I believe elevons are primarily used on flying wing models where there are only two control surfaces looking like ailerons on a standard plane. These ailerons are driven by two seperate servos on their own channels usually controlled by a computer radio. By using elevon mixing, the ailerons become elevons being able to control both pitch and roll. Pulling ch-2 (elevator) towards you will raise the elevons causing the plane to climb. Pushing ch-1 (aileron) to the right will raise the right elevon and drop the left causing the plane to roll to the right.