by David LeMieux
Fully Loaded Air Cannon
Nearly fourteen years ago I was in a musical performance group called "Thump." We were a bunch of high-school students ripping off, er, paying homage to Stomp and Blue Man Group. We played mostly percussive arrangements and put on, what I would call, a pretty rockin' stage show.
My job in the group was Lighting and Effects manager. I didn't play an instrument but I ran the lights, help make the tickets, ran the website, and handled other duties to help make the performance more professional. One project that I had for our second round of shows was to make an air cannon to shoot paper streamers across the audience during a particularly impactful part of the show. Air cannons of this sort were nothing new, but we didn't have a budget and so everything had to be made or acquired on the cheap.
I studied the basic mechanics of air cannons for a while. I consulted with local college and high-school physics professors to make sure my design was sound and would work. When I thought I had a good design I built a prototype. I used a small compressed air tank, some pipes, plumbing, an air gage, and a large aperture manual valve. I had wanted to use an electric valve but they were too expensive. After a few test runs I figured out the right way to pack it, how to add a paper cap at the end to ensure proper pressure distribution, and how to fire it on cue.
The night of the first performance things went better than expected and the air cannon effect provided an exclamation point to the already great performance. It went so well that as a group we decided we wanted two for the next night. The stage was pretty wide and the air cannon only effectively reached half of the audience. We wanted more coverage. Since I already had a working design I went out and bought all the same parts and put them together in the same way, or so I thought.
The second show was a few hours from staring and so I began to prepare the cannons. I packed them carefully with rolls of paper confetti. I checked the valves and all the connections. Then I asked a friend to fill them up with air to a predetermined pressure. I would have done it myself, but since I also ran the lights and other effects I needed to get those set up before people started filing in.
As the final number came we got the cannons in to position. We quickly reviewed firing them (I had been doing it on my own the night before, and this time I needed help) and we got the timing down with a non-firing practice. We armed the cannons and got in to position. The cue came, we turned the valves — and nothing.
"Well, at least they both failed together" I thought when I saw the absence of paper streamers, but I was wrong. The cannon on the far side, controlled by my friend, didn't fire. I forgot to tell him that the air gage was stuck and so when he was filling them he thought it already had air in it. My cannon had fired, but it took a few seconds for me to realize that I was left holding only half of it. The entire barrel, a long length of 3-inch PVC pipe filled with confetti rolls, had rocketed in to the audience much like an untied ballon when the end is let go. The barrel weighed anywhere from three to ten pounds. I instantly remembered I had failed to add the last application of PVC glue. The result was that when I opened the valve it filled the barrel with air then sent it in to the audience like a rocket. The barrel cleared a four foot pit wall, sailed over the aisle, and back many rows in to the audience. I never asked how many exactly, but given the angle of launch, it had to be at least ten.
Luckily it "landed" in the lap of a friend and not on the head of a stranger. Actually, it landed in his girlfriends lap and she was okay. I could have seriously injured or possibly killed someone.
I don't know what happened to those air cannons. They were at a group member's home for a bit. I left for college and so did everyone else. They were probably thrown away. Sometimes I wish I still had them though. Those kinds of projects, in high-school, college, and throughout my life have been key in forming my education and experience. I learned so much from almost killing someone with a failed air cannon than I wish everyone could have similar, if perhaps safer, experiences of their own.
Is "killing" hyperbole? Sure, but how I felt in that moment I was afraid I had. I imagined all the worst scenarios.
I am grateful I had the opportunities I had when I was younger and it is a personal dream of mine to be able to enable others to do so in the future.