Most competitive aircraft are fitted with flaps on the wings, which work in conjunction with the elevator to increase the pitch maneuverability. When up-elevator is applied, the flaps on the wings go down, and vice versa. This results in the wing, which is otherwise of a symmetrical section, to be cambered in the direction needed to enhance maneuvering. Aircraft without flaps can be flown successfully and are typically simpler, but flapped models typically fly more smoothly and can be heavier. Some of the simpler stunt models make excellent control-line trainers, as the predictable control response, low speed, and strong line tension make them easy to fly successfully.