chasingmars Posted November 12, 2007 Share Posted November 12, 2007 Hello all. I got one of those "bright ideas" so before I go mess something up, I figured I'd post and see if there's good reason not to do it... While I'm still plodding throught chapter 7, I got my LG components the other day, so I've been reading ahead a bit in the plans to see whats involved. I've read that chapter nine involves a huge number of hours, and I'm looking to find ways to change things to take longe... um... I mean, save some labour. Anyhow, I was looking at the first part, where one lays offset cut UNI, 8 layers in all, from two directions, in pieces, without getting the fibres bent This is to provide additional torsional strength to the gear. I'm not entirely sure why 35 degrees was chosen, and why the angle is biased towards the directionality of the S-glass hoop, given that for a tubular skin in torsion, the principle stresses would be at +/- 45 degrees (skin in shear), and the addition of the bending of the hoop would offset this in different directions on top and bottom as the top's in combined shear/compression with the bottom in combined shear/tension. Maybe I'm missing something and Marc or someone else with a better stuctures background than I can fill me in. Anyhow, the reason this is on my mind is that I noticed that the gear circumference tailors fairly well to that of 4" diameter braided sleeve, which is pretty commonly available these days. At the fattest parts, the gear is about 12-1/2 to 12-3/4 around, which would have a 4" sleeve at just about 45 degree bias, then as it tapers it would pass through 35 degrees about 2/3s to the wheel (10.2" circumference) tapering to about 27 degrees at the strut end and on the other side about 24 degrees through the centre where it necks down. So what I was thinking is, since I figure it's probably a lot easier to get straight consistant fibres by smoothing down a braided tube over the landing gear, is there any glaring reason why this shouldn't work if I run the numbers to account for the glass strength of the braid and account for the variation in angle? I haven't done all the math yet, but something like 3 layers of 24oz braid should be easier that the 13 pieces of UNI? What do the folks that did it the plans way think of the plans process, is it as much of a bear as I'm thinking it will be, or does it just sound complicated and is easier in practice? Has anyone worked with braid before, from a manufacturing standpoint, is what I'm suggesting workable or is there something I haven't considered? Are there advantages to more layer of lighter braid? Should I put a finishing layer or interlayers of lighter braid between heavier keep the resin weight down? And from a stuctural standpoint, am I missing anything significant here? From a weight perspective, I don't mind a *little* extra glass to make up for the change in approach, as I'm much more easily able to vac bag a braided LG hoop than a plans done one (the supports make it more complicated) and a good vac bag here can probably save 1-2 pounds given that there's about 6 sq yards of glass in this wrap. Anyhow, thoughts? I want to have a nice warm fuzzy before trying it as it's an awfully expensive piece to mess up. your feedback is appreciated! Quote Craig K. Cozy IV #1457 building chapter seven! http://www.maddyhome.com/canardpages/pages/chasingmars/index.html Link to comment Share on other sites More sharing options...
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