im building a potato launcher and it aint working? help!?

Question

i have made a crude potato launcher using pvc pipe, screws, 2-core speaker cable and a car battery. i have screwed two machine screws into the pipe so that the ends are very close (but not touching) and have the cable wrapped around the screws and hooked up to the battery at the other end. The idea being that i fill the pvc pipe with aerosol, turn on the battery, electrical charge travels up the cable, to the screws and jumps from one to the other, igniting the gas and launching my potato. my problem is im not getting a spark, what am i doing wrong? (the cable is touching both the pvc and the screws, would this create a problem)

Answer 1

possible sources of error:
1) distance between screws is too far apart
2) wire is too flimsy
3) battery is too weak
4) you need to store a charge - use a Tesla coil design to store up a big enough electric pulse before letting it through the wires

aerosol isn't all that good either, use a gasoline/rubbing alcohol mixture

also if you want a better bang to it, get some KNO3 and put some of that in there

Answer 2

You actually only need a 1/4 inch hole in the side of the tube. Ignite the escaping vapors with a butane lighter. Those lighters with the super-long reach are great for that sort of thing.

You need more voltage to do it with an arc. 12 V won't just a signifcant gap. Rig up a automobile ignition coil. Alternately, you could explode a very thin wire with the car battery. That only requires lots of amps, which car batteries are good for. Take apart an old power cord and use a *single* thin filament of the multifilament copper wire. Screw it securely across two studs inside the tube. You have to replace the wire between shots, but it's quicker to set up than an ignition coil.

Answer 3

Good idea, but you need more air in tube,oxygen gets it off on a bang.