Hawker Hunter - WikiHQ

The Hawker Hunter is a transonic British jet-powered fighter aircraft that was developed by Hawker Aircraft for the Royal Air Force (RAF) during the late 1940s and early 1950s. It was designed to take advantage of the newly developed Rolls-Royce Avon turbojet engine and the swept wing, and was the first jet-powered aircraft produced by Hawker to be procured by the RAF. On 7 September 1953, the modified first prototype broke the world air speed record for aircraft, achieving a speed of .

The single-seat Hunter was introduced to service in 1954 as a manoeuvrable day interceptor aircraft, quickly succeeding first-generation jet fighters in RAF service such as the Gloster Meteor and the de Havilland Venom. The all-weather/night fighter role was filled by the Gloster Javelin. Successively improved variants of the type were produced, adopting increasingly more capable engine models and expanding its fuel capacity among other modifications being implemented. Hunters were also used by two RAF display teams: the Black Arrows, who on one occasion looped a record-breaking 22 Hunters in formation, and later the Blue Diamonds, who flew 16 aircraft. The Hunter was also widely exported, serving with a total of 21 overseas air forces.

During the 1960s, following the introduction of the supersonic English Electric Lightning in the interceptor role, the Hunter transitioned to being operated as a fighter-bomber and for aerial reconnaissance missions, using dedicated variants for these purposes. Two-seat variants remained in use for training and secondary roles with the RAF and the Royal Navy until the early 1990s. Sixty years after its original introduction it was still in active service, being operated by the Lebanese Air Force until 2014.

The Hunter saw combat service in a range of conflicts with several operators, including the Suez Crisis, the Aden Emergency, the Sino-Indian War, the Indo-Pakistani War of 1965, the Indo-Pakistani War of 1971, the Rhodesian Bush War, the Second Congo War, the Six-Day War, the War of Attrition and the Yom Kippur War. Overall, 1,972 Hunters were manufactured by Hawker Aircraft and its successor, Hawker Siddeley, as well as being produced under licence overseas. In British service, the Hunter was replaced in its principal roles by the Lightning, the Hawker Siddeley Harrier and the McDonnell Douglas F-4 Phantom II.

Development

Background

thumb|upright|RAF Hunters of the [[Black Arrows performing aerobatics at Farnborough Airshow, 1960]]

In late 1945, as the Second World War came to a close, the Attlee government came to power in Britain. The new government's initial stance on defence was that no major conflict would occur for at least a decade, and thus there would be no need to procure any new aircraft until 1957. In accordance with this policy, aside from a small number of exceptions, the majority of Specifications issued by the Air Ministry for fighter-sized aircraft during the late 1940s were restricted to research purposes. Aviation author Derek Wood describes this policy as being: "a fatal error of judgement which was to cost Britain a complete generation of fighters and heavy bomber aircraft". By this time, it had also become apparent that newly developed jet propulsion would form the future of fighter aircraft development. Many companies were quick to devise their own designs to harness this means of propulsion. Hawker Aviation's chief designer, Sydney Camm, had proposed the Hawker P.1040 for the RAF, but the demonstrator failed to interest them. Further modifications to the basic design resulted in the Hawker Sea Hawk carrier-based fighter for the Royal Navy. However, the Sea Hawk possessed a straight wing and was powered by the Rolls-Royce Nene turbojet engine, both features that rapidly became obsolete.

An "experimental aircraft for investigation into the controllability and stability of swept wings at low speeds" was the subject of Air Ministry issued Specification E.38/46. Sydney Camm designed the Hawker P.1052, which was essentially a Sea Hawk outfitted with a 35-degree swept wing. Performing its first flight in 1948, the P.1052 demonstrated good performance and conducted several carrier trials, but was ultimately determined to not warrant further development into a production aircraft. Following interest from the Australian government – which was seeking an all-round jet fighter to replace Mustangs operated by the RAAF – Hawker reworked the second P.1052 prototype into the Hawker P.1081. This had swept tailplanes, a revised fuselage, and a single jet exhaust at the rear. On 19 June 1950, the P.1081 conducted its maiden flight. However, as the needs of the RAAF, in the Korean War, had become more urgent, Australia instead ordered a mature design, the Gloster Meteor. Further development of the P.1081 was stalled by difficulties with the engine's reheat. In 1951, the sole P.1081 prototype was lost in a crash.

P.1067

A day interceptor powered by a single axial compressor jet engine – either the Rolls Royce AJ.65 (later known as the Avon), or the Metrovick F.9 (later known as the Armstrong Siddeley Sapphire) – was the subject of Air Ministry Specification F.43/46, in 1946. The interceptor was to be capable of mounting a radical weapon that would remain purely hypothetical: a 4.5 inch (114 mm) recoilless cannon. In response, Camm designed a swept-wing aircraft powered by a RR Avon. The major advantages of axial compressor jets were greater thrust and a much smaller engine diameter; the Avon engine output roughly the same power as two Rolls-Royce Derwents (the powerplant of the Gloster Meteor, which was to be replaced by the fighter proposed under F.43/46).

In March 1948, the Air Ministry replaced Specification F.43/46 with Specification F.3/48, which demanded a speed of 629 mph (1,010 km/h) at 45,000 ft (13,700 m) and a high rate of climb, while carrying an armament of four or two 30 mm (1.18 in) cannon (rather than the large-calibre gun demanded by the earlier specification). As the Hawker P.1067, Camm's 1946 design was adopted for the new Specification. Initially fitted with a single air intake in the nose and a T-tail, the project rapidly evolved into the more familiar Hunter shape. The intakes were moved to the wing roots to make room for weapons and radar in the nose, and a more conventional tail arrangement was devised as a result of stability concerns.

While the RAF itself had little direct involvement in the Korean War, it underlined the need for new interceptors. This was felt to be so pressing that the RAF was willing to consider accepting interim fighter aircraft, while more capable fighters would continue to be pursued. In particular, the RAF felt that a pair of proposed fighter aircraft from Hawker Aircraft and Supermarine were of high importance and thus placed orders for these proposed fighters 'off the drawing board' in 1950. The reasoning behind these two aircraft being ordered in 1950 was intended to serve as an insurance policy in the event of either one of these projects failing to produce a viable aircraft; these two aircraft would later become known as the Supermarine Swift and the Hawker Hunter respectively.

thumb|left|The prototype Hunter WB188, modified to Mark 3 standard, displayed in its world speed record colours in 1976.

thumb|left|"Miss Demeanour" – a privately owned Hawker Hunter F.58A, 2007.

On 20 July 1951, the P.1067 made its maiden flight, flown by Neville Duke, from RAF Boscombe Down, powered by a single 6,500 lbf (28.91 kN) Avon 103 engine. The second prototype, which was fitted with production-standard avionics, armament and a Avon 107 turbojet, first flew on 5 May 1952. As an insurance against development problems on the part of the Avon engine, Hawker modified the design to accommodate another axial turbojet, the Armstrong Siddeley Sapphire 101. Fitted with a Sapphire, the third prototype flew on 30 November 1952.

On 16 March 1953, the first production standard Hunter F.1, fitted with a single Avon 113 turbojet, made its first flight. The first 20 aircraft were, in effect, a pre-production series and featured a number of "one-off" modifications such as blown flaps and area ruled fuselage. On 7 September 1953, the sole Hunter Mk 3 (the modified first prototype, WB 188) flown by Neville Duke broke the world air speed record for jet-powered aircraft, attaining a speed of over Littlehampton, West Sussex. This world record stood for less than three weeks before being broken on 25 September 1953 by the Hunter's early rival, the Supermarine Swift, flown by Michael Lithgow.

Design

Overview

thumb|The cockpit of a preserved Hunter

The Hunter entered service with the Royal Air Force as an interceptor aircraft. It was the first jet aircraft produced by Hawker for the RAF. From the outset it was clear that the type had exceptional performance, being the first RAF aircraft capable of effectively matching the English Electric Canberra bomber. The Hunter also set numerous aviation records, including absolute speed records. The type was also lauded for its quick turnaround time, enabled by features such as its removable gun pack and pressurised fuelling system, and for its easy handling in flight. the Hunter proved far more successful, and had a lengthy service life with various operators, in part due to its low maintenance requirements and operating costs, while further development of the Swift programme was cancelled in 1955.

As the RAF received newer aircraft capable of supersonic speeds to perform the air interceptor role, many Hunters were modified and re-equipped for undertaking ground-attack and reconnaissance missions instead. Hunters deemed surplus to the RAF's requirements were also quickly refurbished for continued service abroad. The Hunter would be procured by a considerable number of foreign nations. In addition to former RAF aircraft, roughly half of the nearly 2,000 Hunters produced had been manufactured specifically for overseas customers. The Hunter would be in operational service with the RAF for over 30 years. As late as 1996, hundreds were still in active service with various operators across the world.

Armament and equipment

thumb|upright|A Hunter's removable weapons pack. In the foreground are the ADEN cannons.

The single-seat fighter versions of the Hunter were armed with four 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. Later versions of the Hunter were fitted with SNEB pods; these were rocket projectiles in 18-round Matra pods, providing an effective strike capability against ground targets.

The Hunter featured a nose-mounted ranging radar, providing range input to the gyro gunsight for air-to-air gunnery only. Typically, export Hunters were equipped to be compatible with additional types of missiles, such as the AIM-9 Sidewinder air-to-air missile and the AGM-65 Maverick air-to-surface missile.

Late-production F.6s also featured an "all-moving tailplane", in which the entire tailplane pivoted to provide better transonic flight control. The elevator was retained as part of the all-moving tailplane.

The airframe of the Hunter consists of six interchangeable major sections: the forward fuselage (housing the cockpit and armament pack), center fuselage (including the integral wing roots and air duct intakes), rear fuselage, tail unit assembly, and two individually produced wings. Production was divided up so major sections could be completed individually and manufacturing of the type could be dispersed to reduce vulnerability to attack. Establishing initial full-rate production for the type was difficult, as manufacturing the Hunter required the development of 3,250 tool designs and the procurement of 40,000 fixtures, jigs, and tools.

Engine

thumb|The tail and rear fuselage are detachable, providing maintenance access to the aircraft's single engine

The P.1067 first flew from RAF Boscombe Down in Wiltshire on 20 July 1951, powered by a Rolls-Royce Avon 103 engine from an English Electric Canberra bomber. The practice of "fuel dipping", reducing fuel flow to the engine when the cannon were fired, was a satisfactory solution.

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 of thrust, and was the engine for the Hunter F.6.

Operational history

Royal Air Force

thumb|Hunter T.7 of the Empire Test Pilots' School, [[Farnborough Air Show, September 1959]]

The Hunter F.1 entered service with the Royal Air Force in July 1954. It was the first high-speed jet aircraft equipped with radar and fully powered flight controls to go into widespread service with the RAF. The Hunter replaced the Gloster Meteor, the Canadair Sabre, and the de Havilland Venom jet fighters in service. Initially, low internal fuel capacity restricted the Hunter's performance, giving it only a maximum flight endurance of about an hour. A fatal accident occurred on 8 February 1956, when a flight of eight Hunters was diverted to another airfield owing to adverse weather conditions. Six of the eight aircraft ran out of fuel and crashed, killing one pilot.

Another difficulty encountered during the aircraft's introduction was the occurrence of surging and stalling with the Avon engines. The original split-flap airbrakes caused adverse changes in pitch trim and were quickly replaced by a single ventral airbrake. This meant, however, that the airbrake could not be used for landings. A distinctive Hunter feature added on the F.4 was the pair of blisters under the cockpit, which collected spent ammunition links to prevent airframe damage. Crews dubbed them "Sabrinas" after the contemporary movie star. For most of the conflict the Hunters engaged in local air defence due to their lack of range.

During the Brunei Revolt in 1962, the Royal Air Force deployed Hunters and Gloster Javelins over Brunei to provide support for British ground forces; Hunters launched both dummy and real strafing runs on ground targets to intimidate and pin down rebels. In one event, several Bruneian and expatriate hostages were due to be executed by rebels. Hunter aircraft flew over Limbang while Royal Marines from 42 Commando rescued the hostages in a fierce battle.

The Hunter F.6 was retired from its day fighter role in the RAF by 1963, being replaced by the much faster English Electric Lightning interceptor.

thumb|Hunter F.6A in flight near [[RAF Abingdon, 1979]]

In Aden in May 1964, Hunter FGA.9s and FR.10s of No. 43 Squadron RAF and No. 8 Squadron RAF were used extensively during the Radfan campaign against insurgents attempting to overthrow the Federation of South Arabia. SAS forces would routinely call in air strikes that required considerable precision, and, predominantly using 3-inch high explosive rockets and 30 mm ADEN cannon, the Hunter proved an able ground-attack platform. Both squadrons continued operations with their Hunters until the UK withdrew from Aden in November 1967.

Hunters were flown by No.63, No. 234 and No. 79 Squadrons acting in training roles for foreign and Commonwealth students. These remained in service until after the Hawk T.1 entered service in the mid-1970s. Two-seat trainer versions of the Hunter, the T.7 and T.8, remained in use for training and secondary roles by the RAF and Royal Navy until the early 1990s; when the Blackburn Buccaneer retired from service. The requirement for Hunter trainers disappeared so the Buccaneer-orientated trainers were retired, leaving the RN T.8Ms to soldier on for a while longer.

Royal Danish Air Force

As early as 1953 the first Hunter flew over Denmark, when test pilot Neville Duke demonstrated the F.1 over Copenhagen Airport. During this demonstration, the pilot broke the sound barrier in a shallow dive.

Air Force officials were very impressed with the demonstration and since the Royal Danish Air Force (RDAF) were looking for a replacement for the Gloster Meteors in service at the time, the Hunter was a natural choice. Consequently, a contract for delivery of 30 F.51 was signed on 3 July 1954. RDAF took delivery of the first two of these on 31 January 1956 and nine months later all 30 Hunters had been delivered to 724 Squadron.

Since the Hunter was a significantly different aircraft to fly, compared to older types such as the Meteor, the need for a two-seat trainer soon arose, and the RDAF took delivery of two T.53 two-seat trainers in 1958.

In contrast to most other users of the Hunter, RDAF never converted the Hunter to the fighter-bomber role. Although some studies and experiments carried out in 1959, the project never materialised and the Hunter carried on as a day fighter until its retirement in 1974.

The last flight of the Hunter in RDAF service was carried out on 30 April 1974. The entire fleet was initially preserved at Aalborg Air Base, in the hopes of a future sale to other users. No such sale was ever carried out, but 16 F.51s and four T.53 (two additional T.53 had been purchased from the Netherlands in 1967) were sent back to Hawker Siddeley in December 1975. Ultimately, most Hunters were sold either to private buyers or to military museums around the world. Only one example (47-401/E-401) was reserved for museum use in Denmark and currently resides in Danmarks Flymuseum in Stauning. at the same time that Pakistan announced its purchase of several North American F-86 Sabre jet fighters. The Indian Air Force (IAF) was the first to operate the Hunter T.66 trainers, placing an initial order in 1957. The more powerful engine was considered beneficial in a hot environment, allowing for greater takeoff weights. During the 1960s, Pakistan investigated the possibility of buying as many as 40 English Electric Lightnings, but Britain was unenthusiastic about the potential sales opportunity because of the damage it would do to its relations with India, which at the time was still awaiting the delivery of large numbers of ex-RAF Hunters.

By the outbreak of the Sino-Indian War in 1962, India had assembled one of the largest air forces in Asia, and the Hunter was the nation's primary and most capable interceptor. During the conflict, the Hunter demonstrated its superiority over China's Russian-sourced MiGs and gave India a strategic advantage in the air.