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