Date: Mon, 06 Jan 1997 20:09:57 -0500 From: Jim Hocut Subject: COZY: Doin' the Twist (Stupid Mistakes 101) Every once in a while I have to question my sanity in attempting to build and fly my own airplane. I've again reached one of those points, and am so disgusted I don't even want to look at my project right now. I had been very careful while building my canard to ensure that there was absolutely no twist. I used two straight edges which I scrupulously checked for level etc. which were bondoed to my worktable. I post-cured the canard while it was bondoed to the two straight edges to be sure that no twist was introduced. After all of this the most twist I could measure was 0.1 degrees. Life was good. Well....for the past few weeks, the few momentswhen I've been able to go out to my workshop have been spent on finishing the canard. While I may have been taking longer to get an acceptable level of finish than someone who's built a fiberglass plane before, each cycle of micro - sand saw me getting closer to perfection, so I was pretty much happy with my progress. For most of the past three weeks the canard has been clamped to a 2X4 with C-clamps on the lift tabs (with tape on the lift tabs and a scrap of wood between the tab and clamp to protect the lift tabs). Well, tonight I was showing off my work and bragging on how little twist I had, and just had to get out the electronic level to prove my point. Much to my horror, there is now at least 1.2 degrees of twist from one end of the canard to the other, with about 3/8 inch of dihedral to boot. After the proper amount of screaming, yelling, cussing, and throwing things I discovered that the 2X4 I was clamping the canard to had serious twist. Apparantly, over the course of 2 or 3 weeks I managed to get the canard to mimic the twist of the 2X4. I think I'll eventually be able to untwist the canard, I may even be able to get rid of the unwanted dihedral. So, don't repeat my experience. Be very scrupulous in the choice of clamping surfaces, and either unclamp your work, or at least loosen the clamps, after a work session. Jim Hocut jhocut@mindspring.com