SonexBuilders.net

Good evening everyone!

I'm getting ready to start adding skins to my right wing but I want to make extra sure I have it nice and square first. I read the Sonex instructions here http://www.sonexaircraft.com/documents/ ... W07-02.pdf , but they focus more on getting the twist out, which seems like the easier part.

Anyway, I came up with what I think is a pretty good system but I'd like to see if anyone spots any issues with this before I call it good!

So here's what I did:

1) I marked the center of a bolt and put it in the hole at wing station 0. Then I measured outboard 19" and marked a line on the main spar at W.S. 19, which is what the hole in the rear spar should line up with.



2) I leveled the main spar the long way, and then dropped a plumb bob from the rear spar hole down to the main spar.



3) I made an adjustable length jig out of bar stock to go from the W.S. 0 hole to the rear spar hole, and then I adjusted it until the plumb bob sat on the W.S. 19 line.





This makes sense, right? I think it does, but then again I've been staring at it for a while!

I think once I'm confident I have everything square, I'll just cleco the two chunks of bar stock together so they don't shift, then I'll lay the wing flat and do the leveling/twist elimination process like Sonex recommends.

Oh yeah one last note, on the B model they have you install ribs 1-12, then drill the skins to the wing, and then use the skins as a guide to locate the root ribs. Then you go back and rivet the root ribs and then finally rivet the skins. So that's why my root rib isn't there in the pictures.

Thanks guys!

I built my wings vertically just the way you have yours set up. I used some brazing rod I had on hand to make a couple of plumb indicators for each end of the wing. I bent a 90 degree angle into the rods so they would reach across the rear tooling holes of two ribs. The long leg came down just past the forward tooling hole. This stayed in place while the skins were fitted providing a constant check on the level of the wings. With the spar level in two planes and both the plumb indicators showing vertical, there can't be any twist to the wing. Worked well and no need to lay it flat and worry about the table being square. Also allows working on both sides without flipping the wing.

Chris,
Your method looks good. A bit more elegant than what I did as shown on this page:
viewtopic.php?f=39&t=578&start=590

A key sanity check: with the skin clecoed to the aft spar the rib blue lines should line up under the holes. They may not all be perfect but it should not take heroics to make them behave.