N6GKJ Nerf Rocket Launcher

I designed and built this originally to launch the small NERF rockets. These are commonly used on AIRSOFT and Paintball Fields.
I soon found out however that this has great applications in Amateur Radio. This will send a NERF rocket more than 400 feet.
I have launched a nylon cord at least 80' straight up! This would be ideal for stringing up a long wire antenna.
This is the completed unit. I have built several of these units. They operate from a 12gr co2 cartridge. I bought an adapter at the paintball shop and and made an adaptor to connect to 1/2 water pipe.
These are early versions of the final unit
Notice the gauge reads to 1200 psi? I can typically get 600 psi to 800 psi in each charge. This specific unit is a version 3 proto-type. I designed a piston valve to work with a 1/2" water pipe system. A common sprinkler valve is also a piston valve. The best sprinkler valve is only good to 90 psi.
This is what the valve assembly looks like. The internal parts consist of an aluminum piston, and "O" ring, a heavy spring and a release valve all in a small package.
I used this set up to test the valve. The air-blower is used to release the pressure in the rear half of the valve. Piston valves operate on pressure equalization as long as the air pressure on both sides of the piston are equal the valve stays closed because of the heavy spring. The spring serves 3 functions, it holds the valve closed, it slows down the piston and keeps it from tearing the valve body apart and returns the piston closed after the pressure is zero. This particular setup used a 75 psi tank for the test