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

Vance, check page 319 of Aircraft Vibration and Flutter
Robert H. Scanlon & Robert Rosenbaum
Dover Publications 1951.

The work was done in R&M 1506 by Cox & Pugsley.

R&M is some sort of British technical publication.

It is the aileron reversal speed.

If the elastic axis is forward of the 49.5% [ha!] chord position
the reversal speed will be lower than the divergent speed.

Paul Lamar

        Check the latest issue of TO FLY, The Sport
Aviation Mag, Virg

BTW a bit more info on R&M 1506.

Cox, R.H. Pugsley, A.G. "Theory of the Loss of Lateral
Control Due to Wing Twisting," Br. R & M 1506, October 1932!!!!!!!

Our British version of the FAA, the PFA types, are right up to 
moment on high tech :-)

Paul Lamar
 
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