RC Airplane Elevator: On the tailend of an airplane, hinged control surfaces on the horizontal stabilizer are the elevators. The position of the elevator controls whether the nose of the airplane is pointing up or down and thus moving up or down. The nose of the plane moves in the direction of the elevators. Point the elevator up and the nose goes up and the airplane climbs. Move the elevator so it is pointing down and the nose goes down and the airplane descends.
On an RC airplane transmitter, the elevator is controlled by the forward and backward movement of one of the sticks. For a typical 3-channel transmitter and 4-channel transmitters using Mode 2 (most common in US) the right stick controls the elevators. In Mode 1 (common in UK, used in training mode sometimes too) the elevator control is on the left stick.
RC Helicopter Main Rotor: Although RC helicopters don't have elevators, the term is also used in RC helicopter flight to describe the controls for the cyclic pitch -- forward and backward pitch or tilting of the main rotors for climbing and diving. The elevator controls forward and backward movement and altitude when in flight. This is typically controlled by the right stick of the RC helicopter controller although other configurations are possible.
