Dale Rogers <rogersda@cox.net> wrote:

"""
 Ummm, Marv,
 
   What you gave is the description of "plain weave".
 Rutan "BID" (RA7725) is not a plain weave.  It consists
 of paired strands of yarn crossing under/over crosswise
 pairs of yarn.  That's enough to make a major difference
 in the way the fabric "drapes".  It's like comparing
 gingham to challis.
"""

Hi Dale,

Actually, I (and most other folks) use the term "BID" as an all encompassing sort of term to differentiate between bi-directional and uni-directional or multi-directional fabrics.  It's a sort of generic term (at least in my mind) that's tossed around pretty freely without regard to the actual weave-type. There are many forms of BID, whether plain weave, mock leno, 4-harness (crowfoot) and 8-harness satins, and probably others that I don't even know about because it's not my area of expertise.  As I'm sure you know, when you need to get specific with the actual makeup of the weave the term "BID" just doesn't offer enough info.  Take a look at any of the larger commercial suppliers' websites and you're inundated with a huge number of different "plain", "satin", "volan" and other weaves to choose from.  Unfortunately, the casual user who's making up the occasional odd part seldom has any more info than a recommendation to use a "BID" fabric on his part.  You are right that satins are easier to work around corners and curves, and are the material of choice for general applications, being more forgiving than some of the other weave types.  Learning exactly which weave to specify for a given task takes a lot more engineering knowledge than the average builder possesses, so we're relegated to choosing a cloth that one of our friends might have used on their project, or we put ourselves in the hands of the guys who actually sell the stuff trusting that their recommendation based on our description of the intended part will give us the best material for the task.  Just my take on the situation.

    <marv>