Thread: Build Log Neos
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Old Nov 05, 2012, 10:02 AM
MattN is offline
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a.k.a. Matt Nelson
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North Tustin, CA
Joined Oct 2008
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Nick - nice pictures of your build. You obviously have some finely tuned skills!

I do have some comments re: joining the wings - please do not take them as criticism, as your work is very good. I have thought about the wing joint a lot in the past, and have come to the conclusion that Oleg has it figured out perfectly in his Taboo building instructions. When I sat down and thought about the forces exerted on the wing joint (tension and compression) and which materials come into play to resist them (skins, spar, splooge), I quickly converged on Oleg's joining method.

Specifically:
  • Poking holes in the face of the root joint is pointless. The foam cannot resist tension - imagine trying to pull apart a wing with only the foam faces glued together; the foam would tear out very easily. The epoxy in the root joint is there to fill any gaps between the faces to ensure that compressional forces are spread out over the entire surface.
  • Hollow-out the foam under the skin edge. If you look closely at Oleg's pictures, you can see that on each root face, he scrapes out a very small line of foam under the edge of the wing skin. When joined, this gap creates a bead of epoxy that very strongly bonds the skins together across the joint. This is very important, as the skin is one of the structural components that resists tensional forces on the joint.
  • Join the spars with a resin column. Hollow out a groove of foam between the upper and lower spars. This creates a void that will be filled by epoxy creating a structural column between the upper and lower spars - this column will strengthen the spar structure, and help prevent "buckling" failure at the root joint.

Take it or leave it - but I'm convinced that Oleg got it right.

Once again, beautiful build (I like the ball link - nicely done!). That Neos is looking better and better all the time!

-matt
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