Which control surface primarily increases the lift of an aircraft?

The control surface that primarily increases the lift of an aircraft is flaps. Flaps are located on the wings and are designed to extend and change the shape of the wing when deployed. When the flaps are extended, they increase the surface area and curvature of the wing, allowing the aircraft to generate more lift at lower speeds. This feature is particularly beneficial during takeoff and landing when a higher lift is needed to safely operate at reduced speeds.

In contrast, ailerons are used primarily for roll control and managing the aircraft's attitude during flight rather than directly influencing lift. The rudder is essential for controlling yaw, helping the aircraft maintain a straight path, especially during turns. Elevators, located on the tail, control pitch, affecting the angle of attack but not directly increasing overall lift like flaps do.