Hawker-Siddeley Harrier

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Hawker-Siddeley Harrier
Image:Harrier gr3 over belize.jpg
RAF Harrier GR3, over Belize in 1982
Type	VTOL strike aircraft
Manufacturer	Hawker-Siddeley
Maiden flight	28 December 1967 (Harrier)
Introduced	1 April 1969
Primary users	Royal Air Force United States Marine Corps Spanish Navy Royal Thai Navy
Produced	1967 - ?
Developed from	Hawker P.1127/Kestrel FGA.1
Variants	Sea Harrier AV-8 Harrier II BAE Harrier II

The Hawker Siddeley Harrier GR.1/GR.3 and the AV-8A Harrier are the first generation of the Harrier series, the first operational close-support and reconnaissance fighter aircraft with V/STOL capabilities. The Harrier was the only truly successful V/STOL design of the many that arose from the 1960s.

The Harrier was extensively redeveloped, leading to the Harrier GR7/GR9 and AV-8B Harrier II, that were built by BAE Systems and Boeing.

[edit] Background

Main article: Hawker P.1127

The Hawker P.1127 and the Hawker-Siddeley Kestrel FGA.1 were the development aircraft that led to the Hawker-Siddeley Harrier.

[edit] P.1127

The Harrier family was started with the Hawker P.1127. Design began in 1957 by Sir Sydney Camm, Ralph Hooper of Hawker Aviation and Stanley Hooker (later Sir Stanley) of the Bristol Engine Company. Rather than using rotors or a direct jet thrust the P.1127 had an innovative vectored thrust turbofan engine and the first vertical take-off was on October 21, 1960. Six prototypes were built in total, one of which was lost at an air display.

[edit] Kestrel FGA.1

The immediate development of the P.1127 was into the Hawker Siddeley Kestrel FGA.1, which appeared after Hawker Siddeley Aviation had been created. The Kestrel was strictly an evaluation aircraft, and only nine were produced, the first flying on March 7, 1964.

These equipped the Tripartite Evaluation Squadron formed at RAF West Raynham in Norfolk of 10 pilots from the RAF, USA and West Germany. One aircraft was lost but the remainder transferred to the US for evaluation by the Army, Air Force and Navy, under the designation XV-6A Kestrel.

An order for 60 production aircraft was received from the RAF in 1966, and the first pre-production Harriers, then known as the P.1127(RAF) were flying by mid-1967.

[edit] P.1127(RAF)

At the time of the development of the P.1127, Hawker had started on a design for a supersonic version, the Hawker P.1154. After this was cancelled in 1965, the RAF began looking at a simple upgrade of the Kestrel as the P.1127(RAF).

In mid-1966, the P.1127(RAF) was ordered by the RAF as the Harrier GR.1, with the first preproduction aircraft flying the following year.

[edit] Variants

[edit] Harrier GR.1

The Hawker-Siddeley Harrier GR.1 was the first production model taken from the Kestrel, it first flew on December 28, 1967, and entered service with the RAF on April 1, 1969. Construction took place at factories in Kingston-upon-Thames in southwest London and at Dunsfold, Surrey. The latter adjoined an airfield used for flight testing; both factories have since closed.

The ski-jump technique for STOVL use by Harriers launched from Royal Navy aircraft carriers was tested at the Royal Navy's airfield at RNAS Yeovilton (HMS Heron), Somerset. Their flight decks were designed with an upward curve to the bow following the successful conclusion of those tests.

The air combat technique of vectoring in forward flight, or viffing, was developed by the USMC in the Harrier to outmaneuver a hostile aircraft or other inbound weapons.

[edit] Harrier GR.1A

The GR.1A was an upgraded version of the GR.1, the main difference being the uprated Pegasus Mk 102 engine. Fifty-eight GR.1As entered RAF service, 17 GR.1As were produced and a further 41 GR.1s were upgraded.

[edit] Harrier GR.3

The Harrier GR.3 featured improved sensors (such as a laser tracker in the lengthened nose), countermeasures and a further upgraded Pegasus Mk 103 and was to be the ultimate development of the 1st generation Harrier. This model saw extended service in the Falklands War. (See Service History below)

The RAF ordered 118 of the GR.1/GR.3 series Harrier.

[edit] Harrier T.2

Two-seat training version for the RAF.

[edit] Harrier T.2A

The Harrier T.2A was an upgraded version of the T.2. The T.2A was powered by a Rolls-Royce Pegasus Mk 102 turbofan engine.

[edit] Harrier T.4

Two-seat training version for the RAF.

[edit] Harrier Mk 52

Two-seat company demonstrator. One aircraft only.

[edit] AV-8A Harrier

Single-seat ground-attack, close air support, reconnaissance fighter aircraft. The AV-8As of the US Marine Corps were very similar to the early GR.1 and GR.1A versions. 113 aircraft were ordered for the US Marines and the Spanish Navy. The AV-8A was armed with two 30-mm Aden cannon pods under the fuselage, and two AIM-9 Sidewinder air-to-air missiles. The aircraft was powered by a 21,500-lb thrust Roll-Royce Pegasus Mk 103 turbofan engine. It was also a very manouverable and a potent air-to-air fighter, being able to outmanouvre any other fighter aircraft. Company designation was the Harrier Mk 50.

[edit] AV-8C

Upgraded AV-8A aircraft for the US Marine Corps.

[edit] AV-8S Matador

Export version of the AV-8A Harrier for the Spanish Navy. Later sold to the Royal Thai Navy. Spanish Navy designation VA-1 Matador. Company designation Harrier Mk 53 for the first production batch, and Harrier Mk 55 for the second batch.

[edit] TAV-8A Harrier

Two-seater training version for the US Marine Corps. The TAV-8A Harrier was powered by a 21,500-lb Rolls-Royce Pegasus Mk 103 turbofan engine. Company designation Harrier Mk 54.

[edit] TAV-8S Matador

Export version of the TAV-8A Harrier for the Spanish Navy. Later sold to the Royal Thai Navy. Spanish Navy designation VAE-1 Matador. Company designation Harrier Mk 54.

[edit] Controls and handling

While the Harrier is one of the most flexible aircraft ever made, the level of understanding and skill needed to pilot it is considerable. The Harrier is capable of both forward flight (where it behaves in the manner of a typical fixed-wing aircraft above its stall speed), and VTOL and STOL manoeuvres (where the traditional lift and control surfaces are useless). This requires skills and understanding more usually associated with helicopters. Most services demand great aptitude and extensive training for Harrier pilots, as well as experience of piloting both types of aircraft. Many recruit trainee pilots from the most experienced and skilled helicopter pilots in their organisations. Image:Vector-nozzle-sea-harrier-jet.jpg The Harrier has two control elements that a fixed-wing aircraft does not usually have. These are the thrust vector and reaction control system. The thrust vector refers to the slant of the four engine nozzles and can be set between zero degrees (horizontal, pointing directly back) and 98 degrees (pointing down and slightly forwards). The 90 degree place is generally used for VTOL maneuvering. Thrust vector is adjusted by a control next to the thrust lever. The reaction control is achieved by manipulating the control stick and is similar in action to the cyclic control of a helicopter. While irrelevant during forward flight mode, these controls are essential during VTOL and STOL, and are used together during these manoeuvres. Wind direction and the point of reference of the aircraft to this is also crucial during VTOL manoeuvres (in this sense operation is limited compared with a helicopter, which can take off and land in side winds). The Harrier's landing gear configuration also complicates normal landing; it is necessary to ensure that the wing-mounted stabiliser struts contact the runway simultaneously; bounce or tilt to one side can result if this is not achieved.

The procedure for VTO involves parking the aircraft facing into the wind. The aircraft is brought to a halt, throttle to idle, wheels locked. The thrust vector is set to 90 degrees and the throttle brought up to maximum. The aircraft leaves the ground rapidly. The throttle is trimmed until a hover state is achieved at the desired altitude. During the ascent and hover, the reaction control system is continuously adjusted to maintain position over the patch of ground, much as it is with a helicopter. The aircraft has to face into the wind when taking off in this way. A side wind causes the aircraft to pitch away from the lee side. This would alter the thrust vector away from vertical and cause the aircraft to slew sideways. This is hard to control and dangerous. In severe cases the aircraft can settle with power while moving to the side. While taking off in windy conditions is always more difficult when within ground effect, it is easier to maintain heading away from the ground effect as the tailplane tends to stabilise the heading into the wind. At hover, the thrust vector is slowly returned to horizontal while the altitude and angle of attack is maintained in a specified range. At or shortly after normal take off speed, the thrust vector is set to horizontal and thrust is usually trimmed back to control acceleration.

The STO procedure involves proceeding with normal take off and then applying a thrust vector (less than 90 degrees) at a runway speed below normal take off speed. For lower take off speeds, the thrust vector applied is greater. The vector and thrust is then trimmed until take off speed. Several procedures have been described for different runway lengths.

In forward flight, the Harrier is at an advantage compared with fixed wing aircraft in that in the event of stalling, recovery is possible by quickly adjusting the thrust vector and throttle. For STOL and VTOL landing, it is necessary to drop below the normal stall speed and apply this method (against all the instincts of the trained fixed wing pilot). The thrust vector control allows for the engine nozzles to be adjusted to a maximum stop of 98 degrees. This facilitates backward motion as needed but is not normally applied during VTOL as the heading into the wind tends to require some forward thrust via attitude control to maintain a fixed hovering position.

The Harrier is capable of vectored-thrust maneuvers, in which the thrust nozzles are rotated beyond 0 degrees in forward flight for the purpose of decreasing the loading of the wing, and thusly, increasing instantaneous and sustained turn performance in the horizontal plane. Because this reduces thrust to the aft of the aircraft, acceleration and maneuvers in the vertical plane are hampered by thrust vectoring, where thrust-to-weight is more necessary than low wing loading.

[edit] Service history

The major combat experience for the Harrier in British service was during the Falklands War where both the Sea Harrier and Harrier GR.3 were used. The Sea Harrier, based on the GR3, was important to the naval activities. Twenty Sea Harriers were operated from the carriers HMS Hermes and Invincible mainly for fleet air defence. Although they destroyed 23 Argentine aircraft in air combat (in part due to using the American-supplied latest variant of the Sidewinder missile and the Argentine aircraft operating at extreme range) they couldn't establish complete air superiority and prevent Argentine attacks during day or night nor stop the daily flights of C-130 Hercules transports to the islands. Three Sea Harriers were lost to ground fire and another three due to operational accidents, none to enemy aircraft. The Harrier GR.3 was operated by the RAF from Hermes and provided close support to the ground forces and attacked Argentine positions but were unable to destroy the Port Stanley runway. If the Sea Harriers had been lost they would have replaced them in air patrol duties.

The RAF Harriers would not see further combat, the Hawker Siddeley airframes would be replaced by the larger Harrier II developed by McDonnell Douglas.

The Sea Harrier FRS.1 saw combat during the Bosnia conflict, with one aircraft being shot down by Serbian defences in 1994. These missions continued as the Sea Harrier force was updated to the FA2 standard. During the Kosovo War, combat patrols were flown, but no weapons were fired. The Sea Harrier patrolled over Iraq during the 12 years of enforcing no-fly zones.

The Sea Harrier and Harrier GR7 forces were merged to formed Joint Force Harrier in 2000. With the retirement of the Sea Harrier in 2006 the RAF and RN will share the GR9 fleet until the introduction of the F-35 Joint Strike Fighter.

[edit] RAF service

Squadrons

No. 1 Squadron RAF
No. 3 Squadron RAF - until replaced with GR.5
No. IV Squadron RAF
No. 20 Squadron RAF - Harrier GR.1
No. 233 Operational Conversion Unit RAF

Flights

No. 1417 Flight RAF - Deployed to the Central American nation of Belize from 1981 to 1993.
No. 1453 Flight RAF - Deployed to Port Stanley, in the Falklands Islands from June 1982 to 1985.

Locations