What is a balance tab?

A balance tab is an auxiliary control surface that is linked to the primary control surface but is designed to move in the opposite direction. Its primary function is to relieve some of the control forces required to move the primary control surface, making it easier for the pilot to operate. By assisting in controlling the primary surface, balance tabs help maintain the aerodynamic balance of the aircraft.

This makes the fixed linkage aspect critical since the movement of the primary control surface automatically causes the balance tab to move, providing aerodynamic assistance without requiring additional pilot effort. This is particularly beneficial in large aircraft, where control forces can be significantly high. Understanding this function is essential for recognizing how aircraft control surfaces interact and the role that balance tabs play in managing those interactions effectively.