This is the firing tutorial, it describes the process for loading and firing potato guns.
Projectile-look at my page for ammo, the best stuff is citrus, or potatos, unless you want to make a metal round...I'll make a page for that sometime.
Fuel-hair spray, propane, butane, etc. Start with hair spray.
1. Load the projectile via the muzzle. If you are using a potato, or apple and have beveled the edge of the muzzle, just make sure that the fruit/vegetable covers all the way around and push straight down.
2. Push the projectile all the way down to the breach (where the barrel and chamber connect) but not into the chamber. Flip the gun over so you are now looking into the chamber.
3. Put in your aeresol fuel. If using hair spray (Aqua Net!), and an 8 inch/3 inch chamber just put in about a 1-2 second spray, if using a bigger chamber you may want ot use a little bit more. Adjust this as you shoot more. After you have played around with it for 20-30 shots, you'll find the optimum mixture. Putting in more does not necessarily give a better shot, as there might not be enough oxygen to induce combustion. If your first shot doesn't work, try using LESS fuel, odds are the first time you used too much fuel, a 6 second shot will not work, no matter the size of your chamber.
4. Point the barrel down range, away from any people, animals, cars, and things you care about. Make sure there is nothing valuable beyond your target, as it will be severely screwed up. The best thing to fire at is a brick wall, hill, or a piece of 1/2+in plywood. WARNING: a potato will go throught a piece of 1/4in plywood, I've seen it happen.
5. Hold on and press the ignitor on your gun. Go down range and check out the results.
Was that fun? Mail me with the results and I will tell you many a way to improve your potato gun.