6781 is an 8 harness satin weave of S-2 glass fiber. As a dry fabric it has no shear modulus. As a composite the shear modulus would be determined mainly by the resin properties.
Following specs do not list fabric #6781... #7781 is as close as I can come...
MIL-Y-1140 YARN, CORD, SLEEVING, CLOTH AND TAPE-GLASS AMS-C-9084 Cloth, Glass, Finished, For Resin Laminates ASTM D579 Standard Specification for Greige Woven Glass Fabrics
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
6781 is the identical to 7781 except for the use of S2-glass rather than E-glass (most just call it S-glass but the original S-glass, which was qualified to a number of defense and ballistic missile programs, is no longer made. S2 is made to commercial specifications rather than military, just like E-glass. You can easily find information through a google search. This thread was hit number four on google.
As for phenolic resin, you need to know the exact proprietary product formulation for properties. Resin properties can be all over the map and depends on the exact formulation and processing. You can generally only get that from the manufacturer. SC-1008 is one of the most common phenolics used in aerospce composites. This resin can be used straight out of the drum or with additives.
What is the secrete handshake [document, etc]: how/where do You know/get info "6781 is the identical to 7781 except for the use of S2-glass rather than E-glass..." ??????????
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
I have worked with this material for 35 years and heard the stories from customers. The only data I have seen on any fabrics comes from the technical handbooks that weavers give their customers. These all look very similar with a similar layout. Here is the Hexcel handbook with 6781 on page 68:
