Thrust vectoring Thrust vectoring , also thrust vector control or TVC , is the ability of an aircraft , rocket , or other vehicle to manipulate the direction of the thrust from its engine ( s ) or motor in order to control the attitude or angular velocity of the vehicle . In rocket ry and ballistic missile s that fly outside the atmosphere , aerodynamic control surface s are ineffective , so thrust vectoring is the primary means of attitude control . For aircraft , the method was originally envisaged to provide upward vertical thrust as a means to give aircraft vertical ( VTOL ) or short ( STOL ) takeoff and landing ability . Subsequently , it was realized that using vectored thrust in combat situations enabled aircraft to perform various maneuvers not available to conventional - engined planes . To perform turns , aircraft that use no thrust vectoring must rely on aerodynamic control surfaces only , such as ailerons or elevator ; craft with vectoring must still use control surfaces , but to a lesser extent . Thrust vectoring methods . Rockets and missiles . Thrust vector control is effective only while the propulsion system is creating thrust . At other stages of flight , separate mechanisms are required for attitude and flight path control . Nominally , the line of action of the thrust vector of a rocket nozzle passes through the vehicle ' s center of mass , generating zero net moment about the mass center . It is possible to generate pitch and yaw moments by deflecting the main rocket thrust vector so that it does not pass through the mass center . Because the line of action is generally oriented nearly parallel to the roll axis , roll control usually requires the use of two or more separately hinged nozzles or a separate system altogether , such as fins , or vanes in the exhaust plume of the rocket engine , deflecting the main thrust . Thrust vectoring for many liquid rocket s is achieved by gimbal ling the rocket engine . This often involves moving the entire combustion chamber and outer engine bell as on the Titan II ' s twin first stage motors , or even the entire engine assembly including the related fuel and oxidizer pumps . Such a system was used on the Saturn V and the Space Shuttle . Another method of thrust vectoring used on early solid propellant ballistic missile s was liquid injection , in which the rocket nozzle is fixed , but a fluid is introduced into the exhaust flow from injectors mounted around the aft end of the missile . If the liquid is injected on only one side of the missile , it modifies that side of the exhaust plume , resulting in different thrust on that side and an asymmetric net force on the missile . This was the control system used on the Minuteman II and the early SLBM s of the United States Navy . A later method developed for solid propellant ballistic missile s achieves thrust vectoring by deflecting the rocket nozzle using electric servomechanism s or hydraulic cylinder s . The nozzle is attached to the missile via a ball joint with a hole in the center , or a flexible seal made of a thermally resistant material , the latter generally requiring more torque and a higher power actuation system . The Trident C4 and D5 systems are controlled via hydraulically actuated nozzle . Some smaller sized atmospheric tactical missile s , such as the AIM - 9X Sidewinder , eschew flight control surfaces and instead use mechanical vanes to deflect motor exhaust to one side . Aircraft . Most currently operational vectored thrust aircraft use turbofans with rotating nozzle s or vanes to deflect the exhaust stream . This method can successfully deflect thrust through as much as 90 degrees , relative to the aircraft centerline . However , the engine must be sized for vertical lift , rather than normal flight , which results in a weight penalty . Afterburning ( or Plenum Chamber Burning , PCB , in the bypass stream ) is difficult to incorporate and is impractical for take - off and landing thrust vectoring , because the very hot exhaust can damage runway surfaces . Without afterburning it is hard to reach supersonic flight speeds . A PCB engine , the Bristol Siddeley BS100 , was cancelled in 1965 . Tiltrotor aircraft vector thrust via rotating turboprop engine nacelles . The mechanical complexities of this design are quite troublesome , including twisting flexible internal components and driveshaft power transfer between engines . Most current tiltrotor 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 drastic and unplanned roll . Thrust vectoring is also used as a control mechanism for airship s . An early application was the British Army airship " Delta " , which first flew in 1912 . It was later used on HMA ( His Majesty ' s Airship ) No . 9r , a British rigid airship that first flew in 1916 and the twin 1930s - era U . S . Navy rigid airships " USS Akron " and " USS Macon " that were used as airborne aircraft carrier s , and a similar form of thrust vectoring is also particularly valuable today for the control of modern non - rigid airship s . In this use , most of the load is usually supported by buoyancy and vectored thrust is used to control the motion of the aircraft . But , designs have recently been proposed , especially for Project WALRUS , where a significant portion of the weight of the craft is supported by vectored thrust . The first airship that used a control system based on pressurized air was Enrico Forlanini ' s " Omnia Dir " in 1930s . Now being researched , Fluidic Thrust Vectoring ( FTV ) method diverts thrust via secondary fluidic injections . Tests show that air forced into a jet engine exhaust stream can deflect thrust up to 15 degrees . Such nozzles are desirable for their lower : mass and cost ( up to 50 % less ) , inertia ( for faster , stronger control response ) , complexity ( mechanically simpler , fewer or no moving parts or surfaces , less maintenance ) , and radar cross section for stealth . This will likely be used in many unmanned aerial vehicle ( UAVs ) , and 6th generation fighter aircraft . Nozzles . Thrust - Vectoring flight control ( TVFC ) is obtained through deflection of the aircraft jets into the pitch , yaw and roll directions . In the extreme , deflection of the jets in yaw , pitch and roll creates desired forces and moments enabling complete directional control of the aircraft flight path without the implementation of the conventional aerodynamic flight controls ( CAFC ) . When TVFC is implemented to complement CAFC , agility and safety of the aircraft are maximized . To implement TVFC a variety of nozzles both mechanical and fluidic may be applied . This includes , but is certainly not limited to convergent and convergent - divergent nozzles that may be fixed or geometrically variable . Within these aircraft nozzles , the geometry itself may vary from two - dimensional ( 2 - D ) to axisymmetric or elliptic . Thus , it is necessary to clarify some basic definitions used in thrust - vectoring nozzle design . Axisymmetric : Nozzles with circular exits . Conventional Aerodynamic Flight Control ( CAFC ) : Pitch , Yaw - Pitch , Yaw - Pitch - Roll or any other combination of aircraft control through aerodynamic deflection using rudders , flaps , elevators and / or ailerons . Converging - Diverging Nozzle ( C - D ) : Generally found on fighter aircraft , the jet stream is taken through a reduction in area to achieve Mach 1 and then expanded through a diverging section to achieve a supersonic speed greater than Mach 1 before issuing forth . Converging Nozzle : Nozzle used on standard subsonic transport and passenger jet aircraft . After the turbine , the nozzle converges to the designed exit area where the jet stream issues forth at Mach 1 or less . Effective Vectoring Angle : The average angle of deflection of the jet stream centerline at any given moment in time . Fixed Nozzle : A Thrust - Vectoring Nozzle of invariant geometry or one of variant geometry maintaining a constant geometric area ratio , during vectoring . This will also be referred to as civil aircraft nozzles and represents the nozzle thrust vectoring control applicable to passenger , transport , cargo and other subsonic aircraft . Geometric Vectoring Angle : Geometric centerline of the nozzle during vectoring . For those nozzles vectored at the geometric throat and beyond , this can differ considerably from the effective vectoring angle . Nozzle : Either convergent or convergent - divergent nozzles , focusing on those generally implemented in aircraft . Pitch : Vertical directional movement of the nozzle exit or nose of the aircraft . Roll : Circular directional movement of the aircraft around the body axis vector . Thrust Vectoring ( TV ) : The deflection of the jet away from the body - axis through the implementation of a flexible nozzle , flaps , paddles , auxiliary fluid mechanics or similar methods . Thrust Vectoring Flight Control ( TVFC ) : Pitch , Yaw - Pitch , Yaw - Pitch - Roll or any other combination of aircraft control through deflection of thrust generally issuing from an air - breathing turbofan engine . Two - Dimensional ( 2 - D ) : Nozzles with square or rectangular exits . Two - Dimensional Converging - Diverging ( 2 - D C - D ) : Square or rectangular supersonic nozzles on fighter aircraft . Variable Nozzle : A thrust vectoring nozzle of variable geometry maintaining a constant effective nozzle area ratio , during vectoring . This will also be referred to as military aircraft nozzles and represents the nozzle thrust vectoring control applicable to fighter and other supersonic aircraft . Yaw : Horizontal directional movement of the aircraft or nozzle . Methods of Nozzle Control " Geometric Area Ratios " – Maintaining a fixed geometric area ratio , from the throat to the exit during vectoring . The effective throat is constricted as the vectoring angle increases . " Effective Area Ratios " – Maintaining a fixed effective area ration from the throat to the exit during vectoring . The geometric throat is opened as the vectoring angle increases . " Differential Area Ratios " – Maximizing nozzle expansion efficiency generally through predicting the optimal effective area as a function of the mass flow rate . Methods of Thrust Vectoring Type I – Nozzles whose baseframe mechanically is rotated before the geometrical throat . Type II – Nozzles whose baseframe is mechanically rotated at the geometrical throat . Type III – Nozzles whose baseframe is not rotated . Rather , the addition of mechanical deflection post - exit vanes or paddles enables jet deflection . Type IV – Jet deflection through counter - flowing or co - flowing auxiliary jet streams . Fluid - based jet deflection . Operational examples . A famous example of thrust vectoring is the Rolls - Royce Pegasus engine used in the Hawker Siddeley Harrier , as well as in the AV - 8B Harrier II variant . Widespread use of thrust vectoring for enhanced maneuverability in Western production - model fighter aircraft would have to wait until the 21st century , and the deployment of the Lockheed Martin F - 22 Raptor fifth - generation jet fighter , with its afterburning , thrust - vectoring Pratt & Whitney F119 turbofan . Lockheed Martin F - 35 Lightning II is currently in the pre - production test and development stage . Although this aircraft uses a conventional afterburning turbofan ( F135 or F136 ) to facilitate supersonic operation , the F - 35B variant , developed for joint usage by the US Marine Corps , UK Royal Air Force and Royal Navy , also incorporates a vertically mounted , low - pressure shaft - driven remote fan , which is driven through a clutch during landing from the engine . Both the exhaust from this fan and the main engine ' s fan are deflected by thrust vectoring nozzles , to provide the appropriate combination of lift and propulsive thrust . The Sukhoi Su - 30 MKI , produced by India under license at Hindustan Aeronautics Limited is in active service with the Indian Air Force , and employs 2D thrust vectoring . The 2D TVC makes the aircraft highly maneuverable , capable of near - zero airspeed at high angles of attack without stalling , and dynamic aerobatics at low speeds . The Su - 30MKI is powered by two Al - 31FP afterburning turbofans . The TVC nozzles of the MKI are mounted 32 degrees outward to longitudinal engine axis ( i . e . in the horizontal plane ) and can be deflected ±15 degrees in the vertical plane . This produces a corkscrew effect , greatly enhancing the turning capability of the aircraft . Examples of rockets and missiles which use thrust vectoring include both large systems such as the Space Shuttle Solid Rocket Booster ( SRB ) , S - 300P ( SA - 10 ) surface - to - air missile , UGM - 27 Polaris nuclear ballistic missile and RT - 23 ( SS - 24 ) ballistic missile and smaller battlefield weapons such as Swingfire . The principles of air thrust vectoring have been recently adapted to military sea applications in the form of fast water - jet steering that provide super - agility . Examples are the fast patrol boat Dvora Mk - III craft , the HAMINA Stealth Attack craft and the new U . S . Littoral Combat Ships [ LCS ] . A few computerized studies add thrust vectoring to extant passenger airliners , like the Boeing 727 and 747 , to prevent catastrophic failures , while the new experimental X - 48C may be jet - steered in the future . List of vectored thrust aircraft . Thrust vectoring can convey two main benefits : VTOL / STOL , and higher maneuverability . Aircraft are usually optimized to maximally exploit one benefit , though will gain in the other . References . 8 . Wilson , Erich A . , " An Introduction to Thrust - Vectored Aircraft Nozzles " , ISBN 978 - 3 - 659 - 41265 - 3