Edge forming

[RyanB]

Hi everyone

We are just about ready to rivet our wing akins on, and have an edge forming question.

We will obviously be rolling an edge onto the top skin where the 2 wing skins overlap in the middle, but what about where the skins attach to the main spar. Did you guys roll these edges (where the butt joint is)?

Thanks in advance

[Flyin'Bryan]

On my RV-8 I formed the edges of the LE that attach to the spar, and will do the same for the fuel tanks when I get to that point. I also formed all skin-to-spar-flange edges and all overlapping (top side) skin edges for each wing skin. I was told to do this by several builders as well as Vans folks to ensure that the skin edges don't curl up too much when you rivet them on. I have not riveted them yet but I hope to in the next month or so.

I used the forming tool from Cleaveland Tools and it worked quite well for this as long as you set it up correctly. The only "problem" I am having with it is that with both the LE skin and main wing skin edges formed, when you re-cleco everything back on the wing spar, the forming seems to leave a fairly noticeable gap between the LE skin and main wing skins that attach to the wing spar flanges, and I sincerely hope that this gap closes back up again when I start riveting everything. Past experience on other parts has shown that any gaps are usually closed up when you rivet them tightly to the substructure, so I am not overly concerned about that.

[wirejock]

I didn't edge break on the spar. Only overlapping skins. They fit perfect with virtually no gap.

[RyanB]

Thank you so much gents

[alpinelakespilot2000]

The gap you are seeing after edge forming likely has nothing to do with the edge forming. Getting the leading edge skins to butt up against the top and bottom skins has more to do with getting the nose ribs tight into the LE skins. Once you start riveting, perhaps with the help of some tie down straps to keep things tight and/or clecos in most of the holes, things will tighten right up.

FWIW, I edge formed all butt joints (as well as, of course, overlaps) and they turn out great that way. Just remember to do the edge forming step before you start dimpling for the screws or rivets!

[wirejock]

Originally Posted by alpinelakespilot2000

The gap you are seeing after edge forming likely has nothing to do with the edge forming. Getting the leading edge skins to butt up against the top and bottom skins has more to do with getting the nose ribs tight into the LE skins. Once you start riveting, perhaps with the help of some tie down straps to keep things tight and/or clecos in most of the holes, things will tighten right up.

FWIW, I edge formed all butt joints (as well as, of course, overlaps) and they turn out great that way. Just remember to do the edge forming step before you start dimpling for the screws or rivets!

+1 what Steve said. Forgot about the straps and breaking edge before dimpling. Thanks for catching that.

[Flyin'Bryan]

With using the straps, and plus 2 for edge forming BEFORE dimpling. Prior to forming the edges, they were butting up together very nicely without using any straps - everything was just clecoed in place. I'm pretty sure using the straps and simply riveting everything down tight to the ribs as mentioned will close the edge gap up again.

Thanks for the reminder about the straps - this is also important because I see myself using the LP 4-3 and LP 4-4 or 4-5 pop rivets to secure the LE rear rib flanges to the wing spar web, instead of trying to contort my arms, hands, finders, back, etc. into strange and painful positions to buck solid rivets in those locations, while trying to fit my big arms through the LE nose rib lightening holes. Using a rivet puller in these areas will be challenging enough for me, so straps are needed to help with that as well.