Nobody's shown me a torque for KR wing attach fittings. It's not in the plans. Why is that? Because friction was not even considered in the analysis of the wing attach joint. It was a pure shear calculation. It's simply a pinned joint, and safe enough on that basis alone.
Although I'm certainly not advocating anybody do this, you could likely fly around with cottered pins in place of the bolts to keep them from sliding out of place, and you'd be fine. I'm pretty sure there are airplanes and ultralights that use simple pinned joints. Sure, torquing the bolts to some reasonable number is the common-sense thing to do, and as Larry pointed out, people do exactly that. Calculating optimal torque for a lubricated fastener and nut is commendable, but not necessary. I'm a mechanical engineer, and recognizing that it's simply a pinned joint, I just torqued them by feel and got on with my business. Sure...considering friction would be nice, but the designer simply can't count on these connections being done perfectly, so he designs them to be foolproof, and then add a factor of safety on top of that. That's what we're dealing with on these WAFs. After all, this plane was touted as being buildable with only simple tools... Mark Langford ML at N56ML.com http://www.n56ml.com
