This is the first launcher I built for myself, as part of the set of original spudguns I built as Christmas presents. This launcher has undergone a few improvements over time, but the basic layout has remained the same. This is a good basic launcher, and IÕve had a lot of fun with this thing.
Chamber construction: I built the patriot with a chamber volume that is 1.5 times as large as the barrel volume, so itÕs very loud. The chamber has a volume of approximately 2900ml, and is made from pressure rated 4Ó PVC pipe. The barrel is about 5 feet long and is made from pressure rated 1.5Ó PVC pipe. The barrel has a bevel on the tip for cutting spud plugs from potatoes. Then a ramrod must be used to push the spud all the way down the barrel, so this is a muzzle loader.
Ignition: The ignition source is a pushbutton BBQ grill igniter. I mounted this igniter inside a piece of 3/4Ó PVC pipe, and then attached this to the chamber using electrical conduit straps. The ignition wires are concealed by the 3/4Ó pipe, except or where they attach to the electrodes. I used four machine screws for the electrodes, and arranged these screws to create two spark gaps inside the chamber. Each of these screws is held in place by the tight fitting PVC holes drilled in the pipe; and for added safety I also used washers and nuts to firmly hold the screws in place.
Fuel: I originally fired this gun using Right Guard deodorant as the propellant. However, I have added a standard female quick disconnect, so that this launcher can be fueled by my detachable propane meter. Photos of the propane setup can be seen on the chrony page of my website.