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How do you strengthen balsa wood fins?

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MERector

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Before I attach the fins to my crossfire rocket I was curious about how I could go about strengthening the balsa wood to lower the chances of them breaking upon impact with the ground? I was considering doing a thin coating of Elmer's wood glue, but then I was worried it may bow the fins, also not sure if the wood glue would be good to paint over. I'm really itching to get out and do my first rocket launches.

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MERector

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I never would have thought of using paper. Thank you!

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ActingLikeAKid

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+1 for paper. Make sure to use CA(superglue) to keep the edges down. After everything's COMPLETELY dry, pick at them to make sure they don't come up. If they do, no worries, just glue them back down. But if you don't double-check, they'll pop up at the worst time (say, as you're putting your final coat of paint on and admiring how good it looks).

Added bonus of paper is that it creates a nice smooth surface for primer.
 

JRobinsonUSAF

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Coat the fins with thin CA. Hit with accelerator and sand immediately. Hard and strong. It also keeps edges from getting dinged.
 

MERector

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Would this work as CA, since it does contain cyanoacrylate?



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neil_w

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That is CA but it is gel, you don't want to use that (at least not here).

As far as I'm concerned papering is the way to go. I do it with self-stick label paper which is *incredibly easy*. I'll post some links to the technique later. Either way, practice on a few pieces of scrap balsa and you'll get the hang of it.
 

neil_w

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CZ Brat

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Papering or using thin/super thin CA. I recommend the Jet or Zap brands and stay away from "Loctite" or "Krazy Glue".
 

MERector

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Excellent. Thanks for all the tips. I decided not to take the gel superglue home from work. Hopefully Michael's has the glue I need.
Thanks for the link(s) neil_w


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neil_w

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Excellent. Thanks for all the tips. I decided not to take the gel superglue home from work. Hopefully Michael's has the glue I need.
Thanks for the link(s) neil_w
Michael's is iffy on the thin CA, almost certainly don't have ultra-thin.

Note that if you should choose the self-stick label paper route, you do *not* use CA, just yellow wood glue (I thin it a bit so it's easier to work with.)
 

JRobinsonUSAF

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Loctite makes a thin CA that works pretty well, but if you get super thin CA from a hobby shop, that is the best.

JR
 

ActingLikeAKid

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Related to the OP: My wife is starting her first build; naturally, I want to do everything I can to make it super awesome. It's a Chuter Two, which has a conical balsa nose cone. Has anyone ever tried papering a nose cone?
 

neil_w

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Related to the OP: My wife is starting her first build; naturally, I want to do everything I can to make it super awesome. It's a Chuter Two, which has a conical balsa nose cone. Has anyone ever tried papering a nose cone?
It's been discussed but I haven't seen any evidence where it's been tried. I papered a balsa transition recently and it seemed to work fine. Getting a single paper wrap around a conical nose could be a little tricky but should work if you're careful.

However, when I originally asked about this, I concluded that it wasn't really worth it, because it wouldn't really add the kind of strength that a nose cone needs. Papering adds great stiffness to fins, but nose cones need surface hardness to avoid getting dinged up.
 

K'Tesh

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samb

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My two cents:

For balsa strengthening purposes, I use whatever superglue falls into my cart at Walmart or the Dollar store.

superglue.jpg

Apply the CA to balsa in a well ventilated area and keep your eyes and nose well clear.

IMO any lamination technique using paper, thin ply, tissue, or fiberglass cloth will create a stronger result than using just a liquid (CA, wood glue, epoxy, etc.) on balsa treatment.

Hope this helps.
 

rc dude

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I have used .75oz fiberglass on balsa fins before, it worked pretty good. Just another option besides paper.
 

Andy Greene

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Paper is your friend on fins , I just started using this process after a bunch of reading - and from a BARS prospective . Its simple and strong . I find myself overbuilding stuff these days using this method.
Stronger is better imho.
 

dford

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Last rocket I built I papered the fins then glued about an inch wide paper into the fillet "transition" between the BT and fins...I had deployment issues on a G motor flight, ripped the chute clean off. When the rocket came back only thing wrong was a corner tape (paper) had lifted a little on one fin.

Next build I'm waiting to paper the fins to lay an entire "fin to fin" paper. Over the body tube onto the fin beside it.

Papering helps tremendously.
 

gjrockets

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I would recommend skipping using balsa altogether. Use model aircraft grade plywood instead.
It's a little more difficult to work with but once cut it will almost NEVER break. You can make through the wall fin tabs that will attach directly to your motor mount for greater structural integrity. AND, if you have fin pieces from kits that normally are glued together before putting on the rocket, now with the plywood you can just go ahead and make these all as one piece instead of multiple pieces.
When I got back into rocketry over 20 years ago, it didn't take me long to realize I didn't want to use balsa anymore. Too prone to ding (especially for nosecones) or for fins to break.
 

jpbell

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I have never had a balsa fin break. I have had them come off rockets before...or come lose but never have had one break!

My Gosh what are you doing to your rockets?
 

Rex R

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I have had fins break...from impacts, and I have heard of fin breakage during transport.
Rex
 

EXPjawa

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I had a fin on my Binary Star break at URRF3 when it landed, of all things, on the folded up step ladder than was on the ground near the high power pads. Lots of open field and soft, tilled dirt and it lands on a ladder. Balsa fin breakage happens a lot, especially when the balsa isn't the harder variety that it seems only Estes gets in large quantities. If you haven't broken a fin on landing yet, it doesn't mean you never will...
 

bill_s

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I would recommend skipping using balsa altogether. Use model aircraft grade plywood instead.
It's a little more difficult to work with but once cut it will almost NEVER break. You can make through the wall fin tabs that will attach directly to your motor mount for greater structural integrity. AND, if you have fin pieces from kits that normally are glued together before putting on the rocket, now with the plywood you can just go ahead and make these all as one piece instead of multiple pieces.
When I got back into rocketry over 20 years ago, it didn't take me long to realize I didn't want to use balsa anymore. Too prone to ding (especially for nosecones) or for fins to break.
Actually, the next step up from balsa is basswood. Good stuff.... To me, aircraft ply is overpriced and the warping of cheaper ply makes me not trust any of it. Somehow Estes gets ply that's good and not too expensive for them, though.
 

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