Page 496 - PPL-engelsk 2025

Principles of flight

5.7.7 Aeroelasticity

The wings of the aircraft are more or less

elastic.

This means that they can bend in several

ways to cushion the impacts to which the

aircraft is exposed.

When the wings are no longer loaded, they

straighten out again.

This elasticity works in the same way as the suspension of a vehicle driving on

an uneven road.

In this way, the design helps to absorb turbulence during flight.

Twisting moments from ailerons can change the angle of attack at the wingtip.

Even large commercial aircraft have a certain elasticity in their wings. This can

be seen if you look at the wings before takeoff, and when the aircraft is during

its initial take-off run and then compare them with the wings when the pilot lifts

the nose of the aircraft, creating maximum lift for Take Off.

At too high loads and too high speeds, this elasticity can have unfortunate side

effects, for example, the tip can twist so much that the ailerons start to flutter

(harmful vibrations), which can tear the wing apart.

A maximum speed of the aircraft, Vne (Velocity never exeed), is specified to take

this problem into account.

Wear and slack in control wires and cables can make the aircraft more “elastic”,

thereby risking damage at very high speeds.

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Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 496