What do ailerons primarily control on an aircraft?

Ailerons are critical flight control surfaces primarily used to control the bank angle of an aircraft around its longitudinal axis. When the pilot moves the control stick or yoke to one side, one aileron deflects upward while the other deflects downward. This differential movement causes the aircraft to roll in the direction of the aileron that deflected downward, allowing the aircraft to bank effectively.

Banking is essential for making turns, as it helps change the aircraft's flight path without significantly altering altitude or airspeed. The manipulation of the ailerons, therefore, directly influences the aircraft's rotational motion about its longitudinal axis, allowing for more precise maneuvers during flight.

While climb rate, speed, and yaw are important aspects of flight, they are primarily controlled by other flight controls such as the elevator and rudder. The elevator manages pitch and climb rate, while the rudder is responsible for controlling yaw. Hence, the primary function of ailerons is distinctly tied to controlling the bank angle.