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Tail forward spar attachment

PostPosted: Wed May 23, 2018 4:05 pm
by bvolcko38
I am in the process of attaching the tail. There is a non uniform gap between the forward spars and the bulkhead that everything gets bolted to.
The gap varies from 1/8" to zero I am assuming this space needs to be shimmed but how do you shim a varying space like this

Re: Tail forward spar attachment

PostPosted: Thu May 24, 2018 8:09 am
by peter anson
Hi Bill, I just happened to visit a friend, Brian Rebbechi, who is building a Xenos, so asked him about this. Got to admit I am not completely familiar with the structure, but it may be that the variation in gap is due to slightly different bends in the forward spars (hockey sticks?). Brian made sure of correct fit by matching the bulkhead location to the spars before riveting in place. If it is not possible to go back and remake the bulkhead, shimming is an option. It is possible to make a tapered shim if you know someone with a milling machine. Alternatively you could fill the gap with "liquid shim" or "liquid metal" which are just epoxy putties with a filling of metal powder. 1/8" is a pretty big gap to fill in a shear joint though. Might be a good time to get some advice from Sonex.

Peter

Re: Tail forward spar attachment

PostPosted: Thu May 24, 2018 8:30 am
by bvolcko38
I built the tail 2 years ago and the fuse 1 year ago, never thinking ahead on how these two surfaces would fit. Just built to the plans.
Sonex says to go ahead and shim but i am having trouble figuring out how to measure the shim thicknesses required.
I would post pictures but not sure how to.
BV

Re: Tail forward spar attachment

PostPosted: Thu May 24, 2018 11:34 am
by Bryan Cotton
I've made tapered shims before. Just belt sand it down until it fits, remake as necessary!