Adam,

It is difficult to spend the time making a reply. I am not an eng= ineer and I did not play one on TV -but- there is plenty of literature conce= rning "composite" construction. Composite generally meaning a matrix (= fiberglass, carbon fiber, kevlar, wood fiber) and a bonding agent (epoxy, gl= ue) thus we end up with results that have certain properties, like our glass= /carbon construction and plywood. There are many weaves of glass and c= arbon cloths and even more "epoxies" with certain designed properties. =

The kinds of epoxies we use, consisting of a resin and a hardener, are=20= brittle when cured if there is no matrix or the matrix was too wet. If= you were a builder, you could go out to your shop and take that excess cure= d epoxy sitting in the mixing cup and whack it with a hammer - it would prob= ably shatter. Using the proper techniques and materials, there is no k= nown life limit and no natural enemy of glass/epoxy combination save for ult= raviolet radiation.

BTW, everything is porous at the microscopic level, especially molecule= s with those goofy atoms and silly electrons spinning around in space. = Perhaps he should contact Boeing, the Rutan boys, Diamond Aircraft, Cirrus,= Lancair and all the composite kit companies about his paper - - By golly, I= am going to run out and watch my 320 disintegrate before my very eyes since= the moldings were done in 1989, a whole 14 years ago. Maybe this guy=20= should stick to something like the chemical composition of Jalapena pep= pers - that complex demonic chemistry attacks every useful orfice of th= e human body.

Scott Krueger
Sky2high@aol.com
II-P N92EX IO320 Aurora, IL (KARR)

In a message dated 10/24/2003 12:13:06 PM Central Daylight Time, propje= t882aw@cox.net writes:

I recently had a disconcerting conversation w= ith an engineer. Like me, he was also a flight enthusiast. Unlike me, he was= not thrilled with my dreams of fast glass. (For the record, I didn't mentio= n any specific model--I just told him I was looking at a cross-country cruis= er and an amphib. Because of this, I know he didn't have any bad experiences= and was biased against them.) Later I learned why he was dismayed. It was n= ot because of the composite construction--it was because of the epoxy that w= e use for the structural adhesive. When I asked him what he meant, he told m= e that he had published a paper on it. He then proceeded to tell me about ho= w epoxy is hard, brittle, and porous (on a microscopic level). The first tra= it I thought was a good idea. The second two I wasn't too sure about. He exp= lained to me that the issue that worried him was fatigue. NOT of the composi= te structure but the epoxy itself. In a traditional metal aircraft, you can=20= x-ray structures to determine their state of fatigue and replace the hinge p= ins, bolts, etc if needed. He said that you can not do this w/ the epoxy. In= a nutshell <these types of joints don't fail little by little. When they= fail, they fail catastrophically and we have no way of determining when tha= t will be>. I don't know if he is talking about delamination or what--I'm= still a low-time PP.