Page 511 - PPL-engelsk 2025

Principles of flight

5.10.2.3 Best climb angle Vx

When you need to find Vx, you must use the speed at which the propeller pulls

the most in relation to the drag. When you hold the plane on the brake and give

full throttle, the propeller pulls forward very well.

From the diagram you can

see that when, in this case,

you fly at, for example, 90 Kt,

there is not as much excess

power as when you fly at, for
example, 72 Kt.

5.10.2.4 Best climb angle Vx vs. best climb speed Vy

Here is an illustration of how Vx and Vy change with altitude.

Vy decreases, while with altitude you have to increase the speed to climb with

Vx.

When you reach the aircraft's top altitude, Vx and Vy are

the same.

The illustration below shows how you can find Vx and Vy when climbing at

different speeds.

The vertical axis is the rate of Climb, R/C,

which is read on the aircraft's variometer.

The tangent to the curve is Vx, and the
peak of the curve indicates Vy.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 511