Supermarine Spitfire (early Merlin-powered variants)

Spitfire
Polish Spitfire VB from 303 (Polish) Squadron flown by S/Ldr Zumbach.
Role	Fighter
Manufacturer	Supermarine
Designer	R. J. Mitchell
First flight	5 March 1936
Introduction	1938
Retired	1955, RAF
Primary user	Royal Air Force
Produced	1938–1948
Number built	20,351
Variants	Seafire Spiteful

The British Supermarine Spitfire was the only Allied fighter aircraft of the Second World War to fight in front line service from the beginnings of the conflict, in September 1939, through to the end in August 1945. Post-war, the Spitfire's service career continued into the 1950s. The basic airframe proved to be extremely adaptable, capable of taking far more powerful engines and far greater loads than its original role as a short-range interceptor had called for. This would lead to 19 marks of Spitfire and 52 sub-variants being produced throughout the Second World War, and beyond. The many changes were made in order to fulfill Royal Air Force requirements and to successfully engage in combat with ever-improving enemy aircraft. With the death of the original designer, Reginald J. Mitchell, in June 1937, all variants of the Spitfire were designed by his replacement, Joseph Smith, and a team of engineers and draftsmen.

These articles present a brief history of the Spitfire through all of its variants, including many of the defining characteristics of each sub-type. This particular article deals only with Spitfire variants powered by early model Rolls-Royce Merlin engines, which mostly utilised single-speed, single-stage superchargers. The second article describes Spitfire variants powered by later model Merlins, featuring two-stage, two-speed superchargers, while the final article covers the later Spitfire variants which were powered by the larger Rolls-Royce Griffon engines.

The Spitfires with the single-stage Merlin engines used four different wing types, Type A, B, C and D wings, which had the same dimensions and plan but different internal arrangements of armament and fuel tanks. All Mk Is, IIs, and Vs and their derivatives had small, rectangular undercarriage indicator pins which projected at an angle from the upper wing surfaces when the undercarriage legs were locked down, providing a positive mechanical indication that the landing gears were indeed down and locked, since the pilot could not see the landing gear for himself. These were a backup to the indicator lights on the instrument panel, in case the lights malfunctioned or failed. All of these variants used Dunlop AH2061 tyres, mounted on alloy mainwheels which had five openings. The fixed, castering tailwheels used Dunlop AH2184 tyres.

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