The hair spray is ignited by the spark arcing from one bolt to the other, and the resulting explosion sends the potato up and out of the cannon's barrel, flying into lunar orbit without any help from NASA.

What Actually Happened

The PVC cannon's construction was fairly straight-forward, since we all had a pretty good idea of what we were doing. All of us had played with PVC artillery back home, and we all had different ideas as to how the cannon should be constructed. The net result of our planning was a cannon that was powerful enough to punch through a street sign with a pipe fitting, but light enough to carry at high speed if the need for a quick exit arose.

After the glue had dried, the cannon was ready to be tested. Our first test involved filling the blast chamber with hairspray, then firing it without anything loaded. The rather interesting result of this test was a large plume of flame spewing out of the end of the cannon's barrel, accompanied by a noise that sounded like the yelp a puppy makes when it has just been accidentally stepped on. The noise echoed off into the night, probably waking up most of our apartment complex.

Our second test involved launching something soft from the cannon. One of my socks was the next lucky contestant, so we filled the blast chamber with hairspray, rammed the sock down the barrel, and fired. The cannon fired the sock with a MUCH louder boom, and my sock, now on fire and travelling in a nice arc, sailed a short distance and then landed in the pond at the middle of our complex with a quiet plunk.

It was finally time for the main event. I once again filled the blast chamber with hairspray, but this time an honest-to-goodness potato was rammed down into the cannon's two-inch-wide barrel. I pointed the cannon off of the second-floor balcony of our apartment and into the night. We all held our breath.

What happened next is probably still being told as a story by the people in the next apartment complex over, since I later found out that our little friend actually dented the roof of their leasing office upon landing.

The quiet click of the sparker was completely drowned out by the Earth-shattering BOOOOOOOOOM of the cannon. The gases inside the blast chamber expanded, winning the battle with friction, and the potato shot into low Earth orbit. The spud sailed high into the air, with a cruise speed somewhere around mach one, and landed in the apartment complex next to ours. I was knocked backwards from the blast, my ears ringing, and slammed into our sliding glass door. The next morning all of our neighbors were complaining that someone in the neighborhood had "fired a gun in the middle of the night", and I had a black and blue mark of my leg that was about the size of the bottom of a coffee cup.

After the cannon's "trial by fire", it went on to bigger and better things. One evening at a soccer game at our college, all of the players stopped playing and just looked up at the sky when a potato came sailing out of the woods with a deafing BOOOOOOOOOM and flew over the soccer field. Another time, a pair of underwear was tested to see if it was "tough enough to handle Earth re-entry" when it was launched high into the air, landing in the highest limbs of a tree (where I imagine it is still hangs today).

Lessons Learned