|Hawker Hunter F58 "Miss Demeanour - Photo Chris Lord|
At the end of the Second World War, it was apparent that jet propulsion would be the future of fighter development. Many companies were quick to come up with airframe designs for this new means of propulsion, among these was Hawker Aviation's chief designer, Sydney Camm. The origins of the Hunter trace back to the Hawker Sea Hawk straight-wing carrier-based fighter, which had originally been marketed towards the Royal Air Force rather than the Fleet Air Arm of the Royal Navy; however the demonstrator Hawker P.1040 did not attract the RAF's interest. The Sea Hawk had a straight wing and used the Rolls-Royce Nene turbojet engine, both features that rapidly became obsolete. Seeking better performance and fulfilment of the Air Ministry Specification E.38/46, Sydney Camm designed the Hawker P.1052, which was essentially a Sea Hawk with a 35-degree swept wing. First flying in 1948, the P.1052 demonstrated good performance and conducted several carrier trials, but did not warrant further development into a production aircraft. As a private venture, Hawker converted the second P.1052 prototype into the Hawker P.1081 with swept tailplanes, a revised fuselage, and a single jet exhaust at the rear. First flown on 19 June 1950, the P.1081 was promising enough to draw interest from the Royal Australian Air Force (RAAF), but further development was stalled by difficulties with the engine reheat. The sole prototype was lost in a crash in 1951.
The Hunter was a conventional all-metal monoplane with a retractable tricycle landing gear. The pilot sat on a Martin-Baker 2H or 3H ejector seat, while the two-seat trainer version used Mk 4H ejection seats. The fuselage was of monocoque construction, with a removable rear section for engine maintenance. The engine was fed through triangular air intakes in the wing roots and had a single jetpipe in the rear of the fuselage. The mid-mounted wings had a leading edge sweep of 35° and slight anhedral, the tailplanes and fin were also swept. The aircraft's controls were conventional but powered. A single airbrake was fitted under the ventral rear fuselage on production models.
The definitive version of the Hunter was the FGA.9, on which the majority of export versions were based. Although the Supermarine Swift was initially viewed more favourably politically, the Hunter proved to be far more successful, having a long life due to its low maintenance and operating costs. The Hunter served with the RAF for over 30 years, and as late as 1996 hundreds were still in active service in various parts of the world.
The single-seat fighter version of the Hunter was armed with four 30 mm (1.18 in) ADEN cannon, with 150 rounds of ammunition per gun. The cannon and ammunition boxes were contained in a single pack that could be removed from the aircraft for rapid re-arming and maintenance. Unusually, the barrels of the cannon remained in the aircraft while the pack was removed and changed. In the two-seat version, either a single 30 mm ADEN cannon was carried or, in some export versions, two, with a removable ammunition tank. A simple EKCO ranging radar was fitted in the nose. Later versions of Hunter aircraft were fitted with SNEB Pods; these were 68 mm (2.68 in) rocket projectiles in 18-round Matra pods, providing an effective strike capability against ground targets.
The rear fuselage can be removed to gain access to the engine for maintenance. The P.1067 first flew from RAF Boscombe Down on 20 July 1951, powered by a 6,500 lbf (28.91 kN) Avon 103 engine from an English Electric Canberra bomber. The second prototype was fitted with a 7,550 lbf (33.58 kN) Avon 107
turbojet. Hawker's third prototype was powered by an 8,000 lbf (35.59 kN) Armstrong Siddeley Sapphire 101. Production Hunters were fitted with either the Avon or the Sapphire engine. Early on in the Hunter's service the Avon engines proved to have poor surge margins, and worryingly suffered compressor stalls when the cannon were fired, sometimes resulting in flameouts. The practise of "fuel dipping", reducing fuel flow to the engine when the cannon were fired, was a satisfactory solution. Although the Sapphire did not suffer from the flameout problems of the Avon and had better fuel economy, Sapphire-powered Hunters suffered many engine failures. The RAF elected to persevere with the Avon in order to simplify supply and maintenance, since the same engine was also used by the Canberra bomber. The RAF sought more thrust than was available from the Avon 100 series; in response Rolls-Royce developed the Avon 200 series engine. This was an almost wholly new design, equipped with a new compressor to put an end to surge problems, an annular combustion chamber, and an improved fuel control system. The resulting Avon 203 produced 10,000 lbf (44.48 kN) of thrust, and was the engine for the Hunter F.6.