Plain English Meaning

A flap built with two or more small openings that let air pass through them when the flap is lowered. Those openings keep the air flowing smoothly over the flap, so the wing can produce more lift at slower speeds.

Full Definition

Describes a wing flap design that incorporates two or more narrow gaps (slots) between the main wing and the flap segments, allowing high-pressure air from beneath the wing to flow through the slots and energize the airflow over the upper surface of the extended flap. This delays airflow separation at high flap deflection angles, producing greater lift and permitting steeper, slower approaches than a plain or single-slotted flap.

Context Anchor

Seen in discussions of flap effectiveness, high-lift wing designs, , , and - flap .