Today is a red letter day- we're finally putting on wing skins!
First thing this morning I carefully clamped the spar and rib assembly to the table and shimmed the ends to eliminate any twist. My 1968 Mooney G model actually has twisted wings, but I'm pretty sure Van did not want twist in these wings. The plans show clamping the spar directly to the table, but rivets and bolts get in the way of getting the assembly flat, so I had to shim up one end 1/4". I also put another 1/4" shim under the spar about 5 ribs in to get rid of a slight bow in the spar.
My flying buddy, Richard stopped by today to help with the riveting. He sold his Mooney several years ago and bought an RV-6 and has been bugging me to hurry up and finish my 14. Today was his first time on the rivet gun and he took to it like a duck takes to water. Not a single smiley all day!
Rather than back rivet as the manual suggests, I purchased a large 2" mushroom head for the gun. The face of it is slightly rounded and highly polished. We put clear packing tape over it to keep the rivets clean and skins smooth. You have to be careful to get the gun centered on each rivet and to keep the rivet gun perpendicular to the work, but if you do all that it leaves very nicely set heads with no puckering. Richard figured it all out after the 2nd rivet.
We didn't quite finish the whole wing- we went slow and careful. We started in the middle of the inner skin and worked out towards where the 2 skins overlap. We stopped 1 rib short of the joint. Then we started in the middle of the outer skin and worked our way in towards the joint. Then we riveted the sub spar, j-stiffener and leading edge lines working our way into the joining rib. Next we riveted the skin join and last but not least we riveted the join rib. So far there is no oil canning or puckering of the skins.
Here's the overlap joint where the two skins come together.
Here's the back side (my side today) of the joint. It was a little tricky getting the overlap of the j-stiffeners to lie down flat but we got it there with a little extra pressure.
After Richard left, I squeezed rivets into the nut plates on the end rib. There are about 4 rivets at the end of the sub-spar that we couldn't figure out how to set because the doubler plate and it's rivets are in the way. I ground down a bucking bar that I think will do the job- I'll try it out tomorrow.
Here's the nut plates on the end rib.
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