Which control surface primarily affects roll in an aircraft?

The control surface that primarily affects roll in an aircraft is the ailerons. Ailerons are located on the trailing edge of each wing and are responsible for controlling the aircraft’s roll about its longitudinal axis. When one aileron is deflected upward, it decreases lift on that wing, while the opposite aileron is deflected downward, increasing lift on the other wing. This differential lift causes the aircraft to roll towards the wing with the lower lift, allowing the pilot to maneuver the aircraft effectively during flight.

In contrast, the elevator controls pitch, determining the nose-up or nose-down attitude of the aircraft. The rudder, located on the vertical stabilizer, is responsible for yaw, or the side-to-side movement of the aircraft’s nose. Flaps are used to increase lift and drag during takeoff and landing, but they do not play a direct role in controlling roll. Understanding these functions helps in comprehending how an aircraft is controlled in three-dimensional space.