Page 520 - PPL-engelsk 2025

Principles of flight

The forces while gliding with the engine idling can be seen in the figure on the

next page.

There is lift/drag at the top, and at the bottom we have the weight of the aircraft.

Gravity pulls the aircraft down. The weight is the driving force when the engine
is turned off.

A forward component of the weight matches the drag, and we glide at a constant
speed.

If you have engine support, the glide angle and rate of descent are reduced.

The weight of the aircraft is therefore not of decisive importance for the glide

ratio of the aircraft!

However, heavier aircraft glide at a higher speed to achieve the best glide ratio,

and thus the heavier aircraft reaches the ground first. However, it lands in the

same place as the lighter aircraft.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 520