# Thrust Vector Control:
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 rockets is achieved by gimballing 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 missiles 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 SLBMs of the United States Navy.
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Table of Contents:
- What Is Thrust Vector Control?
- Reasons For Thrust Vector Control
- Thrust Vector Control - Pitch, Yaw And Roll
- Thrust Vector Control With A Single Nozzle
Mechanical Deflection Of The Nozzle
Insertion Of Heat-Resistant Movable Bodies Into The Exhaust Jet
Injection Of Fluid Into The Side Of The Diverging Nozzle Section
Separate Thrust-Producing Devices - Schematic Diagrams of Eight Different Thrust Vector Control Mechanism
- Thrust Vector Control With Multiple Thrust Chambers Or Nozzles