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ezgb59a
08-26-2008, 11:26 PM
Okay ... my son built the Viking for 4H. He did pretty much all of it by himself - even the fins. Overall he did a solid job and that little rocket rocks with a C6 engine ... at least I think that was the engine we used last.

Anyhow, tail fin assembly was a challenge. Two years he has had problems getting them connected and having them be straight. I really couldn't come up with a solution that worked. He didn't really care at the time - he just wanted to launch it this year and get it recovered (last year did the Pip Squeak - launched the night before the fair and that little rocket went into the middle of an alfalfa field and some cow probably ate it this past winter.)

So, what suggestions do you have for connecting tail fins? I know he would like to do well at the next fair - possibly even take the grand champion award as the kid who won it the past several years finally graduated and is in college - he was talented and did very well.

Thanks
ez

CPMcGraw
08-27-2008, 12:41 AM
...tail fin assembly was a challenge. Two years he has had problems getting them connected and having them be straight. I really couldn't come up with a solution that worked... what suggestions do you have for connecting tail fins?...

Two things:

1. Use Titebond II. Apply thin layers to the tube and to the root edges of the fins. Let dry completely. Apply a second layer to the root edge and press the fin onto the tube (on top of the glue layer). Hold for about 15 seconds before turning loose. Wipe away the excess with a wet finger or moist art brush.

2. Use a fin jig to set the alignment. This can be as cheap as a couple of shirt cardboard slide-ons with a close-cut hole for the tube and slots for the fins. I use this method all the time.

After about an hour, you can slide the guides off and apply the glue fillets to the joints for reinforcement. Don't omit this step.

Solomoriah
08-27-2008, 06:57 AM
I've had equally good luck with any brand of yellow wood glue. Put a thin bead on the root of the fin, press it in place, then pull it off and lay it somewhere it won't stick (I have a plastic toolbox I use for this). Let the glue get almost dry (doesn't take long), apply another thin bead to the fin and press it on again. Hold it just a few seconds, and the glue should grab.

Generally I do them all at the same time, that is, I do the first step for all, wait, then do the second step for all; then, I stand the body tube upright, fins up, propping it if necessary, and let 'em dry.

I check the alignment (before the glue is dry, obviously) by simply looking up the length of the tube. If the trailing edge doesn't hide the rest of the fin when I look at it straight on, I know it's crooked. I've never owned a fin jig, and only rarely wished I did.

Finally, after the glue is dry, I often fillet with white rather than yellow glue; it doesn't shrink as much, so it doesn't take as many coats to get a nice fillet.

Intruder
08-27-2008, 09:11 PM
With any technique, the best tool is patience. Take your time, pay attention, and it will turn out looking good. :)