On Jan 2, 6:13*am, Andy wrote:
On Jan 1, 4:52*pm, wrote:

One interesting experiment would be to deflect the wings on the ground
and release them - with and without water - and measure the difference
in the frequency of the oscillations.

That would be of interest if the flutter limit speed was set by
primary wing structure, *Is it, or do the control surfaces flutter
first.

In my experience in transport aircraft flight test the flutter testing
is always done with maximum allowable free play in control linkages.
Do glider manufacturers do that, it not, does flutter speed reduce as
control links wear?

Andy

I cut a corner or two on my post Andy.

The only glider wing flutter video I've seen looks like an interaction
between the main wing bending and tortional elasticities - wing bends
up, gains a little angle of attack and bends/twists more as a result
until the restoring force gets big enough to bring it back down (or
the wing breaks). This creates a symmetric wing flapping kind of
flutter. I would think if the ailerons were significantly involved
you'd be more likely to see something asymmetric, or more tortional
motion - which I'm sure can occur under some set of circumstances.

The reason I picked this mode of flutter was also its likely the one
most affected but water ballast which should up the natural frequency
in bending mostly.

Just educated guesses on my part, but that was my logic.

9B