In the following section I will attempt to explain exactly how my latest launcher works without the use of math(yay!). Everything I can think of will be covered here but if I get enough questions about certain things I will update as necessary.
A pneumatic launcher basically consists of three components: the barrel, the valve, and the air chamber. When you pump in air into the air chamber you are pressurizing it. In simple terms, air does not like to be at a higher pressure than normal, so it will try anything it can to equalize with the air around it. This is why using inadequate piping could cause the gun to explode since the air inside is pushing with more force than the pipe can handle. A pneumatic launcher harnesses this pushing power of the air by controlling where the air goes. This is where a valve comes in. A valve releases the air and directs itís force into the barrel. As the air rushes through it encounters the projectile. Air will find the easiest way to get out so it will push the projectile along with it until it reaches the end of the barrel. This is why it is super important to make sure you have a tight seal around the projectile so the air doesnít rush past it.
The breech loader makes it easy to load ammo quickly. Basically the barrel is broken down into three parts. We will call these the back, middle, and front. The back part connects to the valve. The middle part consists of the magazine clip where the ammo is stored. The front is where the ammo travels to pick up speed. So basically the ammo travels from the middle section and continues through the front. Theoretically a longer barrel makes the projectile shoot faster since the ammo has more time to accelerate. However we must take into consideration the drag effect the barrel has on the ammo which slows it down. It is difficult to say what the perfect balance is at this moment since I myself am still trying to figure this out. A 31" front barrel and the 5" middle barrel comes out to 36" or 3 feet. This is what I deem to be the longest it could be before it starts getting impractical to carry. You may experiment with different lengths and let me know how it comes out.
The barrel support simply does what itís name implies: supporting the barrel. When you make this part you have to make certain that it lines up correctly with the barrel. If, when youíve slid the barrel through the support, the end of the front barrel does not align with the back of the barrel, you must make adjustments. If itís too high or too low you should adjust the area that contacts the air chamber to make it flat. If it goes off to the side simply turn it so that it faces correctly. Remember, the straighter the barrel the less problems you will have with the gun later on.
The air chamber is made of the pressure tank, tire valve, and pressure gauge. The larger the pressure tank is, the power your launcher will have. However the larger it is the more you will have to pump to get it to an adequate pressure. I cannot tell you what a perfect tank size is because I am still testing it myself. The tank size for my launcher is about 75 cubic inches. This is the minimum size for any launcher. You can try testing larger tank sizes and see how long they take to pump. Test the time it takes to pump with the pump you intend to use in battle.
The main valve of the launcher is what connects the barrel to the air chamber. Inside the solenoid valve there is a diaphragm made of rubber blocking the pathway to the barrel. The pressurized air also fills into a small chamber above the diaphragm, causing it not to cave in and release the pressure by keeping it sucked up. Basically the solenoid, a magnetic rod that is moved up down using an electric pulse, releases pressure in the small chamber above the diaphragm. Without pressure sucking on the diaphragm, it collapses down and opens up the airway to the barrel. Solenoid valves are the best kinds of valves for water balloon launchers because they open really fast (unlike ball valves which open slowly and waste a lot of air), and they are very compact (unlike a dump valve which is technically a better valve but it is way too big). On a good valve, such as my RainBird Professional, the valve comes complete with a manual bleed, which helps relieve pressure but is NOT to be used as a mechanism to operate the valve. I learned this the hard way when I used the manual bleed to operate my launcher and it eventually broke since the manual bleed is not meant to be used on a regular basis. On my valve there is also a manual on/off switch for the solenoid. This is a very useful item because it can be used regularly, and it is in the perfect position when youíre running with the launcher and you want to keep your finger on the trigger. I only use the electric push button when Iím in Sniper mode and want as much accuracy as I can get.