On Sat, 20 Dec 2003 15:47:22 -0800, LakeCapt wrote:

Hello,

Has anyone seen any data/research showing the performance gains of filling
the fiberglass weave of a composite aircraft such as a KR-2?

For example, if a KR is built with a RAF-48 or NACA wing (non-laminar), if
layups were done over a smooth substrate (smooth foam), and the weave of
an "average" weave glass was left unfilled (after peel-ply), how would
speed be effected? Dacron-covered planes of course get by with a bit of
weave showing.

If the cruise speed of a given KR-2 was 120mph "filled," any idea on how
much slower it would cruise if left bare but painted?

The looks would probably suffer, but how about performance and safety? All
opinions and ideas are welcome.

I'm not sure I would want to try this. The results would probably be
somewhere between like having frost on the wing and 40 grit sand paper.

Many people have gone off the end of the runway when trying the "I wonder
if it will fly with frost on the wing" experiment. 40 grit sandpaper is
used to simulate a thin layer of rough ice on the leading edge of the
wings as part of the icing approval flight testing on recent transport
category aircraft. I've flown these flight tests on two different types,
and there is a very large lift loss if the slats are retracted - something
like 40% loss in maximum lift IIRC.

So, I would spend the time to get a fairly smooth surface, at least up to
the point of maximum thickness of the wing. The aft part of the wing is
less critical, so you might get away with leaving the weave unfilled there.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com