On 3 Jun 2006 04:22:57 -0700, "expresstechonsite"
wrote:

What are the differences between standard "Rip-Stock" material I can
get from my local fabric store (or even wal-mart) for $1.00/yd and the
polyester fabrics approved for covering an aircraft?

none of the other replies got it right.

polyester fabrics go through a process during manufacture to get the
threads to sit into position that involves heating, stretching, and
reheating them to get the threads to conform to the woven shape.

aircraft fabrics are polyester fabrics that have not had the final
heat and conforming process done to them. that is the key difference.

after you glue the fabric to the aircraft structure you go all over
the fabric with a dry steam iron set to 250 farenheit. this shrinks
the fabric into the condition of your store bought poly fabric and in
the process shrinks it by up to 10%. this shrinking is what tensions
the fabric. this is quite unlike natural fibres such as cotton where
the shrinkage of the applied dope is what creates the fabric tension.

I would encourage you to obtain the manual for the Polyfiber process.
This will explain in full detail all the aspects of developing a
competent fabric covering in polyester fabric. Much of the polyfiber
process addresses issues surrounding the impermeability of the
polyester fabric and the lack of adhesion that occurs with traditional
finishes.

My personal belief is that the more recent manuals have been dumbed
down and the original stits manual has the better detail.
My polyfiber manual is dated feb 1993 and this has all the detail.

Stealth Pilot