The last couple of days I’ve spent a couple of hours trimming the aft most bulkhead. To clear the weld on the tail wheel mount, I had to file down the bulkhead cutout a surprising amount. It now sits flush against the flange of the tail wheel mount, and the bottom skin cutout fits nicely around the mount also. This weekend I’ll drill a couple of holes and countersink then, then touch up the primer.
Today I test fit the aft bottom skin, aft bulkhead, and tail wheel mount. The bottom skin cutout was pretty close, needing just a small enlargement to clear the tail wheel mount. The aft bulkhead needs a bit trim so the skin and contact the bulkhead flanges, and the weld bead can clear the bulkhead. I spent a couple of hours assembling, disassembling, trimming and repeating before it started to fit well. I still have some more work to go before this is final.
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I will need to use some shims to close the gap between bulkhead and mount. Right now the gap is large, almost 1/8th of an inch. This is in part due to the weld pushing on the aft bulkhead, keeping these apart. Will be interesting to see how many shims/spacers I’ll be up needing here.
Today I cut out the aft bottom fuse skin template from the manual, and marked out the areas a needing to be trimmed. I found that taping the template to the outside of the skin resulted in good placement, and some masking tape held it in place while I drew out the area to trim.
I used a variety of tools to make the cut, a handsaw, bandsaw, vixen file and small files like the one in the picture. I was happy with the way this turned out.
Tonight I hit a milestone, as I clecoed on the side skins and rolled the aft fuse right side up. It’s great to have a major part of the fuselage taking shape!
I started by reading up on the systems that need to be laid out in the aft fuse. There are a number of wiring runs that need to pass down one of the left hand j-channels between the side wall and the bulkheads. It’s much easier to do this before putting the side skins on, so I studied the diagrams to understand it all. I identified that one of the wires shown in the plans was not in the wiring harness, but I went ahead anyway. [edit] I’ve since confirmed with Vans that the wire has been deleted from the plans.
I didn’t attempt to use the wire ties at this stage, and instead used a little masking tape to hold the wires in place while getting everything set up.
I ran the wiring harness and phone cable, then carefully clecoed on the left side skin. Then I carefully rolled the assembly upright.
Once upright, the right j-channels and longeron can be installed, the aft bulkhead (#11) clecoed on, and then the right side skin is clecoed on. With both side skins on, you can really get a sense of the size of the airplane. The longerons extend forward, and diverge from each other at surprisingly wide angles. The bulkheads sit tall and highlight how much space there is going to be up forward. The cockpit will be wide and tall… this thing is big!
Last night and again today I spent a few hours dimpling the side skins. Doing in one session would have been faster, but each time I started I got interrupted. In any case, I rigged up some extensions by placing some sheets of particle board cover with carpet on boxes, and strapping them down with tie downs. I was able to adjust them a little to ensure I had the right support. The holes on the curved edges were the most difficult, but I found a way to make it all work.
Today I primed the side skins. It was quite straightforward, and aside from looking a bit patchy, I’m happy with how things came out.
Tonight I finished countersinking the longerons. Another round of very consistent holes. One more thing I found useful was a countersink drilling table another builder had made by measuring the thickness of the skin to be mated, he came up with a range of hole sizes. This is easier to measure than the depth of a rivet in the countersunk hole.
Today I countersunk one of the longerones, which took an hour or so. First I set up my single flute countersink, and dialed it in on the drill press. With that done, I hooked up my air drill and countersunk one of parts.
I was really happy with how it worked out. The single flute is superior, and requires a lot less pressure to cut. The consistency of my holes was much better than with the 3-flute sink, and it felt easier to use for some reason.
After a lot of drilling, it was midnight and the compressor had been running almost continuously. I decided to tackle the other one tomorrow
Over the last two nights I deburred the side skins for the aft fuselage. I spent probably two hours total time, including a few minutes to remove the vinyl on the exterior side. I used an oversized drill bit to debur the holes, which I found more effective than using a countersink bit.
