RE: trailing edges
I think that any trailing edge influence on flutter is due to small
fluctuating vortices that arise there and happen to occur at a
frequency that 'excites' the structure. A rounded trailing edge is
probably the worst in this regard, because the separation point
in a rounded trailing edge will be able to move around. A squared
off trailing edge will always separate at the corners, which tends
to minimize one source of the fluctuations. A sharp trailing edge
is the least likely to give rise to the little fluctuating vortices.
I would have to guess that control surfaces that flutter due to
the trailing edge treatment probably have a different problem,
like too much slop in the linkage.
banktoturn