The Aussie Mortar
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The Aussie Mortar
This device is very easy to build, quite safe (if you keep your distance) and marvelously noisy. It is simply an electronically fired mortar of surprising power, and can be modified in terms of power and manufacture to suit your specific environmental requirements.
Here's what you need:
1 4ft length PVC tubing, slightly larger in diameter than a soft drink can
1 soft drink can (the projectile!)
1 roll duct tape
1 tin black powder (FFF - the superfine stuff works best)
1 bunch of plastic 35mm film canisters (available free from your friendly
1 hour film processing lab)
1 Polaroid flash bar (you know the type..
they have ten magnesium wool bulbs mounted within a plastic
shell, and probably available from the same friendly photo lab)
1 electric drill
40ft twin-strand insulated wire (the longer this is, the
further from the detonation you are. Think about it.)
1 nine volt battery (no, don't press it on the end of your tongue.)
1 lump of wood
Making the charges:
Drill two small holes in the bottom of the film canister about half
an inch apart. You don't necessarily need an electric drill to do this,
but it makes the process appear more technical. You can wear a
white lab coat too, to complete the mood. Break open the Polaroid
flash bar and extract all ten bulbs, being careful to leave as much
wire as possible extending from each bulb. Put one of the bulbs
into the canister and insert the wires through the drilled holes. Put
a small strip of tape over the holes to seal them and hold the bulb in
place, leaving a bit of the wires exposed. Fill the canister with
black powder (or half-fill, depending on how game you are. Try one
of each for starters.) and place the cap on top. I usually connect
about six inches of insulated wire to each of the protruding bulb
wires to make it more manageable to handle, because the next step
is to wrap the entire device (Hey... a device! It's starting to sound
like the Manhattan project!) in duct tape. Use your own judgement
on this, but ten or so thicknesses is about enough to contain the
blast pressure effectively. Anyway, you're now the proud owner of a
mortar charge.
Making the mortar (this is the easy bit):
Dig a shallow hole in the ground and place the lump' o'wood at the
bottom. This acts as the baseplate for the mortar. Connect the 40ft
insulated wire to the wires protruding from the bottom of the
charge. (Make sure the other end of the wire is nowhere near
electrical instruments, such as your cat playing with a styrofoam
cup on a nylon carpet.) Put the charge on the wood and place the
PVC tube over it and fill in the earth around it. You can rest the
tube against something at roughly an 80 degree angle. Height of the
projectile rather than distance is more impressive. Wrap some duct
tape around the base of the soft drink can so it fits not-quite-snugly
in the tube, i.e. slides down just like a real mortar projectile. Half
fill the soft drink can with water (for momentum) and drop it in the
end of the tube.
The fun bit:
Stand back and connect the wires to the battery terminals. I think
you can guess the rest. I've had one reach roughly 300ft. Very, very,
cool. The reason I use such a loose base on the mortar is that the
earth tends to absorb extraneous blast and no damage occurs to the
PVC tube (surprisingly). You could make one with a sealed end,
but this would have to be of all-metal construction hence costly,
heavy, and potentially (more) dangerous.
Anecdotes associated with this:
1: Wandering around the hardware store with a soft drink can,
inserting it into all manner of pipes and tubes to find the best fit.
Salespeople very bewildered.
2: When visiting Carlsbad Caverns in your wonderful country, I found a
discount bin of Polaroid flash bars at the counter of the souvenir shop.
$1.50 each. I bought heaps. Salesperson very bewildered again. Hey, if you're
ever there, I left plenty behind. The caverns are kinda groovy to look at as
well.
3: Made a fuzed charge for the projectile, timed for an air
burst at its apogee (I had to look that word up). Fast fuse... blew the
ever-loving shit out of the tube. I would have laughed harder if I
wasn't left with a one-foot mortar with which to finish the day's
entertainment.
Anyway, have lots of fun with this. It's not expensive, you can make
heaps of charges if you get a production line going with a few
friends, and it is actually quite safe if you avoid the explosive
projectile idea (unlike a certain individual who shall remain
nameless). I eventually did get one to blow in mid-air. That was
VERY impressive.
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