The McDonnell Douglas (now Boeing) AV-8B Harrier II is a second-generation vertical/short takeoff and landing (V/STOL) ground-attack aircraft. An Anglo-American development of the British Hawker Siddeley Harrier, the Harrier II is the final member of the Harrier family that started with the Hawker Siddeley P.1127 in the early 1960s. The AV-8B is primarily used for light attack or multi-role missions, and is typically operated from small aircraft carriers, large amphibious assault ships and simple forward operating bases. The AV-8B is used by the United States Marine Corps (USMC), Spanish Navy and Italian Navy. A variant of the AV-8B, the British Aerospace Harrier II was developed for the British military. The TAV-8B is a dedicated two-seat trainer version. The Harrier II and other models of the Harrier family have been called "Jump Jets".
The AV-8B was extensively redesigned by McDonnell Douglas from the earlier AV-8A/C Harrier. It has a new wing, an elevated cockpit, a redesigned fuselage, and other structural and aerodynamic refinements. The number of hardpoints was increased from five to seven. Later upgrades, which resulted in the AV-8B(NA) and AV-8B Harrier II Plus, added radar and night-attack capabilities. British Aerospace joined the improved Harrier project as partner in 1981. Since corporate mergers in the 1990s, Boeing and BAE Systems have jointly supported the program.
A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to take-off or land vertically or on short runways. Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do not require runways at all. Generally, a V/STOL aircraft needs to be able to hover. Helicopters are not considered under the V/STOL classification as the classification is only used for airplanes, aircraft that achieve lift in forward flight by planing the air, thereby achieving speed and fuel efficiency that is typically greater than helicopters are capable of.
Most V/STOL aircraft types were experiments or outright failures from the 1950s to 1970s. V/STOL aircraft types that have been produced in large numbers include the Harrier, Yak-38 Forger and V-22 Osprey.
A rolling takeoff, sometimes with a ramp (ski-jump), reduces the amount of thrust required to lift an aircraft from the ground (compared with vertical takeoff), and hence increases the payload and range that can be achieved for a given thrust. For instance, the Harrier is incapable of taking off vertically with a full weapons and fuel load. Hence V/STOL aircraft generally use a runway if it is available. I.e. short takeoff and vertical landing (STOVL) or conventional takeoff and landing (CTOL) operation is preferred to VTOL operation.
V/STOL was developed to allow fast jets to be operated from clearings in forests, from very short runways, and from small aircraft carriers that would previously only have been able to carry helicopters.