From SKYbrary Wiki
Flaperons are a specialised type of aircraft flight control surface that combine aspects of both flaps and ailerons. Flaperons respond to roll commands, made by the pilot via the control wheel or stick, in the same manner as conventional ailerons. However, the flaperons can also be symmetrically lowered to function similarly to a dedicated set of flaps. Pilot controls for lowering or raising the flaperons are separate from those controlling the aileron function. A mixer is incorporated in the design to combine the two pilot inputs appropriately.
The use of flaperons instead of separate flaps and ailerons can result in an overall reduction in the weight of an aircraft. Flaperons are often mounted well clear of the trailing edge of the wing to ensure undisturbed airflow across the flight control surface whilst at low speed or at high angles of attack. This helps to reduce stall speed and improves low speed handling characteristics.
Flaperons were incorporated in a number of World War II era designs including the Junkers Ju87 Stuka dive bomber. Current utilisation is limited and is largely confined to light, experimental category (homebuilt) aircraft. Flaperons are also incorporated into the design of the V-22 Osprey tilt rotor aircraft.