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The Hawker Typhoon was a British single-seat fighter-bomber, produced by Hawker Aircraft. While the Typhoon was designed to be a medium-high altitude interceptor, and a direct replacement for the Hawker Hurricane, several design problems were encountered and the Typhoon never completely satisfied this requirement. Other, external events in 1940 prolonged the gestation of the Typhoon.
Nicknamed the Tiffy in RAF slang, the Typhoon's service introduction was also plagued with problems and for several months the aircraft faced a doubtful future. However in 1941 the Luftwaffe brought the formidable Focke-Wulf Fw 190 into service. As the only fighter in the RAF inventory capable of catching the Fw 190 at low altitudes the Typhoon secured a new role as a low altitude interceptor. In addition the Typhoon won the support of pilots such as Roland Beamont. Through their dedication the Typhoon established itself in roles such as night-time intruder and a long range fighter. From late 1942 the Typhoon was equipped with bombs; from late 1943 ground attack rockets were added to the Typhoon's armoury. Using these two weapons the Typhoon became one of the Second World War's most successful ground-attack aircraft.
Even before the new Hurricane was rolling off the production lines in March 1937, Sydney Camm had moved on to designing its replacement. This was to be a large fighter designed around the large and more powerful 24 cylinder Napier Sabre engine. The work proved useful when Hawker received Specification F.18/37 from the Air Ministry in January 1938 which asked for a fighter based around either the Sabre or the Rolls-Royce Vulture engine. Both engines used 24 cylinders and were designed to be able to deliver over 2,000 hp (1,491 kW); the difference between the two was primarily in the arrangement of the cylinders — an H-block in the Sabre and an X-block in the Vulture.
The two designs became known as the "R" and "N" (from the initial of the engine manufacturer) and were very similar; the Vulture-powered R type (the Tornado) had a rounder nose profile and a ventral radiator, whereas the Sabre-powered N (the Typhoon) had a flatter deck and a chin-mounted radiator. The basic design of both was a combination of traditional Hawker and more modern construction techniques; the front fuselage structure, from the engine mountings to the rear of the cockpit, was made up of bolted and welded duralumin or steel tubes while the rear fuselage was a flush riveted, semi-monocoque structure. The forward fuselage and cockpit skinning was made up of large, removable duralumin panels allowing easy external access to the engine and engine accessories and most of the important hydraulic and electrical equipment.
The design used a large 41 ft 7 in (12 m) shallow-angle inverted gull wing of NACA 22 wing section, with a thickness to chord ratio of 19.5% at the root tapering to 12% at the tip; this was much thicker than those on designs like the Supermarine Spitfire. This wing had great structural strength, provided plenty of room for fuel tanks and a heavy armament, and helped the aircraft to be a steady weapons platform. Wing area was 279 sq ft (29.6 sq m). The inner wings, outboard of the fuselage had a 1º anhedral while the outer wings, attached to the inner just outboard of the undercarriage legs, had a dihedral of 5½º. Each of the inner wings incorporated two fuel tanks; the "main" tanks, housed in a bay outboard and to the rear of the main undercarriage bays, had a capacity of 40 gallons while the "nose" tanks, built into the wing leading edges, forward of the main spar[9], had a capacity of 37 gallons each.[9][14] Also incorporated into the inner wings was an undercarriage with a track of 13 ft 6¾ in. Although the Typhoon was expected achieve 460 mph (740 km/h) in level flight, at just over 400 mph (644 km/h) the thick wings created a large drag rise and prevented higher speeds. Tests revealed that the Typhoon was capable of 410 mph at 20,000 feet although the climb rate and performance above that level was considered disappointing. If the Typhoon was dived at speeds of over 500 mph (805 km/h) the drag rise led to buffeting and trim changes. The problems with compressibility led to Camm designing thinner wings with a laminar flow section, leading to the Tempest as a follow on to the Typhoon.
The first flight of the first Typhoon prototype, P5212, made by Hawker's Chief test Pilot Philip Lucas from Langley, was delayed until 24 February 1940 because of the problems with the development of the Sabre engine. On 9 May 1940 the prototype suffered from a mid-air structural failure, at the join between the forward fuselage and rear fuselage, just behind the pilot's seat. Philip Lucas could see daylight through the split but, instead of baling out, he was able to land the stricken Typhoon and was later awarded the George Medal. On 15 May the Minister of Aircraft Production, Lord Beaverbrook, ordered that resources should be concentrated on the production of five main aircraft types (Spitfire, Hurricane, Whitley, Wellington and the Blenheim). As a result development of the Typhoon was slowed, production plans were postponed and test flying continued at a reduced rate.
A second prototype, P5216 first flew on 3 May 1941. In the meantime the Air Ministry had given Hawker an instruction to proceed with the construction of 1,000 of the new fighters. It was felt that the Vulture engine was more promising so the order covered 500 Tornadoes, 250 Typhoons with the balance to be decided once the two had been compared. It was also decided that because Hawker was dealing with increasing Hurricane production the Tornado would be built by Avro while Gloster would build the Typhoons at Hucclecote. As a result of good progress by Gloster the first production Typhoon R7576 was first flown on 27 May 1941 by Michael Daunt, just over three weeks after the second prototype.
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