Topic 2 Copy

The rear portion of the airfoil rotates downwards on a simple hinge mounted at the front of the flap. Owing to the greater efficiency of other flap types, the plain flap is normally only used where simplicity is required.

The rear portion of the lower surface of the airfoil hinges downwards from the leading edge of the flap, while the upper surface stays immobile. A split flap acts much like a spoiler, adding significantly to drag. It adds a little to the lift coefficient

A gap between the flap and the wing forces high pressure air from below the wing over the flap and increases lift. 

A flap that slides rearwards for a distance prior to hinging downwards. It first increases wing surface area and then increases camber. This produces a flap that can optimize both takeoff and landing performance. This type of flap or one of its variations is found on most large aircraft.