On Thu, 15 Apr 2004 13:52:47 GMT, Ernest Christley
wrote:

Richard Lamb wrote:


Butyrate shrinks quite a bit.
Even the "non-taughtening" variety pulls up a bit.

So a glass skin would rely on the coating for taughtness
(not in the MS dictonary?) - just like linen does.

If this is the case, and please note that I'm not saying it isn't, then
the fabric in flight will be getting it's strength from only the
butyrate until it is stretched enough to engage the fabric. Up until
that point, the fabric is just a filler holding the butyrate together.

It would then follow that the FG/butyrate system would experience more
deflection in light use, even though it has a higher utltimate strength,
because the polyester based systems would engage the stronger fabric
earlier in the defelection. Does this actually occur, and do you have to
account for it by choosing a paint system that will accept the
stretching from the deflection?

Ernest, did you miss this post by Robert Little? See below, it
explains how taught the fabric is.

Corky Scott

Many of you have some ideas about glass fabric that may or may not be
valid. First of all, I own the RAZORBACK FABRIC Company. The company
started in 50's and the FAA signed a letter in 60's that deemed our
glass covering as a permanent covering that no longer needed testing
as all other fabrics do on certified airframes do. This is due to the
fact that all hydrocarbon based material deteriorate in the presents
of UV radiation.

It is true that our fabric is heavier than the choices that are now
available. It was originally designed for agricultural aircraft,
Stearmen to be exact. It weighs 3.6 oz. and uses less dope than Grade
A cotton that weighs 4 oz. So technically, it weighs 17% less than
the original fabric on J-3s, BC-12s, and etc. So with 35 yards for a
average project, the total weight difference from a temporary dacron
fabric of 2.4 oz per yard and the less expensive, but 200% stronger,
permanent glass fabric system doesn't add up to all the negative talk
about weight to the economists.

As in a poorly installed rivet, I supposed our glass could frett. Our
shop is dedicated to repairing and recovering frieght aircraft and so
far, I have never seen this ocurrance. I have seen poorly installed
fabric wear away the aluminum, though. It is much harder than
aluminum and steel and care should be taken to protect the rivet and
etc. with anti-shafing tape, as with any fabric installation.

Once installed correctly, it has a much stiffer surface than the more
flexible and stretchy dacron. I have seen many pictures on the covers
of
aviation magazines that show the top of the wing with pillows
deforming between the ribs as the fabric stretches under the
aerodynamic load of flight. Properly installed glass fabric does not
stretch and will remain closer to the profile of the ribs than any
other covering short of metal. Many of our customers comment that our
fabric has gained them real increases in airspeed beyond the fact of
being covered with a fresh finish. This also allows your paints to
last longer as the flexing really stresses the surface coatings.
Plus, you don't have the worry of falling through it if you
should mis-step on a low wing. You can walk on it as long as the rib
underneath it can handle the weight.

By the way, since our fabric does not rot, deteriorate in acid rain
and sunlight or even burns and is easily applied and repaired, it is
still the only synthetic fabric that is authorized for use by our and
other militaries. It is FAA-PMA'd, FAA-STC'd, MIL SPEC and ISO 9002
rated. Our biggest sales are still the military. Yes, C-130s and
C-141 still have fabric on them and in them.

We don't own chemical companies and we are not trying to corner the
fabric market. But if you want a permanent awning, aircraft covering,
or a firewall, you might want to find out more about RAZORBACK
FABRICS, INC.

Thank you for your time.

Robert Little