Ailerons are roll-control control surfaces of the RC Airplanes. Ailerons provide roll by moving in opposite direction to each other. When one aileron moves down the other moves up thus providing more lift on one side as oppose to the other causing the RC Airplane to roll. Ailerons are at the trailing edge of RC Airplane wing and towards the wing tips.
Flaps provide additional lift to the RC Airplane by increasing the maximum lift coefficient of RC Airplanes. The flaps can be used to increase the lift during landing and take-off to better take advantage of the ground effect. The flaps move simultaneously. When both flaps move down it is known as flaps-down and increases lift of the wing. When flaps move up it is known as flaps-up. Sometimes, flaps are designed so that they only move down or come to the neutral position and not move up.
Elevators are the pitch-control control surfaces of the RC Airplanes. Elevators provide pitch control by moving either up or down simultaneously causing the airplane to pitch about the center of gravity of RC Airplane. When elevator is moved up the nose of the airplane rises and is known as pitch up. When the elevator is moved down the nose of the RC Airplane moves down and is known as pitch down.
Rudder is the yaw-control control surface of the RC Airplanes. Rudder provides yaw control by moving to either side be it left or right. The rudder yaws the RC Airplane about the center of gravity cg of RC Airplane causing the RC Airplane nose to move right or to move left. A right rudder maneuver causes the RC Airplane to move to the right. A left rudder maneuver causes the RC Airplane to the left.