What purpose do the ailerons serve on a Cessna 172?

Ailerons play a crucial role in controlling the roll of the aircraft around its longitudinal axis. On the Cessna 172, as well as in other aircraft, the ailerons are located on the outer trailing edge of each wing. When the pilot deflects the control yoke to the left or right, one aileron moves up while the other moves down. This movement creates differential lift on the wings—where the wing with the aileron that goes down produces more lift than the other wing, which causes the aircraft to roll in the desired direction.

This roll control is essential for maneuvering the airplane, especially during turns. Effective use of ailerons allows the pilot to maintain a coordinated flight path and manage the aircraft's attitude in various flying conditions.

While the other options mention altitude control, yaw, and drag reduction, these functions are primarily managed by different flight control surfaces or design elements of the aircraft. For example, altitude is primarily controlled through the elevator, yaw is controlled by the rudder, and drag is a factor of aerodynamic design and can be reduced with specific techniques, but not primarily through aileron use.