Page 757 - PPL-engelsk 2025

Aircraft general knowledge

The performance of the propeller depends on:

- propeller design

- propeller angle of attack

- propeller area

- propeller speed

- air density

The efficiency of the propeller depends on:

- geometric pitch

- effective pitch

- slip

Look at the front

plane in the

drawing here.

When its propeller moves one revolution, the plane should actually come into

the same position as the rear plane.

At least that is purely geometrically what should happen.

In reality, the plane only moves correspondingly from the rear planes position to
the middle planes position (blue curve).

So, our effective pitch, or pitch of the propeller, means that we barely get as far

as we would like to. A slip occurs, and the smaller this slip is, the greater the

efficiency of the propeller.

Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 757