January 12 – February 4: I had been putting this task off as I was apprehensive about riveting the trailing edge and keeping it straight. As it turns out, the double flush riveting was easier than I thought it would be and the finished trailing edge is pretty dead-on straight.
Having a flat surface is essential, and my EAA1000 workbenches are good in that aspect. But in order to help it a bit more, I used a leftover Formica kitchen countertop that I had been holding onto from our last house. And I went to Home Depot and picked up a 1-1/2×1-1/2 inch piece of steel angle. My original thought was to match drill the trailing edge to the steel angle, but decided against it as overkill, so I just used it to enhance the flatness of the countertop.
I was going to follow Van’s instructions and use the double-sided tape method, but had spoken with other local builders who mentioned that they had some adhesion issues with the tape. So while we were in San Diego in December, we made a side trip to Aircraft Spruce in Corona and I picked up a pint kit of tank sealant, among other items.
I put down some painters tape to keep things from getting too messy and then match drilled the trailing edge directly into the bottom surface of the MDF countertop. I mixed up the first batch of tank sealant and then clecoed the right rudder skin and trailing edge wedge directly into the MDF surface after applying a very thin layer of tank sealant. Mating surfaces were scuffed with 150 grit sandpaper and cleaned with acetone and then 91 percent isopropyl alcohol and allowed to dry thoroughly.
This assembly was then allowed to sit for a week (Sunday to Sunday) to cure. The angle was clamped to the edge of the countertop just to serve as an additional source of flatness.
After curing a week, now comes the part where you need four hands. I mixed up another batch of tank sealant, then applied a very thin layer to the upper surface of the trailing edge wedge and clecoed the lower corner into the workbench as described in the instructions. Here’s where the MDF countertop was an inadequate surface for what was to follow.
I don’t have photos of this process, as we both had our hands full. The “upper” (left) rudder skin is fixed at the bottom trailing edge corner and then is rolled downward onto the tank sealant, clecoed to the benchtop, and the stiffeners are blind riveted to the shear clips attached to the “lower” skin, gradually rolling the skins together.
With all the movement entailed at the beginning of this process, the lower 10 or so holes in the MDF hogged out and wouldn’t hold a cleco. In hindsight, I should have used a piece of aluminum angle, which I happened to have around. To compensate, I used a piece from the trim bundle that Vans throws into the kit as a makeshift clamping surface to allow the clecos to grip. Not the best solution, but it worked out fine.
To ensure that things stayed together, I used some bucking bars, hammers, lead counterweights and an exercise weight (wrapped in tape) to hold the skins at these lower holes together a little better for a couple of days. The upper set of holes seemed to hold up better, and these stayed clamped much better.
I allowed this completed assembly to cure for a full two weeks just to make sure. In the meantime I cut out the foam trailing edge ribs and started work on the tailcone pieces listed in 10-02 and 10-03. I also fabricated the F-01411D HS attach bar support. These were all completed, deburred and are ready for primer as soon as it warms up enough.
After putting it off long enough, I decided to dive into the double flush riveting that I had been dreading. I took my back-riveting set to the garage and clamped it into the vise and drove the roll pin out with a drift punch. This left me with a small diameter flush rivet set.
Following the instructions, I assembled the rudder spar assembly into the completed skins with no issues. I then riveted the skins to the spar using the squeezer as much as possible. The last few rivets on the bottom had to be driven with the gun as the yoke I have isn’t deep enough.
I put a strip of painter’s tape down the trailing edge then labeled the holes 1 through 10 and then repeating. I also taped the edges of my back riveting plate to avoid scratching, even though I have already rounded them off and polished them.
Now for the task I had been apprehensive about. I loaded the holes with rivets, applied rivet tape and flipped it over. Starting in the center, I partially set every tenth rivet following the instructions in Section 5. After the first few, I started to get the hang of the process, starting perpendicular to the back rivet plate, then smoothly pivoting to perpendicular to the trailing edge wedge in one motion. After each round of rivets, I eyeballed the trailing edge to ensure it didn’t start creeping out of straightness. So far so good.
After getting all the rivets 90% set, I went back over the trailing edge and finished setting them in the same every-tenth pattern, checking for straightness along the way. I ran my fingers along the rivet line, finishing any that felt like they were proud of the surface more than others. The final results turned out better than I expected. I suspect the tank sealant and the leisurely cure time helped keep everything together well during the riveting. Nothing shifted at all. Any tank sealant that squeezed out was cleaned up with acetone, and the rudder was put on the shelf with the other mostly-completed parts. On to priming the elevator and tailcone parts and waiting for spring. In the meantime I am starting on a PVC tubing spray booth in the garage.