Vectored thrust
Thrust vectoring was developed for short take-off and vertical landing (STOVL) aircraft. The Pegasus turbofan, power for the Harrier ‘jump-jet’, is the unique example of this concept. The engine has four linked, swivelling nozzles to direct the gas stream from vertically downward for upward lift, through an arc to horizontally rearward for conventional forward flight. The bypass air is discharged through the two front nozzles and the hot gas exhaust through the two rear nozzles.

Afterburning
Afterburning, or reheat, increases engine thrust for short periods to improve aircraft take-off, climb and combat performance. Because the fuel in a gas turbine burns in an excess of air, sufficient oxygen remains in the exhaust to support further combustion, particularly in a turbofan. By injecting and burning additional fuel in the jet pipe, the exhaust velocity and consequently the engine thrust is increased

Reverse thrust
Thrust reversal, found on most commercial jets, is used to provide a braking force to add to the effect of an aircraft’s wheel-brakes when the aircraft lands. It is particularly useful in adverse weather conditions and is achieved by mechanically deflecting some or all of the exhaust stream of a gas turbine in a forward direction.