25 Hrs – Ch 19 – Wings/Center Spar Attach

Wing AlignmentI hauled the center spar out of the basement and rearranged the garage to prep the spar and wings for match drilling.

I spent all day Sunday getting the wings aligned to the spar, with little luck.  Every time I fix one thing, it causes something else to be off.  In trying to keep the waterline on the wing completely level, my hard points are not matching up.  Thinking that I will have to add some dihedral into the wing to get things to line up, but will sleep on it before I commit to it.

Wing Span in GarageAfter getting a warm fuzzy from Dennis, I continued with aligning the wings to the center spar.  I ended up having to add a little dihedral into the wings to get the hard points to match up correctly.  At the outboard ends of the wings, the waterline is .9” – 1” higher than the 17.4” waterline.  The plans state that the dihedral is a non critical component for alignment, and this is a minor change in the wing angle, so I am not concerned.  I Bondo’s the wings to the spar, and drilled my ¼” holes through the wing hard points.  Ron White stopped by to check on my progress and gave me a few tips.  It’s always good to hear that things are looking good.

Wing Spar DrillingRon had a 5/8” bit with a ¼”pilot at the tip that he loaned me for match drilling the holes between the Center Spar and the Wings.  I spent most of the night drilling out the hard points.  I had to switch from my cordless drill to my larger electric drill, and even then, the motor was getting pretty hot!

I spent some time removing the bondo from the wing/spar.  I attempted a dry fit, but I had to raise the wings and spar about 12″ so I would have room to insert the bolts, then spent several hours cutting the bushings to length.  I was sure to number them all, and positioned them so the number on the bushing was positioned top center for consistency.

I had to repair a delamination on the inboard right wing hard point with 1 ply BID and peel ply before floxing the bushings in.

Sanded the outside cadmium coating off the bushings, and floxed them in place in the wings and spar.  Placed the bolts in place and tightened up with Nylon washers, so flox will not stick to them.  I will check after cure, but it appears that I will need 1 extra washer on the left-lower-outboard bolt to make up for the 0.3 degree difference between the wing and spar.

After cure, I removed the bolts and found some flox oozed on to the bolts and threads, which made some of them hard to get apart.  After removing the flox, I reassembled everything with the correct hardware (minus the AN nuts) and checked for level again.  Still looks like I will need an additional “L” washer in the Left-Lower-Outboard bolt as a shim, as first thought.  Then I put a foam plug in the front of the spar for the inboard holes with 2 ply BID, and added the 1 BID on the aileron inboard wing hole that I still needed.  Finished with peel ply.

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About Tarmac Grazer

I have recently purchased Cozy MK IV Plans #1627, and will be using this blog to log my build progress.
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