I had a busy week on the rudder. The skeleton went together quickly last week, with all mating surfaces coated with an anti-corrosion film (Cortec) and the bits reassembled for riveting.
On Wednesday riveting began, with some missteps. I got carried away and put a half-dozen rivets in the skeleton where they won’t supposed to go yet, so got some experience in drilling out blind rivets without enlarging the hole. That turned out to be easier than I had expected. Everything aligned as expected, and in a couple hours every rivet was in its place on the skeleton and I was ready to put on the skin.
Thursday was a day of great progress. The skin went on with little difficulty — it’s a pleasure to work on an airplane kit where the vast majority of holes are drilled to size and ready for assembly. It didn’t take long to get the skin in place and cleco’d up.
One of the pleasures of this project is where I get to work on it. I’m taking classes in the aerospace program at Renton Technical College, this quarter learning precision machining and related skills like inspection. As part of that, I have access to an incredibly well-equipped aviation workshop, which I’ll detail a bit more in another post. I also have the benefit of working under the instruction of Vincent Phillips McLellan, who founded and runs the aerospace program. He’s given invaluable advice in how to attach the skin to keep it as flat and straight as possible, how to correctly use the tools, and many other skills. A lot of the reason I have confidence in what I’m doing (more on that later) is being able to draw on these resources.
On Friday came the fun part, pulling rivets on the skin. In short time I had the end cap assembled and cleco’d in, and the rudder horn in place. At Vince’s recommendation I’ve started at the trailing edge, in the middle of the rudder, and worked my way out and up. Shop lighting makes the skin exaggerates the waves between the ribs — outdoors and in regular lighting it’s straight. I’m about a third of the way through riveting, but will need to do a little remediation first.
Now, for some mistakes. Putting on the top cap assembly I inadvertently drilled a hole straight through both sides of the skin. After cursing, I followed the advice of the Zenith assembly manual — if you put a hole in the wrong place, just put in a rivet and don’t sweat it. In this case, the extra rivet is at the top a tall rudder, in a place where it will be inconspicuous. And lesson learned.
A bigger concern to me is getting the rivets in true. After wrapping up for the day I did a pretty thorough inspection of the rivets I’ve placed so far on the skin. There are a lot that aren’t sitting as flat as I’d like. The manual says it’s not seated correctly if you can put a fingernail under the rivet, and probably a quarter of what I’ve pulled so far fails the fingernail test.
I’ll be spending the weekend reviewing my Homebuilder Help videos and assembly manual to figure out what I’m doing wrong, and marking the rivets that need a do-over. On Monday I’ll get some help from Vince and starting drilling out some rivets.
Now I’m started to understand why Zenith includes the rudder in the tail kit, whether or not you’ve already built the rudder starter kit. Depending on how this piece turns out, it’s possible I’ll build a second rudder to get my work as high-quality as possible. Hey, it’s a learning process, right?