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Preloaded Cartridge Prototype

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: Davidvaini » Tue Jun 24, 2008 3:52 pm

UPDATE: I did a stress test today and 1 layer of the foil tape that I have holds 55psi empty and 65psi loaded.

I also tried to test out duck tape as a burst disk material for the small 3/4 shells but no matter what the size of the duck tape it just tears slightly and doesnt work.
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Unread postAuthor: the unit » Tue Jun 24, 2008 8:25 pm

i have built a design essentially the same, with the exception that it is 1 1/2" pipe instead. what i want to do is make this a preloaded cartridge as well, the only problem i am seeing is how will i keep my burst disk sealed against the pipe as not to lose pressure. i was thinkin an oring (if i have one that size) or a silicone layer along the circumference of the pipe, both which would seal against the double layer aluminum foil i am using as a burst disk

in addition i was wondering if anybody could help me in figuring the most or closest to most efficient dimensions for the chamber, because with a small barrel(the coupler) i can see having a large air chamber would be overkill as much of it would be wasted
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Unread postAuthor: Davidvaini » Tue Jun 24, 2008 8:50 pm

actually a large air chamber is not a waist. lol... Also you can add a barrel after the coupling if you want added performance. The coupling pinches the burst disk against the pipe so you get a seal.... so Idk why you would need an O-ring. You put the foil on top of the pipe ( air chamber) and then you pinch it down by adding on the coupling. Unless you are using really cheap aluminum foil idk why you would lose pressure.

For a 1.5 inch shell I would have the air chamber be at least 4 inches.
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Last edited by Davidvaini on Tue Jun 24, 2008 8:55 pm, edited 1 time in total.
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Unread postAuthor: VH_man » Tue Jun 24, 2008 8:53 pm

Davidvaini wrote:actually a large air chamber is not a waist.


sorry it made me chuckle... :lol:
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Unread postAuthor: the unit » Tue Jun 24, 2008 9:02 pm

with a small barrel if i had a massive air chamber, would the projectile not have exited before all of the air? also im trying to keep the round small as i am using it in a M203 look-a-like.

you really think that aluminum foil and then pipe alone will create a seal where i will not lose significant pressure over the course of a game(paintball)?
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Unread postAuthor: Davidvaini » Tue Jun 24, 2008 10:21 pm

Well I havent tried aluminum foil but I know foil tape keeps the pressure.

Unit, look at the video on the main page. I have the nerf ball at the end of the shell but it still gets all of the air behind it. Now a longer barrel would certainly help and you can add the barrel if you wish. Now I realize you want to make the shells small so you can use them in a m203 launcher look-a-like.

Do you realize a real m203 launcher is 15 inches, the barrel length is 12 inches. My shell which is effective is only 7 inches long. So why not have a 5-6 inch chamber, coupling and then a 4 or 5 inch barrel?

EDIT: Did you mean the M203A1 which has a 9 inch barrel? in which case you could do a 5 inch air chamber and 3-4 inch barrel.
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Last edited by Davidvaini on Tue Jun 24, 2008 10:40 pm, edited 1 time in total.
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Unread postAuthor: the unit » Tue Jun 24, 2008 10:33 pm

i was runnin some stats through the ggdt and a 6" chamber and barrel are producing good results compared to other combinations that add up to a foot in length...

on a side note how do i know the flow coeffecient?
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Unread postAuthor: Davidvaini » Tue Jun 24, 2008 10:55 pm

is your flow coef set at 45?
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Unread postAuthor: the unit » Wed Jun 25, 2008 3:39 pm

yes my coef is set to 45

also im not sure if i will make it an m203, after i have a working prototype of the full launcher i will decide between an m203 or another semi auto grenade launcher.
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Unread postAuthor: ImHUGEnJAPAN » Fri Jun 27, 2008 2:58 pm

the unit wrote:yes my coef is set to 45

also im not sure if i will make it an m203, after i have a working prototype of the full launcher i will decide between an m203 or another semi auto grenade launcher.


I would also like to use this design for paintball. I made the chamber and I also have a small barrel cut to length of a pod.

The idea is to be able to carry a preloaded cartridge and barrel in my pod pack. I could quickly assemble the barrel to the cartridge and fire the grenade or grape shot. I still need to go buy some foil tape.

LOL...I tried duct tape too, plus plastic bags, and multiple layers of latex gloves...ummm ya.....they didn't work. The latex gloves made a lot of noise when they popped at a whopping 10 psi.

I guess I'll have to drop $15 on some foil tape.
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Unread postAuthor: Davidvaini » Fri Jun 27, 2008 3:02 pm

well 100 feet of foil tape is 800 shots... well yours are 2" so more like 600 shots but yeah...
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Unread postAuthor: Davidvaini » Fri Jul 11, 2008 12:06 pm

Update:

[youtube]http://www.youtube.com/watch?v=qlPTHqJT_NM[/youtube]

Imortal87 shown in the picture firing with the co2 inflator for the first time... didn't know about the amount of blow back caused from the inflator.
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Unread postAuthor: Bando_Red » Fri Jul 18, 2008 5:37 pm

Hi guys,First time posting.I love this idea so much.Do you think it would be possible to make a flare-gun type of pistol with this system,or is a pistol too small to fit it in?I plan on a top break breech-loading barrel with a modified cap gun striking mechanism that causes the hammer to pierce the foil in the back. Sorry if this is a noob question,but I am a noob after all.
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Unread postAuthor: Davidvaini » Thu Aug 07, 2008 12:35 pm

both the vortex cap and the burst disk cartridge designs by me will work in small applications such as a pistol.
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Unread postAuthor: Phil23 » Sun Aug 31, 2008 9:41 pm

Hey, what CO2 inflation are you using?


EDIT: Sorry for somewhat necro post.
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