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pneumatic mortar

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: ALIHISGREAT » Sun Dec 23, 2007 10:24 am

i remeber JSR talking about using sellotape as a burstdisc but it was for a tiny bore smaller than 15mm and it held alot of pressure in the 400psi region i think...
i may be mistaken though because i can't find anything by searching :?
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Unread postAuthor: Ragnarok » Sun Dec 23, 2007 10:42 am

ALIHISGREAT wrote:i may be mistaken though because i can't find anything by searching :?

You're not. 6mm burst disc pneumatic. Approx ~400 psi burst.
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Unread postAuthor: Carlman » Sun Dec 23, 2007 10:47 am

s**t i need something WEAK then lol
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Unread postAuthor: Ragnarok » Sun Dec 23, 2007 10:57 am

As bore size increases, burst pressure of any material will drop. Sellotape would go at maybe... 150 psi in a 15mm diameter barrel. If you found a way of triggering it, it could go at any pressure you wanted up to that.
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Unread postAuthor: Carlman » Sun Dec 23, 2007 11:09 am

if 1 layer of sellotape was holding back say 100psi and a nail sized hold was punctured would it tear from that hole ouwards thus 'bursting'?
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Unread postAuthor: Ragnarok » Sun Dec 23, 2007 11:31 am

Easily. It would burst at well under that if it has a hole poked in it.

Think about a balloon. Takes quite a lot of blowing up to burst, but it will go well under that if you ram a pin through it.
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Unread postAuthor: koolaidman » Sat Dec 29, 2007 1:39 pm

Yeah I was the idiot that tried to make that prototype. I pressurized a 3/4" round and dropped it into a 1.5" with a nail. It failed miserably. It worked perfectly in theory, but even at 60 psi only had enough power to pop it up about 1". I like carlman's diagram though, i never really considered pressurizing the chamber on the base rather than the round itself. I would be confident that his would work, i will probably give that a shot as well.
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Unread postAuthor: Carlman » Sun Dec 30, 2007 5:42 am

yes please do as it saves me having to do it lol, if it works then tell me!

and why would you think of presuring round oh well its an idea to play with
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