On Thu, 15 Apr 2004 19:00:06 GMT, Ernest Christley
wrote:

wrote:

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

Corky Scott

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.

Robert Little

Guys, either I'm missing something here or I'm just not smart enough to
get my mind wrapped around it.

How is the FG stretched tight enough to make it stiff? Is the butyrate
a hard substance once it dries/cure/whatever-butyrate-does? Is the
following statement correct?

If there is any looseness at all in the fabric, and it is
pulled tight by the dope, then the dope is what will carry
the stress, not the fabric.

If the butyrate is carrying the stress, then would this system be any
stronger that chopped strand composites?

Yes. It is true. I do NOT know what I'm doing. But I will before I'm
done!

Ernest, it isn't the dope that provides the strength, not with
Razorback fabric or with any fabric. The fabric itself is what gives
the wing it's strength and/or stiffness against the wind. The initial
application of the correct dope, in the case of the Razorback fabric,
or a calibrated heating iron, in the case of the Polyfiber fabric, is
what shrinks it.

The application of paints on top of the fabric serve to protect it
from UV rays, make it waterproof, and look nice, but do not add
strength.

You should participate in one of Ron Alexander's fabric covering
sessions and see for yourself how it's done. They offer hands on
experience and you learn how to properly apply fabric to wings and
control surfaces. You will discover that the fabric is incredibly
taught, once properly shrunk. The skin of a drum comes to mind.

You can shrink the fabric too much and actually crush or bend the
framework beneath it, the fabric has that kind of strength.

Corky Scott