Replace fabric with glass

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?


--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

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

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!

Robert, do you sell 'practice kits' like AS and others sell for the
other types of fabric?

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

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

wrote:

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





Corky, the polyester fabrics have long chain molecules that 'curl up'
when you heat them. This makes the actual threads shorter, so that
after the actual fabric is shrunk to size.

The butyrate doesn't shrink the fiberglass threads. It just grabs a
couple and pulls them closer together. "Chain is only as strong as its
weakest link" comes to mind. Until a butyrate coated covering stretches
enough to take out the slack that was there when the fabric was first
put on, it is only being held together by the butyrate.

That is the mental picture I have. I could be wrong, and I don't even
know if it is good or bad. For starters, I don't know how strong
butyrate dope is. It could be much stronger than polyester, and just
needs the fabric to give it some shape. I'm in unknown territory and
just need a compass and a map, or maybe just a practice kit to play with.

Didn't I read somewhere that butyrate dope can be found in most hardware
stores under a different name?

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

Didn't I read somewhere that butyrate dope can be found in most hardware
stores under a different name?


Reminds of my childhood...

made a few of those gawdawful to make model airplanes made with 10 million
sticks of blasa wood, glue, and tissue paper...

Then there was the process of doping it shrink the tissue paper...

Had a friend.....he didnt use dope on his....he use spray on starch (you know
the kind for ironing your clothes)....seemed to work pretty well....never did
find out if that was some insider secret or not.....asked how he knew and he
said it just seemed like it would work to him!

take care

Blll

PS...no Im NOT saying use spray on starch on a real airplane

On Thu, 15 Apr 2004 16:39:33 -0400,
wrote:



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.


Corky Scott you surprise me cobber. mistakes like the one contained in
the paragraph above are what led to Steve Wittman's death.

in the case of cotton, irish linen, razorback and any of the non
shrink fabrics it IS the dope which causes the fabric to tighten as
the solvents evaporate from the dope.

polyfiber is unique in that the fabric is applied in the grieged state
and ironing it at the appropriate temperature shrinks it to create
it's taughtness. the vinyl finishes applied have solvents in them to
displace the manufacturing lubricants in the fabric. the vinyls simply
fill the weave.

dopes should not be applied to polyester fabrics that still have the
manufacturing lubricants in them. they will simply not adhere. even
on clean fabric the dope does not penetrate the fibers.

my Auster had a section of the turtledeck applied this way and once
cracked the finish peeled off with about the tenacity of a 3m post it
note also there is a ceconite covered piper cub on the local
commercial field that has areas of the underside wing finish held in
place with tape because it has peeled away.

dopes work well with absorbent natural fibers.
polyfiber is different in the way it works.
make the mistake of mixing the two and the headlines will be
"Corky Scott's fatal accident identical to Wittman's, when will they
ever learn?"

end of safety lesson

Ernest if you are an EAA member hunt out the construction articles in
Sport Aviation for an aircraft called "ol' Ironsides".
it is a wood frame single seat wittman tailwind I think. the
construction techniques were quite well described and are epoxy/glass
panels as you have been asking about. the guy used the polished faces
of masonite sheets with release agent to do his layups. the resultant
sheets were then bonded to the framework. afaik it is still flying.
the articles were quite charming - well written. lots of photos. a
good aircraft I think.

(you're forgiven corky. it is THE fatal error with fabric finishes and
it must be understood or people will die. simple as that.)
Stealth Pilot
Australia.

On Fri, 16 Apr 2004 21:08:23 +0800, Stealth Pilot
wrote:


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.


Corky Scott you surprise me cobber. mistakes like the one contained in
the paragraph above are what led to Steve Wittman's death.

in the case of cotton, irish linen, razorback and any of the non
shrink fabrics it IS the dope which causes the fabric to tighten as
the solvents evaporate from the dope.

Stealth, what are you smoking? That's what I said.

Here's my sentence:
"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.

Now you say: in the case of cotton, irish linen, razorback and any of
the non shrink fabrics it IS the dope which causes the fabric to
tighten as the solvents evaporate from the dope."

But you are just repeating what I said. Did you read it a bit too
quickly?

Corky Scott

In charles.k.scott@
dartmouth.edu wrote:
On Fri, 16 Apr 2004 21:08:23 +0800, Stealth Pilot
wrote:


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.
Corky Scott you surprise me cobber. mistakes like the one contained in
the paragraph above are what led to Steve Wittman's death.

in the case of cotton, irish linen, razorback and any of the non
shrink fabrics it IS the dope which causes the fabric to tighten as
the solvents evaporate from the dope.

Stealth, what are you smoking? That's what I said.

Here's my sentence:
"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.

Now you say: in the case of cotton, irish linen, razorback and any of
the non shrink fabrics it IS the dope which causes the fabric to
tighten as the solvents evaporate from the dope."

But you are just repeating what I said. Did you read it a bit too
quickly?

I spoke with my instructor at the A&P school again and he was pretty
adamant that the main shrinking agent with the natural fibers was water.
The tautening effect of the dope is actually a negative if you put it on
too thick.

I did misunderstand him, however, as far as the cause of the sagging
razorback in cold weather. He said it isn't so much caused by the
underlying frame contracting, and didn't think that would be a
noticeable problem with a steel frame. He claims that there is a
definite issue with the stuff in cold weather that can't be explained as
poor application technique.

Mind you, I am just passing this along. I would personally like to see
some testing done, and would be interested in leaving a small test frame
covered with each major process outside in my backyard over the winter.
It often gets down to 20 below or so around here so it would be a valid
test.

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

On Fri, 16 Apr 2004 11:46:27 -0400,
wrote:

On Fri, 16 Apr 2004 21:08:23 +0800, Stealth Pilot
wrote:



But you are just repeating what I said. Did you read it a bit too
quickly?

Corky Scott

I'm intrigued. I replied to an attribution that seemed to have a
clanger error. reading all the way back through it now I cant find it.
huh?
freudian reading error?
Stealth Pilot