What is the primary function of flaps on an aircraft?

The primary function of flaps on an aircraft is to create extra lift. Flaps are movable surfaces located on the trailing edge of the wings, and they are deployed during critical phases of flight such as takeoff and landing. When extended, flaps increase the curvature (camber) of the wing, which improves the airflow over the wing and allows it to generate more lift at lower speeds. This extra lift is essential for allowing the aircraft to safely take off and land, especially in shorter distances and under various weight conditions.

While it is true that deploying flaps can also increase drag—making option two a potential consideration—the primary design intent and functional role of flaps is to enhance lift. The other choices, which refer to controlling yaw or adjusting thrust, are unrelated to the specific purpose of flaps. Yaw is typically controlled by the rudder, and thrust adjustments are managed by the engines, which further delineates the unique role flaps play in aircraft performance.