Minumum Sink Rate/Best L/D at 17,000 feet ?

Here's a reference to complement the DG video and also a discussion of
changes in certification requirements w.r.t. flutter. An interesting
read.

http://www.dg-flugzeugbau.de/dg1000-flattern-e.html

Some of the wording is a bit ambiguous, but the way I read it there
are two conclusions that are relevant to this discussion:

1) Holding on to the stick tends to damp out one mode of wing flutter
(and perhaps other controls too). It is a mode that is exacerbated by
the fact that when the wing flexes up an unbalanced aileron will tend
to deflect downward and vice versa.

2) Adding water ballast can decrease the flutter speed. If I read it
right the DG-300 had it's Vne reduced due to the test depicted in the
video.

9B