Tail Kit

Yesterday and today I riveted the bottom j-channel to the side skin. I also riveted the side skins to the bulkheads where the skin curves inwards toward the bottom skin. Everything went well, although I did remove a rivet when it cleaved over.

Since I’m bucking these rivets, and doing it by myself, I can’t actually see the shop head of the rivet. So I came up with a way to make sure the bucking bar is at the correct angle, since the j-channel is attached to the side skin at a point where it’s already starting to curve inwards to join the bottom skin. By putting some clecos in “backwards” and tying a string between them, I had an angle gauge for the bucking bar. Most of the rivets came out nicely.

Next, I’m going to attempt to back-rivet the remaining rivets on the bottom, starting with the last rivets on the curved surface of the side skins. I couldn’t quite reach these with the gun and bucking bar, so I’m hoping to back-rivet them, as other builders have done.

For the last four evenings I’ve chipped away at setting the rivets on the aft fuse side skins. With only an hour or so each time, and some tricky rivets to access, progress has been slow. On the plus side, my technique seems to be improving. I did have to drill out a couple of rivets, but mostly it went well.

On Sunday evening I modified a long bucking bar so that it would fit around the tailwheel mount, and the bolts that secure it to the bulkhead. I cut this with a hacksaw and then polished on the grinding wheel, then wrapped it in electrical tape. It made bucking the rivets on the bottom aft side of the F-01411 bulkhead possible. In order to set the rivets, I turned the fuse on it’s side and carefully placed the bucking bar. I only had one rivet that I decided to replace, and that turned out to be a major pain. Unfortunately in the process of removing the rivet, I bent the flange up and away from the skin, just enough to be a problem. Without any way to hold the flange down, or bend it back, I ended up putting a BS319 pop rivet in the hole, and moved on. By cutting a piece of scrap wood into a series of weird shapes, I was able to hold the flange down and set the rivet. I need to check with Vans to see if a Cherrymax is required in that hole, in which case I will replace it.

Tonight I used my new torque wrench to set the two bolts holding the tailwheel mount to the forward bulkhead. Van’s suggest orienting these bolts with the nuts forward, and I can see why. Trying to get a torque wrench into the aft side of the bulkhead would be unworkable due to the tight access. I torqued these to 99 inch pounds, per the guidance in Van’s instructions; 85 inch pounds for AN4 bolts with self locking nuts. Plus another 14 to account for the friction of the self-locking nuts on the bolts. The wrench was easy to use and it worked out great.

I started riveting the side skins, below the longerons. I started with the bulkheads, and worked down the sides. I got through the upper j-channels, meaning about half way through this step. Hoping to finish riveting (at least as much as I can do myself) this week, so I can move on to the aft deck.

It was good to have a helper today! She did a good job putting rivets in holes, getting ready to rivet. I find I can move much faster if I pre-populate the rivet holes with a rivet and a little bit of rivet tape to hold them in place.

I like to use a piece of tape on the head of the swivel head. This helps it grip, minimizing the chance of a slip.

Happy with how these rivets worked out. I can’t directly observe the shop head of the j-channel rivets while riveting. But it’s good to have the solid edge of the j-channel to brace against.

Tonight I started riveting the side skins onto the aft fuse. I started with the longerons, where I could use my squeezer to set all the rivets. To assist with alignment, I packed up the front edge of the yoke, one for the bottom row of rivets, and a larger pack for the top row. This worked out nicely and everything set well. I did both sides, except for a few rivets down aft where I plan to leave things open until I have the aft bottom skin riveted on.

Today I fiddled around with the aft skin, and finally managed to get everything to fit just right. The challenge was deciding how many spacers I needed to fit between the tail wheel mount bracket and the bulkhead to which it is bolted. Vans supply 3 of these shims made from two thicknesses of aluminum. I started with all 3, and ended up needing just the two thinner shims to get a perfect fit. I used fresh bolts, washers and nuts, as I’ve attached and reattached these parts several times now. My torque wrench isn’t quite up to the task, as it maxes out at 80 inch pounds, whereas I need 85. Additionally, being a beam-style, there’s an access issue getting to the nuts. I’ve ordered a new tool, should be here on Friday.

I riveted the aft fuselage to the aft bottom skin, and then to the tail wheel mount. 10 rivets in total, all squeezed with a variety of yokes.

Green touch up primer on the mount, and splotches of white on the bulkhead makes everything look messy. The iterative process of shaping these parts to fit well scratched off primer and powder coating, so a touch-up was needed.

Today I did a final round of fitting and then drilled the two keeper holes from the aft bulkhead into the tail wheel mount. Then I primed the aft fuse bottom skin and shims.

There is a slight twist in the bulkheads and the tail wheel mount doesn’t quite sit flush against the aft bulkhead. After checking with Vans, this is common and due to the sandwiching of pieces used to make up the bulkheads. With a little hand pressure, I was able to straighten it out and drill the two keeper holes. Then I countersunk them on the drill press. I was disappointed in the quality of the three fluted countersink after using the single fluted sink on the longerons. I need to buy some more countersink cages, and a couple more single fluted sinks.

I decided to prime the outside of the aft bottom skin, as it had been scratched up in the trimming and drilling process. I may regret this at some point in the future, but it seems like the right thing to do for now.

I also cleaned, dried, and primed the inside of the tail wheel mount using some green self-etching rattle-can primer.