Hawker Siddeley Harrier

Harrier / AV-8A/C
An RAF Harrier GR3 on display at Bletchley Park, England
RoleVTOL strike aircraft
National originUnited Kingdom
ManufacturerHawker Siddeley
First flight28 December 1967 (Harrier)
Introduction1 April 1969
StatusActive
Primary usersRoyal Air Force
United States Marine Corps
Spanish Navy
Royal Thai Navy
Produced1967 - 1970s
Number built718
Developed fromHawker Siddeley P.1127/Kestrel FGA.1
VariantsBAE Sea Harrier
Developed intoAV-8B 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 Vertical/Short Takeoff and Landing (V/STOL) capabilities, colloquially referred to as a "jump jet". The Harrier was the only truly successful V/STOL design of the many that arose from the 1960s.

In the 1970s, the Harrier was developed into the radar-equipped BAE Sea Harrier for the Royal Navy. The Harrier was also extensively redesigned as the BAE Harrier II and AV-8B Harrier II, which were built by British Aerospace and McDonnell Douglas.

Development

Background

Main article: Hawker Siddeley P.1127

The Harrier's lineage began 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 takeoff was on 21 October 1960. Six prototypes were built in total, one of which was lost at an air display.

The immediate development of the P.1127 was the Kestrel FGA.1, which appeared after Hawker Siddeley Aviation was created. The Kestrel's first flight was on 7 March 1964. It was strictly an evaluation aircraft, and only nine were built. These equipped the Tripartite Evaluation Squadron formed at RAF West Raynham in Norfolk, numbering 10 pilots from the RAF, USA and West Germany. One aircraft was lost and six of the remainder were transferred to the U.S. for evaluation by the Army, Air Force and Navy, designated XV-6A Kestrel.

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).

An order for 60 production aircraft was received from the Royal Air Force in mid-1966, and the first pre-production Harriers, then known as the P.1127 (RAF), were flying by mid-1967, becoming known as Harrier GR.1.

Production

The Hawker Siddeley Harrier GR.1 was the first production model derived from the Kestrel, it first flew on 28 December 1967, and entered service with the RAF on 1 April 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 used 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 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.

The AV-8As of the United States Marine Corps were very similar to the early GR.1 version, but with the more-powerful engine of the GR.3. The aircraft was powered by a 21,500 lbf (95.6 kN) thrust Roll-Royce Pegasus Mk 103 (F402-RR-402) turbofan engine. The AV-8A was armed with two 30 mm ADEN cannons (podded under the fuselage) and two AIM-9 Sidewinder air-to-air missiles. A total of 113 were ordered for the US Marines and the Spanish Navy.

Design

The Harrier is a subsonic attack aircraft. It features a single Pegasus turbofan engine with two intakes and four vectorable nozzles. It has two landing gear on the fuselage and two outrigger landing gear on the wings. The Harrier is equipped with four wing and three fuselage pylons for carrying weapons and external fuel tanks.

Controls and handling

Sea Harrier FRS2 ZA195 thrust vector nozzle

The level of understanding and skill needed to pilot the Harrier is considerable. The aircraft 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 maneuvers (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 come from the most experienced and skilled helicopter pilots in their organisations.

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 maneuvers. Wind direction and the point of reference of the aircraft to this is also crucial during VTOL maneuvers (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.

An AV-8B Harrier II+ of VMA-223 prepares for landing on the flight deck aboard the USS Nassau (LHA 4)

The procedure for vertical takeoff 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 short takeoff procedure involves proceeding with normal takeoff 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.

British Aerospace Harrier GR9 at RIAT 2008

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 technique of vectoring in forward flight, or "VIFFing", involves rotating the vectored thrust nozzles into a forward-facing position during normal flight. It was a dog-fighting tactic for both (a) higher turns rates than would normally be possible for an aircraft with such a short wing-span and (b) sudden braking. The latter causes a chasing aircraft to overshoot and present itself as a target for e.g. air-to-air missiles. This air combat technique was formally developed by the USMC in the Harrier in the early 1970s. Because VIFFing reduces forward thrust, acceleration and manoeuvers in the vertical plane are hampered by thrust vectoring, where thrust-to-weight is more necessary than low wing loading.

In addition to normal flight controls, the Harrier has a lever for controlling the direction of the four vectorable nozzles. The nozzles point rearward with the lever in the forward position for horizontal flight. With the lever back, the nozzles point downward for vertical takeoff or landing.

At heavier weights, the Harrier's hover time can become limited due to its reliance on the use of water injection for additional thrust, approximately 90 seconds of which is available. At lighter loads the aircraft can hover for as long as 5 minutes before requiring conventional flight modes to allow the engine to cool.

Operational history

An AV-8S Matador flies over the Spanish aircraft carrier Dédalo(R01).

The first major combat experience for the Harrier in British service was during the Falklands War where both the BAE Sea Harrier FRS.1 and Harrier GR.3 were used. The Sea Harrier, developed from the GR.3, 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 21 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.

Harrier GR.3s were operated by the RAF from Hermes, and provided close support to the ground forces and attacked Argentine positions. However, they were unable to destroy the Stanley runway. If most of the Sea Harriers had been lost, the GR.3s would have replaced them in air patrol duties. Four Harriers GR.3s were lost to ground fire, accidents, or mechanical failure. The RAF Harriers would not see further combat, as the Hawker Siddeley airframes were replaced by the larger Harrier II developed jointly by McDonnell Douglas and British Aerospace.

China

Perhaps among the most important near operators of the Harrier was China who was approached by the UK beginning in the early 1970s during the warming of relations with the west in effort to modernize the Chinese military. The deal in progress was canceled by the UK after the invasion invasion of Vietnam by China.

Variants

A Royal Air Force Harrier GR.3 aircraft parked on the flight line during Air Fete '84 at RAF Mildenhall.

Harrier GR.1

The first production model derived from the Kestrel

Harrier GR.1A

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, a further 41 GR.1s upgraded.

Harrier GR.3

Featured improved sensors (such as a laser tracker in the lengthened nose and radar warning receiver on the fin and tail boom) and a further uprated Pegasus Mk 103. It was to be the ultimate development of the first-generation Harrier. The RAF ordered 118 of the GR.1/GR.3 series.

Harrier T.2

A US Marine VMA-231 AV-8A with a camouflage paint during pre-flight operations. Harrier has two napalm bombs on its right wing.

Two-seat training version for the RAF.

Harrier T.2A

Upgraded T.2, powered by a Pegasus Mk 102.

Harrier T4

Two-seat training version for the Royal Air Force, equivalent to the GR.3.

Harrier T4N

Two-seat training version for the Royal Navy.

Harrier Mk 52

Two-seat company demonstrator, one built.

A US Marine TAV-8A Harrier from Marine Attack Squadron (Training) 203 (VMAT-203) sitting on the flight line.

AV-8A Harrier

Single-seat ground-attack, close air support, reconnaissance, and fighter aircraft; similar to the earlier GR.1, but with the GR.3 engine. 113 ordered for the U.S. Marines. Company designation Harrier Mk 50.

AV-8C

Upgraded AV-8A for the U.S. Marine Corps.

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 Mk 55 for the second batch.

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.

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.

Operators

A Spanish Navy AV-8S Matador aircraft.

Spain Spain

  • Spanish Navy
    • No. 008 Escuadrilla - AV-8S and TAV-8S Matador

Thailand Thailand

  • Royal Thai Navy
    • Squadron 1 Wing3 (HTMS Chakri Naruebet Flying Unit) - AV-8S and TAV-8S

United Kingdom United Kingdom

  • Royal Air Force
    • No. 1 Squadron RAF
    • No. 3 Squadron RAF
    • No. IV Squadron RAF
    • No. 20 Squadron RAF
    • No. 233 Operational Conversion Unit RAF
    • No. 1417 Flight RAF - Deployed to the Central American nation of Belize from 1981 to 1993.
    • No. 1435 Flight RAF - Deployed to Stanley, in the Falklands Islands from June 1982 to 1985.

USA United States

  • United States Marine Corps
    • VMA-231 - AV-8A/C Harrier
    • VMA-513 - AV-8A/C Harrier
    • VMA-542 - AV-8A/C Harrier
    • VMAT-203 - AV-8A and TAV-8A Harrier

Aircraft on display

  • GR1 XV277 on display at the National Museum of Flight, East Fortune, Scotland.
  • GR1 XV278 on display at the Luftwaffenmuseum der Bundeswehr, Gatow, Germany.
  • GR3 XV748 on display at the Yorkshire Air Museum, Elvington, England.
  • GR3 XV751 on display at the Gatwick Aviation Museum, Surrey, England.
  • GR3 XV752 on display at Bletchley Park, Buckinghamshire, England.
  • GR3 XV779 on display at the gate to RAF Wittering, England.
  • GR1 XV798 on display at the Bristol Aero Collection, Kemble, Gloucestershire, England.
  • T4 XW934 on display at the Farnborough Air Sciences Trust, Farnborough, Hampshire, England.
  • GR3 XZ133 on display at the Imperial War Museum Duxford, England.
  • GR3 XZ997 on display at the Royal Air Force Museum, Hendon, England.
  • GR3 XZ998 is on display at the Flugausstellung Leo Junior at Hermeskeil in Germany.
  • T52 G-VTOL is on display at the Brooklands Museum, Surrey, England.
  • AV-8A 159233 is on display at the Imperial War Museum North, Manchester, England.
  • AV-8A 158966 is on display at the Canada Aviation Museum, Ottawa, Ontario, Canada

Specifications (Harrier GR.1)

General characteristics

  • Crew: One
  • Length: 45 ft 7 in (13.90 m)
  • Wingspan: 25 ft 3 in (7.70 m)
  • Height: 11 ft 4 in (3.45 m)
  • Wing area: 201 ft² (18.68 m²)
  • Empty weight: 12,190 lb (5,530 kg)
  • Loaded weight: 17,260 lb (7,830 kg)
  • Max takeoff weight: 25,350 lb (11,500 kg)
  • Powerplant: 1× Rolls-Royce Pegasus 101 turbofan with four swivelling nozzles, 19,000 lbf (84.5 kN) Four vertical flight puffer jets use engine bleed air, mounted in the nose, wingtips, and tail, and provide up to 1,000 lbf (4 kN) of thrust.

Performance

  • Maximum speed: 735 mph (Mach 0.97) (1,185 km/h)
  • Range: 1200 mi (1900 km)
  • Combat radius: 260 mi (418 km) on strike mission without drop tanks (hi-lo-hi)
  • Service ceiling: 49,200 ft (15,000 m)
  • Rate of climb: 2 min 23 sec to 40,000 ft or initial climb (VTOL weight) 50,000ft/min (15,240 m/min)
  • Thrust/weight: 1.10
Harrier GR.3 firing entire salvo of 4 rocket pods

Armament

  • Guns: 2× 30 mm (1.18 in) ADEN cannon pods under the fuselage
  • Hardpoints: 4× under-wing & 1× under-fuselage pylon stations holding up to 5,000 lb (2,268 kg) of payload
  • Rockets: 4× Matra rocket pods with 18× SNEB 68 mm rockets each
  • Missiles:
    • Air-to-air missile: 4× AIM-9 Sidewinders
    • Air-to-surface missile: 2× Anglo-French AS-37 Martel missiles
  • Bombs: A variety of unguided iron bombs
  • Others:
    • 1× Reconnaissance pod
    • 2× drop tanks for extended range/loitering time