What is a servo trim tab designed to do?

A servo trim tab is specifically designed to assist in the movement of a control surface by creating aerodynamic forces. When installed on a control surface such as an elevator or aileron, the trim tab positions itself in a way to counteract aerodynamic forces acting on that surface. Thus, it helps to relieve the pilot from having to apply constant control inputs to maintain desired flight attitudes or trim conditions.

By adjusting the trim tab, the pilot can set an attitude where the aircraft remains stable without continuous control pressure, allowing for smoother and more comfortable flying. This capability to assist in control surface movement is vital for efficient operation, especially during long flights or when flying at different speeds and altitudes.

The other options focus on outcomes that are not the primary function of a servo trim tab. For example, while increasing lift or limiting airflow are important aerodynamic concepts, they do not directly pertain to the function of the servo trim tab. The main objective is primarily about providing aerodynamic assistance to maneuver the aircraft effectively and maintain controlled flight.