Definition
A type of trailing-edge wing flap that extends rearward on tracks before deflecting downward. The rearward motion increases the wing's surface area, and the downward deflection increases its curvature, producing a large gain in lift with relatively little drag at small flap settings, and high lift with high drag at full extension.
Plain English
A flap that first slides backward to make the wing bigger, then tilts down to make it more curved. This combination gives the airplane much more lift for slow flight, takeoff, and landing.
Context Anchor
Seen in airfoil design, aircraft systems descriptions, and normal takeoff or landing procedures for airplanes equipped with this flap type.
Derivation
Named after Harlan D. Fowler, the American engineer who developed the design in the 1920s. Knowing it is a person's name (not a descriptive word) prevents the reader from trying to guess the meaning from English roots.
Why Pilots Care
They produce greater lift at low speeds than simpler flap types, shortening takeoff and landing distances on larger or heavier aircraft.
Analogy
A Fowler flap is a bit like pulling a small shelf out from the back of the wing and then tilting it downward. The wing effectively gets more lifting surface for slower flight.
Intuition Check
Do not think of Fowler flaps as simple panels that only hinge downward. Their key feature is that they slide rearward, increasing wing area, as well as deflecting downward.
Example Sentence 1
On final approach, the pilot selected full Fowler flaps to steepen the descent and reduce the landing speed.
Example Sentence 2
Because the Fowler flaps added both camber and surface area, the aircraft could maintain level flight at a lower airspeed.