Replace fabric with glass

Question for the Razorback Fabric guy:

I'm currently finishing up the training for my A&P certificate at the
school here in Anchorage, and as it so happened, the lecture this
morning was about fabric covering. The instructor brought up Razorback
fabric, mentioned that it is great stuff, but then added that we don't
see much of it here in Alaska because it tends to sag in cold weather
compared to the shrunk-on polyester fabrics. As I recall from the
lecture, he said it was due more to contraction of the underlying
airframe in sub freezing temperatures, than any change in the fabric.
The heat shrunk fabrics apparently don't suffer as much from this
because there is enough extra tautness is added during the shrinking
process to make up for any dimensional change in the airframe at low
temperatures.

I was just wondering if you have any comments in this regard?

----------------------------------------------------
Del Rawlins-
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Del Rawlins wrote:

Question for the Razorback Fabric guy:

I'm currently finishing up the training for my A&P certificate at the
school here in Anchorage, and as it so happened, the lecture this
morning was about fabric covering. The instructor brought up Razorback
fabric, mentioned that it is great stuff, but then added that we don't
see much of it here in Alaska because it tends to sag in cold weather
compared to the shrunk-on polyester fabrics. As I recall from the
lecture, he said it was due more to contraction of the underlying
airframe in sub freezing temperatures, than any change in the fabric.
The heat shrunk fabrics apparently don't suffer as much from this
because there is enough extra tautness is added during the shrinking
process to make up for any dimensional change in the airframe at low
temperatures.

I was just wondering if you have any comments in this regard?

----------------------------------------------------
Del Rawlins-
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Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

Just one. Thanks for passing that on to the group.

In actuality, we do sell quite a bit of fabric to the Northern reaches. ERA
has worn our fabric on their DC-3s and the military sure has used it on a
lot of cargo planes in the northern frontier over the years. We are always
sending out belly repair kits to Maules owners there, as well as a large
contigent of Stinson owners. It is plausible that there could be a problem
with improper installation or very poor conditions during istallation.
Cellulose Acetate Butryate dope is an organic laquer that is sensitive to
atmospheric conditions (usually needing 70 plus degrees of heat during the
application) but is usually very stable once it dries. Again, dope on cotton
and linen has been used for the 50 years prior to the introduction of the
newer fabrics.

I know that a cannon ball drop test was performed on our fabric at many
different sub temperatures and published. Nothing was printed about loss of
tautness due to temperature, only poor application due to following the
instructions. Even an aircraft manufacturer was repremanded for not
following the installation manual by not reinforcing the stress points over
longerons and formers (also as per the A.C. 43-13) with reinforcing tape.
They were saving time and labor by not doing so. The owners paid for the
time saving twenty to thirty years later.
"Del Rawlins" wrote in message
...
Question for the Razorback Fabric guy:

I'm currently finishing up the training for my A&P certificate at the
school here in Anchorage, and as it so happened, the lecture this
morning was about fabric covering. The instructor brought up Razorback
fabric, mentioned that it is great stuff, but then added that we don't
see much of it here in Alaska because it tends to sag in cold weather
compared to the shrunk-on polyester fabrics. As I recall from the
lecture, he said it was due more to contraction of the underlying
airframe in sub freezing temperatures, than any change in the fabric.
The heat shrunk fabrics apparently don't suffer as much from this
because there is enough extra tautness is added during the shrinking
process to make up for any dimensional change in the airframe at low
temperatures.

I was just wondering if you have any comments in this regard?

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

In Robert Little wrote:

very stable once it dries. Again, dope on cotton and linen has been
used for the 50 years prior to the introduction of the newer fabrics.

Yes, but both of those fabrics have built in shrinking ability and will
continue to shrink as they age. How can you make fiberglass cloth
shrink? Maybe I just don't understand enough about your process to get
it. Do you have a website with technical information, or could you post
an excerpt from the relevant part of your application manual?

----------------------------------------------------
Del Rawlins-
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Del Rawlins wrote:

In Robert Little wrote:

very stable once it dries. Again, dope on cotton and linen has been
used for the 50 years prior to the introduction of the newer fabrics.

Yes, but both of those fabrics have built in shrinking ability and will
continue to shrink as they age. How can you make fiberglass cloth
shrink? Maybe I just don't understand enough about your process to get
it. Do you have a website with technical information, or could you post
an excerpt from the relevant part of your application manual?

----------------------------------------------------
Del Rawlins-
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Del,

Check the model airplane supply houses.
You can find glass down to 1/2 ounce per yard.

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.

In Richard Lamb wrote:
Del Rawlins wrote:

In Robert Little wrote:

very stable once it dries. Again, dope on cotton and linen has been
used for the 50 years prior to the introduction of the newer
fabrics.

Yes, but both of those fabrics have built in shrinking ability and
will continue to shrink as they age. How can you make fiberglass
cloth shrink? Maybe I just don't understand enough about your
process to get it. Do you have a website with technical information,
or could you post an excerpt from the relevant part of your
application manual?

Del,

Check the model airplane supply houses.
You can find glass down to 1/2 ounce per yard.

I'm not sure what this has to do with the effects of cold weather on the
glass cloth. I think you are confusing me with Ernest.

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.

I thought that the natural fiber coverings like linen or cotton were
primarily shrunk using water? I.E. they get most of their tautness from
natural shrinkage as the water dries, prior to the coating being applied.
Or am I all wet? I don't know a lot about fabric covering and am just
trying to get a clear understanding of the various systems.

----------------------------------------------------
Del Rawlins-
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"Del Rawlins" wrote in message
...
In Richard Lamb wrote:
Del Rawlins 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.

I thought that the natural fiber coverings like linen or cotton were
primarily shrunk using water? I.E. they get most of their tautness from
natural shrinkage as the water dries, prior to the coating being applied.
Or am I all wet? I don't know a lot about fabric covering and am just
trying to get a clear understanding of the various systems.

No, the water was just to take out the natural shrinkage of the fabric
before putting in the artificial tautening that occurs from either the
nitrate or butyrate dope. Either dope can tauten so much that with too much
application they can actually crush the airframe. The dope grabs hold of
each fiber and pulls the spaces between the fibers closer together. This is
the tautening action achieved with using dope whether it is cotton,
polyester or glass. And yes, you can find glass fabric in the model plane
catalogs that can acheive similar results.

We would be glad to send anyone our instruction manual for free if they will
just send us their snail-mail address. I hope that I've sparked som
interest in the alternatives available to the aircraft builders.

One other thing, though. The use of epoxy or polyester resin combined with
glass again starts the deterioration clock. The glass is permanent, but the
resins are what age so quickly in the presense of UV radiation. Old
fiberglass boats look rough after a few years and will burn like gasoline.
The glass does not age and will be the big mess left after the fire since it
does not burn. Our process doesn't use any resins as one usually assumes
when glass is mentioned. The "temporary cellulose" base dope is used to
fill and tauten only. It can burn off but the glass will remain in place
with little to no loss of strength to the fabric. The late Bill Hale always
used our fabric on his acrobatic aircraft due to the glass acting as a fire
wall to the occupant. Many NASA experimental windmill and wind tunnel
blades have been covered with our glass as well.
----------------------------------------------------
Del Rawlins-
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Robert Little wrote:

One other thing, though. The use of epoxy or polyester resin combined with
glass again starts the deterioration clock. The glass is permanent, but the
resins are what age so quickly in the presense of UV radiation. Old
fiberglass boats look rough after a few years and will burn like gasoline.
The glass does not age and will be the big mess left after the fire since it
does not burn. Our process doesn't use any resins as one usually assumes
when glass is mentioned. The "temporary cellulose" base dope is used to
fill and tauten only. It can burn off but the glass will remain in place
with little to no loss of strength to the fabric. The late Bill Hale always
used our fabric on his acrobatic aircraft due to the glass acting as a fire
wall to the occupant. Many NASA experimental windmill and wind tunnel
blades have been covered with our glass as well.


Robert, you're starting to sound like a very bad salesman, creating dark
ghost where everyone else sees daylight. Epoxy is not a vampire that
burst into a cloud of dust if the blinds are raised. In fact, the
proper formulation can sit in the sun for years without measurable
effects. I personally plan to take the very unusual step of painting my
airplane to keep it from rotting away in the sun. Where are these
people who don't paint their aiplanes after having paid to get them covered?

Furthermore, if my elevons catch on fire then I will have been burned to
death long before. A quick look at the Delta planform will explain why.
But this begs the question of, "If the FG can take the forces and
stresses of flight without the butyrate without excessive deformation,
then what is the point of the butyrate?" Didn't you say the glass was
glued on with the butyrate? If it's not necessary, why not just tie on
the FG cloth, spray a coat of paint or two, and go flying?

That is not a redundant question or a taunt. I am really trying to
understand the role each of the parts play in your system. I want
enough information to know if I can apply your product, or a variant of
your product, to my situation. I have a firewall already, and I don't
need a windmill or wind tunnel. I need a very light elevon.

On a more serious note, I think I called you Richard in another post.
Do you have practice kits available?

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

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