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''For the band with a similar name, see The Ailerons''

'Ailerons' are hinged control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. They are used to control the aircraft in roll. The two ailerons are interconnected so that one goes down when the other goes up: the downgoing aileron increases the lift on its wing while the upgoing aileron reduces the lift on the other wing, producing a rolling moment about the aircraft's longitudinal axis. The word ''aileron'' is French for "little wing."
An unwanted side-effect of aileron operation is adverse yaw — a yawing moment in the opposite direction to the turn generated by the ailerons. In other words, using the ailerons to roll an aircraft to the right would produce a yawing motion to the left. As the aircraft rolls, adverse yaw is caused primarily by an increase in induced drag on the rising wing, and a decrease in induced drag on the falling wing. One wing is rising in response to increased lift caused by the greater effective camber of the wing and downward-deflected aileron, and the other wing is falling in response to reduced lift caused by the reduced effective camber of the wing and upward-deflected aileron. Increased lift causes increased induced drag, and reduced lift causes reduced induced drag. A secondary contribution to adverse yaw is caused by the wing on the outside of the turn traveling faster than the inside wing and thus the outer wing experiences more parasitic drag than the inner wing. Modern aileron systems have minimal adverse yaw, such that it is barely noticeable in most powered aircraft. This may be accomplished by the use of ''differential ailerons'', which have been rigged such that the downgoing aileron deflects less than the upward-moving one. ''Frise ailerons'' achieve the same effect by protruding beneath the wing of an upward-deflected aileron, most often by being hinged slightly behind the leading edge and near the bottom of the surface, with the lower section of the leading edge protruding slightly below the wing's undersurface when the aileron is deflected upwards, increasing drag on that side. Ailerons may also use a combination of these methods.
With ailerons in the neutral position the wing on the outside of the turn develops more lift than the opposite wing due to the variation in airspeed across the wing span, and this tends to cause the aircraft to continue to roll. Once the desired angle of bank (degree of rotation on the longitudinal axis) is obtained, the pilot uses opposite aileron to prevent the aircraft from continuing to roll due to this variation in lift across the wing span. This minor opposite use of the control must be maintained throughout the turn. The pilot also uses a slight amount of rudder in the same direction as the turn to counteract adverse yaw and to produce a "coordinated" turn where the fuselage is parallel to the flight path. A simple gauge on the instrument panel called the inclinometer, also known as "the ball", indicates when this coordination is achieved.
The device first appeared on a monoplane, built by New Zealand inventor Richard Pearse in 1902, but most researchers believe the aircraft achieved no more than short, poorly controlled flights. The first aircraft accepted to have had a fully controlled flight using an aileron was 14 Bis by Santos Dumont. It was later developed independently by the Aerial Experiment Association, headed by Alexander Graham Bell, and by Robert Esnault-Pelterie, a French aircraft builder. Ailerons superseded the earlier wing warping technique, developed by the Wright Brothers.

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Combination with other control surfaces

See also

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Combination with other control surfaces

★ A control surface that combines an aileron and flap is called a 'flaperon'. A single surface on each wing serves both purposes: used as an aileron, the flaperons left and right are actuated differentially; when used as a flap, both flaperons are actuated downwards. When a flaperon is actuated downwards (i.e. used as a flap) there is enough freedom of movement left to be able to still use the aileron function.

★ A further form of roll control, common on modern jet transport aircraft, utilises spoilers in conjunction with ailerons. This is called a 'spoileron'.

★ In a delta-winged aircraft, the ailerons are combined with the elevators to form an 'elevon'.

★ Modern military aircraft may have no ailerons on the wings at all, and combine roll control with an all-moving tailplane. This is a 'taileron' or a rolling tail.

See also

★ Flight controls

★ Trailing edge

External links

★ NASA Glenn Research Center aileron article with Java demo and more pictures