Gliders > Slope Soaring
West Wings Skylark build thread
angry_muppet:
Forgive me for using metric measurements...
The wing chord is 158mm
The distance between centers of the wing mounting dowels is approx 147mm
The relaxed length of the supplied band is 105mm...
As the band needs to "wrap around" the wing to the dowel, we're talking a stretched length of 170mm... That's triple the figure suggested by Little Keith
Is it possible the bands are creating too much force on the wing?
Happy Days:
I suspect that it is the bands that are supplying the force that broke the first joiner, but I'm having trouble understanding how. :o The tension that the bands apply when simply holding the wing to the fuse shouldn't stress the wing joiner,........ provided both wing halves are level. Which you've already said they are.
David, when the two wing halves are joined together on a flat surface (kitchen table I believe in your case ;)) with the wing joiner in place..................is the top of the L.E and top of the T.E of each wing half level. Or does the front (or rear) of one wing half stand up proud above the other wing half?
I'm thinking that if one wing half is twisted or warped, or the joiner isn't sitting flush against the side of the spar, then when you fit the bands, they might be applying torsional stress (or twist) to the joiner which will cause it to snap!
K.
billscottni:
Slightly surprised that the distance between the dowels is less than the wing chord? It would usually be the same or very slightly more. With it being less you're effectively "pinching" the wing with the bands, as they have to go back under the LE or TE to get to the dowel. Having said that I suspect it's mainly the band tension and the use of Lite ply that are the issue. If the band is going from 105mm to over 158mm thats over 50% stretch and I'm surprised you're not damaging things just getting them on! Couple that with a lite ply brace and somethings bound to give!
angry_muppet:
Kudos to Rogallo who kindly provided me with a few off-cuts of birch ply to reconstruct the brace! 8)
A pair of braces have now been manufactured to fill the full depth of the wing; I can now report back on the state of affairs...
There is a small amount of difference in the underside of the wing (about 2 - 3mm). This appears to be due to a misgluing of the TE on the port wing with a slight upward inflection. :-[ (No... I didn't glue the LE in upside down...) There doesn't appear to be any difference in the majority of the underside; the LE and balsa sheeting are flush. I would doubt that such a minor deflection wouldn't cause excessive torsion or create an issue with control? It would (theoretically) slightly affect the attitude of the aircraft by altering the wing's angle of attack... :-X
Any ideas before I glue the lot together?
rogallo:
Loads of epoxy and cover it up. It will be fine, ever see any of my models!
Twill be grande 8)
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