GLOSSARY & DEFINITIONS Elevator Control surfaces at the trailing edge of the tail plane. Surfaces Aileron deflect up & down to control the vertical pitch and speed of the model. Control surfaces at the trailing edge of the wing. Surfaces deflect up & down on opposite sides of the wing to provide a rolling force. Right roll is right aileron up, left down (viewed from rear). Ground speed The models speed as seen by the pilot and compared to the ground.