What is the Difference Between Flaps and Ailerons?

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Flaps and ailerons are both flight control surfaces found on aircraft, but they serve different purposes and have distinct characteristics.

Ailerons:

  • Control the roll of an airplane by increasing or decreasing lift on the wing.
  • Located on the trailing edge of the wing, typically closer to the wingtip.
  • Can deflect up and down.
  • Hinge point is usually inside the wing, and some ailerons are even sealed to reduce drag.
  • Typically moved via cables or hydraulic actuators.

Flaps:

  • Deployed during takeoff and landing to increase lift at lower speeds.
  • Movable panels on the trailing edge (back) of the wing.
  • Usually only deflect down.
  • Hinge point is typically below the wing to create a small gap when deflected, increasing lift.
  • Typically moved via a jackscrew, which may be hydraulically or electrically powered.

In summary, ailerons are used to control the roll of an airplane by adjusting lift on the wings, while flaps are deployed during takeoff and landing to increase lift at lower speeds. Ailerons can deflect both up and down, whereas flaps usually only deflect down.

Comparative Table: Flaps vs Ailerons

Here is a table comparing the differences between flaps and ailerons:

Feature Flaps Ailerons
Purpose To create more lift and decrease the stalling speed of the aircraft To control the rolling motion of the aircraft
Location Trailing edge of the wing, between the ailerons and the fuselage Found on the trailing edge of the wing, typically closer to the wing tip
Shape Retractable 'extensions' of the wing, changing the angle of the airfoil Control surfaces that are part of the wing
Control Controlled by a lever or button in the cockpit Controlled by the yoke or control stick
Movement Usually only deflect down Can deflect up and down
Construction Typically larger and subjected to higher dynamic pressure loads Typically smaller and can be deflected at higher speeds
Hinge Point Hinge point below the wing to create a small gap when deflected Hinge inside the wing, some are even sealed to reduce drag
Counterweight Flaps do not have counterweights, as they are deployed at lower speeds Counterweights are used to prevent flutter, as ailerons can be deflected at higher speeds

Flaps and ailerons are both control surfaces on an aircraft's wing, but they serve different functions and have distinct characteristics. Flaps are used to increase lift and decrease stall speed, while ailerons are used to control the roll of the aircraft.