Thrust vectoring
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Thrust vectoring is the ability of an aircraft to direct the thrust from its main engine(s) in a direction other than parallel to the aircraft's length. The technique was originally envisaged to provide upward vertical thrust as a means to give aircraft VTOL or STOL capability. Subsequently it was realised that the use of vectored thrust in combat situations enabled an aircraft to perform various evasive maneuvers not available to conventional-engined planes.
Most currently operational vectored thrust aircraft use jet engines with rotating nozzles or vanes to deflect the exhaust stream. Although this method can successfully deflect thrust through as much as 90 degrees, relative to jet aircraft without thrust vectoring capability this imposes a weight penalty and tends to preclude the use of afterburners, particularly if a large range of thrust angles is desired.
A fluidic nozzle diverts the thrust via fluid effects. Tests have shown that air forced into the exhaust stream can effect deflected thrust of up to 15 degrees. Currently in the experimental stage, fluidic nozzles are desirable for their lower weight, mechanical simplicity (no moving surfaces) and lower radar cross section and will likely be featured on many 6th generation fighter aircraft.
Tilt-rotor aircraft achieve thrust vectoring by rotation of turboprop engine nacelles. The mechanical complexities of this solution are quite troublesome, including the twisting of flexible internal components and driveshaft power transfer between engines. Some believe this type of rotor thrust is significantly more susceptible to vortex ring conditions than traditional helicopter propulsion.
The pioneer and best known example of thrust vectoring is the Hawker Siddeley Harrier (with variants built by McDonnell Douglas). The technique has also been used in various experimental and development planes, some with vectored thrust in directions other than upwards.
Rockets or rocket-powered aircraft can also use thrust vectoring. Many missiles use this technique since at launch they are moving so slowly that to be able to steer effectively they would need massive fins, and they would impose a serious drag penalty once they are moving very fast. In addition, rockets often go very high up into the atmosphere or even beyond it, where aerodynamic surfaces are useless, so they need to use gas-dynamic steering. Examples of rockets and missiles which use thrust vectoring include the S-300P (SA-10) surface-to-air missile, AIM-132 ASRAAM air-to-air missile, UGM-27 Polaris nuclear ballistic missile and RT-23 (SS-24) ballistic missile.
List of vectored thrust aircraft
- Boeing V-22 Osprey (Turboprop)
- General Dynamics F-16 MATV (Multi-Axis Thrust Vectoring)
- Hawker Siddeley Harrier
- NASA Dryden F-15 ACTIVE
- Lockheed Martin F/A-22 Raptor
- Lockheed Martin F-35 Joint Strike Fighter
- McDonnell Douglas/British Aerospace AV-8B Harrier II
- McDonnell Douglas F-18 HARV (High Alpha Research Vehicle)
- McDonnell Douglas X-36
- Rockwell-MBB X-31
- Mikoyan-Gurevich MiG-35 MFI
- Moller Skycar
- Rockwell-MBB X-31
- Sukhoi Su-30 (in the MK and MKI versions)
- Sukhoi Su-37
- X-44 MANTA
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