Which control surface primarily affects the rotation of the aircraft?

The control surface that primarily affects the rotation of the aircraft is the ailerons. Ailerons are located on the trailing edge of the wings and operate in opposition to one another; when one aileron deflects upward, the other deflects downward. This movement alters the lift on each wing, allowing the aircraft to roll. By rolling the aircraft, the ailerons facilitate changes in the bank angle, which is essential for turning.

In contrast, the elevator primarily controls pitch, which is the angle of the aircraft's nose in relation to the horizon. The rudder primarily controls yaw, which is the left or right movement of the aircraft’s nose. Flaps are used to increase lift and drag during takeoff and landing but do not contribute directly to the rotational motion of the aircraft. Understanding the specific roles of these control surfaces is crucial for flight dynamics and aerodynamics.