Flaps

More lift, more drag

January 10, 2023 By Jill W. Tallman

As you learn about the four forces that affect an airplane in flight—lift, thrust, gravity, and drag—it might interest you to know that flaps on an airplane create two of those forces all by themselves.

Flaps are mounted on the trailing edge of the wing, and when deployed they transform the shape of the wing, thus adding camber and sometimes area to the wing. This creates both lift and drag. Thus, flaps can be optimized for each phase of flight: takeoff, cruise, descent, and landing.

On simpler aircraft, you may see flaps that can be operated manually by a flap handle—a bar attached to a cable that runs back to the wing. On many newer aircraft, however, flaps are activated via an electrical switch.

You will use flaps most commonly in the approach and landing phases of flight, depending on the configuration specified in your airplane’s pilot’s operating handbook (POH). Here, flaps reduce the stall speed and allow an airplane to descend at steeper angles without gaining airspeed.

You may also need to use partial flaps to improve takeoff performance in unusual conditions, such as when taking off from a short, soft, or rough runway. Again, consult the POH. The use of partial flaps shortens the ground roll, but you will experience a lower rate of climb.

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