A flaperon is a type of aircraft control surface that combines aspects of both flaps and ailerons. 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 dedicated set of flaps. Both ailerons could also be raised, which would give spoilerons.
The pilot has separate controls for ailerons and flaps. A mixer is used to combine the separate pilot input into this single set of control surfaces called flaperons. The use of flaperons instead of separate ailerons and flaps can reduce the weight of an aircraft. The complexity is transferred from having a double set of control surfaces (flaps and ailerons) to the mixer.
Many designs that incorporate flaperons mount the control surfaces away from the wing 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 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.
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