GB Cannon
Ebay is to blame for this one! I saw some Goyen quick exhaust valves on Ebay. They were going at a ridiculously low price, only $9.99 for 3 valves! After shipping they were only $15 for 3! I got the valves, which I thought were only 1/4-1/2" valves. It turns out they were much bigger!
Armed with 3 new valves and a dream I set out to fulfill my destiny. (LOL, just kidding) I found that the valves had a flange on the inlet side and an unknown size on the outlet. I researched various pipe sizes with no luck. I ended up taking a piece of 2" sch80 with 1.5" sdr 21 sleeved inside of it, boring the sdr 21 out slightly, and securing it to the valve with JB Weld. I fabricated a flange to fit onto the valve's flange out of a 1.5" sch80 PVC flange. The rubber gasket between the flanges was freakishly found on the ground outside of a metal scrap yard. I couldn't have asked for a more perfect fit on the gasket!
The valve is triggered by a Gregory high flow blowgun. The gun is filled through a male quick connect fitting. If you have ever played with quick connect fittings, you know that the males are not air tight. If I were to release the hose, the gun would trigger. To avoid this, I followed the quick connect fitting with a 1/4" inline check valve. These can be found at mcmaster.com.
The chamber is made of 4" clear pvc. I had planned on using it for a combustion, but couldn't resist the coolness of a clear pneumatic. When fired, the chamber becomes filled with vapor from depressurization.
Overall, I am amazed with the power of this gun. The Goyen valves are much more powerful than a sprinkler valve of the same size. Its hard to explain, but a sprinkler valve, even a pneumatic modded one shoots kind of "squishy." Sort of a whoosh-bang sound. The Goyens dump very crisply, with a sharp retort. They remind me more of a piston valve than a diaphragm valve.
The day after initial testing, my stomach was really sore. I had rested the gun on my stomach and legs so I could hold the barrel shut with my hands while firing. The recoil gave me some nice bruises!
"Bolt Action" Loading Mechanism
I decided to try a new method of loading with this launcher. It has a golf ball "bolt action" mechanism. The mechanism consists of a 2" repair coupling (sliding type). It is attached to a 2" sch80 barrel, which has 1.5" sdr 21 sleeved inside of it. When pushed forward, the loading hole is exposed. You drop a golf ball in, and pull the repair coupling back. The repair coupling is airtight via o-rings but slides easily. The golf ball is sandwiched between the short gold screws and the inner barrel. As you push the barrel/coupler back the golf ball is loaded into the inner barrel.
There is a slight problem on the barrel. When fired the bolt/ barrel flies forward, letting air escape from the loading hole. This reminds me of a gas blowback system, which could in some cases be useful. A semi automatic design would be one of these uses. I will be fixing the barrel so it will not slide forward when firing.