Trim tab is defined as?

• A. A fixed portion of the wing
• B. A device to measure wind speed
• C. A navigation aid
• D. A small auxiliary hinged portion of a movable control surface that can be adjusted during flight to a position resulting in a balance of control forces

Answer: (D)

Trimming means using a small, adjustable surface to balance the forces on the movable control surface so the airplane can hold a steady flight path with less effort from the pilot. A trim tab is that small auxiliary hinged portion of a movable control surface that, when deflected, creates an aerodynamic force that helps position the main control surface toward the desired attitude. By adjusting the tab in flight, you set a moment that counteracts the forces the airplane is experiencing, allowing the aircraft to maintain the desired pitch, roll, or yaw without continuous pressure on the controls. This is different from a fixed part of the wing, a device to measure wind speed, or a navigation aid.