44 AEROSPACE
Two approaches to achieving short takeoff and vertical landing
After 40 years in service, the Harrier is due to be replaced by a variant of the Lockheed Martin F-35 Lightning II joint strike fighter that is designed for short takeoffs and vertical landings. Alistair Rae looks at the two aircraft and the different technologies employed to achieve similar goals.
Après 40 ans de service, le Harrier va être remplacé par une variante de l’avion de combat multirôle Lockheed Martin F-35 Lightning II conçu pour les décollages courts et les atterrissages verticaux. Alistair Roe examine les deux avions et les différentes technologies utilisées pour obtenir des résultats similaires.
Nach 40 Dienstjahren soll der Harrier-Jet durch eine Variante des Lockheed Martin F-35 Lightning II Joint Strike Fighter ersetzt werden, der für kurze Startbahnen und vertikale Landungen konstruiert worden ist. Alistair Rae sieht sich die zwei Flugzeuge und die unterschiedlichen Technologien an, mit denen ähnliche Ziele erreicht werden.
T
he Harrier Jump Jet is in service with air forces and navies around the world, including the UK’s Royal Air Force (RAF) and Royal
Navy which use the GR7/7A, T10 two-seater and GR9/9A types. As well as the aircraft’s performance capability, you also have to admire its longevity; the Harrier can trace its roots back to 1957, though the first pre-production Harriers did not fly until 1967. Harriers first entered service a remarkable forty years ago in 1969. At the heart of the Harrier is the 48 inch
(1.22 m) diameter Rolls-Royce Pegasus turbofan engine with a unique thrust vectoring system that utilises four swivelling nozzles to give the Harrier lift and/or forward thrust. Current versions of the Pegasus engine have a thrust range up to 23 800 pounds. While the Harrier is probably the best know
VTOL (vertical takeoff and landing) or STOVL (short takeoff and vertical landing) aircraft, there are others. The Yakovlev Yak-38 (known within NATO as the Forger) was the Soviet Naval Aviation’s VTOL multi-role combat aircraft, entering service in 1976. Following that, the Yakovlev Yak-141 (known within NATO as the Freestyle) was a supersonic VTOL fighter aircraft. As with the Yak-38, the Yak-141 gained its VTOL capability through a combination of a lift and lift/cruise engines. Two lift jets were mounted behind the cockpit and contributed to takeoff only; once the aircraft was in horizontal flight, the lift engines were shut down. The main engine was installed in the rear of the fuselage, with a swivelling nozzle and an afterburner. For takeoff and hovering, the exhaust from the jet was vectored downwards through 90 degrees to work in conjunction with the forward lift jets. To obtain sufficient power for vertical takeoff, it was necessary to use the afterburner, which limited the types of runway surfaces that could be used. In August 1991
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the programme was halted due to budgetary constraints.
Lightning II
Inevitably it has become necessary to replace the Harrier and the route being taken is to develop a variant of the Lockheed Martin F-35 Lightning II joint strike fighter (JSF). The conventional Lightning II, designated the F-35A, is a single-engined supersonic multirole aircraft that benefits from integrated stealth capability. Two other variants are also in development: the F-35C carrier variant (CV) for the US Navy; and the F-35B short takeoff/vertical landing (STOVL) variant for the US Marine Corps and the UK’s Royal Air Force and Royal Navy. Flight testing of the F-35B began on 11th June 2008, initially using conventional takeoffs and landings. It is expected that the F-35B will be available from 2012 onwards. Primary customers for the F-35B will be the US Marine Corps, the UK’s Royal Air Force and Royal Navy, and the Italian Navy. Unlike the Harrier, the F-35B is supersonic,
though it still shares the Harrier’s ability to operate from small ships, roads and austere bases. Internal fuel capacity is seven tons, providing an unrefueled range of more than 900 miles (1450 km) without external tanks. Despite being almost identical in appearance to the F-35A, the F-35B incorporates a counter-
Fig. 1. Lockheed Martin’s F-35B variant of the Lightning II joint strike fighter is designed for short takeoff/vertical landing capability.
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