Flaperon

A flaperon (a portmanteau word) on an aircraft's wing is a type of control surface that combines the functions of both flaps and ailerons. Some smaller kitplanes have flaperons for reasons of simplicity of manufacture, while some large commercial aircraft may have a flaperon between the flaps and aileron.

In addition to controlling the roll or bank of an aircraft, as do conventional ailerons, both flaperons can be lowered together to function similarly to a set of flaps.

On a plane with flaperons, the pilot still has the standard separate controls for ailerons and flaps, but the flap control also varies the flaperon's range of movement. A mechanical device called a "mixer" is used to combine the pilot's input into the flaperons. While the use of flaperons rather than ailerons and flaps might seem to be a simplification, some complexity remains through the intricacies of the mixer.

Some aircraft, such as the Denney Kitfox, suspend the flaperons below the wing (rather in the manner of slotted flaps) to provide undisturbed airflow at high angles of attack or low airspeeds. When the flaperon surface is hinged below the trailing edge of a wing, they are sometimes named "Junker Flaperons", from the doppelflügel (lit., "double wing") type of trailing edge surfaces used on a number of Junkers aircraft of the 1930s, such as the Junkers Ju 52 airliner, and Junkers Ju 87 Stuka iconic World War II dive bomber.

Current research seeks to coordinate the functions of aircraft flight control surfaces (ailerons, elevators, elevons, flaps, and flaperons) so as to reduce weight, cost, drag, inertia, and thereby achieve improved control response), reduced complexity, and reduced radar visibility for stealth purposes. Beneficiaries of such research might include drones (UAVs) and the latest fighter aircraft.

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