Section 14 – Top Skin

Yesterday I continued working on the inboard and outboard top skins for the left wing. I removed a small amount of material from about 1″ of the forward corner of the inboard and outboard skins where they overlap to help them lay flat. Then after complete deburring, it’s time to dimple.
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I got the top inboard skin dimpled. For the most part, I used the Cleveland spring-back dimple dies in the DRDT-2 but on the holes along the forward edge, I used the smaller Avery die so it wouldn’t flatten the slight bend.

I also added a new fixture to the workshop.
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I built the DRDT-2 table expecting to use it in conjunction with the main workbenches. But of course, they are occupied holding the wing so I need something to support skins while dimpling. I purchased a bench grinder stand from Harbor Freight and added castors. I think it was $40. I then attached a piece of the 3/8 plywood (shipping crate top) and carpet and it is a handy movable surface for supporting the skins. I couldn’t have built anything any cheaper and this will also be useful holding the grinder or band saw.

Section 14 – Wing Walk

No pictures today (because I forgot to take them) but a quick note to say that I finished countersinking the inboard top skin / wing walk doublers. This section of the skin is countersunk because there's two layers of .032 aluminum making it a little thick for dimples. The rest of the top inboard and outboard skins are dimpled and that's the next task.


Section 14 – Preparing Top Skins

Today I got the 3/8 inch hole reamed in the aft spar thanks to the helping hand of Ashley. Then I got the aft spar riveted onto the ribs. I squeezed most of the rivets but the bottom row of rivets was tough to get to (without a longeron yoke…may need to invest) so I drove those with the gun. In the end, it would have been faster to drive all of them because I wouldn’t have had to mess with new squeezer settings for each different size of rivet. Maybe I’ll do that for the right wing. The third rivet from the top on each rib is left open for attachment of the aileron and flap gap faring.IMG 2287
After getting the spar on the ribs, I started on Section 14 by clecoing the wing walk doublers and the inboard top skin onto the wing. This is done so you can match drill the skins with the doublers and to use the skin to match drill the nutplate rivet attach holes into the rib spar.

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I also found where I made a small mistake. It instructs you to dimple all wing ribs LOWER FLANGE back in chapter 12. I dimpled lower and upper flanges. But now on page 14-02, it tells you not to dimple the upper flanges where the wing walk doublers cover the first 4 ribs. This is because the skins are to be machine countersunk in this area. I don’t think this is too big of a deal, I can undimple the few affected holes.