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 designed the Spitfire’s distinctive elliptical wing to have the thinnest possible cross-section; this thin wing 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 from cancer 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 (July–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 Luftwaffe. However, because of its higher performance, Spitfire units had a lower attrition rate and a higher victory-to-loss ratio than those flying Hurricanes.
After the Battle of Britain, the Spitfire superseded the Hurricane to become the backbone of RAF Fighter Command, and saw action in the European, Mediterranean, Pacific and the South-East Asian theatres.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 Merlin 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 capabilities improved, sometimes dramatically, over the course of its life.
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. 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. Of the seven designs tendered to F7/30, the Gloster Gladiator biplane was accepted for service.
Mitchell had already begun working on a new aircraft, designated Type 300, with a 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 and, 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, the Air Ministry formalised the contract and a new specification, F10/35, was written around the aircraft.
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 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 meant the Spitfire reached 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.
The British public first saw the Spitfire at the RAF Hendon air-display on Saturday 27 June 1936. Although full-scale production was supposed to begin immediately, there were numerous problems that could not be overcome for some time and the first production Spitfire, K9787, did not roll off the Woolston, Southampton assembly line until mid-1938. The first and most immediate problem was that the main Supermarine factory at Woolston was already working at full capacity fulfilling orders for Walrus and Stranraer flying boats. Although outside contractors were supposed to be involved in manufacturing many important Spitfire components, especially the wings, Vickers-Armstrong (the parent company) was reluctant to see the Spitfire being manufactured by outside concerns and was slow to release the necessary blueprints and subcomponents. As a result of the delays in getting the Spitfire into full production, the Air Ministry put forward a plan that production of the Spitfire be stopped after the initial order for 310, after which Supermarine would build Bristol Beaufighters. The managements of Supermarine and Vickers were able to convince the Air Ministry that the problems could be overcome and further orders were placed for 200 Spitfires on 24 March 1938, the two orders covering the K, L and N prefix serial numbers.
In February 1936 the director of Vickers-Armstrongs, Sir Robert MacLean, guaranteed production of five aircraft a week, beginning 15 months after an order was placed. On 3 June 1936, the Air Ministry placed an order for 310 aircraft, for a price of £1,395,000. Full-scale production of the Spitfire began at Supermarine’s facility in Woolston, Southampton, but it quickly became clear that the order could not be completed in the 15 months promised. Supermarine was a small company, already busy building Walrus and Stranraer flying boats, and Vickers was busy building the Wellingtons. The initial solution was to subcontract the work. The first production Spitfire rolled off the assembly line in mid-1938, and was flown by Jeffrey Quill on 15 May 1938, almost 24 months after the initial order.
The final cost of the first 310 aircraft, after delays and increased programme costs, came to £1,870,242 or £1,533 more per aircraft than originally estimated. Production aircraft cost about £9,500. The most expensive components were the hand-fabricated and finished fuselage at approximately £2,500, then the Rolls-Royce Merlin engine at £2,000, followed by the wings at £1,800 a pair, guns and undercarriage, both at £800 each, and the propeller at £350.