout the world.
The Spitfire was designed as a short-range, high-performance interceptor aircraft by R. J. Mitchell, chief designer at Supermarine Aviation Works, which operated as a subsidiary of Vickers-Armstrong from 1928. In accordance with its role as an interceptor, Mitchell supported the development of the Spitfire's distinctive elliptical wing (designed by B. Shenstone) to have the thinnest possible cross-section; this enabled the Spitfire to have a higher top speed than several contemporary fighters, including the Hawker Hurricane. Mitchell continued to refine the design until his death in 1937, whereupon his colleague Joseph Smith took over as chief designer, overseeing the development of the Spitfire through its multitude of variants.
During the Battle of Britain, from July to October 1940, the Spitfire was perceived by the public to be the RAF fighter, though the more numerous Hawker Hurricane shouldered a greater proportion of the burden against the Nazi German air force, the Luftwaffe. Spitfire units, however, had a lower attrition rate and a higher victory-to-loss ratio than those flying Hurricanes because of its higher performance. Spitfires in general were tasked with engaging the Luftwaffe fighters (mainly Messerschmitt Bf 109E series aircraft which were a close match for the Spitfire) during the Battle.
After the Battle of Britain, the Spitfire superseded the Hurricane to become the backbone of RAF Fighter Command, and saw action in the European,Mediterranean, Pacific and the South-East Asian theatres. Much loved by its pilots, the Spitfire served in several roles, including interceptor, photo-reconnaissance, fighter-bomber and trainer, and it continued to serve in these roles until the 1950s. The Seafire was a carrier-based adaptation of the Spitfire which served in the Fleet Air Arm from 1942 through to the mid-1950s. Although the original airframe was designed to be powered by a Rolls-Royce Merlin engine producing 1,030 hp (768 kW), it was strong enough and adaptable enough to use increasingly powerful Merlins and, in later marks, Rolls-Royce Griffon engines producing up to 2,340 hp (1,745 kW); as a consequence of this the Spitfire's performance and capabilitiesimproved over the course of its life.
Development and production
R. J. Mitchell's 1931 design to meet Air Ministry specification F7/30 for a new and modern fighter capable of 250 mph (400 km/h), the Supermarine Type 224, was an open-cockpit monoplane with bulky gull-wings and a large fixed, spatted undercarriage powered by the 600 horsepower (450 kW) evaporatively cooled Rolls-Royce Goshawk engine. This made its first flight in February 1934. Of the seven designs tendered to F7/30, the Gloster Gladiator biplane was accepted for service.
The Type 224 was a big disappointment to Mitchell and his design team, who immediately embarked on a series of "cleaned-up" designs, using their experience with the Schneider Trophy seaplanes as a starting point.  This led to the Type 300, with retractable undercarriage and the wingspan reduced by 6 ft (1.8 m). This was submitted to the Air Ministry in July 1934, but was not accepted. The design then went through a series of changes, including the incorporation of a faired, enclosed cockpit, oxygen-breathing apparatus, smaller and thinner wings, and the newly developed, more powerful Rolls-Royce PV-XII V-12 engine, later named the "Merlin". In November 1934 Mitchell, with the backing of Supermarine's owner, Vickers-Armstrong, started detailed design work on this refined version of the Type 300
On 1 December 1934, the Air Ministry issued contract AM 361140/34, providing £10,000 for the construction of Mitchell's improved F7/30 design. On 3 January 1935, they formalised the contract with a new specification, F10/35, written around the aircraft. In April 1935, the armament was changed from two .303 in (7.7 mm) Vickers machine guns in each wing to four .303 in (7.7 mm) Brownings,following a recommendation by Squadron Leader Ralph Sorley of the Operational Requirements section at the Air Ministry.
On 5 March 1936,[nb 2] the prototype (K5054) took off on its first flight from Eastleigh Aerodrome (later Southampton Airport). At the controls was Captain Joseph "Mutt" Summers, chief test pilot for Vickers, who is quoted as saying "Don't touch anything" on landing.[nb 3] This eight-minute flight came four months after the maiden flight of the contemporary Hurricane.
K5054 was fitted with a new propeller, and Summers flew the aircraft on 10 March 1936; during this flight the undercarriage was retracted for the first time. After the fourth flight, a new engine was fitted, and Summers left the test-flying to his assistants, Jeffrey Quill and George Pickering. They soon discovered that the Spitfire[nb 4] was a very good aircraft, but not perfect. The rudder was over-sensitive and the top speed was just 330 mph (528 km/h), little faster than Sydney Camm's new Merlin-powered Hurricane. A new and better-shaped wooden propeller allowed the Spitfire to reach 348 mph (557 km/h) in level flight in mid-May, when Summers flew K5054 to RAF Martlesham Heath and handed the aircraft over to Squadron Leader Anderson of the Aeroplane & Armament Experimental Establishment (A&AEE). Here, Flight Lieutenant Humphrey Edwardes-Jones took over the prototype for the RAF. He had been given orders to fly the aircraft and then to make his report to the Air Ministry on landing. Edwardes-Jones's report was positive; his only request was that the Spitfire be equipped with an undercarriage position indicator. A week later, on 3 June 1936, the Air Ministry placed an order for 310 Spitfires, before any formal report had been issued by the A&AEE; interim reports were later issued on a piecemeal basis.