![Slotted flap](https://webarchive.library.unt.edu/eot2008/20080920084017im_/http://centennialofflight.gov/essay/Dictionary/thumb/DI104G1.jpg)
The basic slotted flap.
![How a spoiler affects lift.](https://webarchive.library.unt.edu/eot2008/20080920084017im_/http://centennialofflight.gov/essay/Dictionary/thumb/DI104G2.jpg)
How a spoiler
affects lift.
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Flight
Control Surfaces
The
rudder, elevator, and aileron are the primary control surfaces on an airplane.
The rudder controls the airplane's yaw, the elevator controls its pitch,
and the aileron controls its roll (see the individual dictionary entries
for each of these.) Others are addressed below.
Wing
flaps are a movable part of the wing, normally hinged to the trailing
edge (rear edge) of each wing closest to the airplane body. The pilot
extends and retracts the flaps. Extending the flaps increases the wing
camber and the angle of attack of the wing. This increases wing lift and
also increases drag. Flaps enable the pilot to make a steeper descent
when landing without increasing airspeed. They also help the airplane
get off the ground in a short distance. There are many different types
of flaps. Some hinge, some slide, some open with slots, and some help
smooth the air over the wing even when high angles of attack are flown
during landing.
Slats
are protrusions from the leading edge (front edge) of a wing. They add
to the lift of a wing. Slats and flaps work together to maintain laminar
flow (a smooth airflow) over the top of the wing.
Spoilers
reduce lift. Spoilers are found along the top of the wing. When they aren't
being used, they fit into or flush with the wing's surface. When they
are used, they protrude from the wing's surface into the airflow and destroy
the laminar flow for a portion of the wing. The size of the spoiler varies
according to how much lift is to be "spoiled." Different spoiler
designs are found on different types of planes, but their function is
the same.
Some
devices only produce drag without affecting the wing's lift. These include
speed brakes, air brakes, dive flaps, or drag parachutes. They may be
located on the wing's trailing edge or may protrude from the fuselage.
These devices allow very steep descents and rapid changes in airspeed.
The pilot can stop their effect almost instantaneously by retracting the
devices.
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