The V-tail or vee-tail (sometimes called a butterfly tail[1] or Rudlicki's V-tail[2][citation needed]) of an aircraft is an unconventional arrangement of the tail control surfaces that replaces the traditional vertical and horizontal surfaces with two surfaces set in a V-shaped configuration. It is not widely used in aircraft design. The aft edge of each twin surface is a hinged control surface called a ruddervator, which combines the functions of both a rudder and elevator.