An elevon on an aircraft is a flap that combines the functions of an elevator and an aileron. The name is derived from these two words. (ELEV-ator and ailer-ON). In a traditionally designed aircraft the elevators control pitch and the ailerons control roll.
The elevons are placed on the trailing edge of the wings. From here they are controlled by the pilot with a traditional joystick. Computers inside the aircraft translate the action of the pilot into the required action of the elevons as if he still had the individual flaps at his disposal.
They are most commonly seen on flying wing type aircraft. An elevon that is fitted separately from the wings on the tail is known as a taileron.
In the simplest form pitch in controlled by moving the flaps in the same direction, forcing the nose of the aircraft up or down. For a turn or roll one elevon will raise and the other will move downwards.
In a traditional aircraft such as a jumbo jet the elevators are the flaps found on the horizontal section of the tail assembly. By raising these elevators the air is slowed over the tail assembly, reducing lift and the plane pitches forwards. The opposite effect is true if the elevators are dropped.
The ailerons are the flaps on the trailing edges of the wings. They are inset into the wing and often have smaller trim flaps inserted into them. They are interconnected so that as one rises the other falls. They are used to control the roll of an aircraft, and so steer it. The mathematics of the motion induced is complex, with opposing forces causing yaw or wobble that has to be adjusted for by the differential use of the ailerons or by the use of the rudder.
The Wright brother’s very first aeroplane, the Kitty Hawk, featured elevators, but no roll control. Ailerons were introduced in the early twentieth century before powered flight, and Henry Farman introduced the first aileron on a powered aircraft in around 1908. His is not the only claim for this with William Whitney Christmas (1914) and Glenn Curtis (1908) also having a claim. The history of early aviation is littered with claims and counter claims with many people developing similar advances at similar times, and record keeping being poor.
The inventor of the elevon is not easily identified as elevons were largely developed for military applications.