Not to say that either system is superior, 'cause I have used probably gallons of T88 but I think that you would have a hard time telling Jim Clement, who has built at least 10 Tailwinds, that he is using T88 instead of West............ Go to the Tailwind Groups on Yahoo and Matronics and you will see what is being used and how.....
Just my long nose and nickles worth......... On 1/27/06, Larry H. <[email protected]> wrote: > > OK netters I guess I will step off into it. > Wittman Tailwinds do have wooden truss ribs. All Wittman Tailwind wings > that I know of in recent years are glued together with T88. I keep up with > the Wittman guys closely, I know many of them, I attend their get togethers. > The older ones used the powder mix for gluing theirs, I don't rember what > you call that stuff. > The Wittman has two wooden spars just like a KR. The ribs are actually > 1/2" wide. The reason is so there is a larger gluing surface for the sheets > of plywood that get glued down and covers the wings. Once all the plywood > is glued, set, sanded smooth the current trend is to cover them with a layer > of fiberglass cloth mostly for sealing but for some strength. Most builders > in the last 8 to 10 years are using the West epoxy system for wetting out > the fiberglass cloth that covers the outside surface of the Wittman wings. > Steve Wittmans plans tell you to cover the wings with doped fabric, as in > Stits/Poly Fiber, but actually the predecessor to the Poly Fiber system. > Unfortunately what killed Steve Wittman was a mix up in technique . Steve > had always used the old covering system which allowed you to lay fabric (I > am talking about fabric covered airplanes type of fabric not fiberglass) on > the wood and wet it out with the dope just like we do with fiberglass cloth. > The dope would penetrate through the fabric and then it was stuck down, no > problem, that is the old way of covering the plywood wings as specified by > Mr Wittman. > When he built the O&O Mr Wittman used the Stits system, but he did it > wrong, he did it like the old stuff. What he was supposed to do was paint > the new stuff (Poly Tak) on the plywood first, laying the fabric on top of > that while it was still wet, covering a little at a time to make sure the > Poly Tak stays wet when the fabric is applied to it, then use the second > step, paint (Poly Brush) on top of the fabric. > The fabric on the O&O managed to stay on the plane for about 10 years I > think it was. He had built this plane to carry all of his things to his > winter home in Ocala Fl from Oshkosh, that is why he named it the O&O for > those of you who don't know. The last flight that Steve Wittman made from > Ocala headed back to Oshkosh for the summer of course was his last, the > fabric had delaminated from the plywood, set up flutter and tore the wing > off of the airplane. I think EAA had an article about it, I never read it so > I am not sure what they wrote about it but this is what happened to it. > Bottom line is know your systems, attempt to know what you are doing and > by all means pay attention.. > I for one would never use West Epoxy for gluing ribs or a wooden airplane > together. I have never known anyone to have done such. Not saying that there > is not someone who has but I would never do that. > I know a guy who built his wooden truss ribs with model airplane CA glue, > I warned against that but a guy has to do what a guy has to do. > I have known guys who use the wrong stuff to build all kinds of airplane > parts. I will rephrase that and say the wrong stuff as far as I am > concerned. > Larry H. > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to [email protected] > please see other KRnet info at http://www.krnet.org/info.html > -- Jerry Mahurin - aka - KRJerry EAA# 0034283 Lugoff, SC 29078
