APH help

Build a homemade water gun or water balloon launcher and tell us about it.
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Commander Soakage
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APH help

Post by Commander Soakage » Thu Jun 19, 2008 9:10 pm

so i've decided to build an APH. first question how much PSI does an APH need to get 50 ft of range.
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Silence
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Re: APH help

Post by Silence » Thu Jun 19, 2008 9:15 pm

Not much, and it hasn't been measured, as far as I know. At any rate, difference in nozzle size, nozzle shape, nozzle quality, and barrel size are going to invalidate nearly all the information that you might receive. At any rate, you should be able to hit 50 feet with a 1/2" PVC pump (which is about 5/8" in diameter) and moderate strength, unless you have bad nozzles.

If you want to find out how much pressure you can generate, measure the most force you're willing to exert while pumping repeatedly by lifting a few weights or something of known mass (say, a volume of water). Then divide that force by the cross-sectional area of the pump, using these charts for diameter reference. That link also has zipped Excel file that has several useful statistics and an easy way to calculate the pressure.

Short answer to your question: Who knows. Unfortunately, I don't.

aEx155
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Re: APH help

Post by aEx155 » Thu Jun 19, 2008 9:47 pm

Commander Soakage wrote:so i've decided to build an APH. first question how much PSI does an APH need to get 50 ft of range.
It all depends on how you make your gun. If you make your gun really crappy, then you probably will never reach 50 ft. at any pressure. But with the right stuff, then you can probably make 50 ft easily. Technically, there is no pressure that raeches 50 ft. because it varies by gun; also, it's how much force you can apply (pressure you can reach) that sets the range, not the other way around...

And just to slip this in: I'm not sure, but somewhere I remember Ben saying that CPS guns get better range...correct me if I'm wrong...

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Silence
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Re: APH help

Post by Silence » Thu Jun 19, 2008 10:13 pm

CPS guns can get better range. They definitely get better range after the first 25% of the shot, since the pressure dropoff cripples other soakers. And good CPS and air pressure water guns mostly get similar range. But the best air pressure water guns have large tubing and unlimited pressure potential (which isn't necessary), which is why Supercannon II can trounce SuperCPS in range, at a fraction of the maximum pressure.

There's no way a CPS soaker would beat an air pressure one unless the latter was just designed poorly. APHs have all the advantages - higher peak pressure, higher flow coefficients, and the nozzles should be the same. Ben may have said that CPHs in his experience outperformed APHs, but that probably comes down to other factors like nozzles.

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SSCBen
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Re: APH help

Post by SSCBen » Thu Jun 19, 2008 11:26 pm

CPS guns have better range for most of the shot. That's what matters. Your peak pressure, which is what a pressure gauge would measure, doesn't say much about how the water gun will perform because it only has that pressure for a fraction of a second. I think average pressure over the interval is most accurate.

60 PSI should be plenty adequate to get 50 feet of range with the right sized nozzle. ;)

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