Let's make some fins.
First I had to cut and assemble the main fins, which I chose to make out of two pieces because it seemed like the right thing to do, with grain parallel to the leading and trailing edges. My big concern was cutting them precisely enough to fit together properly.
After cutting the two pieces, I placed them against a straightedge (in this case the ever-useful aluminum angle) to test that the two pieces fit together *and* would sit flat on the root edge. I then sanded until everything seemed correct, like so:
The leading and trailing edges were rounded; the edges on the inside were left square. Just because.
Then I glued the two pieces together while holding them against the angle, to *guarantee* that they really came out straight (of course they didn't come out exactly straight). I did a bit more sanding after assembly to get the root to sit as flat as possible.
With all four fins glued, it was time to have my first adventure with papering fins. Because it seemed so darn easy, I chose to try Avery self-stick label paper (hereafter referred to as SSLP). Mine were half-page sized sheets, which turned out to be a good size for one of these fins. I was a little concerned about dealing with the rounded fine edges, but it seemed manageable. Here goes.
1) Lay the fin on on the sheet of SSLP, with the leading edge in the middle:
2) Fold the SSLP tightly over the leading edge, trying to keep it as tight and flat as possible:
Here I will note that the SSLP seems to lie flat on the balsa with almost no fiddling. No bubbles, no creasing, no nothing. Super-easy. For now.
3) Rough-trim the excess:
4) Sand off the excess. For the trailing edge, it turned out to be surprisingly easy, despite the curve. I was pleasantly surprised. However, the paper didn't cut in the same spot on each fin, probably due to the variance in the edge shape:
To get to this point was ridiculously, almost embarrassingly easy. It is at times like this that I can feel Murphy lying in wait for me, ready to pounce.
5) To seal the edges, I chose good old Elmer's Carpenter's Wood Glue. It was suggested that CA doesn't play particularly nicely with the SSLP, and Titebond doesn't sand too well, so Wood Glue it is. On the root edges, I allowed myself to be a bit sloppy, since those areas were going to be covered by fillets eventually. On the other edges, I tried to get the glue only a couple of millimeters off the edge. This turned out to be harder than expected, because the wood glue gets really sticky really quickly. I just couldn't control it as precisely as I wanted to. When I was finished, it looked OK but a little messy, and I hoped I'd be able to sand off the excess. I also had a bit of trouble getting the label to adhere around the very sharp leading point of the fine. No matter what I did, neither stickem nor glue wanted to hold it together. Somehow, though, when I was finished, they all seem to have settled down and stuck. Ok then.
6) Finally, I sanded. Some of the messy areas did indeed prove hard to sand, and I didn't get them perfect. However, the other bits came out good, and the sanded wood glue made a really glassy smooth edge on the trailing edge (I didn't care so much about the edges "under" the fin, although they came out fine too).
At this point I'm thinking success, and boy oh boy was it easy compared to sanding CWF. Nothing left to do but prime, so I masked off the root edges and a couple of millimeters up each side, and sprayed my usual Filler/Primer (I ran out of Duplicolor after the first side, so I did the other half with Rustoleum. Both seem to perform about equally).
They sanded up really nice and I think I am declaring victory. They also feel really strong, despite the spindly point in the front.
Sanding revealed the high spots, like at the glue joint between the two halves of the fins. No matter, all is well.
Oh, and while I was priming the fins I did this, because why the hell not: