The Supermarine Spitfire

Rarely are a commercial product and a major historical event so popularly linked as the Supermarine Spitfire and the Battle of Britain. The Spitfire's basic credentials – an outstandingly beautiful airframe, cutting-edge technology, and a Rolls-Royce Merlin engine – merge naturally with the nonchalant heroism of the young men who fought off the German Luftwaffe during the summer and autumn of 1940. But it became an all-time classic fighter aircraft in spite of itself. To say the least, the Spitfire was idiosyncratic and in some respects far from a perfect design.

The Spitfire in flight

An unusual feature of the Spitfire design was the twist in its elliptical wing. The angle of incidence of the wing was plus 2 degrees at its root (where it joins the fuselage) and minus half a degree at the wing tip. The wing roots therefore stalled before the wing tips, reducing the tendency to roll and improving manoeuvrability at low speeds. This was a great advantage in combat when performing tight turns as close as possible to the plane's limits.

The bulged cockpit canopy provided especially good visibility whilst in flight (especially compared to the German Messerschmitt Bf-109E). Pilots previously used to open cockpits often found the closed canopy claustrophobic and flew with it open. On the ground with the tailplane down, the Spitfire's long nose obscured the forward view and to see where they were going pilots had to swing the tail from side to side as they taxied. Many were not familiar with a retractable undercarriage and forgot to raise it on takeoff or to lower it on landing. The forward landing wheels were quite close together (so that the undercarriage could fold away into the plane's relatively shallow wings). Together with the undercarriage's rather fragile construction, this made crosswind landings somewhat hazardous.

As a combat aircraft, the Spitfire's flying performance against that of its foe was obviously of fundamental importance. Until the autumn of 1941 its main adversary was the Messerschmitt. The two were fairly evenly matched, the Spitfire being more manoeuvrable and faster at low level but the ME 109 better in the climb and slightly faster at a higher altitude.

Their respective engines also behaved differently. The Messerschmitt's fuel-injected Daimler-Benz engine did not have the disadvantage of the Spitfire's float-type carburettor causing the engine to cut out during certain manoeuvres. Another weakness of the Spitfire was the heavy stick force the pilot had to contend with from the ailerons when flying at high speed. Although the plane's design was under constant development throughout the war, this aspect was never properly cured.

The Spitfire had a fuel tank directly in front of the pilot, between the engine and the cockpit. The high-octane fuel used in high intensity air combat put the pilot at high risk. A single enemy bullet could ignite the fuel, filling the cockpit with roaring flame. The pilot's only escape was to pull back the canopy and flip the plane upside down in the hope of a safe escape by parachute, all in the space of about eight seconds. Many suffered horrific burns, their hands and faces completely erased by fire. The injury was given its own name – Airman's Burn – and led to the development of new forms of severe burns treatment by the RAF surgeon Archibald McIndoe at a cottage hospital in East Grinstead. His patients were to form the now celebrated Guinea Pig Club which still exists to this day and whose President is His Royal Highness The Prince Philip.

By the time the The Mk V design was introduced early in 1941 the Spitfire had become the full equal of the Messerschmitt Bf-109F, and various modifications were available for different fighting conditions. These included extended or 'clipped' wing tips for high or low altitude performance, sand filters for the North African desert, and various combinations of both cannons and machine guns (some even carried bombs). The carburettor was also improved to prevent engine cut-out under negative 'G'.

Late in 1941 Germany brought out the Focke-Wulf Fw-190 and for a time the Spitfire was outmatched, but an Fw-190 was captured in 1942 and was used to test further developments of the Spitfire. This resulted in the Mk IX, comparing favourably with a much improved rate of climb and top speed. By 1944 the Spitfire Mk XIV was in use, polished gunless versions intercepting German V1 flying bombs either by shooting them down or sending them off course by flying up close and upsetting their internal gyros with the plane's wing tips. The Spitfire F.21 entered service early in 1945, some of which were fitted with contra-rotating propellers to improve handling under power and make the plane more stable as a gun platform.

During tests in 1944 a Spitfire Mk XI, fitted with a special propeller and flown in a 45 degree dive, achieved a speed of 606 mph, although the propeller broke and the pilot had to glide the 20 miles back to the airfield. The highest ever recorded altitude for any Spitfire was 51,550 feet during a survey flight over Hong Kong in 1952. When the pilot, Flight Lieutenant Ted Powles, tried to reduce altitude to raise the cabin pressure the plane dived – shaking out of control – all the way down to 3,000 feet, where at last he was able to recover it and land safely.

The origins of the Supermarine Spitfire

In the early 1930s the British Air Ministry was looking for a new eight-gunned monoplane fighter to counter the growing threat from the Luftwaffe. Vickers Supermarine Ltd of Southampton already had extensive experience of producing successful planes for the Schneider Trophy air races. The Supermarine S6B (pictured) won the 1931 contest and went on to set the world speed record, becoming first aircraft to exceed 400 mph. Supermarine put the Type 224 forward to the Air Ministry, an open-cockpit gull-winged design by their Chief Designer, R.J. Mitchell.

With its steam-cooled engine the Type 224 was slow, and the Air Ministry was unimpressed. Mitchell had already begun work on another prototype which would have a newly-developed Rolls-Royce Merlin engine and employ revolutionary techniques in airframe construction. Although it did not have room for eight guns, a wooden mock-up impressed the Air Ministry enough for Vickers to press ahead. Mitchell's new F37/34 had an elliptical wing with a much greater 'chord' (the distance from the front to the back of the wing) which allowed the guns to fit in the wings without increasing drag. It first flew in March 1936, reaching an impressive 350 mph.

Further official trials were held in May 1936, and in June the Royal Air Force placed a production order for 310, by which time the new fighter had been dubbed the "Spitfire". Mitchell died from illness in 1937 and the project taken on by Supermarine's new Chief Designer, Joseph Smith. The first production Spitfire Mk 1 was delivered in August 1938 and by May 1939, 19 Squadron Royal Air Force at Duxford was fully operational with sixteen planes. Ten more squadrons were operational by August. The Second World War began on 3rd September, and a squadron of Spitfires was first 'scrambled' on 16th October to meet German Ju 88s on their way to attack the Royal Navy at Rosyth.

[ October 3rd, 2006 ]