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Cutting holes in balsa fins

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solrules

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I was wondering if anyone has taken out the center to balsa fins and put a lamination layer of cardstock/paper to cover the entire fin? Would that save much weight? It would certianly be cool to have hollow fins. It would almost seem to me that it would add weight from the glue, but what's your opinion?
 

jflis

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A better choice would be to *assemble* a fin from thin struts then cover it in mono-kote (*much* lighter than paper and glue...). Jap-tissue would also be a good choice.

Something like this (see attachment)
 

wwattles

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I can definitely see the advantages of Jim's idea over the original of just cutting holes in the basic fin. You have the advantage of minimizing the balsa while still maintaining the maximum strength because you won't end up with a long strip comprised of short-grain wood. By using individual struts, the grain runs the length of each of the pieces of balsa, keeping it strong but light...

WW
 

Silverleaf

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The idea Jim shows has been used forever - or so it seems by RC pilots. The idea is a strong surface, yet very light weight.

I like the concept of lowering weight on low powered designs, but unless you Fiberglass (theres that word again..ick, back ye foul beast), you have to make a choice between less weight, and possibly damaging the fins on liftoff/landing.

Cheers,
 

wwattles

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Originally posted by Silverleaf
... and possibly damaging the fins on liftoff/landing.
I agree on that one. You're stuck between needing slow lift-off speeds and making your rocket as light as possible to get those max-acceleration adrenaline rushes. You'd probably also want to oversize the chute to get really slow descent rates (or use a rear-ejection so the nose cone hits the ground first). But again, that adds weight, decreasing the overall effect of lightening the fins.

WW
 

solrules

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Thanks! Jim's idea looks very strong. I would imagine you could even fill the gaps with some type of foam, then monokote over it to make a very strong fin. Has this type ever been upscaled for use in High Power? I would imagine the closest thing to this is Giant Leap's honeycomb material.
 
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