Vectoring nozzles

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Vector nozzle on a Sea Harrier Jet
An axisymmetric vectoring nozzle, used on the F-16 MATV

Vectoring nozzles are specialized nozzles that facilitate the upward or downward movement of thrust vectoring so an aircraft can fly forward or hover over the ground.

The term originated from the design of the British Aerospace Harrier Vertical Take Off and Landing fighter/bomber aircraft, powered by the Rolls-Royce Pegasus gas turbine engine. In this aircraft, the conventional, rearwards jet exhaust was re-configured so that the gases were expelled from four swivelling nozzles mounted on the side of the fuselage. By altering the angle of these nozzles, the ratio of longitudinal thrust to lift thrust could be varied, such that with the nozzles directed towards the ground, the aircraft could hover, stationary to the ground, and could even move backwards.

Vectoring nozzles can also be used for Vectoring In Forward Flight or "viffing", e.g. a rapid braking allowing a chasing fighter jet to overtake thus bringing itself into the range of forward firing weapons. Viffing was used to great effect during the Anglo-Argentinian Falklands War, where 28 Royal Navy and 6 RAF jets did not incur any losses in dogfighting against a force of more than 200 Argentine Air Force jets. The Harrier Jump Jets in question were subsequently referred to as 'The Black Death' by the Argentinian pilots. Viffing also allowed a much tighter turn in combat manoeuvres, although there is little evidence to suggest that it was regularly taught to pilots, as the loss of airspeed could make the aircraft vulnerable to attack.

On more recent fighter aircraft, pitch-axis thrust vectoring has been added to improve the turn rate of the aircraft by deflecting the exhaust gas stream using directional efflux nozzles. The Lockheed Martin F-22 Raptor and Sukhoi Su-30MKI are some example.

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