The directional control of a fixed-wing aircraft takes place around the lateral, longitudinal, and vertical axes by means of flight control surfaces designed to create a movement about these axes. These control devices are hinged or movable surfaces through which the attitude of an aircraft is controlled during takeoff, flight, and landing.
The primary control surface of airplanes is Aileron, Elevator, and Rudder. These are used to control the direction of an airplane by actuating to do roll, pitch, and yaw movement in six degrees of freedom.
Aileron is one of the directional control surface of an aircraft. It is fixed at the trailing edge of the aircraft wing. Aileron is used to actuate roll in an airplane. It takes place in the longitudinal axis to roll the aircraft in the left and right directions. The left roll actuation is done when the right aileron actuates downwards and left aileron actuates upwards, the pressure variation in right aileron makes the right-wing to lift up and the left-wing to dropdown. Similarly, the right roll actuation is done when the left aileron actuates downwards and right aileron actuates upwards, the pressure variation in left aileron makes the left-wing to lift up and the right-wing to dropdown.
The elevator is fixed at the trailing edge of the aircraft horizontal stabilizer of the tail section. The elevator is used to control the pitch movement of the airplane. It takes place in the lateral axis of the plane. The control of the elevator is to lift the aircraft upwards and downwards by actuating its control surface. For pitch up, movement, the elevator moves upwards so the pressure increases in the tail section and will lift the aircraft upward. For pitch down elevator moves downwards, the pressure decreases in the tail section and makes the aircraft to drop downwards. Elevators play an important role in the take-off and landing of an aircraft.
The rudder is the primary control surface that causes an aircraft to yaw or move about the vertical axis. This provides directional control and thus points the nose of the aircraft in the direction desired. Most aircraft have a single rudder hinged to the trailing edge of the vertical stabilizer. It is controlled by a pair of foot-operated rudder pedals in the cockpit. When the right pedal is pushed forward, it deflects the rudder to the right which moves the nose of the aircraft to the right. The left pedal is rigged to simultaneously move aft. When the left pedal is pushed forward, the nose of the aircraft moves to the left.