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Aerofoils: controlling aircraft in flight

Short answer

Aerofoils produce lift by curved upper surfaces causing faster airflow and lower pressure, with higher pressure beneath. Movable surfaces control flight: ailerons roll the aircraft, elevators change pitch, rudder controls yaw, flaps increase lift/drag, and trim tabs adjust balance.

How do aerofoils function to control the aircraft in flight? (Aerofoils)

An aerofoil is a shaped surface, such as a wing, tailplane or propeller blade, designed to produce a useful force when air flows past it. Aerofoils both lift the aircraft and control its movement.

How an aerofoil produces lift

        ___________
     _.-'           '-._     upper surface curved:
 -->(__________________)-->  air moves faster, lower pressure
                             lower surface flatter:
                             higher pressure --> LIFT
  • The upper surface of the wing is curved and the lower surface is flatter. Air passing over the top travels faster, so its pressure is lower than the pressure beneath the wing.
  • The pressure difference, along with the downward deflection of air by the inclined wing (angle of attack), creates lift.

Control of flight

Movable aerofoil surfaces change the forces on the aircraft:

  1. Ailerons (on the wings) move in opposite directions. One wing gains lift and the other loses it, so the aircraft rolls, used in banking and turning.
  2. Elevators (on the horizontal tailplane) move up or down to raise or lower the nose, controlling pitch (climb and descent).
  3. Rudder (on the vertical fin) swings the nose left or right, controlling yaw.
  4. Flaps (on the wing's rear edge) increase lift and drag at low speed, for take-off and landing.
  5. Trim tabs and spoilers adjust balance and reduce lift or increase drag.

The pilot works these surfaces through controls, so that changing the airflow over each aerofoil gives control in the three axes.

✓ Answer checked by Claude Opus 5.5 (high effort)

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