November 15, 2019

Upper Wing Skin Fit Check

After flipping the wing back to normal, I started clecoing down the top skins. The inboard skin seems to fit fine, but the outboard skin doesn’t look right – there are ripples when I cleco it down. I had similar fit issues with the other wing, so I’ll have to go back into the archives to see what I did. I don’t think the problem is caused by the twist jigs being out of alignment; my digital level says they are within 0.1 degrees of each other.

I exhausted my entire supply of 1/8″ and 5/32″ clecos pinning up this wing… Mostly because it does take a lot of clecos to hold all the ribs plus skins in place, but also because I have some other assemblies hanging out in the storage area that are clecoed together, like the right-side fuel tank. Lesson learned: Don’t skimp out on clecos! You’ll definitely use them all.

Looks so pretty, wish I could just glue the skin down without rivets!
Here are the ripples I talked about – this is looking at the aft edge of the outboard skin after I installed just a few 5/32″ clecos
The troublesome outboard skin. I start with clecoing to the main spar since it is the most rigid part of the wing, then the rear spar, then the ribs. In this picture I removed the 5/32″ clecos from the rear spar since that was causing the skin to ripple; it sits nice and flat again after removing those clecos.
This appears to be the issue: holes are not aligned correctly… the green you see is the rear spar underneath the skin. On the left side wing, I reamed these holes a bit to fit. Towards the wing tip, this mis-alignment was severe enough that I had to upsize the holes from 4.0mm to 4.8mm. I’m going to try wiggling things around first.

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