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geezer
n00b
Joined: 26 Jan 2008
Posts: 5
Location: Akron
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 Posted: Sun May 11, 2008 7:41 am Post subject: Launcher - math, AAARRRGGHHH! |
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Math is hard and I really suck at it. I am building a pvc launcher and am using sch 80 pipe and fittings for the valve body and making different barrels out of both sch 80 and sch 40 pvc.
I am using the tried and true nelson based valve design; with one exception, ok, two. There will be no bolt and when the hammer strikes the power tube it will hold the tube back till the pressure chamber is completely empty.
Here is my set up thus far, the source is a tenk on a remote with either a stock ion reg or a palmers stab to adjust the pressure. the pressure chamber will have two 200 psi safety pop offs it will have a 300 psi gauge, and a 1/8th ball valve with quick connect for filling. the power tube will be made of either 1/2" or 3/4" type L copper I prefer 3/4 but I may have to use 1/2.
My question is this, how big would the pressure chamber have to be to launch the nerf or jcs at a given velocity. I want the pressure chamber to be as small as possible.
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VIPER1
Paint Magnet
Joined: 11 Apr 2008
Posts: 21
Location: GEORGIA
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Bulldog
Delta Squad Member
Joined: 27 Jul 2005
Posts: 1411
Location: Columbus, Ohio
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| Posted: Sun May 11, 2008 9:06 am Post subject: |
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You need either two or three times the volume of your barrel- I forget. The Spudlauncher site probably has a table somewhere.
It's worth noting that the thread linked doesn't specify what pressures he was running or what setup he was using, beyond PVC. That said, I don't think PVC is rated for 200 psi- most PVC launcher operate around90 psi, with a 120psi pop-off. I've got a rating list for pipe at work.
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Squirlly
Post-Count Whore
Joined: 28 May 2007
Posts: 364
Location: Pataskala
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| Posted: Sun May 11, 2008 1:21 pm Post subject: |
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Geezer is a Certified Master Plumber I'd trust my life with anything he has built from PVC pipe  He asked this question over on another forum we are both on and knew bulldog would have the answer that's why I had him ask here.
-Tim
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geezer
n00b
Joined: 26 Jan 2008
Posts: 5
Location: Akron
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| Posted: Sun May 11, 2008 2:45 pm Post subject: |
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Sch 80 pvc has a working pressure of almost 500 psi and can be tapped and threaded. Tapping and threading reduces the psi rating but only by about 150 psi so that still gives me nearly 300 psi to work with. I am just trying to figure out size and expansion rates for a given pressure through 1/2 or 3/4 tubing. since the power tube will be full open almost instantly I am thinking the loss of power during tranfer will be minimal.
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