Replace fabric with glass

[Ernest Christley]

Most of the fabric covered aiplanes I've seen didn't seem that hard.
That is, you could walk up to them and push the fabric in with your
hand. The way I understand the fabric process, it is basically a
composite structure. You have a nylon cloth with a paint "epoxy".

Could a much stronger and lighter covering be made by wetting out some
2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping
it around the airframe? The epoxy would be much lighter than paint, and
fiberglass cloth is MUCH stronger than nylon.

I've seen some places where builders used composites in place of fabric,
and it seemed that they all aimed for a multlayer, stiff panel, putting
the weight far above the original. I just don't understand why?

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

[jls]

"Ernest Christley" > wrote in message
m...
> Most of the fabric covered aiplanes I've seen didn't seem that hard.
> That is, you could walk up to them and push the fabric in with your
> hand. The way I understand the fabric process, it is basically a
> composite structure. You have a nylon cloth

Most cloth like Polyfiber's and Ceconite's is polyester, trade name Dacron.
Nobody uses cotton any more because it can't hold a candle to polyester. I
don't know of any use for nylon on aircraft wings.

with a paint "epoxy".

The coatings are nitrocellulose or vinyl base, not epoxy,afaik. Paints for
Polyfiber are vinyl based or polyurethane with a flexitive.

much stronger and lighter covering be made by wetting out some
> 2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping
> it around the airframe? The epoxy would be much lighter than paint, and
> fiberglass cloth is MUCH stronger than nylon.

One of the covering processes uses fiberglas cloth. I remember Ray Stits
badmouthing it on his videotape. It has at least one desirable quality ---
resistance to deterioration from UV rays.
>

[Kevin Horton]

On Thu, 08 Apr 2004 20:01:51 +0000, Ernest Christley wrote:

> Most of the fabric covered aiplanes I've seen didn't seem that hard. That
> is, you could walk up to them and push the fabric in with your hand. The
> way I understand the fabric process, it is basically a composite
> structure. You have a nylon cloth with a paint "epoxy".
>
> Could a much stronger and lighter covering be made by wetting out some
> 2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping it
> around the airframe? The epoxy would be much lighter than paint, and
> fiberglass cloth is MUCH stronger than nylon.
>
> I've seen some places where builders used composites in place of fabric,
> and it seemed that they all aimed for a multlayer, stiff panel, putting
> the weight far above the original. I just don't understand why?

The fabric must be quite taut so that the external surface of the aircraft
maintains the correct shape, even when subjected to the force of the
airflow. How would you achieve this with fibreglas without having
excessive weight?

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

[gerrcoin]

Ernest Christley wrote:
> Most of the fabric covered aiplanes I've seen didn't seem that hard.
> That is, you could walk up to them and push the fabric in with your
> hand. The way I understand the fabric process, it is basically a
> composite structure. You have a nylon cloth with a paint "epoxy".

You have a cloth material coated with a doping silver compound to
reinforce the material and make it taut, on top of which paint is
applied. The former does not penatrate the material but is on one side.

> Could a much stronger and lighter covering be made by wetting out some
> 2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping
> it around the airframe? The epoxy would be much lighter than paint, and
> fiberglass cloth is MUCH stronger than nylon.

Keep in mind that fabric covered structures are not Load-bearing in
the structural sense of the term. The fabric is there to keep the
aerodynamic shape and provide an area for the pressure to act on. It
is not a stressed skin structure in that the fabric takes pressure
loading, especially on the wings, but does not contribute to the
strength of the underlying framework as in metal skined designs. As
such, the extra strength is not really required on existing fabric
covered structures. You could maybe argue for a weight saving factor
in the days of lead based paints, but now... There is the advantage of
better UV resistance and not cracking or pealing over the lifetime.

> I've seen some places where builders used composites in place of fabric,
> and it seemed that they all aimed for a multlayer, stiff panel, putting
> the weight far above the original. I just don't understand why?

This is where there is some skin loading required. Stressed skin
designs can make the use of very thin aerofoil sections possible by
taking some of the load off the spars and ribs making for lighter and
stronger structures.

[Nolaminar]

Cotton (rare these days) is not worth a hoot. Probably no better lasting than
say....15 years. Linen is only good for maybe.... 20.
GA

[Orval Fairbairn]

In article >,
Ernest Christley > wrote:

> Most of the fabric covered aiplanes I've seen didn't seem that hard.
> That is, you could walk up to them and push the fabric in with your
> hand. The way I understand the fabric process, it is basically a
> composite structure. You have a nylon cloth with a paint "epoxy".
>
> Could a much stronger and lighter covering be made by wetting out some
> 2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping
> it around the airframe? The epoxy would be much lighter than paint, and
> fiberglass cloth is MUCH stronger than nylon.
>
> I've seen some places where builders used composites in place of fabric,
> and it seemed that they all aimed for a multlayer, stiff panel, putting
> the weight far above the original. I just don't understand why?



There have been some fibreglass/dope coverings around for at least 45
years. I remember a couple of Stearmans that the University of Illinois
had that were covered in glass/acetate dope. They looked like wrinkled
shirts whenever theweather was coll & humid. I understand that CAB dope
works bettere here. The shrinkage of the butyrate dope provides the
taughtness that the fabric needs.

Another disadvantage of this process is weight -- glass weighs more than
Dacron.

The glass process is also more susceptable to "ringworm" -- little
ring-shaped cracks in the finish.

As others have posted, fabric provides very little in the way of
structural loads -- all it really does is help to provide aerodynamic
shape.

[Corky Scott]

On Thu, 08 Apr 2004 19:01:51 GMT, Ernest Christley
> wrote:

>Most of the fabric covered aiplanes I've seen didn't seem that hard.
>That is, you could walk up to them and push the fabric in with your
>hand. The way I understand the fabric process, it is basically a
>composite structure. You have a nylon cloth with a paint "epoxy".
>
>Could a much stronger and lighter covering be made by wetting out some
>2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping
>it around the airframe? The epoxy would be much lighter than paint, and
>fiberglass cloth is MUCH stronger than nylon.
>
>I've seen some places where builders used composites in place of fabric,
>and it seemed that they all aimed for a multlayer, stiff panel, putting
>the weight far above the original. I just don't understand why?

Not sure that the fiberglass cloth plus the resin would be lighter
than the cloth plus the paint. For one thing, you left out the paint
on the fiberglass, or were you going to leave it the opaque look that
the fiberglass gets after wetting out and curing?

The other thing is that the fabric covered wing was designed for a
fabric covering. In some cases where a wing was "metalized" the
airplane ended up with a performance that was not as good as the
fabric covered wing.

Finally, as was pointed out already, there is no benefit to putting a
stiff panel around the wing. You don't save weight because the wing
is structurally designed for a fabric covering so it's internally
braced. If you wanted to use a stiff skin to cover the wing, you
should redesign the wing such that it gets it's stiffness from the
covering, not the internal bracing, and save weight.

For instance, the wing I built is fabric covered. The spars are wood,
and the ribs are wood. The wing is braced with drag and anti drag
wires that are actually 1/4" drill rod. Because they tend to try to
draw the spars together, the spars need to be held apart with steel
tubes called compression tubes. There are around six of them.

There's also a diagonal brace at the wing root to prevent the wing
from swaying back and forth, or in my case, a plate of sheet aluminum
instead. All this is to make sure the wing is stiff enough to
withstand the forces it's expected to encounter in flight. It's the
result of many years of aviation experience and engineering.

If I were to cover the wing with metal instead of fabric, I could do
away with all of the braces mentioned above.

Corky Scott

[Stealth Pilot]

On Thu, 8 Apr 2004 15:32:43 -0400, " jls" >
wrote:

>

>
>One of the covering processes uses fiberglas cloth. I remember Ray Stits
>badmouthing it on his videotape. It has at least one desirable quality ---
>resistance to deterioration from UV rays.
>>
>
that is razorback. it's weakness is that it will fret away where it
goes over a former or stringer. the glass vanishes over time and you
are left with glass panels joined by just the finish.

polyfiber is nothing to be afraid of. it is the best system going so
far. if you use polytone paint it is permanently repairable.
Stealth Pilot

[Ernest Christley]

Orval Fairbairn wrote:
> In article >,
> Ernest Christley > wrote:
>
>
>>Most of the fabric covered aiplanes I've seen didn't seem that hard.
>>That is, you could walk up to them and push the fabric in with your
>>hand. The way I understand the fabric process, it is basically a
>>composite structure. You have a nylon cloth with a paint "epoxy".
>>
>>Could a much stronger and lighter covering be made by wetting out some
>>2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping
>>it around the airframe? The epoxy would be much lighter than paint, and
>>fiberglass cloth is MUCH stronger than nylon.
>>
>>I've seen some places where builders used composites in place of fabric,
>>and it seemed that they all aimed for a multlayer, stiff panel, putting
>>the weight far above the original. I just don't understand why?
>
>
>
>
> There have been some fibreglass/dope coverings around for at least 45
> years. I remember a couple of Stearmans that the University of Illinois
> had that were covered in glass/acetate dope. They looked like wrinkled
> shirts whenever theweather was coll & humid. I understand that CAB dope
> works bettere here. The shrinkage of the butyrate dope provides the
> taughtness that the fabric needs.
>
> Another disadvantage of this process is weight -- glass weighs more than
> Dacron.
>
> The glass process is also more susceptable to "ringworm" -- little
> ring-shaped cracks in the finish.
>
> As others have posted, fabric provides very little in the way of
> structural loads -- all it really does is help to provide aerodynamic
> shape.

There have been a lot of very informative responses in this thread, but
they don't seem to address the question I have; therefore, my
conclusion is that I didn't ask the question very clearly.

Razorback has been mentioned several times. Everyone seems to agree
that it's heavy, the glass will last forever...IF it is supported
properly, and that the dope which makes it taught needs some care.

Corky and several others make the point that the fabric doesn't need to
be strong, it's just there to catch the wind.

So let's take an example. I have an aileron that was designed for a
medium weight fabric (which is 4oz/sq yard?). A 2oz FG woven finish
fabric would still be much stronger by far, but it will be much thinner.
Being thinner, it won't need as much "filler" (whether that be epoxy,
dope, or paint).

The process would go like this. I cut a piece of fabric the dimension
of my aileron with an inch or so overlap. I wet out the glass on a
sheet of 6mil plastic, set the aileron on top of it and bring the
fabric/plastic up around the aileron sides...just wrap it over. The
fabric is bonded to the ribs and around all the edges. No shrinkage
necessary, since it will be the exact size. Once that cures, I repeat
the process for the other side. The FG will add no more to the
structrual integrity than the fabric did. It's bonded to the ribs, so
no more attachment work or possibility of fretting. It has the smooth
FG look, and even with an exterior coat of paint will be thinner and
hopefully lighter than the medium weight fabric. Concerning Corky's
excellent point about the aerodynamics, a suitably flexible epoxy will
allow the fabric to have just a slight amount of give just like a fabric
covering.

This seems like a way to make a stronger, lighter skin without as much
work. But on the other hand, I'm dreadfully afraid of falling out of
the sky. How could this technique be safely tested?

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

[Corky Scott]

On Fri, 09 Apr 2004 14:59:24 GMT, Ernest Christley
> wrote:
>
>So let's take an example. I have an aileron that was designed for a
>medium weight fabric (which is 4oz/sq yard?). A 2oz FG woven finish
>fabric would still be much stronger by far, but it will be much thinner.
> Being thinner, it won't need as much "filler" (whether that be epoxy,
>dope, or paint).
>
>The process would go like this. I cut a piece of fabric the dimension
>of my aileron with an inch or so overlap. I wet out the glass on a
>sheet of 6mil plastic, set the aileron on top of it and bring the
>fabric/plastic up around the aileron sides...just wrap it over. The
>fabric is bonded to the ribs and around all the edges. No shrinkage
>necessary, since it will be the exact size. Once that cures, I repeat
>the process for the other side. The FG will add no more to the
>structrual integrity than the fabric did. It's bonded to the ribs, so
>no more attachment work or possibility of fretting. It has the smooth
>FG look, and even with an exterior coat of paint will be thinner and
>hopefully lighter than the medium weight fabric. Concerning Corky's
>excellent point about the aerodynamics, a suitably flexible epoxy will
>allow the fabric to have just a slight amount of give just like a fabric
>covering.
>
>This seems like a way to make a stronger, lighter skin without as much
>work. But on the other hand, I'm dreadfully afraid of falling out of
>the sky. How could this technique be safely tested?
>
Ernest, from what I've read and seen in the world of fabric covered
airplanes, it's really hard to substitute something for the fabric
itself and do any better in the weight saving department.

I've heard of people laying up fiberglass as a sheet and applying it
to fuselages, but the airplane ended up being heavier than when it was
covered with just fabric.

Fabric works fine by the way, it was used right through WWII on a
number of airplanes including bombers and fighters. The Corsair, one
of the most powerful fighters to fly originally had a portion of the
wing covered with fabric and even during the Korean War still flew off
carriers with a fabric covered rudder. The P-51 Mustang, one of the
fastest fighters of the war had a fabric covered rudder.

Are you trying to save money or weight, or both? When you wet out the
fiberglass fabric, it sometimes takes a lot of primer to fill the
weave, depending on the weight of the cloth. That could make for a
looonnnnggggg time of finishing to make it look good.

So what's the thought process you're going through? Why are you
interested in making the substitution? If you are looking for
additional strength, you don't really have to. Here's why: When a
friend of mine was covering his biplane, he thought it would be
interesting to test the fabric for strength, just for fun. He had a
metal stool with two loops on either side so he glued fabric across
the loops and taughtened it with the iron just like he did with the
wing. He then reached into his toolcabinet and pulled out a 16oz
ballpeen hammer. He made a half hearted swipe at the fabric and the
hammer bounced off without a mark. He swung harder and got bounced
off harder. So he stepped back and lunging forward, put every ounce
of his strength behind the swing. He hit the fabrice right in the
middle and was rebounded so hard he almost hurt himself. The fabric
was undamaged. Try that with an aluminum wing. ;-)

Corky Scott

[Richard Lamb]

Stealth Pilot wrote:
>

> polyfiber is nothing to be afraid of. it is the best system going so
> far. if you use polytone paint it is permanently repairable.
> Stealth Pilot

That's one I agree with totally.

Ease of use, repairability, and a nice high quality finish.

Using Polyfiber with and electric HVLP is about as easy as covering
an airplane can get.

Richard

http://home.earthlink.net/~n6228l

[Ernest Christley]

Corky Scott wrote:

> Are you trying to save money or weight, or both? When you wet out the
> fiberglass fabric, it sometimes takes a lot of primer to fill the
> weave, depending on the weight of the cloth. That could make for a
> looonnnnggggg time of finishing to make it look good.
>

Doubt it would be any cheaper. Thought it could be a little lighter.

I guess a benefit would be a simplification in this project. I'm
already having to do a lot of fiberglass work with the wings and
turtleback. The fabric is a whole 'nuther skill set, tool set, and
chemical set. The fabric entails, gluing, shrinking, fabric-riveting
(which I understand is slightly different than metal riveting) then
filling the weave. While maybe all minor skills, they are all something
to be learned and all have their set of pitfalls. For instance, I've
been warned that when sanding the primer, the abrasive pad can easily
slice through the fabric at the edges of ribs or other hard supports.

I'm already doing the FG thing, so I'd get to amortize the learning
curve a little more. As I understand it, a 2oz fine-weave cloth doesn't
need much filling and if you wet it out on plastic, it won't need any.
It will come out as smooth as the plastic. The process would boil down
to wet out the glass between 2 sheets of plastic, pull of the top sheet
and wrap the rest around the part to be covered. Scuff sand and and
it's ready for paint.

I'm really not that concerned about strength, other than the FG is so
much stronger that you should be able to size it down accordingly.
Whichever type you choose, the resulting coverings weight will be
determined in large part by how thick the fabric was to begin with. It
seems that a thinner fabric wouldn't need as much filler to get 'full'.
And 2oz FG has got to be thinner than 4oz polyester. The comments
have been that the Razorback system is heavy, and I don't understand why
that should be. Why not use a thinner fabric since it has the strength
to spare?


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

[Richard Lamb]

Ernest Christley wrote:
>
> Corky Scott wrote:
>
> > Are you trying to save money or weight, or both? When you wet out the
> > fiberglass fabric, it sometimes takes a lot of primer to fill the
> > weave, depending on the weight of the cloth. That could make for a
> > looonnnnggggg time of finishing to make it look good.
> >
>
> Doubt it would be any cheaper. Thought it could be a little lighter.
>
> I guess a benefit would be a simplification in this project. I'm
> already having to do a lot of fiberglass work with the wings and
> turtleback. The fabric is a whole 'nuther skill set, tool set, and
> chemical set. The fabric entails, gluing, shrinking, fabric-riveting
> (which I understand is slightly different than metal riveting) then
> filling the weave. While maybe all minor skills, they are all something
> to be learned and all have their set of pitfalls. For instance, I've
> been warned that when sanding the primer, the abrasive pad can easily
> slice through the fabric at the edges of ribs or other hard supports.
>
> I'm already doing the FG thing, so I'd get to amortize the learning
> curve a little more. As I understand it, a 2oz fine-weave cloth doesn't
> need much filling and if you wet it out on plastic, it won't need any.
> It will come out as smooth as the plastic. The process would boil down
> to wet out the glass between 2 sheets of plastic, pull of the top sheet
> and wrap the rest around the part to be covered. Scuff sand and and
> it's ready for paint.
>
> I'm really not that concerned about strength, other than the FG is so
> much stronger that you should be able to size it down accordingly.
> Whichever type you choose, the resulting coverings weight will be
> determined in large part by how thick the fabric was to begin with. It
> seems that a thinner fabric wouldn't need as much filler to get 'full'.
> And 2oz FG has got to be thinner than 4oz polyester. The comments
> have been that the Razorback system is heavy, and I don't understand why
> that should be. Why not use a thinner fabric since it has the strength
> to spare?
>
> --
> http://www.ernest.isa-geek.org/
> "Ignorance is mankinds normal state,
> alleviated by information and experience."
> Veeduber



Glass is a highly frangible material compared to polyester.
It is strong, yes, but brittle.

While tensile strength is a good thing, it is not the only thing
we need to consider.

My new plane is covered with 1.7 ounce dacron and Poly Fiber finish.
For a lightly loaded, low speed plane, this is quite adequite.

3.2 ounce fabric is twice as strong.
Why _not_ use it? (trick question!)

Because it's FOUR times heavier when finished?


Richard

[Robert Little]

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

"Ernest Christley" > wrote in message
m...
> Most of the fabric covered aiplanes I've seen didn't seem that hard.
> That is, you could walk up to them and push the fabric in with your
> hand. The way I understand the fabric process, it is basically a
> composite structure. You have a nylon cloth with a paint "epoxy".
>
> Could a much stronger and lighter covering be made by wetting out some
> 2.5oz glass cloth on plastic, waiting till it's tacky and then wrapping
> it around the airframe? The epoxy would be much lighter than paint, and
> fiberglass cloth is MUCH stronger than nylon.
>
> I've seen some places where builders used composites in place of fabric,
> and it seemed that they all aimed for a multlayer, stiff panel, putting
> the weight far above the original. I just don't understand why?
>
> --
> http://www.ernest.isa-geek.org/
> "Ignorance is mankinds normal state,
> alleviated by information and experience."
> Veeduber

[Veeduber]

>
>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
-----------------------------------------------------------

To All:

Listen to the man.

Common Sense has become such uncommon stuff in the aviation community that the
antique phreaks give each other extra points for using heavier and less durable
(but All Original) Irish linen, while across the field the fabric experts are
happily selling Polly Needles for rib-stitching Polly Thread thru Polly Holes
in Polly Fabric, knowing they can charge the same inflated prices to the next
Polly Idiot to own the thing.

Razorback has the potential to put all the Polly People out of business, which
is probably the reason it is always damned with faint praise.

-----------------------------------------------------

Fabric is not always stitched. Most homebuilders are aware that it is sometimes
glued to the structure but most are not familiar with the many other
time-tested methods. On some airframes it is attached with canes & nails (!)
and for metal ribs, with spring clips, wire, sheet metal screws and even
rivets. When Razorback is attached with these methods you end up with a
virtually permanent skin.

-R.S.Hoover

[Ernest Christley]

Veeduber wrote:

> Fabric is not always stitched. Most homebuilders are aware that it is sometimes
> glued to the structure but most are not familiar with the many other
> time-tested methods. On some airframes it is attached with canes & nails (!)
> and for metal ribs, with spring clips, wire, sheet metal screws and even
> rivets. When Razorback is attached with these methods you end up with a
> virtually permanent skin.
>
> -R.S.Hoover

John Dyke's prototype, N555A (I hope I got that right), has the fabric
riveted to the elevon ribs, rudder and tailfin. It is glued to the belly.

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

[Ernest Christley]

Robert Little wrote:
> 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.
>

So, why do you not offer the process in a lighter fabric?

The application that I'm looking at is an elevon that is hinged from its
leading edge. The top speed is limited by the possibility of speed
induced flutter in the elevon. A lighter elevon corresponds to a higher
top speed, so this is one of the few places on this airplane where I'm
actually concerned about ounces ('cause flutter stories scare me more
than all the others).

It's late, and way past my bedtime, but 3.6oz FG sounds like a lot more
strength than is needed and way stronger that the specified fabric.
I'll do the math tomorrow. But is there a reason that a lighter fabric
can't be used? Since the fabric is 200% stronger, why couldn't you
replace the 2.4oz Dacron with 1.2oz Razorback?

BTW, I haven't seen any prices listed, but LESS expensive than Dacron?
Dacron is fairly cheap as far as coverings go.

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

[Robert Little]

With the superior strength of glass cloth, why not offer it in a litter
weight? A very good question that I asked the president of the Ultra Light
Aircraft Association. Because of the very expensive process of getting a
new product "certified" by the FAA, I had that organization do a survey for
interest in a permanent fabric. There was no interest at all. After many
years of instructing rib stitiching and fabric installation at the Oshkosh
EAAFly-In, the survey was not too surprizing.

We realize that we don't have to get the blessings of the FAA to sell to the
home builder and can sell "uncertified" fabric as the other companies do.
But unfortunately, that light-weight uncertifed fabric usually shows up on
certified aircraft, regardless of the regulations and recommendations. And
yes, wing loading, speed and flight regimen does mandate the different
weights of fabric. A good reference is the A.C. 43-13.1B.

So, until I think that I can sell enough of our 1.5 oz that test in at 92
lbs/ inch that will break even with the cost of certification, we will not
offer it to the public. (New Grade A cotton only tests at 80 lbs/inch)

The cost difference of glass fabric is 80% greater than polyester. But it
is glued with butyrate dope (no nitrate-laced glue), taunten with butyrate
dope, filled with non-tauntening butyrate dope and should be topped with
butyrate dope, although, the top coat is the installer's choice. We still
buy MIL SPEC butyrate dope for less than $16 a gal. I'll let you figure the
total cost of a cover job from these figures.

I hope that this has answered some of your questions. All things are based
on economics. As I've said before, I wish all fabric was permanent so that
we didn't have to hide our beautiful airplanes deep in dark hangers. It
doesn't make very much sense that the owners of the most economical and most
fun to fly aircraft are afraid to come out into the sun and fly. The
temporary fabrics that are on the market today have stolen a great heritage
from us. Most of these airplanes are so rare in flight that insurance
ratios are astronomical. and training is getting quite rare. there are tens
of thousands of ragwings hiden away in hangers that are afraid to come out
and stay current. It is sad.


"Ernest Christley" > wrote in message
.. .
> Robert Little wrote:
> > 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.
> >
>
> So, why do you not offer the process in a lighter fabric?
>
> The application that I'm looking at is an elevon that is hinged from its
> leading edge. The top speed is limited by the possibility of speed
> induced flutter in the elevon. A lighter elevon corresponds to a higher
> top speed, so this is one of the few places on this airplane where I'm
> actually concerned about ounces ('cause flutter stories scare me more
> than all the others).
>
> It's late, and way past my bedtime, but 3.6oz FG sounds like a lot more
> strength than is needed and way stronger that the specified fabric.
> I'll do the math tomorrow. But is there a reason that a lighter fabric
> can't be used? Since the fabric is 200% stronger, why couldn't you
> replace the 2.4oz Dacron with 1.2oz Razorback?
>
> BTW, I haven't seen any prices listed, but LESS expensive than Dacron?
> Dacron is fairly cheap as far as coverings go.
>
> --
> http://www.ernest.isa-geek.org/
> "Ignorance is mankinds normal state,
> alleviated by information and experience."
> Veeduber

[Stealth Pilot]

On Wed, 14 Apr 2004 00:17:15 -0500, "Robert Little"
> wrote:


>I hope that this has answered some of your questions. All things are based
>on economics. As I've said before, I wish all fabric was permanent so that
>we didn't have to hide our beautiful airplanes deep in dark hangers. It
>doesn't make very much sense that the owners of the most economical and most
>fun to fly aircraft are afraid to come out into the sun and fly. The
>temporary fabrics that are on the market today have stolen a great heritage
>from us. Most of these airplanes are so rare in flight that insurance
>ratios are astronomical. and training is getting quite rare. there are tens
>of thousands of ragwings hiden away in hangers that are afraid to come out
>and stay current. It is sad.
>
owner of the company or not you do write some bull**** robert.
if you have never seen the fiberglass fretted away so that only the
finish remained then you need to get out more. <expletive deleted>

my tailwind has a 19year old polyfiber finish that just will not die.
I will eventually rip it off in airworthy condition so that I can
check for cracks and recoat the steel tubes.

btw the problem with these modern fabrics is that they are so
permanent that the underlying structures are not getting the regular
maintenance attention that they would have in the days of cotton. that
is the problem. not the BS you write.
obviously ymmv
Stealth Pilot
Australia

[Ernest Christley]

Robert Little wrote:
> With the superior strength of glass cloth, why not offer it in a litter
> weight? A very good question that I asked the president of the Ultra Light
> Aircraft Association. Because of the very expensive process of getting a
> new product "certified" by the FAA, I had that organization do a survey for
> interest in a permanent fabric. There was no interest at all. After many
> years of instructing rib stitiching and fabric installation at the Oshkosh
> EAAFly-In, the survey was not too surprizing.
>
> We realize that we don't have to get the blessings of the FAA to sell to the
> home builder and can sell "uncertified" fabric as the other companies do.
> But unfortunately, that light-weight uncertifed fabric usually shows up on
> certified aircraft, regardless of the regulations and recommendations. And
> yes, wing loading, speed and flight regimen does mandate the different
> weights of fabric. A good reference is the A.C. 43-13.1B.
>
> So, until I think that I can sell enough of our 1.5 oz that test in at 92
> lbs/ inch that will break even with the cost of certification, we will not
> offer it to the public. (New Grade A cotton only tests at 80 lbs/inch)
>
> The cost difference of glass fabric is 80% greater than polyester. But it
> is glued with butyrate dope (no nitrate-laced glue), taunten with butyrate
> dope, filled with non-tauntening butyrate dope and should be topped with
> butyrate dope, although, the top coat is the installer's choice. We still
> buy MIL SPEC butyrate dope for less than $16 a gal. I'll let you figure the
> total cost of a cover job from these figures.
>
> I hope that this has answered some of your questions. All things are based

You answered the questions, very good answers, in fact; however, it
doesn't help me. I hear you paraphrasing Ford. "You can have anything
you want, as long as it is what we sell." Which is OK, it just doesn't
help me any.

What I'm after is a 1) lighter elevon and 2) simpler to build elevon.
If it is stronger or cheaper, we can party on those points, too, but
they are secondary. Your process, while excellent, helps on neither point.

I don't mean to tell you your job here, but did you ever consider asking
the Ultralight Association if they would be interested in a LIGHTER
fabric. My impression of the ultralighters I know is that they look at
their planes as dirt bikes. They are not serious modes of
transportation, they're toys. Why would you EVER worry about a
permanent fabric on a toy! But if those guys think they can cruise 1mph
faster or climb 1fpm quicker they'll ransom their children for pixie
dust. I guess it is equally true for the GA crowd, and especially for
the tube'n'rag crowd. For the most part, tube'n'rag crafts are not
serious transportation; therefore, PERMANENT COVERING means zilch.

Now if you'd like to sell some 1.5oz cloth, I'd like to do some test
with substituting a standard epoxy for butyrate dope.

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

[[email protected]]

On Wed, 14 Apr 2004 18:03:49 GMT, Ernest Christley
> wrote:

>You answered the questions, very good answers, in fact; however, it
>doesn't help me. I hear you paraphrasing Ford. "You can have anything
>you want, as long as it is what we sell." Which is OK, it just doesn't
>help me any.
>
>What I'm after is a 1) lighter elevon and 2) simpler to build elevon.
>If it is stronger or cheaper, we can party on those points, too, but
>they are secondary. Your process, while excellent, helps on neither point.
>
>I don't mean to tell you your job here, but did you ever consider asking
>the Ultralight Association if they would be interested in a LIGHTER
>fabric. My impression of the ultralighters I know is that they look at
>their planes as dirt bikes. They are not serious modes of
>transportation, they're toys. Why would you EVER worry about a
>permanent fabric on a toy! But if those guys think they can cruise 1mph
>faster or climb 1fpm quicker they'll ransom their children for pixie
>dust. I guess it is equally true for the GA crowd, and especially for
>the tube'n'rag crowd. For the most part, tube'n'rag crafts are not
>serious transportation; therefore, PERMANENT COVERING means zilch.
>
>Now if you'd like to sell some 1.5oz cloth, I'd like to do some test
>with substituting a standard epoxy for butyrate dope.

I'm building a rag and tube airplane and I sort of break the mold I
guess. I'm interested in outdoor storage, because it's a lot less
expensive, and I'm also interested in traveling places.

I won't go anywhere enormously fast, but I'll get there.

So a permanent fabric REALLY interests me.

Corky Scott

[Del Rawlins]

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/

[Richard Lamb]

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

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

[Robert Little]

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/

[Del Rawlins]

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

[Richard Lamb]

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

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.

[Del Rawlins]

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

[Ernest Christley]

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

[Robert Little]

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

[[email protected]]

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

[Ernest Christley]

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

[Ernest Christley]

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

[[email protected]]

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

[Ernest Christley]

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

[BllFs6]

>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 :)

[Stealth Pilot]

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.

[[email protected]]

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

[Del Rawlins]

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/

[Stealth Pilot]

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