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Although the behemoth known as a spud cannon is fun (see below), I also like the smaller, and safer, eponymous device which is basically a squirt gun except that you load it by shoving the tip into a potato, and you fire it by pulling a handle which compresses the air within the chamber enough to expel the little bit of edible starchy tuber. Not nearly as satisfying, but it's great for doing live-action Quake, namely because it won't actually kill anyone. It is to a blaster as a spud cannon is to a railgun.

Real-life Quake could be fun...


Spud Cannon

Also known as spud guns, these are frighteningly easy and cheap to make. My brother and I made one by taking a 3"x2" 'why' PVC junction (used to attach a 2" PVC pipe to a 3" main), putting about 3" of 2" PVC in the branch, putting a cap on the end of that, and affixing a Coleman lantern flint into the length of pipe. This became the handle and trigger. For the back of the 'why' (which is the mixing chamber), we attached a cleanout adaptor (used to attach a screw-on cap for the purpose of, well, cleaning out the pipeline), as well as a screw-on cap. On the front, we put a 3"x2" flange bevel (allows you to put a 2" pipe into a 3" fixture), and about 2.5 feet of 2" pipe into the bevel. Before attaching the pipe, we cut a pair of notches in the end and put a cut-off nail across it (this serves as a stop to keep the ammunition from falling into the mixing chamber). After that, we filed the tip of the pipe, making it sharp, so that it could cut a potato. Everything gets sealed tight (except the end cap, which needs to come on and off). We also took an extra piece of 2" pipe, cut a square hole in it, and attached it to the wrench-hold on the cap so that we could put it on and take it off more easily.

To load: shove a potato onto the end of the muzzle, turn it to cut it, and push it downwards until it's a round chunk in the barrel. Use a long stick (such as a broom handle) to gently push it down until it hits the nail. Turn it over, open up the back, spray in cheap hairspray (I recommend Aquanet, as it's cheap and very high in propane) for a few seconds, immediately cap.

To fire: aim, then with a flick of the wrist, spark the lantern lighter. You should feel a satisfying recoil, hear a resounding pop, and see a chunk of potato be propelled at about 120 MPH into low-earth orbit.

Great for ringing in the new year/millennium.

A potato cannon is a very cool thing. It is a device constructed of PVC or sewer pipe which is capable of launching common potatoes at speeds of up to 200 mph.

There are many variations, but the basic launcher is composed like this:
A combustion camber is attached with a bell condenser (type of pipe) to a barrel. The combustion chamber is short and fat, while the barrel is long and thin. On the end of the combustion chamber is a threaded cap. Poking inside of the combustion chamber is a gas grill lighter, a piezoelectric igniter. The igniter is affixed to a paperclip in such a way that when it is pushed, sparks are produced.

In order to fire the potato cannon, a potato is first rammed (with the aid of a ramrod) down the barrel. The end cap is unthreaded and hairspray or WD-40 is sprayed inside the combustion chamber. The end cap is the put back on, and the plunger of the piezoelectric igniter is pushed, producing sparks in the propellant filled chamber. Needless to say, a small explosion ensues which fires the potato out of the barrel, usually about 200 ft.

Potato cannons have been known to blow holes through doors, and several effects can be produced by combining the potato with flammable materials. The potato cannon is also known as a spud launcher, spudzooka, and spudgun.

If you want to build a potato cannon, plans and kits are available all over the Internet. Plans are usually free, and materials run about $20 US. Designs vary widely, from 14 foot behemoths to miniature launchers built with medicine bottles. I do not endorse any potato cannon building or firing activity. Be safe and have fun.
Potato Cannons, also known as Ethnic Cannons (or Polish Cannons, if you don't want to be politically correct about it) are one of the most awesome high school physics experiments ever.

In the good old days, you used to be able to make your own Ethnic Cannon out of beer cans and lots of duct tape, because beer cans were made of steel. DO NOT use aluminum cans, as the explosion required to launch the potato on its flight of glory will blast straight through the crappy aluminum like a hot potato through butter. If the idea of making your Ethnic Cannon out of cans is just too appealing to you, go to an Asian foods market, as many Asian softdrink companies still use steel cans. Otherwise, use a fiberglass tube.

If you want to have Phun With Physics, get yourself a plastic gallon icecream bucket. I recommend Blue Bunny. If you do not live in a country with gallons, just find a large icecream bucket. Maybe 2 or 3 litres, or so. Anyway, turn this bucket on its side and attach 2 ring hooks, one near the top, and one near the bottom of the bucket. Tie a piece of rope to each ring hook, and attach the other ends to a beam, or the ceiling. Something that is solid and not going anywhere.

    ==o===o==  Beam
      |   |
      |   |  Ropes (3 ~ 4 feet)
      |   |
    |-o---o-|
Top | >(:x) | Bottom
    |_______|

Now, set up some sort of grid on a large sheet of paper or a blackboard, and hang the bucket in front of this grid from a side view, as shown in the diagram above. Now, pack the bucket full of insulation, you know, that pink stuff in your walls. This will keep the potato from smashing through the back of the bucket.

Now gather your friends or students around to be observers. As the potato exists on the macroscopic level, the laws of quantum physics will have little effect, so this should not change the result. Get one person to aim the cannon into the bucket. Have this person level the barrel of the Ethnic Cannon with the center of the bucket, with the end of the barrel of the gun about 4 or 5 feet from the mouth of the bucket.

DO NOT hold the cannon bazooka style, on your shoulder, instead, steady it near your waist, like Rambo with an automatic rifle. This way, if the cannon does explode, it will not destroy your head, but will only sterilize you as bits of Ethnic Shrapnel and flaming potato lambast your genitals.

Fire the cannon. Your observers should watch the bucket swing back and up on the ropes like a pendulum. Have them note which grid mark the bottom of the back end of the bucket reaches. You can now estimate the force created by your Ethnic Cannon.

As a neat little bonus, the rapid accelleration of the potato by the Ethnic Cannon, followed by the rapid decelleration by the insulation-filled bucket will cook the potato nicely. I wouldn't recommend eating it, since the potato will also probably have little insulation fibers sticking out of it.

Thanks to Jerry Wilkes, the most awesome physics teacher ever. Have a happy retirement.

Potato Cannons, commonly refered to as spudguns, potato guns, etc, are typically made of two pipes, one being a reaction chamber and one being the barrel. The potato goes down the barrel, and the chamber is filled with Aqua Net hairspray or WD-40 or something like that, and it is ignited by a barbecue ignition.

THERE IS A BETTER WAY, FOLKS!

I will now tell the story of my friend Richard and I.

Its our senior year of high school, in I town I commonly refer to as Pleasantville, or Hell, and we're both on our school's ASB. We come up with the idea of shooting candy and t-shirts into the bleachers at the upcoming Renaissance assembly. The advisor liked it, and told us to spend whatever we needed to get it done.

Kick Ass.

We set to work. Richard gets ahold of a small 3000 PSI rated fire extinguisher for real cheap, and we set out to Ace Hardware to buy parts. A nice four foot length of PVC did nicely for the barrel, and that two foot high pressure air hose looks nice also... A couple of bushings here and there, and we're out of the store.

We are lucky enough that every sprinkler manufacturer in the world is located in our town, so we head down and buy a $90 solenoid valve rated up to 250 PSI. wow...

Radio Shack is next. Some nine volt batteries, wires, buttons, lights, and a project case and we leave. Back to Richard's garage.

If you haven't already figured it out, we mounted this fire extinguisher case onto my back, put the solenoid in line with a pressure gague, attached it all together with the electronics, and attached a barrel with a nice round button on the end.

Taking an air compressor, we hooked its hose to the fire extinguisher, filled the thing with compressed air, and had a very nice projectile weapon in our hands.

Sure, we used it at school at like 40 PSI, shooting candy and t-shirts into the crowd... but that thing shot a potato three times as far as ANY WD-40 cannon I've EVER seen.

A couple of neat little tricks to try.. Load the barrel with some powdered and mixed thick mashed potato solution, sit in the back of a truck, have someone ring a doorbell as you aim.. They open, you fire, mashed potatoes everywhere! Drive away as quickly as possible. Also, get some of the same pvc pipe you used to make the barrel, and cut off about four or five inches, fill it with water and freeze it. That thing will go through a brick wall.

Have fun, don't get hurt, and know that air pressure kicks ass!

A potato cannon or spudgun powered by compressed air rather than the combustion of a flammable gas or liquid.

It should be noted that all potato cannons are very dangerous.

Pneumatic guns can be much more powerful than their combustion-based counterparts. Several builders have reported ranges of three to four hundred yards. This increased performance is due to the higher operating pressure. Pneumatic guns operate at pressure of 40 to 100 psi. Combustion guns are believed to operate at pressures below about 30 psi.

Pneumatic guns are widely believed to be safer than combustion types, since they do not contain nasty stuff like fire and exploding flammable gasses. This Noder however, believes that the subject is open to debate. Safer or not, pneumatic guns are certainly more predictable and consistent. Combustion guns suffer from variation due to inconsistent loads of propellent, not-enough/too-much oxygen, differences of propellents, etc.

Most pneumatic cannons share the same basic design. Compressed air is contained in a pressure chamber. A valve opens to allow air to escape into the barrel. Air pressure pushes the projectile out the barrel at high speed.

The kinetic energy of the projectile can be roughly calculated like so.

KE = 1/2 * P * Vb * (1 + (Vc / (Vc + Vb))) - Pa * Vb

  • KE = kinetic energy of projectile (Joules)
  • Vb = volume of barrel (meters^3)
  • Vc = volume of pressure chamber (meters^3)
  • P = initial absolute pressure of chamber (newtons/meter^3)
  • Pa = atmosperic pressure (newtons/meter^3)

The above calculation make the following assumptions and ommisions:
  • Ignores friction of the projectile in the barrel.
  • Ignores friction of air moving through the valve.
  • Assumes isothermic and adiabatic expansion.
  • Ignores gravity.
How to make your very own Spud Mortar

THIS IS PROBABLY A BLOODY SILLY THING TO DO, SO IF YOU DAMAGE YOURSELF WHILST DOING THIS DON'T SAY I DIDN'T WARN YOU

Equipment

1 x PVC spaghetti tube (tall cylindrical tube used for storing spaghetti)
1 x large can of hairspray
1 x rolling pin (or any suitably stout prodding device)
A quantity of large potatoes, and
1 x gas hob (preferably one that can be rigged up outside)

Construction and Firing

  • Place the spaghetti tube on the un-lit gas hob

  • Spray hairspray inside said tube, until a inch deep layer is formed

  • Ram a potato into the tube, using rolling pin, ensuring a tight fit all round

  • Light gas hob, and run like fuck

I've only ever seen this monstrosity constructed once, and it managed to fire a reasonably large spud high enough to bounce off the roof in a TV studio, so I'd advise you didn't let it off inside unless you want to knock a hole in the ceiling

Sources include
My memory of an episode of Jeremy Clarksons chatshow broadcast a couple of years ago

A device similar to a potato cannon, in that it fires potatoes large distances. It is far superior, and in this node I'll give you a quick guide on how to build one.

The principle behind a pneumatic air cannon is pretty simple. You have one tube of PVC pressure pipe that holds compressed air (usually to the order of 100 PSI). It is separated from another pipe by a valve. When the valve is opened, the air is released into the second pipe, firing the projectile (usually a potato, but other things can be used).

They are relatively cheap to make. Mine cost about NZ$60 (US$30), but your mileage will vary widely depending on your location, and your supplier. All parts are available at your local plumbing supplies store, except for the tyre valve, which you should get at a mag wheels store.

The cannon described here is a basic "artillery" style one. There are many advances made on it, but this is the cheapest. I measured the range of mine as 130 metres!

What you need

  • 2 one metre lengths of 50mm PVC pressure pipe. This must be able to sustain pressures of at least 125 psi, else it will explode!
  • Valve mechanism. This consists of a 25mm ball valve, and adapters to connect it to the 2 pipes.
  • 1 endcap. Again pressure pipe
  • Car tyre valve
  • Really good solvent.
  • A pump. Not a foot pump The best sort is a 'T' type, that you push down on to operate. A bicycle pump probably won't do the trick unless you're really strong. One's designed for car tyres are best. Alternatively you could use an air compressor.

Construction

Drill a hole near the end of one of the pipes, and attach the valve, so that air can be pumped into the pipe.
Glue the endcap on the end of this pipe. This is the pressure chamber.

Attach the adapters to the pressure chamber and the barrel (the other 50ml pipe). You'll have to work this our yourself as there are heaps different possibilities as to how this works. Basically, you want the valve to be in-between the two pipes.

Once the glue is set, it's ready! You are now ready to fire potatoes and other vegetables large distances.

Operation

Get a potato of a size that it covers the entire end of the barrel. Jam it down to the bottom of the barrel with a broomstick.

Pump up the pressure chamber as much as you can.

Open the valve. You should hear a thoomp sound, followed by the scream of an innocent bystander you hadn't seen.

Getting the Most from Your Cannon

Now that you have your cannon, it's time to tweak it. The design you have is very basic, and there are many advances on it you can make.

Firstly, sharpen the barrel. This makes the potatoes cut better, producing a better seal.

Check all your joins. If there are any leaks, fix them with glue. If they are threaded joins, get some plumbing tape to seal them.

One of the most common things I've seen on the internet is to use a solenoid sprinkler valve instead of a ball valve. This opens much faster, and is electrically operated so you have a trigger. Keep in mind this will double the cost of your cannon.

Make the pressure chamber sit under the barrel. You can achieve this by attaching some elbow joins around the valve. This combined with a solenoid valve means you can carry it around like a gun!

You can look around for more information on different designs. The internet is rife with information, as there are many cannon fanatics out there.

Different Ammo

After a couple of weeks, you'll find that potatoes don't offer the same entertainment that they used to. Now it is time to use different ammo.

When looking to created more destruction, ice is your friend. A frozen orange will cause massive damage at high speed. Get a small portion of 50 ml pipe, and stick and orange or other food product in there. Freeze it over night. It will fit in your cannon, and go through walls.

While on the subject of ice, frozen water balloons are wicked as well. Lube it up, as the rubber will create a lot of friction.

Water (in liquid form). This is fun, half fill your barrel up and it will vaporise the water, giving you a refreshing mist on a hot summers day.

Confetti. Stick some confetti in there and shower your neighbourhood with happiness.

Safety

OK guys be sensible. These things are pretty safe, provided no one is in front of the barrel . I'm not exaggerating, this could kill someone if fired at close range.

Don't do what I did and do you're first test fire straight up in the air. It comes back down and it comes back down fast.

Keep it out of reach of irresponsible morons. The only exception to this rule is if the moron in question is you.

Oh yea, and these are illegal in lots of places, so don't get caught with it by a police officer. If they don’t know what it is they may mistake it for a really weird bong.

Have fun and don't damage/maim/hurt any thing I wouldn't

It's a myth that you can put too much propellant in a potato cannon and have it blow up. The optimal ratio of propellant to air, called the stoichiometric raio, is when there is exactly enough oxygen for all the propellant to combust. If you have less propellant in the combustion chamber, you'll get decreased power becuse there's less propellant to burn, if you have more, you'll lose power because there's not enough oxygen to burn all of it.
Pressure-rated PVC plastic is probably the best allround material for building spudguns. It's relatively lightweight, guaranteed to hold pressure (the ratings also have generous safety margins) and a correctly done solvent weld is just as strong as the rest of the pipe.

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