First time with Pneumatic want to double check the math

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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battlelava
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Sat Feb 11, 2012 1:48 am

So I've started to look at making a pneumatic, primarily because I think they should be quieter then a combustion and less disturbing to the people around me. I was going to use it as an airsoft cannon but after seeing it go at 660 fps I'll have to change it to a mortar which is no big deal. For power i was going to use a bike pump (I could use some more PT anyway) as its free, quiet and I don't need power, but I don't know how realistic it would be to fill 30" of 2" pipe (94cubic inches) to 100 psi. On top of that in GGDT I had it setup for burst disk, but I'm not entirely sure of what size disk it has programmed in (might just be how tired I am), and I'm not sure as what is the most effective type of valve is for this setup I can get a sketch up tomorrow to show how i'm trying to get this work if its not clear. (sorry if i made any stupid mistakes as i'm pritty much sleeping as i type this)
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Proxywars
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Sat Feb 11, 2012 2:20 am

With something like a mortar as you said would not be allowed in official business owned outdoor airsofting arenas. Firing that at a human is very dangerous. If your going for something that big I say you need to be very far from the a human. Btw ur ggdt math is horribly off. Airsoft bb's are all 6-8mm and the ideal weight of the bb you need for a mortar is 0.28g as for long range. Being a mortar You need 100 bbs minimum so times that by .28g and the wadding wont be airtight so theirs more fps loss so up the friction 2psi. The ideal barrel for 100bbs would be 1". The valve I believe you should use for ur first is a modded sprinkler valve. That thing will be loud if it's a mortar. Correct me if I'm wrong Airgun-.22lr sound. You also need good math calculations if your going for an authentic top down mortar. The pro's here will critique this. Sorry if I sound rude.
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sharpshooter11000
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Sat Feb 11, 2012 7:47 am

Proxywars: where I airsoft you are allowed mortars, rocket launchers, tanks anything really as long as it fires bbs at a safe velocity or nerf rockets for use against vehicles.
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battlelava
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Sat Feb 11, 2012 9:15 am

I have no intention on shooting directly at people and we play on our own field so that's not a problem. Ill readjust ggdt and post my results. Do you think the 100 psi is doable from a bike pump setup
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Sat Feb 11, 2012 11:16 am

A bike pump for a 30" section of 2" pipe is perfectly doable.
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Proxywars
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Sat Feb 11, 2012 2:10 pm

sharpshooter11000 wrote:Proxywars: where I airsoft you are allowed mortars, rocket launchers, tanks anything really as long as it fires bbs at a safe velocity or nerf rockets for use against vehicles.
But not at people am I correct. I'm liking that airsoft field haha. I live in the city so can't do that.
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battlelava
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Tue Feb 14, 2012 3:10 pm

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Pritty rough sketch. Apparently my gf doesn't have a ruler so its pritty sloppy. Anythougjts on improvements before I build it.

And do you think ELECTRICAL PVC is strong enough for up to 150 psi its sch 80
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Daltonultra
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Tue Feb 14, 2012 5:42 pm

No. Absolutely not. PVC electrical conduit is not the same stuff as PVC water pipe, and it's not meant for any kind of pressure at all, even if it is sch80.

150psi should be safe on sch40, as long as the pipe and all teh fittings are NSF-pw. If you're going to be treating roughly, as I would expect during airsoft play, then sch80 is probably not a bad idea.
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battlelava
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Tue Feb 14, 2012 5:53 pm

Ok good thing I didn't build it yet. I'll go get some pressure rated PVC. I found a sprinkler valve. Its 1" valve but it looks. Threaded so idk how PVC would work unless I'd have to use a fitting right
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Daltonultra
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Tue Feb 14, 2012 9:35 pm

Yup. They make couplers that go from socket the thread, no worries.
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Wed Feb 15, 2012 12:18 am

if you're using a burst disk, why bother with the sprinkler valve at all.

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The only disadvantage is a couple of milliseconds more delay between trigger squeeze and projectile firing, but if you're using this as an indirect fire mortat that doesn¡t matter ;) and you gain performance by removing the restriction and turbulence caused by the solenoid valve.
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battlelava
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Wed Feb 15, 2012 10:15 am

How can I do that without a paintball tank or hpa tank. I wanted to use a bike pump to pressurize it. Could. I make. Homemade tank to fill up with the bike pump and then hook it up to the blowgun
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