Ron's potato cannon
Back in May of 1998, my co-worker, Ron Harding built a potato cannon. A basic potato cannon consists of various pieces of ABS piping bonded together, with a chamber on the back to hold the combustible gasses and a long, narrow pipe as the barrel through which the projectile, usually a potato, is launched.
The product had caused us much grief during development, so destroying some by shooting a cannon at them felt right.
Note the propane cylinder for fuelling the cannon in the photo. The cannon is fired by igniting the gas with a spark plug. Ron is using a barbecue lighter to create the spark.
This shot was very good timing by the photographer. Note airborne fragments!
The cannon has already recoiled back by about 30 cm. I suspect the object in the sky at the top center is the actual projectile, based on where we found it afterwards.
The projectile was a rectangular hardwood 'plug', with shop towels balled up behind it to provide a good seal. The blue haze at the impact point is most likely the shop towel.
We continued to shoot at successively smaller pieces of pagers. Eventually, some of the surface mount electronic components became embedded in the hardwood projectile. By the time we were done, each circuit board was broken into at least two pieces.
What was left after two firings
The hardwood plug also had the great advantage of being reusable, so we weren't limited by running out of potatoes.
I tried to persuade Ron to try an oxygen/propane mixture for fuel instead of just propane and air, but couldn't convince him. So to try that out, I had to build my own cannon