----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- At 08:21 AM 9/19/02 -0800, Pete Thomson wrote:
Good morning Lynn, my nose cowling is trashed and held together by many patches. My question is this, if a Coupe can shake an aluminum nose cowling apart without abnormal vibration, how can a fiberglass cowling be expected to hold up. I am going to replace the cowling but believe the fiberglass one would shake itself to pieces. Has anyone else had this experience? thanks,Pete Fiberglass is much more resistant to vibration than aluminum. Look at the beating that speedboats take...and some of them have been taking it since the 50's. In fact, there isn't anything on this earth much LESS resistant to vibration than aluminum...it 'work hardens' very quickly, becomes crystalline in composition, and then snaps. The specific alloy can help...the purer the aluminum, the quicker it breaks. Fiberglass, on the other hand is a combination of two materials. A resin (most frequently polyester, but in advanced applications epoxy) which alone is somewhat brittle...and strands of glass in either a random pattern (roving) or a woven pattern (mat). If I recall properly, the 'super bowl' is made up of roving, due to the compound curves, with some edge reinforcement of mat. That's the right way to do it. It does not 'work harden' per se. It can de-laminate, but generally this only occurs where two pieces have been joined after the resin has fully hardened. The nose bowl that Lynn installed in 1999 now belongs to me. The only evidence of wear are places where the initial molding was disturbed somewhat to allow for the vacuum pump. At those points, the 'gelcoat' (the color layer which contributes no strength, but does give a quick, smooth finish, even if paint over it) has chipped where not quite enough care was used to radius ever cut...like aluminum, this forms a 'hard point' and can lead to a chip. I believe it has several hundred hours on it, and truly looks great. Also, aside from the fact that Lynn and Les did great work on the baffles, the claims about the superior cooling of this bowl are true. I rarely see more than 180F, even on a very hot day, when the O-200 is being run pretty hard. Also, to my eye, the cowling just looks WAY better than any of the stock cowls, even the Forney, or the older after-market fiberglass bowl. By the way, I had the older glass bowl on N2906H (fiberglass). It was made up entirely of mat, in what looked like a well-done hand lay-up. It showed no sign of wear in hundreds of hours. It appeared to be basically a fiberglass reproduction of the aluminum original. Highly recommended! Either the old one or the newer one! But especially the new one. And pretty cheap, as airplane body parts go. Greg ================================================================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm
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