Best method to attach fins to body tube?

Hi Everyone,

I was reading another post where someone reinforced balsa wood fins with paper. One person (MarkII) suggested freezer paper in a thread. Anyways, once I make the fins, how does most people attach them to the rocket? Epoxy against the tube? Does anyone cut a slot in the tube to insert part of the fin endge first?

Thanks!

I use wood glue for attaching balsa fins .
I've never tried freezer paper , It has a plastic coating so mabey wood glue will not be the best adhesive in that case.

Hi Warren,

I guess it all depends on what type of rocket you're building, so I'm going to assume you're talking about a standard model rocket built with Estes parts or similar.

For most rockets that are flying on anything smaller than a "D" engine, a fin can be directly attached to the body tube using white or yellow glue ("wood glue"). Many of us like to supplement that by roughing up the body tube to allow the glue to soak in better, or punch pin holes in the tube (you'll hear the term "glue rivets"), or "score" the tube here and there along the fin line with a hobby knife. Again, the idea is to let the glue soak into the tube.

Cutting a slot into the tube for the fin to go into is the next common procedure, but you'll get better results if the fin tab goes all the way to the engine mount tube and can get glued there. The same glues can be used, but slots allow epoxies to be more easily used, so you might want to try them.

For "E" engine rockets and above, you'll probably want to use "through the wall" fin mounting always. Surface-mounted fins can survive a lot of upward flights, but they tend to fail on bigger rockets when they hit the ground, even under parachute (usual parachute speed is ~15 ft/sec), and they sometimes don't survive ejection events up in the air if the nosecone comes back and hits them!

As for reinforcing, I've used self-adhesive label paper, model airplane silkspan applied with superglue, even light "japanese" model airplane tissue applied with clear dope.

Thanks, I will probably rough the tube up and make some pin holes like you suggested. The rocket is going to use a cluster of three C6-3 motors. I just didn't want the fins to come off during flight. I'm not worried too much about after the flight because this will be a one time flight of the rocket for a Boy Scout event.

One the paper, MarkII said he used reynolds freezer paper using the non-smooth side to glue to the balsa fins. Then he used a watered down CA mixture along the edges except what attaches to the rocket to help seal it. I think I might try this method.

Warren

When I use paper lamination to reinforce balsa fins (for low-power rockets), I usually try to keep the paper off of a small zone near the fin root. I try to leave 1/16th or so of the sides of the fin as exposed bare balsa, so that when gluing the fin to the body tube, the glue has a chance to grip just the two parts (balsa and cardboard) directly. I think this is a stronger joint than having a layer of paper in between.

In general, if you build according to the instructions, I think you'll find that the kit manufacturers (the big ones, at least) usually know what they are doing. Follow the directions.

I also agree with RoyAtl's comments above.

That's a great tip too! I'll be sure to leave off a tad of area on the edge so the glue has more wood to attach to and soak in.

WarrenW said:

The rocket is going to use a cluster of three C6-3 motors.

Click to expand...

Warren,

Check out an old Estes design called the Ranger (one of their earliest). It had a triple cluster too, and used simple balsa fins that were glued directly to the BT with a simple butt joint. It flew just fine, many times.

Freezer paper works great. I've used this method on many builds. Last summer I had a rocket land in the street and run over by a car. The fins were TTW and attached with Titebond II. No fins came off the rocket!!