Gav wrote: > It seems to me that the rear spar will mainly take the fore to aft loads encountered from wing drag.
You are correct. The rear spar is mainly there to keep the wing from folding backwards...."to take the moment", and was not designed or expected to do a lot of the lifting, so it can be a little flimsy vertically. Some wings don't even have rear spars, but in that case the main spar is located a little further aft. Rear spar breakage in a KR is not something to lose any sleep over... Mark Langford, Huntsville, Alabama see KR2S project N56ML at http://home.hiwaay.net/~langford email to N56ML "at" hiwaay.net --------------------------------------------------------------