The Halitosis Howitzer

[mklotz]

If you want to get people's (especially younger people) attention at your next engine show or backyard barbecue, you just can't beat a small explosion. I've learned that the nanny-state frowns on 1" smoothbore, black powder cannons firing ball bearings through tree trunks so I built a safe cannon (actually a howitzer) that doesn't sacrifice that head-raising CRACK needed to get yourself noticed.

The top from a soft plastic 35mm film canister is screwed to a block of wood. The piezoelectric sparking element is cannabalized from a commercial butane barbecue lighter and its two wires led through holes in the block to emerge into the cannister top (see detail in second photo. Arrange the wires so, when the piezo button is pressed, you get a nice juicy spark across the wires.

Fuel is provided from a pocket-sized cannister of aerosol breathspray. Spray a bit into the film cannister, immediately mount the cannister on its top on the howitzer, press the piezo button and the cannister will fly twenty to thirty feet with a very satisfying BANG!
The plastic film cannister won't do any damage if it hits something and, with the small amount of propellant, this is actually a pretty safe device.

Aerosol breathspray works well. It contains alcohol and the propellant is butane so it's fairly easy to get a proper mix of propellant and air in the cannister. Non-pressurized breathspray works too but you'll need to experiment a bit to get the right air-fuel mixture. Hairspray works well but leaves a sticky residue. Experiment - but resist the urge to try acetlyene.

If you have younger kids, ensure that they understand that this is Daddy's toy and lock it securely away when not in use.

Oh, one more thing. When testing the piezo element, don't touch the wires. DAMHIKT.