Flight Controls: Overview

Primary Control Services

Controls that rotate the aircraft around its three axes:

1. Elevator (Pitch / Lateral Axis).
2. Ailerons (Roll / Longitudinal Axis).
3. Rudder (Yaw / Normal Axis).

Secondary Flight Controls

Used to change the aerodynamic configuration or assist primary controls.

• Trim Tabs: Relieve control forces.
• Balance Tabs: Assist in moving the control surface (reduce force).
• Anti-Balance Tabs: Increase control feel (increase force).
• Flaps/Slats: High lift devices.
• Spoilers: Lift dumpers / Airbrakes.

Interaction

• Maneuverability vs Stability: A highly stable aircraft is harder to control (heavy controls). A highly maneuverable aircraft (like a fighter) is less stable.
• Control Reversal: At very high speeds, aeroelastic twisting of the wing can cause aileron reversal (deflecting aileron down twists the wing leading edge down, reducing lift instead of increasing it).