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Old 09-16-2020, 12:09 AM
scott_mills scott_mills is offline
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Default Curved balsa fins

Has anyone actually made any rockets with deliberately warped fins, against the grain. I have some ideas that would look neat with fins of that nature.
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Old 09-16-2020, 12:27 AM
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If you soak the balsa in water, it is bendable. Probably easiest to make a form to press the fins against, for uniformity. They need to be held in place for at least 24 hours. I seem to recall hearing that ammonia added to the water aids in bending.

I have used water and a heat gun to moisten a warped fin. Obviously an unsealed/unpainted fin. I misted the fin with a spray bottle, then heated the fin and bent it back straight. Be careful to avoid heating the root edge if the fin is already glued onto the rocket. You can soften the glue joint enough to debond the fin.
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Old 09-16-2020, 01:08 PM
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Quote:
Originally Posted by LeeR
If you soak the balsa in water, it is bendable. Probably easiest to make a form to press the fins against, for uniformity. They need to be held in place for at least 24 hours. I seem to recall hearing that ammonia added to the water aids in bending.


Apogee uses that technique for the blades on the helocopter recovery kits - and yes some ammonia added to the water helps. Just moisten the fins then used something to hold them to the mold form until they dry (I wrapped them with an ace bandage).
If you go here:
https://www.apogeerockets.com/Rocke...er?cPath=1_307&
Tim VM has video's showing how to do it (it's down the page a bit).
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Old 09-16-2020, 08:17 PM
scott_mills scott_mills is offline
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Yes I got on of those, flew so good I lost it on the first flight, probably had a thermal or something. It is a very worthy technique. Rather than mixing water and ammonia, if memory serves he recommended just using window cleaner. I was just curious if anyone had used the technique before for a more conventional rocket. Ie as the actual fins.

Having cloned someone's design called fractal, it looks like a flying pan flute. It amazes me what you can use and still get a perfectly straight and reliable flight.
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Old 09-16-2020, 09:03 PM
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You can use Window Cleaner, but if it has no Ammonia (Ammonium Hydroxide solution) it will work NO better than plain water. The AMMONIA is what causes easier forming of curved wood.
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Old 09-17-2020, 07:28 AM
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Quote:
Originally Posted by ghrocketman
You can use Window Cleaner, but if it has no Ammonia (Ammonium Hydroxide solution) it will work NO better than plain water. The AMMONIA is what causes easier forming of curved wood.

This proves you've built your R/C planes in the past instead of ARFing.
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Old 09-17-2020, 09:55 AM
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Quote:
Originally Posted by scott_mills
Has anyone actually made any rockets with deliberately warped fins, against the grain.

Yes .

Great area for creativity.
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Old 09-17-2020, 10:30 PM
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Have built MANY RC aircraft in the past, but I'm now an ARF guy.
You can't build for what high-quality ARFs cost now.
By the time you buy all the glue and finishing materials for a kit, you are way over ARF cost.
And that doesn't even factor in anything for your own time/labor.
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