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Old 06-01-2012, 09:14 PM
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BMatthews
 
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Default RE: Sailplane Wing Design Round II

Nodd, when I've done rods of this sort I build the whole wing with some brass or aluminium tubing in there that will be a nice fit for the wires or rods. I put a "cutting shim" between the facing ribs so I can later pull it out and have clearance for a razor saw blade to fit and cut the tubing.

By doing the wing panes as a temporary one piece I am certain that the slip tubes for the joiner rods are fully aligned.

Lat but not least. On the bays with the joiners I don't use webbing between the caps. Instead I mix up a batch of epoxy thickened with phenolic or glass micro balloons to thicken the resin and pack it in between the spars. Before it can run out I cap and clamp 1/32 ply outside "webbings" in place to provide a dam to hold the thickened resin in place. When it cures the resin itself becomes the full webbing for those rib bays as well as ensuring that the bending loads are correctly transferred to the carbon or spruce caps.

Once all that is done I also face the balsa face ribs and sheeting edges with full profile face rib of 1/32 ply. It really cuts down on the usual dings that WILL occur to the fragile edges otherwise. If you can leave the tubing a little proud so it sticks out through those face ribs and then file it down so much the better.

The same treatment goes for the alignment wire slip tubes that generally sit back a bit towards the trailing edge. Or since you are using flaps at the hinging spar along the flap hinge line.

I'm not sure if this matches your intended plan of attack but if there's some ideas in there you can use by all means steal them....