slotted flaps

slotted flaps

slotted flapsclick for a larger image
A type of trailing-edge flap. These may be single, double, or triple slotted. They form a slot(s) between their leading edge and the inside of the flap well in the wing. The resultant airflow helps to control the boundary layer, resulting in higher maximum lift but not so much increase in drag. The stalling angle also increases considerably.