Deburring Holes and removing More Blue Vinyl.

No pics tonight - just a quick update on the LE progress. I reviewed the work I did on the new access panel opening. I still have a bit of edge trimming, smoothing, and deburring to do, but other than that the panel opening is pretty much done. I am now mired in thought about how to manage the panel attach brackets for both holes. This is perplexing for me because I really want to trim away as much of the subskin as possible to lighten it up, but still leave the proper amount of material to serve as the mounting platform that I need.

After thinking about it, instead of jumping in a reassembling everything so I could put the LE back on the wing spar, I realized I needed to do some serious deburring of all the holes in the LE skin. I finished deburring all the new holes I drilled the other day for attaching the access panel attach bracket to the LE skin. But then I realized that most of the blue vinyl has remained on the LE skin since I received it many years ago. Even though I had match drilled all the rib holes and the wing spar attach holes, I have never fully deburred these holes, and so this was long overdue.

Before I could start deburring those holes, I needed to remove some vinyl using the tried and true soldering iron method and a straight edge. One thing about this that I ahve contended all along, is that this vinyl is a real problem with pre-bent surfaces such as the LE and tank skins, and the skins for the HS and the VS tail sections. The reason is that none of these skins is form fitting to the underlying rib structure. The skins are only pre-bent so far, and must be forced into their final positions over the substructure. This is how stressed-skins are designed, so that the skin ends up providing a certain amount of support to the total structure. The vinyl around the outer edges of these skins acts as a deterent to bending the skin to its final shape, especially the outer vinyl that goes around the outer leading edge of the skin.

I made a point to remove the vinyl in this area when building the HS, but somehow forgot to do this on the LE skins. So tonight I finally removed the small section of vinyl across the outer and inner edges of the front the LE skin. I also removed the vinyl along the rear spar attach holes and along the outside rib holes  I had managed to remove the vinyl a long time ago where the rib flanges meet the inner skin, to ensure that the rib-to-skin fit was as form-fitting as possible. But that was the only vinyl that I had removed after all this time.

Anyway, I got all the vinyl removed, saw how badly I have botched the rib flange rivet holes for those first two ribs that I have been working on for so long by having to re-drill through them way too many times, and did my best to debur those holes as much as possible. I am now fearing that those holes are much too big for a standard AN426 AD3 rivet, and I my be heading for ordering a new LE skin. But its a bit too early to throw in the towel, and I really won't know how bad this is until I dimple everything and prime it and start riveting.

Every time you have a pre-bent skin, there are 4 sides that have to be deburred - 2 on the outside and two on the inside. I managed to debur the holes on one of the outer sides tonight, so I have 3 more sides to do. I had almost forgotten how much "fun" it is to debur a million holes in a complex piece of aluminum. There sure was a lot of metal shavings on the ground after getting rid of all the burs that were in the holes on the skin - makes me a bit nervous since this skin is only .025 inches thick.

After I get all the skin holes deburred I think I will go ahead and debur and re-straighten the rib flanges, then scuff, clean, and prime the inside of the skin and the remaining ribs.I don't think I will dimple everything until I reassemble the LE again on the wing spar and get the panel attach bracket and subskin plans figured out, and the rear rib flanges drilled out. Once that goes well I will probably try to dimple the LE skin and ribs and the subpanel and see what happens. Lots of work to do yet, and I'm still not quite sure how it will turn out.

KPR.