At this writing, I'm still working on the elevators. I've got all the stiffeners cut, shaped and primed. The left elevator is designed differently from the right because of the trim tab, so the sets of stiffeners are tailored accordingly. Although I had no trouble figuring out the instructions to fabricate the shorter left stiffeners, I was wondering why the plans called for three of the four outboard stiffeners to be shortened very slightly from their otherwise matching right counterparts. I could detect no difference in hole layouts, but both the plans and the instructions were very specific about the modifications, to the point of even giving them different part numbers. Viewing other builder logs didn't quite clear up the issue. Some builders ignored the instructions and built their elevators with matching outboard stiffeners with no apparent problems. Other builders made the modifications, but never mentioned why they were necessary. I wanted to understand the reason for the modifications before making them, so I called Van's Builder Assistance and asked. They explained that the left elevator stiffeners were displaced very slightly outboard to accommodate the width of the trim tab. Keeping the stock lengths could make it a very tight fit at the trailing edge when the skin was bent into its final shape. I followed the instructions precisely and after match drilling all the stiffener holes I labeled the stiffeners with their part numbers, plus designations for left/right and top/bottom. The seven identical stiffeners for the area in front of the trim tab had no trailing edge taper, so I gave them additional placement numbers and directional arrows so that I could be certain of their original placement and orientation. Of course, all these labels and marks would be erased during prepping and priming. I was careful to lay out and photograph all the labeled parts with their correct left/right, top/bottom and up/down orientation. As I hung the parts for painting, I kept the same orientation, so I always knew which parts they were. When I flipped them for the second coat, I kept track of the up/down orientation of the identical stiffeners so that I could re-label them correctly once the primer had cured. That brings up another handy builder's tip: do not re-label your primed parts until the primer is FULLY dry and cured. Partially dry and uncured primer plays hell with a sharpie and causes it to stop writing even if the sharpie has plenty of ink. I found this out the hard way, and it drove me nuts. But I got the job done, and all the parts were correctly re-labeled so I know I can put the stiffeners in their proper places on the skins.
At this point I had other life matters that required my attention; rehearsals, gigs and the extraction of a troublesome molar with an abscess that had been giving me grief for months. Before I had the tooth pulled, I did manage to do some fun flying. I found a Citabria instructor working at the Ann Arbor Airport and did some pattern work on a beautiful fall afternoon. It was so great to fly a Citabria again. It had been about five years since I had flown one, but my tailwheel chops weren't as rusty as I thought they might be. I just wish I could find a Citabria that had the old adjustable front seat. All the ones I've encountered in Michigan have the later welded seat frames; they're not as comfortable for me, and they make it much harder to get in and out of the airplane. But it was still a blast to fly one again, and I look forward to building more time in this bird.
I was taking medication for a few days after the tooth extraction and I didn't want to do any work on airplane parts until things returned to normal. But the creative urge didn't seem to want to give me a break, so I started working on a project that I've been pondering for awhile. Since it will be about eight months before I can even order the quickbuild kits for my wings and fuselage, I wanted to build a dedicated empennage stand that I could use to mount and rig my stabilizers, elevators and rudder. Building it during this down time would be a fun change of pace while still making progress. As is my usual custom building process, I gave it a lot of careful thought, but did the actual designing as it was being built. I started out by building the basic pedestal for the horizontal stabilizer. I designed it so that the stabilizer would rest on the spars, with the pedestal fitted to the space between the bottom skins. I fabricated two notched wooden blocks that would grip the flange of the front spar splice angle to secure the stabilizer. I built two temporary saddles that would fit over the tops of the horizontal stabilizer spars and serve as bases for the vertical stabilizer. Then I designed and built a padded fixture that would cradle the bottom of the aft spar of the vertical stabilizer and mount it to the pedestal. After initial trial fitting, it became obvious that a different approach would be required to position the vertical stabilizer more accurately and securely. I checked out several other builder's sites to get a better sight picture of the correct orientation between the stabilizers. I also sought advice from the VAF forum, and learned the correct angle of the attachment plate for the front spars of the stabilizers. I jigged up two padded wood pieces to fit the contour of the back side of the vertical stabilizer front spar. I built up a more extensive saddle over the front horizontal stabilizer and added wooden spacers to the vertical stabilizer rear spar fixture so it would mount to the pedestal in the correct orientation. Then came the tricky part... notching the contour pieces for the vertical stabilizer front spar at the correct angles and locations so that I could mount it to the horizontal stabilizer front spar saddle. This placement had to be quite precise to allow both vertical stabilizer spars to nest into their correct places without any strain on the parts, holding the stabilizer secure and at the right height and angles in relation to the horizontal stabilizer. I spent a LOT of time figuring out how to jig the contour pieces to make the table saw and band saw cuts in just the right places, angles and depths. I did a lot of additional shaping and had to add a shim plate in one area... but the results were worth all the effort. The fit is just about perfect, and the orientation between the stabilizers is quite accurate. The only thing I didn't bother to factor in was the incidence or angle of attack of the horizontal stabilizer... but that only becomes important when it's time to actually attach it to the fuselage. This stand will serve me well as a rigging stand for the rudder and elevators. With all the extra thought, prototyping, reworking and on-the-fly design work involved, this project took a LOT of time to build... 25 hours to be precise. But I created it all with materials I had on hand; the only things I had to buy were some of the bolts, nuts and washers, a fresh supply of woodworking glue and some carpet tape. Total expenditure was less than $20... and I am very happy with the results.
Now I can get back to working on the elevators... after I clean up the huge mess generated by creating this empennage stand. I've got to convert the wood shop back into an airplane shop again.
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