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| trollhameran |
 Posted: 05/13/2008 13:27 PM Post subject: valveless gun, update with new videos |
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Colonel
Joined: 04 Dec 2007
Posts: 517
1250.77 Spud Bux
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| iknowmy3tables |
| Posted: 05/13/2008 13:43 PM Post subject: |
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Brigadier General
Joined: 15 Dec 2006
Posts: 1133
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| not that impressive, seals surprisingly well, one problem is the lack of any chamber volume
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| trollhameran |
| Posted: 05/13/2008 14:10 PM Post subject: |
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Colonel
Joined: 04 Dec 2007
Posts: 517
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| yh i will have a much bigger chamber volume on the gun when i make it but this was just a test to see if it would seal well enough to be feasable
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| pat123 |
| Posted: 05/13/2008 14:41 PM Post subject: |
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Lieutenant Colonel
Joined: 23 Dec 2006
Posts: 475
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| cool, how much air leaks around the potato? it has to be one of the fastest opening and best flow "valves" if it doesn't leak.
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| trollhameran |
| Posted: 05/13/2008 14:47 PM Post subject: |
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Colonel
Joined: 04 Dec 2007
Posts: 517
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| a very small amount of air leaks out but im going to test it in a day or two with a rubber seal inside to see if that stops the leak completely
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| jrrdw |
| Posted: 05/13/2008 14:56 PM Post subject: |
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Donating Moderator
Joined: 16 Nov 2005
Posts: 3284
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Sgort87 and I was kicking this idea around a little bit. I think you may be the first to build a working model. A potato held back 110 psi, how did you pull the nail out? a tow truck???  Here's what I drew up in paint about a year ago. --
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| FeLeX |
| Posted: 05/13/2008 14:57 PM Post subject: |
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Captain
Joined: 10 Mar 2007
Posts: 308
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| Nice man!! Didn't think potato would seal that good! Make it into a single shot sniper rifle! How much psi were the shots at??
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| trollhameran |
| Posted: 05/13/2008 15:37 PM Post subject: |
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Colonel
Joined: 04 Dec 2007
Posts: 517
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jrrdw: the nail was quite hard to pull out, you could feel there was alot of force pushing against it from the potato. I think what im going to try to do is get a rubber o ring and put it in a coupler then have the barrel one side of the coupler and the chamber the other side so that the o ring is sandwiched in between the barrel and the chamber, hopefully that will help it to seal even better.
FeLeX: it was at 110psi
Im planning on making it into a shotgun but it will have interchangeable barrels so I will most likely make a sniper barrel for it as well.
Possibly going to try to make some custom rounds for it using the same principle as these bottle stoppers  So that when the chamber is filled the pressure will force the round into the trigger and the round will compress and the rubber will be pushed out so that it seals in the barrel then when the trigger is released the round springs open so that the pressure can push it down the barrel.
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| pat123 |
| Posted: 05/13/2008 15:55 PM Post subject: |
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Lieutenant Colonel
Joined: 23 Dec 2006
Posts: 475
103.26 Spud Bux
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I have an idea for the pump action part. have a tube with a 45 degree elbow below the barrel.put an oring across inside the pipe near the top to keep all of them from coming out. put a stick in the other side that seals in the pipe. this is too hard to explain i will post a pic.
i think this would work
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| psycix |
| Posted: 05/13/2008 16:59 PM Post subject: |
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Major General
Joined: 25 Jun 2007
Posts: 1857
355.02 Spud Bux
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@ pat123
I think that setup will blow out the "stick", and make it act like a pneumatic ram, and all balls will fly out too if things break.
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| Eddbot |
| Posted: 05/13/2008 17:56 PM Post subject: |
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Major
Joined: 09 Oct 2007
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| what if you had a valve at the end of the barrel that worked on the same principle as a piston pilot, you load the projectile(think of it as the piston without a stopper), then close the valve at the end of the barrel, then pressurize the chamber, the valve at the end keeps the pressure in(like a blowvalve), then when the valve is opened the projectile is fire out the barrel like when a piston exhausts, but without a bumper to stop the piston, launching the projectile, the only problem i can see is finding a valve that uncovers the whole barrel fast enough
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| trollhameran |
| Posted: 05/14/2008 0:05 AM Post subject: |
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Colonel
Joined: 04 Dec 2007
Posts: 517
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pat 123 i think i have an idea how i could make your idea work, ill draw a design for it then ill post it up here.
Eddbot: do you think you could post a pic of how your idea would be set up so that i can have a look and see exactly how it would need to be made for it to work
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| daxspudder |
| Posted: 05/14/2008 0:21 AM Post subject: |
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1st Lieutenant
Joined: 24 Apr 2008
Posts: 270
607.45 Spud Bux
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| so why not just use a burst disk, there is no valve involved, except the fact that you have to pressurize it somehow, like maybe a SCHRADER VALVE...
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| trollhameran |
| Posted: 05/14/2008 0:40 AM Post subject: |
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Colonel
Joined: 04 Dec 2007
Posts: 517
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| to be honest i dont really understand how burst discs work
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| Hydra |
| Posted: 05/14/2008 0:49 AM Post subject: |
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Staff Sergeant
Joined: 08 Mar 2008
Posts: 122
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Pretty simple.
A burst disk is made from something that ruptures at lower pressures. WHen that pressure is reached, the burst disk bursts.. fulfilling its final job and all the air comes out. Its supposed to be the best valve in terms of performance and flow, but the worst in cost and management.
Its usually used in hybrids. There is alot of pressure already but the disk doesnt break. Now when you explode the pressurised fuel mix there are huge pressure which break the burst disk.
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