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For a long time this was the only operational western aircraft capable of vertical take off and landing (VTOL). The Harrier is a small ground-attack aircraft. VTOL operation is achieved by the four swivelling nozzles of the R.R. Pegasus engine. The basic concepts dates back to 1960, but production still continues. The type was adopted by the USMC as the AV-8. Later versions have enlarged wings, wing root extensions, and longer noses for additional electronics.

The Hawker Siddeley Harrier and the AV-8A are the first generation of the Harrier series, a revolutionary close-support and reconnaissance fighter aircraft with unique V/STOL capabilities. The family is part of a large family of experimental versions and service aircraft, including the much modernized Harrier II. The Harrier continues to serve today as the Harrier GR.Mk 7 and GR.Mk 9 and AV-8B which are built by BAE Systems and Boeing. The current operational British Harriers (GR.Mk 7 and GR.Mk 9) are license-built versions of the McDonnell Douglas (now Boeing) version, respectively the AV-8B Harrier II and AV-8B+ Harrier II Plus.

The Harrier is a single-engine, "jump-jet" fighter-bomber designed to fly from combat areas and aircraft carriers and to support ground forces. It was made by Hawker Siddeley Aviation and first flew on Aug. 31, 1966, after a long period of development. (Hawker Siddeley became part of British Aerospace in 1977, and the latter firm, in partnership with McDonnell Douglas in the United States, continued to manufacture the Harrier). The several versions of the Harrier can take off straight up or with a short roll (Vertical and Short Take-off and Landing, or V/STOL), and thus the Harrier does not need conventional runways. Powered by a vectored-thrust turbofan engine, the plane diverts its engine thrust downward for vertical takeoff using rotatable engine exhaust ports. It can carry a combination of armaments, including air-to-air missiles, air-to-surface antiship missiles, rockets, and bombs. Ground-attack versions of the Harrier carry two 30-millimetre cannons as well as rockets and bombs. The Sea Harrier saw combat in the British campaign during the Falkland Islands War of 1982. A larger and heavier version built for the U.S. Marines (AV-8A) is for both air defense and support of ground forces.

While the Harrier is one of the most flexible aircraft ever made, the necessary understanding and skill to pilot it are considerable. In addition to being able to fly the Harrier in forward flight (above stall speed when it behaves in the manner of a typical fixed-wing aircraft), it is necessary to maintain control during VTOL and STOL manoeuvres when the lift and control surfaces don't work. This requires skills and understanding more associated with helicopters. Most services demand great aptitude and extensive training, with experience of piloting both types of aircraft. Many recruit trainee pilots from the most experienced and skilled helicopter pilots in their organisations.

The Harrier has two control elements that a fixed wing aircraft does not normally have. These are the thrust vector and reaction control. The thrust vector is the angle of the four engine nozzles and can be set between zero degrees (horizontal, pointing straight back) and 98 degrees (pointing slightly forwards). The 90 degree position is generally used for VTOL manoeuvring. Thrust vector is adjusted by a control similar to and beside 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 critical during VTOL and STOL, and are used together during these manoeuvres. Wind direction and the orientation of the aircraft to this is also critically-important 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 skew to one side can result if this is not achieved.

The procedure for VTOL 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 STOL 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.

Harrier II is an extensively modified and updated version of the Harrier GR3/AV-8A Vertical/Short Take-Off and Landing (V/STOL) close air support aircraft, allowing even greater tactical deployment. The ground attack and close air support aircraft has been jointly developed with Boeing and is in service with the Royal Air Force (GR7 and T10), US Marine Corps (AV-8B and TAV-8B) and Spanish Navy (EAV-8B). Like its predecessor, the Harrier II can operate from conventional bases, dispersed sites and a wide range of surface vessels but is able to carry double the payload - or operate over twice the range - of earlier versions. Both the RAF and USMC operate night attack variants of the Harrier II. The AV-8B can carry 50% more internal fuel and 70% more external ordnance compared to AV-8A.


General characteristics (Harrier GR.1)

* 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[24])
* Thrust/weight: 1.10

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:
o Air-to-air missile: 4× AIM-9 Sidewinders
o Air-to-surface missile: 2× Anglo-French AS-37 Martel missiles
* Bombs: A variety of unguided iron bombs
* Others:
o 1× Reconnaissance pod
o 2× drop tanks for extended range/loitering time

General characteristics (AV-8B+ Harrier II Plus)

* Crew: 1 pilot
* Length: 46 ft 4 in (14.12 m)
* Wingspan: 30 ft 4 in (9.25 m)
* Height: 11 ft 8 in (3.55 m)
* Wing area: 243.4 ft² (22.61 m²)
* Airfoil: supercritical airfoil
* Empty weight: 13,968 lb (6,340 kg)
* Loaded weight: 22,950 lb (10,410 kg)
* Max takeoff weight:
o Rolling: 31,000 lb (14,100 kg)
o Vertical: 20,755 lb (9,415 kg)
* Powerplant: 1× Rolls-Royce F402-RR-408 (Mk 107) vectored-thrust turbofan, 23,500 lbf (105 kN)

Performance

* Maximum speed: Mach 0.89 (662 mph, 1,070 km/h) at sea level
* Range: 1,200 nm (1,400 mi, 2,200 km)
* Combat radius: 300 nmi (556 km)
* Ferry range: 1,800 nmi (3,300 km)
* Rate of climb: 14,700 ft/min (4,485 m/min)
* Wing loading: 94.29 lb/ft² (460.4 kg/m²)

Armament

* Guns: 1× 25 mm (0.98 in) GAU-12 Equalizer cannon mounted under-fuselage in the left pod with 300 rounds of ammunition in the right pod (American/Spanish/Italian configuration)
* Hardpoints: 6× under-wing pylon stations holding up to 13,200 lb (5,988 kg) of payload:
* Rockets:
o 4× LAU-5003 rocket pods (each with 19× CRV7 70 mm rockets)
* Missiles:
o Air-to-air missiles:
+ 4× AIM-9 Sidewinder or similar-sized infrared-guided missiles
+ 6× AIM-120 AMRAAM (mounted on radar equipped AV-8B+ variants)
o Air-to-surface missiles:
+ 6× AGM-65 Maverick; or
+ 2× AGM-84 Harpoon; or
+ 2× AGM-88 HARM; or
* Bombs:
o CBU-100 Cluster Bombs (CBUs)
o Mark 80 series of unguided bombs (including 3 kg and 14 kg practice bombs)
o Paveway series of Laser-guided bombs (LGBs)
o Mark 77 napalm canisters
* Others:
o up to 4× 300/330/370 US Gallon drop tanks (pylon stations No. 2, 3, 4 & 5 are wet plumbed) for ferry flight/extended range/loitering time

Avionics

* Raytheon APG-65
* AN/AAQ-28V LITENING targeting pod (mounted on radar equipped AV-8B+ variants)
o Special note: An upgrade program is currently fitting airframes with wiring and software to employ 1760 bus-based smart weapons, such as Joint Direct Attack Munitions