03 Fin Construction

Rocksim provides a fin silhouette as part of the printout, so I grabbed the scissors.

And carefully traced around the template. Titus thought I was doing a good job with this step.

It was out to the jigsaw with them now. A band saw would be fantastic for this operation…but I made do. The good part is that true perfection isn’t necessary, as I’ll be sanding the edges all alike in any case, removing any waves and valleys from my freehand cuts.

Oh, you nuts out there might notice that I didn’t make any accommodation for the woodgrain. Well, I figure, this isn’t balsa wood here. It’s 5-ply birch plywood…so five layers of criss-crossed woodgrain… which grain do you use?

Anyway, once I had them free from their shell, I clamped them together and started to sand them all to size. The bottom edge, as you can see above, are all finished edges from the manufacturer. The root edge (long left side), I cut with the miter saw. Because of this, I was able to match up these two sides really well and just sand the chord and the clipped edge. Saved a lot of time. Another quick note, a nail file (emery board) is pretty useful against this plywood.

After these were nice and smooth…and more importantly, the same size, had to find an alignment guide. So a quick Internet search returned this little diagram, which I promptly printed double-sized and transferred to my motormount.

I used the miter box to hold the tube as I marked the fin positions. Old skool. Once this was done, I positioned the top fin can centering ring and superglued it. This ring gives me an upper guide for the fins’ vertical position. I then only had to pay attention to the horizontal position. Usually, I don’t try to cover up my pencil line, but instead place the fin root to one side…it’s easier to make sure it is straight. So, using the thick CA, I put the fins in place on the motor mount.

I then started the job of putting 30 minute epoxy everywhere. Of course, you can only do one part at a time, since the epoxy is so thin…you have to put where it won’t run or drip off.

Looks like it’s time to work on the lower airframe. That’s a job for another day

Next: Bringing It All Together

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