Thrust Vector Control (TVC) Systems: Overview, Functions, and Technologies

6.2. Thrust Vector Control (TVC) Systems: Overview, Functions, and Technologies#

Written by Marc Budinger (INSA Toulouse), Toulouse, France

6.2.1. 1. Introduction to Thrust Vector Control (TVC)#

Thrust Vector Control (TVC) is a critical subsystem in modern rockets, enabling precise control of the vehicle’s trajectory by adjusting the direction of the engine’s thrust. This capability is essential for maintaining stability, correcting deviations, and executing maneuvers during ascent, especially in the absence of aerodynamic surfaces in the vacuum of space. TVC systems are employed in both liquid and solid rocket engines, ensuring optimal performance and mission success. TVC systems are typically integrated at the interface between the rocket engine and the vehicle’s structure near the base of the rocket, close to the main engines and boosters, to minimize structural loads and maximize control authority.

Rocket family

6.2.2. 2. Functions of TVC Systems#

The primary functions of TVC include:

  • Attitude Control: Adjusting the rocket’s pitch, yaw, and roll to follow the planned trajectory.

  • Trajectory Correction: Compensating for external disturbances (e.g., wind shear) or internal asymmetries (e.g., uneven thrust).

  • Stage Separation: Ensuring proper orientation during stage separation and engine cutoff.

  • Precision Maneuvering: Enabling fine adjustments for orbital insertion or reentry phases.

TVC is particularly vital during the initial ascent phase, where aerodynamic forces are insufficient for control, and in upper stages, where precise orbital maneuvers are required.

6.2.3. 3. TVC Technologies: Hydraulic vs. Electromechanical#

Hydraulic TVC Systems Hydraulic systems use pressurized fluid to drive actuators, offering high force and reliability. They are commonly used in legacy and high-thrust applications, such as the Space Shuttle’s Main Engines or Ariane 5’s Vulcain engine.

  • Advantages:

    • High force output, suitable for large engines.

    • Proven technology with extensive flight heritage.

  • Disadvantages:

    • Complex plumbing and fluid management.

    • Risk of leaks and maintenance requirements.

Ariane 5 launcher – Booster TVC system (Hydraulic technology) EMA technology

Electromechanical TVC Systems Electromechanical Actuation (EMA) systems replace hydraulic fluids with electric motors and gearboxes, providing a more efficient and lightweight solution. This technology is increasingly adopted in modern launchers like Ariane 6 and Vega.

Vega launcher – Booster TVC system (EMA technology) EMA technology

  • Advantages:

    • Simplified architecture with fewer components.

    • Reduced weight and improved reliability.

    • Lower operational costs and easier integration.

  • Disadvantages:

    • Limited force output compared to hydraulic systems (though sufficient for many applications).

    • Thermal management challenges in high-power scenarios.

Ariane 6 such as Vega launchers employ Electromechanical Actuators (EMAs) for its TVC system, marking a shift from the hydraulic systems used in Ariane 5. The EMAs are designed for high efficiency, with lithium-ion batteries providing backup power to ensure functionality even in case of primary power loss. This architecture reduces mass and simplifies ground operations compared to hydraulic systems.

The actuator that we propose to size here is composed of:

  • a permanent magnet synchronous motor

  • a spur gear reducer

  • a roller screw

  • a thrust bearing

  • 2 rod ends

  • a tube / casing assembly (housing)

TVC EMA actuator [Sabca] P80 EMA components P80