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burst disk cartridge idea

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: jackssmirkingrevenge » Mon Apr 07, 2008 7:50 am

I have to make the cartridge and breech so quite a lot of casting involved, though I can save time by using these parts I had made for the preloaded piston cartridge testing. A hammer can be improvised for testing, with a proper system made if results are worthwhile.
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Unread postAuthor: mega_swordman » Mon Apr 07, 2008 11:20 pm

jackssmirkingrevenge wrote:Interesting, pretty much the same idea I was working on here.


Yep, just like JSR said, this is almost exactingly what he is describing in his other project. Not to confuse myself here, but when he says "valve stem", he means along the lines of a schrader valve right?
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Unread postAuthor: jackssmirkingrevenge » Mon Apr 07, 2008 11:28 pm

mega_swordman wrote:When he says "valve stem", he means along the lines of a schrader valve right?


Yes, the bit on the shrader that you'd press on to exhaust the pilot.
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Unread postAuthor: mega_swordman » Mon Apr 07, 2008 11:51 pm

Ah yes. Thanks for the clarification.
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 08, 2008 11:42 pm

Well, my first "proper" cartridge is almost done, just needs to fully cure and some minor finishing. After that I'll test the feasibility of bursting the disk with a sharpened tube and the amound of force that would need, if that works then I think I have a project on my hands :)
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Attachments
bdcart3.jpg
cartridge rear view
bdcart2.jpg
cartridge front view, threaded section attached
bdcart1.jpg
cartridge front view, threaded section removed. Note how I added a notch to enable it to be screwed in.
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Unread postAuthor: THUNDERLORD » Wed Apr 09, 2008 12:01 am

Hello Jsr, I was checking out your cartridge and it looks like a great concept but the thought i have is that there is a principal of firearm shell casings that when fired the shell expands/flex and temporarly glue to the chamber. but maybe with your application the spring force will counteract the pressure/recoil? i have an idea that since your shell won't flex maybe the front should have a thin short metal tip to create this effect.
what do you think about that?
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 09, 2008 12:54 am

There is a principal of firearm shell casings that when fired the shell expands/flex and temporarly glue to the chamber


For what I'm working with, the opposite is true - the cartridge is pressurised before firing, and loses pressure on firing. I observed this effect with my preloaded cartridge prototype, where while the cartridge slid in easily into the breech when it was empty, once I pressurised it the effort to push it in was a lot greater.

In the case of firearms, the blowby of hot propellant gasses at high pressure is a problem because it causes rapid erosion of the metal. In our case however, a bit of air leaking past is largely insignificant, so I'm not too worried about to having a 100% seal as long as it works.
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Unread postAuthor: JDP12 » Wed Apr 09, 2008 7:18 am

wow, looks great JSR, can't wait to see results
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Unread postAuthor: iknowmy3tables » Wed Apr 09, 2008 12:00 pm

so some one acutlly machined that threaded part for you JSR? looks nice
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Unread postAuthor: Sticky_Tape » Wed Apr 09, 2008 12:42 pm

That looks great Jsr maybe you have a chance with some pellet gun manufacturer :wink:
Maybe you should patent this.
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You can tell how awesome a cannon is by the pressure used.
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 09, 2008 12:54 pm

iknowmy3tables wrote:so some one actually machined that threaded part for you JSR? looks nice


Friend of mine at the gun club, all for the princely sum of 10 Euros (that's a bit less than 16 of your finest dollars) :D

Maybe you should patent this


It has to work first, and so far my attempts to burst the disk with a piece of sharpened 6mm brass tube have been less than successful :? I'm experimenting with different materials at the moment, we'll see.
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Unread postAuthor: Sticky_Tape » Wed Apr 09, 2008 1:15 pm

It doesn't have to work to pattent it right I am pretty sure that you can pattent it if it has a good/unique theory. just to say that it is yours.

For the barrel you could have little razor like points made from the barrel itself
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Attachments
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untitled.JPG (8.58 KiB) Viewed 747 times
You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
xnt rnm ne z ahtbg
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Unread postAuthor: THUNDERLORD » Sat Apr 26, 2008 3:28 am

Just wondered if you've considered making the burst disk cartridge out of an actual shell casing? (maybe 9mm) or even something machined the same size/shape(maybe with a bullet shape at the front).

That way it could come as a kit for pistols with a barrel and recoil spring.
But could be loaded in the same magazine and fired as shells.

That seems like it would be great for indoors and maybe the barrels could be a different color so they won't be confused and used in training type application also.
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Unread postAuthor: jackssmirkingrevenge » Sat Apr 26, 2008 5:04 am

THUNDERLORD wrote:That way it could come as a kit for pistols with a barrel and recoil spring.
But could be loaded in the same magazine and fired as shells.

That seems like it would be great for indoors and maybe the barrels could be a different color so they won't be confused and used in training type application also.


Been done, check out the airmunition site ;)

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Unread postAuthor: jackssmirkingrevenge » Tue Oct 07, 2008 4:03 am

Just an update, as there has been considerable interest in this venture by PM of late. I haven't touched the prototype since my last post, on account my my being abroad at the moment, but more R&D is scheduled towards the end of the year with different burst disk materials, results either way will be posted here.
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