How does an Airplane Turn? Forces Working to Turn an Aircraft

The Airbus A380 in a Right Turn. Photo Credit: Peter Pearson

Ever wondered how an airplane turns? You’re not alone!

An aircraft turns by banking the wings in the direction of the desired turn at a specific angle. This angle is referred to as the bank angle. When flying straight and level, the wings of an aircraft produce the force of lift in an upward direction, perpendicular to the wing. However, when a pilot banks the wing, this force is then divided into vertical and horizontal components. It is this horizontal component of the produced lift force, that turns the aircraft. This force, in actuality, acts as a centripetal force, trying to maintain the circular movement of the aircraft.

In order to turn an aircraft in an efficient and fully-coordinated manner, it is necessary that all the four primary controls are available. You need ailerons (rectangular flaps at the back of the wing) to bank and hence initiate the turn, the elevator to maintain your altitude during the turn, the rudder to coordinate the movement of the nose and of course the throttle to increase/decrease thrust while turning, thereby affecting the radius of the turn.

Airplane turns are generally categorized into three types:

  • Planes make shallow turns when the bank angle is less than 20 degrees.
  • A turn is “medium” when the bank angle is between 20 to 45 degrees.
  • Steep turns produce a bank angle greater than 45 degrees.

Click to Read Page Two: Turning an Aircraft

© Copyright 2012 Junaid Ali, All rights Reserved. Written For: Decoded Science

Comments

  1. Robert Karn says

    Thanks for this insight Captain.

    This is quite informative though incomplete. I tend to question about how the sideways force (centripetal force) pulling the aircraft towards the center of the circular path actually change the nose heading. From explanation, the flight path will change but not heading.

    The aircraft wings – where the lift forces are acting from – are ideally at the center of the aircraft longitudinal length. The resultant sideways lift or force will pull (or snatch) the whole aircraft out of original flight path into a new flight path Parallel to the initial flightpath (heading remaining constant). What forces the nose away from the flight path to a new heading in order for the turn to be fully achieved??

    Kindly reply.
    robkarn08@gmail.com
    Am a student pilot

  2. Wortman says

    Re: How does an Airplane Turn? Forces Working to Turn an Aircraft

    While this note reflects the (nearly) universal story on airplane turning, it is suspect at best. One might ask why a sideways force does not just cause the airplane to accelerate sideways. No demonstration is provided that this is a “centripetal” force but once you accept that word, a circular turn is guaranteed by definition. The problem is that a sideways force alone produces no turning torque on the aircraft so its heading would not change although the flight path would. There must be some torque to produce a yaw in the desired direction but it is never provided. One suspects that the standard turning story is at least incomplete. The missing element is that the transverse acceleration will (shortly) produce a transverse component of velocity and the resulting relative wind at an angle to the nose will (via the yaw weathervaning stability) be moved in the direction of the turn due to resulting forces on the vertical stabiliizer and fuselage.

    Yes the standard story is somewhere between wrong and incomplete.

  3. John Austin says

    The text is misleading “when a pilot banks the wing, this force is then divided into vertical and horizontal component”. The bank causes the upward force to be redirected from the vertical towards the horizontal. There is only one force but it is usually represented mathematically as the sum of vertical and horizontal component vectors (when viewed from a given altitude). The horizontal component acts as a centripetal force generating the curved turning path of the aircraft as viewed from the vertical.

    This banking can range from very slight as in a turning airliner to extreme banking in which the aircraft becomes inverted as in air combat maneuvering.

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