After yesterday's incident wherein I inadvertently fired my potato cannon using only the residue of the PVC priming agent as fuel, it occurred to me that a potato cannon could be considered a firearm. There are laws against discharging firearms within the city limits, so that sort of slowed down the testing process, that and the fact that Jean doesn't use Aquanet.
You see Aquanet is the Hoyle-recommended fuel for potato cannons. As you may have noticed, the creation of these devices is very much in the spirit of McGyver. You make use of the materials available. Aquanet is just an aerosol hairspray. As with many aerosols, the propellant is flammable, and that is what makes it useful as a fuel for the potato cannon.
In my desire to test my potato cannon, I was required to do some deep thinking and make some fine distinctions. Putting the potato in the end of it was out of the question. That would make it a firearm. However, if the potato is not in the end, it is not a firearm; it's just a fire starter because it is not propelling anything. With no potato it is a fire starter, with a potato it is a firearm, and with a cap on the end it is a fire bomb.
I tried using Jean's sprayable Pam. It didn't work, and I wondered if, perhaps, sprayable Pam uses nonflammable CO2 as propellant.
It then occurred to me that it might not be necessary to use an aerosol. Given the fact that the primer worked and it wasn't an aerosol, this seemed plausible. I looked for isopropyl alcohol, but we didn't have any. I did have rum left over from Christmas 2 or 3 or 4 years ago. I soaked a piece of cotton wool in it and rubbed it on the inside of the combustion chamber. I couldn't get that to work. Maybe the concentration of alcohol in the rum was too small or maybe I just couldn't convince myself to use enough.
I put it aside for the evening after that. I resolved that I would get Aquanet when I bought donuts on my way to Opolis for church this morning. Then, on my way out the door this morning, I noticed a can of windshield de-icer on a bookshelf in my office. I went outside, sprayed the inside of my combustion chamber briefly, closed the lid, and clicked the button.
It didn't make the boom of the day before, but rather the sound of a Coleman stove lighting. I felt warmth coming from the end and it dawned on me the thing was on fire. I smothered out the flame, loaded up the cannon, the spray, and a potato into my car, and headed to Opolis. There I conferred with Perry who is learned in the lore of the potato cannon. He was able to offer me sound advice.
Later this morning I was able to test the cannon with potato in place. The projectile went 100 feet and it sounded like a 22-rifle going off. This is not a toy. This is not for inside the city limits.