CPL/IFR Seminars 3: How Does an Airplane Turn?

Why Study Theory at All?

        • You can fly an airplane

        • Your physical movements are memorized

        • Pavarotti was a natural singer


        • Pavarotti never learned to read music – he memorized everything

        • Most singers and athletes get coaching

        • Then they are doing something new – and they know what it feels like

OK, Let’s consider how an airplane turns . . .


What turns an Airplane?

  • How do you keep the airplane from turning? (i.e. hold heading)

        • In four words or less.

  • What force does the pilot use to make the airplane turn?

        • (Not what controls does she use.)

What is a Vector?

  • What is the Flight Path Vector?

        • Where the airplane is going

        • How fast

  • What is a Vector in general? (i.e. In mathematics)

        • expresses two things about an object

        • direction

        • quantity

  • What about an arrow as a representation of a vector?

        • An arrow is pointing in some direction (perhaps in 3D)

        • its length can represent a quantity


  • What can vectors represent for a pilot?

      • Vectors can represent Movement

        • Where the airplane is going through the air

        • Where the airplane is going over the ground


        • Wind

        • Vectors can be added. And subtracted!

      • Vectors can represent Forces

        • Lift

        • Gravity

        • Thrust

        • Drag

  • Lift can be controlled by the pilot, in both direction and quantity. How?

        • What control(s) steer lift?

        • What control(s) determine how much lift is produced?

What is Equilibrium?

        • The four forces are balanced


  • When is an aircraft in equilibrium? Answer yes, no, or maybe.

        1. Tied down?

        2. On the ground?

        3. Taxiing?

        4. Takeoff?

        5. Climb?

        6. Cruise?

        7. Turning?

        8. Descent?

        9. Slowing for Approach

        10. Approach (stabilized)

        11. Flare

        12. Landing

        13. When the Flight Path Vector is not changing

    • Answer:

      • 6 yes

      • 5 no

      • 2 maybe

  • Why does the pilot have to be aware?

        • There is much more going on if the airplane is not in equilibrium

        • The pilot has to stop the change when her plan is complete, for example:

          • nearing the heading she is turning to

          • arriving at the new airspeed she wants

          • arriving at the new altitude or V/S she wants

  • Why do we need to know about equilibrium?

        • In equilibrium the Flight Path Vector is not changing

        • If the pilot is happy with that, she has to do nothing

        • If the airplane is not in equilibrium it is because the pilot commanded it so, in order to change the Flight Path Vector

          The closed-loop pilot is always aware that the airplane is not in equilibrium

Which of the Vectors in the following image are Forces? Virtual Forces? Not a Force? Just an Airplane?