Steering an Aircraft: Use Elevators for Longitudinal Control in Planes

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Elevator attached to the trailing edge of the horizontal stabilizer of a Boeing 757. Photo Credit: Dirk-Jan Kraan

How do elevators help pilots turn an airplane?

Pilots generate turning forces, used to maneuver a plane, by changing the pattern of air flowing around the plane. In other words, they turn the plane by changing the position of the aerofoils (surfaces that interact with the airflow to produce a force).

The elevators are movable control surfaces attached to the horizontal stabilizer, at the airplane tail, or empennage. The elevators are  flap-like, and hinged at the trailing edge of the horizontal stabilizer, located at the tail of the aircraft.

The pilot works the elevator by applying back-pressure to the elevator control. This raises the nose of the aircraft in relation to the pilot. Applying forward pressure to the elevator control lowers the nose of the airplane with respect to the pilot.

How Aircraft Elevators Work

The airplane elevators work just like the airplane wings do, by creating an aerodynamic force referred to as the force of lift. However, with the elevators, pilots can control the direction in which this force acts, and its magnitude.

When Applying Forward Pressure on the Elevator Control:

  • The elevators move downwards.
  • The horizontal stabilizer has now an increased surface area exposed to the relative airflow.
  • The pressure difference between the high pressure area under the horizontal stabilizer, and the low static pressure over it, increases to augment the lifting force which acts upwards in this case.
  • This activity creates a “moment,” and the force lifts the horizontal stabilizer upwards.
  • The aircraft pitches over its center of gravity, and the tail rises to lower the nose.

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