From: Militch@aol.com Date: Mon, 17 Jan 2000 23:26:53 EST Subject: COZY: Elevators I hot wired my elevators and put them on the torque tubes this weekend. I only messed up two - so ended up making six elevator half-cores . The error was that I didn't support the ends well enough and that permitted the templates to flex just a little as the hot wire came off the trailing edge end. That resulted in a trailing edge that got cut short by a couple of tenths of an inch for the last foot or so of core. Easy to fix once I did it properly. My question is this. Those cores are tight on the torque tubes. I suppose some micro stayed in as I slowly pushed the tube through the channel - say a milligram or two. Apart from the slight bond I will get when the glass wraps around the visible part of the torque tube, the only thing that will be transferring the torque forces from the tube to the elevator core will be the foam to metal contact and whatever micro managed to get in there. I imagine the forces on the elevators will be considerable, and that they will get a fair beating over their lifetime. Is this really enough? (Or do I need to read ahead and find out that some additional measures are taken to lock the tube to the final, glassed cores?) Regards, Peter Militch #740 Date: Tue, 18 Jan 2000 20:00:06 -0500 From: "Marc J. Zeitlin" Subject: Fwd: COZY: Elevators Peter Militch asks (somewhat rhetorically, IMO :-) ); >I hot wired my elevators and put them on the torque tubes this weekend...... >.....Apart from the slight bond I will get when >the glass wraps around the visible part of the torque tube....... >..... I imagine the forces on the elevators will be considerable, and that >they will get a fair beating over their lifetime. Is this really enough? Let's look at this empirically. Q: How many V.E.'s and L.E.'s, Q-2's, Dragonfly's and Cozy's are there? A: Maybe 2000 - 3000 flying. Q: How many of them have been built using this methodology? A: All of them. Q: How many elevators does that add up to? A: Maybe 4000 - 6000. Q: How many torque tubes have ripped out of elevators? A: None. Zero. Nada. Nil. Zip. Zilch. Goose-egg. So, the epidemiological data would contraindicate a torque tube failure, as well as contraindicating a need for worrying about it :-). After you get your elevators glassed, grab the tube in one hand and try to twist the elevator off it with the other (spread out the force with something large, flat, and stiff). See what happens, if anything :-). -- Marc J. Zeitlin mailto:marc_zeitlin@alum.mit.edu http://www.ultranet.com/~marcz/ Date: Wed, 19 Jan 2000 19:13:35 -0500 From: "L. Wayne Hicks" Subject: Re: COZY: Elevators Militch@aol.com wrote: My question is this. Those cores are tight on the torque tubes. > I suppose some micro stayed in as I slowly pushed the tube through the > channel - say a milligram or two. --------> it's perfectly okay to trim about 1/8th inches off the very thin edges where the torque tubes will go. This makes it alot easier to apply enough micro to the tube and onto the cores, then simply press the tubes into place without splitting the foam cores. Once the micro is cured, you end up sanding away these edges anyway in a later step to make the smooth, round transition onto the tube. I've described this on my Chapter 11 page: http://www.geocities.com/yosemite/falls/2027 Wayne Hicks Date: Thu, 20 Jan 2000 08:38:15 -0600 From: Michael Pollock Subject: RE: COZY: Elevators Militch@aol.com wrote: >My question is this. Those cores are tight on the torque tubes. I used a wooden dowel with sandpaper attached around it to open up the torque tube holes a little on the cores to allow the micro a little room. Worked great! Michael.Pollock@wcom.com Flying Velocity N173DT Building Cozy MKIV #643