Supermarine Spitfire

• 1. Introduction

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  The Supermarine Spitfire first lifted off the ground on the 5th of March 1936, an eight-minute flight from Eastleigh Aerodrome. At the controls was Captain Joseph "Mutt" Summers, chief test pilot for Vickers, who touched down and reportedly told the ground crew just four words: "don't touch anything." That quiet confidence in the machine would prove prophetic. Here was a fighter designed to meet a peacetime specification, yet it would become the only British aircraft in continuous production before, during, and after the Second World War. How does a design born from the frustration of losing a government competition evolve into something that pilots described as almost alive? And how did a small Southampton company, already stretched building flying boats, keep this aircraft flying and fighting through every campaign from the English Channel to the jungles of Southeast Asia?

• 2. The Designer and His Obsession

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  R. J. Mitchell, chief designer at Supermarine Aviation Works, had already suffered a significant defeat before the Spitfire took shape. In 1934, his Supermarine Type 224, an open-cockpit monoplane with bulky gull wings and a fixed undercarriage powered by the 600 hp Rolls-Royce Goshawk, made its first flight and promptly lost a competition to the Gloster Gladiator biplane. The experience stung. Mitchell and his team immediately set about a series of cleaned-up designs, drawing on hard lessons learned from their Schneider Trophy seaplanes.

  The result was the Type 300, steadily refined to include a retractable undercarriage, enclosed cockpit, and the newly developed Rolls-Royce PV XII V-12 engine, later named the Merlin. On the 1st of December 1934, the Air Ministry issued contract AM 361140/34, providing £10,000 for the construction of what would become the Spitfire. By April 1935, a discussion with Squadron Leader Ralph Sorley had settled the aircraft's armament at eight guns, dropping the fuel tanks from 94 gallons to 75 to save weight.

  Mitchell worked on the design with a deadline he may not have known he had. He was diagnosed with cancer, and he died in 1937 before the aircraft entered production. His colleague Joseph Smith took over as chief designer and guided the Spitfire through every variant that followed, from the Mk 1 to the Griffon-engined Mk 24. Jeffrey Quill, the test pilot who flew the first production aircraft on the 15th of May 1938, later wrote of Smith: "If Mitchell was born to design the Spitfire, Joe Smith was born to defend and develop it."

• 3. The Elliptical Wing

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  Beverley Shenstone, the aerodynamicist on Mitchell's team, designed the wing that made the Spitfire distinctive. In 1934, the design team needed a solution to two conflicting demands: the wing had to be thin enough to reduce drag for high speed, yet thick enough at the root to house a retractable undercarriage and eight guns. An elliptical planform, Shenstone explained, was the most efficient aerodynamic shape for an untwisted wing, producing the lowest amount of induced drag. The ellipse was skewed so the centre of pressure aligned with the main spar, preventing the wings from twisting under load.

  Critics later suggested Mitchell had borrowed the shape from the Heinkel He 70, a German aircraft that first flew in 1932. Shenstone rejected this directly, noting that the Spitfire wing was much thinner with a different cross-section, and copying from an aircraft designed for an entirely different purpose would have been "simply asking for trouble." The wing section came from the NACA 2200 series, adapted to a thickness-to-chord ratio of 13% at the root, reducing to 9.4% at the tip.

  At high speeds, however, the wing that gave the Spitfire its grace created serious problems. The Royal Aircraft Establishment measured that at 400 miles per hour indicated airspeed, roughly 65% of aileron effectiveness was lost due to wing twist. The new wing designed for the Spitfire F Mk 21 addressed this directly: its stiffness was increased by 47%, and a redesigned aileron with piano hinges raised the theoretical aileron reversal speed from 580 mph to 825 mph. The ellipse that had been "theoretically a perfection" when first drawn in 1934 was, by the war's end, being pushed toward its limits.

• 4. Production Under Fire

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  The Air Ministry's first order for 310 Spitfires, placed on the 3rd of June 1936 at a cost of £1,395,000, came before any formal test report had been issued. The production that followed was painful. Supermarine was a small company already building Walrus and Stranraer flying boats; Vickers, the parent company, was building Wellington bombers and was slow to release blueprints to subcontractors. The promised rate of five aircraft a week, guaranteed by Vickers-Armstrong director Sir Robert MacLean, was never met. The first production Spitfire rolled off the assembly line in mid-1938, almost 24 months after the initial order. The final cost for those first 310 aircraft came to £1,870,242, more than £1,533 over the original estimate per aircraft.

  The second major factory, the Castle Bromwich Aircraft Factory built in Birmingham in 1938, nearly failed entirely. By May 1940, with the Battle of France under way, the factory had not yet completed a single Spitfire. On the 17th of May, Minister of Aircraft Production Lord Beaverbrook telephoned Lord Nuffield and arranged for control of the plant to pass to his ministry. Experienced staff from Supermarine moved in. Within weeks, 10 Mk IIs were built in June, 23 in July, 37 in August, and 56 in September. By June 1945, when production at Castle Bromwich ended, a total of 12,129 Spitfires had been built there, comprising 921 Mk IIs, 4,489 Mk Vs, 5,665 Mk IXs, and 1,054 Mk XVIs.

  On the 26th of September 1940, Luftwaffe bombing destroyed both main Supermarine factories at Woolston and Itchen near Southampton, killing 92 people, most of them experienced production workers. The production apparatus had already been partly dispersed by the 20th of September. Requisitioned sites across the region took over: Vincent's Garage in Station Square, Reading, produced fuselages; Anna Valley Motors in Salisbury became the sole producer of wing leading-edge fuel tanks for photo-reconnaissance Spitfires. The drawing office moved to Hursley Park, near Winchester. Finished aircraft were transported to airfields on Commer "Queen Mary" low-loader trailers for final assembly and testing.

• 5. Battle of Britain and Beyond

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  The Spitfire entered RAF service on the 4th of August 1938, when the first Mk I, K9789, joined 19 Squadron at RAF Duxford. During the Battle of Britain, fought from July to October 1940, the Hurricane outnumbered the Spitfire and flew more sorties against the Luftwaffe. The Spitfire's assignment was more specific: to counter the German escort fighters, mainly the Messerschmitt Bf 109E series, while Hurricane squadrons targeted the bombers. Spitfire units recorded a lower attrition rate and a higher victory-to-loss ratio than Hurricane units throughout the battle.

  Well-known pilots who flew the Spitfire through the battle and beyond included "Johnnie" Johnson, credited with 34 enemy aircraft shot down across a career that ran from late 1940 to 1945. "Paddy" Finucane scored 28-32 victories in the type before disappearing over the English Channel in July 1942. Commonwealth pilots contributed substantially: George Beurling from Canada was credited with 31 enemy aircraft, "Sailor" Malan from South Africa with 27, and New Zealander C F Gray also with 27.

  After Britain, the aircraft spread across theatres where conditions tested different limits. On the 7th of March 1942-15 Mk Vs carrying 90 imperial gallon fuel tanks under their fuselages flew 600 miles from off the coast of Algeria to reach Malta, the first Spitfires to see service outside Britain. In the Pacific, the aircraft met the Mitsubishi A6M Zero, which could out-turn it and sustain steeper climbs. Air superiority in Southeast Asia improved when the Mk VIII replaced the earlier Mk V, though the theatre remained lower priority than Europe throughout the war. Over Darwin, Australian and RAF Spitfires assigned to No. 1 Wing RAAF defended the port against Japanese Naval Air Force attacks, suffering heavy losses in part because of the Spitfire's limited fuel capacity.

• 6. The Fuel Problem and Tilly Shilling

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  One tactical liability of the early Spitfire had nothing to do with the airframe. The Rolls-Royce Merlin used a carburettor rather than fuel injection, which meant that when a pilot pushed the nose down into a steep dive, the negative g-force cut fuel flow to the engine. A Luftwaffe Bf 109E pilot could escape a Spitfire attack simply by "bunting" into a high-power dive, leaving the pursuing Spitfire behind with a sputtering engine. RAF pilots learned to half-roll before diving, but the disadvantage remained.

  In March 1941, a practical fix arrived. A metal disc with a hole was fitted in the fuel line, restricting fuel flow to the maximum the engine could consume. It did not fully solve the problem of fuel starvation in a dive, but it reduced the more serious risk of the carburettor being flooded by fuel pumps under negative g. The device was invented by Beatrice "Tilly" Shilling, and it became known informally as "Miss Shilling's orifice." A more complete solution, Bendix-manufactured pressure carburettors designed to allow fuel flow in all flight attitudes, arrived in 1942.

  Sir Stanley Hooker, one of the Merlin's designers, later argued the carburettor carried its own advantage. Because the fuel was fed before the supercharger, it evaporated and cooled the intake air by 25 degrees Celsius. That cooling enhanced supercharger performance and increased engine power, particularly at high altitude. The German decision to use fuel injection, Hooker wrote in his autobiography, came with a large penalty on that measure of performance.

• 7. Speed at the Edge

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  Beginning in late 1943, Farnborough engineers chose a Spitfire XI for high-speed diving trials because it had the highest limiting Mach number of any aircraft then available. A fully feathering Rotol propeller was fitted to prevent overspeeding. During these trials, aircraft EN409, flown by Squadron Leader J. R. Tobin, reached 606 mph (Mach 0.891) in a 45-degree dive.

  In April 1944, EN409 was pushed further. Squadron Leader Anthony F. Martindale of the Royal Air Force Volunteer Reserve was flying another dive when the propeller and reduction gear broke off. The aircraft reached Mach 0.92, the fastest ever recorded in a piston-engined aircraft. With the propeller gone and the nose suddenly light, the Spitfire pitched into a zoom climb back to altitude. Martindale blacked out under 11 g loading. When he regained consciousness, the aircraft was at roughly 40,000 feet and its originally straight wings had bent slightly backward. He glided the aircraft 20 miles back to the airfield and landed safely. He was awarded the Air Force Cross.

  On the 5th of February 1952, a Spitfire 19 of 81 Squadron based at Kai Tak, Hong Kong, climbed to 50,000 feet indicated altitude on a routine meteorological survey. The pilot, Flight Lieutenant Edward "Ted" Powles, found his cabin pressure dropping below safe levels and entered an uncontrollable dive, eventually regaining control below 3,000 feet with no discernible damage. Evaluation of the recorded data suggested he reached 690 mph, approximately Mach 0.96, which would have been the highest speed ever reached by a propeller-driven aircraft. The last operational sortie of any RAF Spitfire was flown on the 1st of April 1954, by PS888, a PR Mk 19 of 81 Squadron, photographing jungle in Johore, Malaysia, with the words "The Last" painted on its nose.

• 8. What Survives

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  Approximately 240 Spitfires were preserved as of 2025, with around 70 airworthy. The oldest surviving example is a Mark 1, serial number K9942, preserved at the Royal Air Force Museum Cosford in Shropshire. It was the 155th built, first flew in April 1939, flew operationally with No. 72 Squadron RAF until June 1940, and was eventually allocated to the Air Historical Branch in August 1944 for future preservation.

  In July 2015 at Christie's in London, a restored Mk I Spitfire became one of only four flying Mk I examples at the time and sold for a record £3.1 million, beating a previous Spitfire auction record of £1.7 million set in 2009. A fifth Mk I example, P9372, completed its first post-restoration flight on the 22nd of April 2025.

  Five airworthy Spitfires are maintained as part of the Battle of Britain Memorial Flight, a squadron within the RAF used at air shows. Among them, PM631, a PR Mk 19, was flown in late 1962 in mock combat against an English Electric Lightning F 3 supersonic interceptor at RAF Binbrook. RAF pilots concluded that the Lightning's Firestreak infra-red missiles had trouble acquiring the Spitfire because of its low exhaust temperature, and that the only effective approach was to use full afterburner at a lower altitude and circle behind it for a hit-and-run attack, a tactic contrary to all established fighter-on-fighter doctrine at the time.