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How can i strengthen cardboard.

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arthur dent

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I have made a boattail out of light cardboard.What would be some good methods of strengthening it so it at least has a chance of survivel on landing??
 

powderburner

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Soak the cardboard in CA

Coat the insides with epoxy

Coat the insides with epoxy/chopped glass

Add balsa or spruce stringers to the inside

Foam the inside volume

Glass the outside surface

Use your cardboard as a pattern to fabricate a new part from titanium (oops, can't use lots of metal on rockets!)
 

hokkyokusei

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Of the suggestions listed above I've tried:

-Soaking in CA
-Light fibreglass to the outside
-Coating in epoxy
-Foaming the internals

Of the four, I prefer soaking in CA & a light layer of fibreglass. To me, epoxy alone did not add any significant strength to thin card.
I'd only recomend foamin if either fibreglass or CA have also been used.
 

EMRR

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fill in 1/4" increments with Gorrilla Glue, it foams up and expands.

- or - use PML Expanding Foam.

Nick
 

Karl

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PML 2 part foam will be your best bet!
-Karl
 

sandman

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Aurthur,

You didn't specify how big this tail cone is.

If it's small like say a BT-50 to a BT-55 just soak it in CA glue.

I built my Commando Cody rocket tailcone out of cardstock.

http://www.rocketryforum.com/showthread.php?s=&threadid=2948&highlight=Commando+Cody

It was a for a BT-80 (2.6") to a BT-20 (0.736") and it held up just fine to an Aerotech D21 AU motor and a later deployment. It just shredded the chute and got some mud on the nose cone.

sandman
 

DynaSoar

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Originally posted by arthur dent
I have made a boattail out of light cardboard.What would be some good methods of strengthening it so it at least has a chance of survivel on landing??
Cut another boat tail out of thin styrene sheet and glue it over it. Makes it pretty much ready for finishing. Easy on the glue, though, the stuff warps if it's too thick. I'd paint a layer of regular tube type styrene cement over the cardboard and let it dry, then use thin cement (nearly all solvent) on the inside of the cone and slide it over. The thick stuff is real easy to fillet and seal edges with. 10mil would work. 20 mil would be better, but depending on the size, might not be easy to bend that tight without resorting to heat.
 
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