Rejoice! Biker season is more than halfway through. For months now, hundreds of leather-clad knights of the road have been mounting their silencer-free steel-and-chrome stallions and setting off at first light into the countryside in search of suitable stretches of Tarmac. And, as dawn breaks over villages and hamlets, residents are woken by the nerve-jangling scream of a hundred high-powered Kawahozki 900s as they blast along the winding A roads, their riders unaware of – or unconcerned by – the sound footprint being dragged through rural dreams.
As one of the awoken, I normally spend a couple of hours dozing and planning my revenge. One dastardly scheme involves a huge version of table skittles, called Swing the Badger. On the side of the road, attached by a long rope to a tall pole, is a road-kill badger – the riper the better. The bikers are the skittles. You can guess the rest. This plan has been abandoned, not least because the supply of badgers seems to be diminishing. My latest fantasy weapon is the potato cannon, a tool much discussed by teenage-minded types, but never actually seen in these parts until now. Thanks to the wonders of the internet, and video-sharing websites in particular, any fool can find instructions on how to build one of these legendary weapons of mash destruction.
The concept is simple. You need a barrel (long and thin)and a combustion chamber (shorter and wider) – PVC pressure pipe is light, strong, and easy to cut and glue. You need some propellant, something that will ignite easily and provide the explosion within the chamber. Hairspray is perfect. A way of igniting the propellant is needed – an adapted barbecue lighter is just the thing. And, finally, a projectile: the humble potato – easily shaped to fit into the barrel, and nice and juicy to ensure smooth departure.
The hardest part of the project is sourcing the PVC pipe. There’s something about a big builders’ merchant that is particularly intimidating. You have to be the complete expert in your trade or the utter novice; anything half-way, and they’ll spot you a mile off, and treat you accordingly. “Three feet of your finest PVC pressure pipe, my good man,” I cried in at least five institutions around the south of England. “We’ve only got it in lower aggromulated version. And in six-metre lengths. And no, we can’t cut it to size [pause] Mate,” was the usual reply. At least five times I came away empty-handed because a six-metre length would be a bit awkward in a VW Lupo, and I haven’t a clue what aggromulation is.
But after a few minutes on the internet, I found the perfect supplier. The nice people of the East Riding Koi Company (www.koicarp.net) were delighted to supply all the pressure pipe and reducers I needed, cut to size, next day delivery. They were also keen to hear whether my project was successful – they want to control the pigeons in the warehouse.
Once I had the parts, it took only a couple of hours to as-semble the cannon. At least, I think it was only a couple of hours; the fumes from the solvent cleaner and glue are very strong, and you can, like, wow, man, find yourself, like, tripping. Once you’ve finished hallucinating, it’s worth leaving for several hours to let your glue set – and get some fresh air.
Final testing took place in a meadow, with the cannon inside a metal box mounted on the front of a tractor – just in case. First firing was with hairspray only: a quick squirt through the threaded cap into the chamber gave a nice whomp when the button was pressed. For the next a Desiree was pushed just into the nozzle. All seemed well, so the spud was rodded down the barrel and the hairspray given just a hint more squirt – but still not much more than a second. The result was a stunning crack and the spud flew over 120 paces.
The time had come to go hand-held. I wrapped the chamber in duct tape (again, just in case) and launched from the hip. With a satisfying thump and a nice handful of recoil, the potato flew into the long grass – again, well over 100yd.
What’s next for the potato cannon? It’s possible to get rifled PVC pipe, which will work wonders for projectile stability. Putting half a dozen together with a sequenced launching device could be fun. How big would it have to be to sort out the summer balloons?
Until then, though, a word of advice. If you’re a leather-clad biker loon hurtling along the A272 at max volume, keep an eye out for a grey pipe protruding from the hedgerow. If you see one, you might want to throttle back a bit.
Hacksaw, fine sandpaper, handfile, drill, small
drill bits, screwdriver, lots of rags
Materials, cost, source
The East Riding Koi Co have had so many enquiries about the spud gun piping that you can add the whole kit to your cart at once! Scroll to the bottom of their PVC pipe page
PVC pressure pipe – 39in of 11⁄2in diameter, East Riding Koi Co (ERKC), £8.12 for 3 metres
PVC pressure pipe – 39in of 4in diameter, ERKC,
£31.56 for 3 metres
4in socket x 2, ERKC, £12.24
4in to 2in reducer x 2, ERKC, £10.65
2in to 11⁄2in reducer
x 2, ERKC, £3.52
Socket/thread converter 11⁄2in,
Threaded end cap 11⁄2in, ERKC,
PVC cleaner fluid, ERKC, £9.32
PVC solvent weld glue, ERKC, £7.34
3in 8-gauge screws, local hardware shop, £0.24
Barbecue lighter, Homebase, £5.99
Hairspray, Granny Flindt, free (if no granny to
hand, try Boots)
All free from the farm workshop: length of wire;
soldering iron/solder; insulating tape; duct tape
1. Cut the pipes to length and as square as you can
– can be difficult with a hacksaw, so ask your nice local friendly farmer if
you can use his bandsaw. Round off the edges with fine sandpaper. The muzzle
should be filed down to a sharp edge, so that the potato is cut to the right
size as you jam it on the end.
2. Work in a very well-ventilated area. Clean all
parts to be joined with solvent, then glue all sections together except the
back of the front socket to the front of the chamber tube. Follow the
instructions on the glue pot carefully to make sure you end up with a gas-tight
seal. Be aware that the glue works very fast, so you might only just have time
to “connect and twist a bit” before it sets.
3. Drill two holes slightly back from the front edge
of the rear socket, just big enough to ensure that your two screws fit tightly
in them, and angled so that the screws’ tips will end up half an inch apart in
the middle of the chamber. Prise open the barbecue lighter and find the two
wires that lead to the front tip. Join these two wires to the tops of the
screws using solder and about a foot of extra wire.
Use lots of insulating tape on the joins and connections. There should be a
healthy spark if you press the lighter button. Adjust the screw depth if not.
BEWARE: there may be no spark, but the piezo effect “stores” the spark until a
contact is possible. You can get a nasty jolt if you allow your fingers to act
as the conductors.
4. Glue the last join together. BEWARE: at this
stage, the chamber will be full of solvent vapour. If you press the ignition button,
a very healthy explosion will result. My gun-shy Belgian shepherd is still
under the bed, quivering.
5. If you’re happy that
you’ve let all the glue set properly, try your cannon. Jam a potato on the end
of the barrel, which should then cut it to perfect size. Push down the barrel
with a stick or broom handle. Squirt a short burst of hairspray into the
chamber via the threaded end cap, and do the latter up tight. Cry something
dramatic like “Fire in the hole”, and press the ignition. Failure to work can
be down to too little spray, too much spray, too little oxygen in the chamber
(allow it to ventilate between fusillades) or gummed up screw tips.