Wing flaps have a few purposes. They assist in allowing the aircraft to have greater lift at a lower speed. This prevents stalling and is useful during takeoff and when landing. Flaps do cause drag so they are folded back when not in use although this drag is helpful when landing. There are four main designs for flaps.
They are plain, split, slotted, and fowler flaps. Slotted flaps are the most commonly used on aircraft of all sizes while slotted flaps are unusual today. Flaps can increase the wing area, not decrease it. Flaps do not lessen the pilot’s pressure on the controls.
