vjaqua wrote:

Paul and others - I have a copy of the flutter formula that was given to Ray
Clegg
in England by the PFA as one of the hoops that he had to jump through in
trying to get permission to fly his KIS Cruiser. It is a GIF file from a poor
photocopy that they were provided ( I do not know the original source).
It appears to have all the required factors of goodness applied in what appears
as an imperical expression. The major players in the formula appear to be
torsional stiffness, flexural stiffness, and torsional flexural center. Other
items
such as chord, aspect ratio, taper ratio, etc are also included, but probably
are not big drivers (I have not yet tried to run any portion). The output is
"critical flutter speed" in knots, which I think is a bit presumptious. A more
realistic thing to call it would be" factor of flutter resistance" As I remenber,

Ray Clegg had to bolt his wing section to a rigid wall and load it to get
stiffness numbers (and I have requested copies of those). I wonder if the PFA
has laid this requirement on any of the other designs that they have approved.
I think any well designed composite wing would pass by such a margin that
the caculations would be a waste of time - however, I think the cloth covered
wood wings so favored by European designs would come up short.
Vance

 
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