Originally posted by T.Ryousuke:
Trust-vectoring capabilities sound interesting.
Thrust vectoring is the ability of an aircraft or other vehicle to direct the thrust from its main engine(s) in a direction other than parallel to the vehicle's longitudinal axis. 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 maneuvers not available to conventional-engined planes.
Most currently operational vectored thrust aircraft use turbofans with rotating nozzles or vanes to deflect the exhaust stream. This method can successfully deflect thrust through as much as 90 degrees, relative to the aircraft centreline. However, the engine must be sized for vertical lift, rather than normal flight, which results in a weight penalty. Afterburning (or Plenum Chamber Burning in the bypass stream) is difficult to incorporate and is not practical for Take-off/Landing, because the very hot exhaust leaves scorch marks on the ground. Without afterburning it is difficult to reach supersonic flight speeds.
Thrust vectoring is also used as a control mechanism for airships, particularly modern non-rigid airships. In this application, the majority of the load is typically supported by buoyancy and vectored thrust is used to control the motion of the aircraft. However designs have recently been proposed, particularly for Project WALRUS, where a significant portion of the weight of the aircraft is supported by vectored thrust. The first airship that used a control system based on pressurized air was the Forlanini's Omnia Dir in 1930s.
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.
Most current tilt-rotor designs feature 2 rotors in a side-by-side configuration. If such a craft is flown in a way where it enters a vortex ring state, one of the rotors will always enter slightly before the other, causing the aircraft to perform a rather drastic and unplanned roll.
The best known example of thrust vectoring in an engine is the Rolls-Royce Pegasus engine of the Hawker-Siddeley Harrier (with variants built by McDonnell Douglas). Contrary to popular belief, it was not applied against conventional Argentine fighters in the Falklands War. The technique has been used in various experimental and development planes, some with vectored thrust in directions other than upwards.
Currently the Lockheed Martin F-35 Joint Strike Fighter is being developed. Although this aircraft incorporates a conventional afterburning turbofan (F135 or F136) which facilitates supersonic operation, the US Marine/RAF version also incorporates an (LP) shaft-driven, vertically mounted, remote fan, which is clutched-in during landing. The exhaust from this fan is deflected by a thrust vectoring nozzle, as is the main engine exhaust, to provide the appropriate combination of lift and propulsive thrust during transition.
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.
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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-22A Raptor
* Lockheed Martin F-35 Joint Strike Fighter
* McDonnell Douglas/British Aerospace AV-8B Harrier II
* McDonnell Douglas F-15S/MTD
* McDonnell Douglas F-18 HARV (High Alpha Research Vehicle)
* McDonnell Douglas X-36
* Rockwell-MBB X-31
* Mikoyan-Gurevich MiG-35 MFI
* Mikoyan Project 1.44
* Moller Skycar
* Chengdu J-10 (Super-10)
* Sukhoi Su-30 (MKI versions)
* Sukhoi Su-37
* Sukhoi Su-47
* X-44 MANTA
* Zeppelin NT - an example of a modern thrust vectoring airship
http://en.wikipedia.org/wiki/Thrust_vectoring