I had my first SAAA Technical Counsellor visit today. Brian, my TC, flew down from Melbourne early AM to inspect the workshop and each of the empennage sub-assemblies. The visit went well and I wasn’t advised to turn it into a garden ornament.
Riveting the elevator trailing edges was straightforward. The same angled squeezer die I made for the rudder worked fine and both elevator trailing edges are perfectly straight. I’m really sold on the method, no rivet gun required means less chance of unintended stretching/curving of the trailing edge. Like almost everyone else, I had trouble with the aft most outboard rivets on each elevator. There’s very little room there. The usual fallback is to use MS-319-BS pop rivets. I’ve got a few stainless steel cherry max rivets coming in various lengths for these sorts of situations, so I’ll wait for those.
I also fitted the hinge halves to each elevator and trim tab, and fitted the trim tabs. Used a squeezer for all of this riveting as well. There’s not much clearance and it’s important to not squash the hinge. None of the yokes I had worked for the elevator, so I cut the shaft off a 3/8″ x 1/4″ flush die, ground it smooth, and used a bit of gorilla tape to hold it in place on the fixed side of a 4 inch thin nosed flat yoke. This gave the required clearance to get around the back of the hinge bracket, while still being thin enough to get into the narrow gap in the first place (see pictures).
After closing up the first trim tab and riveting the hinge in place, I went to do the last operation – pop rivets on each end of the trim tab – only to find out that these were specified as countersink rivets, and I had not dimpled the holes. It was impossible to get the ends apart to dimple the holes at this point, so I’m going to have to use flush pop rivets on the right hand elevator. No big deal structurally or drag wise, just something to mentally beat myself up for as long as I own the plane. For the other trim tab, I was able to get the outboard side opened up enough to get a squeezer in there and dimple the holes, so that is one out of four sides done per the plans. I may put a layer of glass over the outboard side that has non-flush rivets, it would only be for aesthetics but there’s enough room to do it.
Now the tail-cone is out of the way, it’s time to go back and complete some jobs I shelved at the time. In this case, the elevator trailing edges and foam ribs, which were not done at the time because I didn’t have any pro-seal. For the trailing edges, I am using the same method as I did with the rudder (described here). In fact I used the same 50 x 50 x 5mm section of angle, just a different side and cut in half to separate the two parts that the left and right elevators were previously match drilled to.
This was my first experience with Pro-seal, a gooey substance that absolutely sticks to everything, especially latex gloves and workbenches. Hopefully I got it all done without gluing an elevator to a workbench. I only used the pro-seal for foam ribs (2 each elevator, 3 each trim tab), preferring to use 3M F9460PC double sided tape for the elevator trailing edges (less mess and avoids gluing the elevator to the straight edge).
I included the previously match drilled (half) hinge on the trim tabs when I cleco’d them up after the foam ribs were glued in place. Once the pro-seal cures it is all ready for riveting.
It took a while but finally I can declare victory for the tail-cone riveting. In the end I back riveted a bit over half of it, but once I decided it was necessary to crawl inside the thing and work it with “Rosie” outside on the rivet gun, we went ahead and completed everything conventionally. The final tailcone statistics include one “oops” rivet, about a dozen drill-outs, with perhaps a few more after a Technical Counsellor visit that I’ve arranged for next week. I managed to do all the inside work without getting stuck or requiring paramedics.
Somewhere in the tail-cone resides the 5,000th rivet driven so far in the project. Only another 15,000+ to go…
As for the small “ding” mark where I dropped a bucking bar (to the left of centre of the only blue plastic bit left, last picture), I’ll get some advice on how best to repair it. It’s easy to access, so drilling for stress relief, dimpling and installing a flush rivet is a likely strategy.
Since the tail-cone will now be in the way while the wings and fuse are built, I made a little trolley on wheels (with brakes!) out of ply from one of the Van’s crates, so I can easily move the thing around.
Continued riveting together the tail cone. It’s taking quite a bit of time, but is going together well. I’ve back riveted most of it but for some parts it was easier to call in “Rosie”.
Not without incident. I always pour a few dozen rivets at a time from the jar into its lid, and use the lid while working. That paid off on no less than three occasions over the last few days after I knocked the lid off the bench and then had to crawl around on the floor picking up rivets. Better a few dozen in the lid than a few thousand from the container! In addition, today for the first time I dropped a tungsten bucking bar onto a skin, and it left a small dent. I swore I would never do this, but now I have. It’s superficial and will be easy to fill in a few years when it comes time to paint, but it’s still annoying to do something like that.