On 04 Apr 2004 00:27:33 GMT, (JJ Sinclair) wrote:

I got a question for you aerodynamasists (is that a word?)

When Schleicher added a bit to the wing span of the ASH-25 (25 m to 26.5m) they
required that 3 Kg of lead be mounted in the leading edge (inside the D tube)
it was to be spread down the D tube for about 10 feet and then glassed in
place.

Why? and why in the leading edge?

To change the flutter frequency of the wing.

It's problematic if the natural oscillation frequency of the controls
and the part the control is mounted on (elevator/ rudder and fuselage,
airleron/flaps and wing) is similar.

If natural oscillation frequencies are similar, an oscillation that is
started on a certain part might cause other parts to ascillate in
harmony - therefore changing the weight or CG of a part is used to
make sure that each moving part has a different oscillation frequency.



Bye
Andreas