Message text written by Graham Singleton
>I have half an idea that the best built foam wings will perform better
than
preformed. Laminar flow depends on an accurate vibration free surface.
Preforms
might vibrate more in response to off balance props/spinners than foam. BTW
I
never admit to being wrong, but I'm not always right {:-)<
Not right in this case, Graham. Laminar flow depends on the accuracy of
the airfoil and condition of the surface. You just can't beat the precision
of a layup in a stiff mold. I don't know about the XS, but instead of
building a "plug" that serves as the "master wing" from which the molds are
taken, today most molds are milled directly into hard plastic by
numerically controlled tooling machines and have a remarkable (like in
incredible) accuracy.
Plus, a good sandwich wing built in molds in sandwich construction over a
stiff spar will not vibrate. Vne on my glider is 149 knots with a 50 foot
wingspan and there are no "vibrations" even at that speed. As far as
repairs of sandwich structures are concerned, most glider clubs have a
qualified repair mechanic who knows what to do when another student put a
runway light through the leading edge of the wing. Anyone who builds a
Europa should easily be able to repair molded (sandwich) structures.
Regards, Herb
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