Since I played in my first game against paintball tanks last year, I have wanted to build a LAW launcher. The ready made ones are expensive as all get out, and I wasn't thrilled with the idea of a pvc pressure chamber. Also somehow the sprinkler valve based ones are too bulky. I had thought of buying some high pressure solenoid valves, but they are expensive.
After searching the net for different people's ideas on nerf/spud launchers I found a site selling T-shirt launchers for sporting events. These were also terriblely expensive, but they had photo's. Their t-shirt launchers were based on a powerwasher spray nozzle valve. So after a trip to Northern and to Lowes I built one.
It uses Schedule 2" 40 pvc for the barrel, with 2" Schedule 80 quick connect fittings to allow breech loading. Since I didn't want a pvc pressure chamber, I first tried to attach a gas source straight to the nozzle inlet. That didn't work well, either with CO2 or HPA. A 12 gram wouldn't push it hard enough to make a good launch and a 12 ounce tank would work good but dump too much CO2, giving only a couple of shots. This sucked, so I tried a HPA bottle, but the reg would not flow enough to work either.
So I made an expansion/dump chamber out of some Stainless pipe fittings and tried it. It works like a charm, causing me to lose a couple of nerf rockets. It shot a lot better than I thought. When using a HPA/CA tank an on/off is used to prevent losing too much gas per shot. It also works well off a 12 gram changer. Since it shoots well, I'll be replumbing the expansion/dump chamber to make it neater.
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Next to a ballvalve launcher.
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