Introduction: Air Powered Potato Cannon

Picture of Air Powered Potato Cannon

I had to build a potato canon for a science project and needed one where I could get a consistent launch force. The typical hairspray cannon would not be appropriate for this purpose so I constructed this air powered launcher as a modified version of Pnewton's Petard from the excellent book "Backyard Ballistics". Typical results were a range of over 300ft using a weight, nonsealing projectile, I am sure a potato would go much farther.

Step 1: Materials

Picture of Materials

The materials needed for constructing the air cannon are as follows:

·shaping file
·22-inch length of 1½-inch diameter schedule-40 PVC pipe
·1.5-inch diameter male-threaded PVC pipe adapter
·PVC primer
·PVC cement
·Teflon pipe tape
·1½-inch diameter female-threaded PVC pipe adapter
·1½-inch diameter to 3/4-inch threaded PVC reducing bushing
·Electric drill with various sized drill bits
·1 rubber-coated, narrow-diameter, replacement-tire air valve
·2 3-inch-diameter PVC end caps
·2 9-inch-long pieces of 3-inch diameter Schedule-40 PVC pipe
·3-inch x 3-inch x 1½-inch PVC tee connector
·3/4-inch diameter short iron pipe nipple
·3/4-inch ball valve (It has also been suggested that a pneumatically modded sprinkler valve would allow for a faster and there for more powerful launch. I have no experience with this so for the sake of this article we will use the ball valve.)
·3-foot length of 1-inch diameter wooden dowel or broom handle
·Foot-stabilized air pump

Below is the diagram and the assembled materials.

SAFETY NOTE: I have received several comments regarding the use of Cellular Extruded Piping. In short - don't use it. It is not meant to deal with air pressure and could explode violently producing hundreds of deadly shards. I have not had this occur yet but if at all possible please use a better piping.

Step 2: Construction

Picture of Construction

The construction of the launch apparatus (see below for a diagram) is as follows.
Attach 22-inch-long pipe to the 1½-inch male pipe thread adapter using PVC cement.
Attach 1½-inch female adapter to 1½-inch to 3/4-inch reducing bushing using PVC cement and allow to cure.
Screw male pipe thread adapter assembly to female pipe thread adapter assembly carefully.
Drill hole in one 3-inch end cap the diameter of the tire valve. Insert the tire valve into the cap.
Attach both 3-inch end caps to 3-inch diameter pipe with PVC cement.
Use solvent weld to attach the 3-inch pipes to the tee connector.
Take the second reducing bushing and attach the 1½-inch opening to the tee connector with PVC cement.
Wrap the heads of the 3/4-inc pipe nipples using Teflon pipe tape.
Insert the nipples into the ball valve (or as it has been suggested the pneumatically modded sprinkler valve).
Screw the ball valve-pipe nipple into the 22-inch barrel.
Screw the new barrel assembly into the pressure chamber.
Allow to cure overnight.
Wrap the pressure reservoir with three layers of duct tape. (optional)

Step 3: Safety

Picture of Safety

To test the safety of and seal of the air chamber additional steps must be taken. Close the launch valve and pump the reservoir up to 10 PSI. Sprinkle soapy water on the joints. If bubbles appear, joints are not airtight and you must restart. If no leaks are found, repeat safety step 2 with 30 PSI. When done, aim the barrel in a safe direction and release the pressure.

Step 4: Firing!

Picture of Firing!

The actual act of firing the cannon requires further knowledge. Use extreme caution in aiming device. Make sure all parts are securely attached. Check launch platform after every launch for signs of wear. DO NOT over pressurize the pressure chamber. 30 PSI should be used as a high average. Use ear protection and eyewear. Clear the area in front of cannon for 200 yards. Clear area around cannon for 25 yards.

I used a weighted ping-pong (filled with clay) for my experiment with tissues as wadding. I needed this to have a consistently sized and weighted projectile. I encourage the use of potatoes however as when you jam one down the barrel, they lock it up and nice airtight. That means you get way more range. Moreover, who doesn't like shooting potatoes?
DO NOT shoot pointed, explosive, fragile, or living projectiles. I am not responsible for any of the damage you may incur in such a case.

An angle of 45 degrees should give you the greatest distance. This cannon shoots very accurately and I can consistently land my projectiles within five feet of each other.
See how close you can land to a target and assign points to see who is the best bombardier.
This cannon is tons of fun but can also be very dangerous, remember to use your head and think about what you're doing. I'm not responsible if you put a potato through someone's head...

Have fun!


Luziviech (author)2016-10-13

well then, why don't you wrap your air chamber into a metal "chamber" - just use pipes that got a bigger inner diameter than the outer diameter of your plastic chamber and fill batting into the interspace to cushion the eventual outburst? (Just an idea)

marshallcan (author)2015-03-20

Is there a way to build this in such a way to have multiple pipes shoot at the same time? Also, is there a way to build this so that the pipes are built to "shoot" at a precise time, like to music? Thank you.

KevinF51 (author)marshallcan2015-11-23

I blieve there is a way. all you have to do is get like 4 t cuplings and 2 elbows. All you have to do is where the barrel is just add 1 t cupling and then exstend off that and then add as many barrels as you want.

PlasmaGuy101 (author)2015-08-05

if you use smaller diameter pipe for the chamber then you can really push the pressure, i have a 1" chamber and can pressurize it to 200 psi .

DaveyH (author)2015-01-12

I remember building one of these for a contest. How I set it up though I was able to hold it and shoot it off my shoulder. We want to get a "bazooka" effect and it worked out pretty well. There was quick a backlash from the kick, but that sucker launched.

nutsandbolts_64 (author)2010-10-30

I still remember when I made my first one. The valve was so tight it took me 1 second to fully open it, therefore, much energy was wasted. The valve used must be airtight and smooth-opening for efficient operation. The faster the valve opens, more air can and will come out in a given amount of time. Just a reminder. And please do use ABS piping, it's safer due to its reaction to a catastrophic failure (i.e. it turns into strips and not bits and pieces similar but not exactly like a grenade, plus PVC will be hard to show up on x-ray)

ilpug (author)nutsandbolts_642012-05-09

Ok, let me clarify something: Combustion powered guns are better built with ABS for the reason you suggested, because the action of a combustion cannon results in an almost instant shock pressurization of the system (I.E, goes boom). ABS is better suited to quick shocks or bumps, so it is superior for combustion cannons.

ABS cannot be used for air cannons though, because it simply cannot hold the pressure. PVC is designed to hold pressures up to 500PSI+, depending on the pipe diameter. The trick is to keep the pressurized air chamber in a safe spot, or pad it against bumps. ABS can, and will, explode if you try to pressurize it.

Pnewtons Petards like this one are pretty safe as far as air cannons go.

jmlazer (author)ilpug2012-10-22

So far, ABS has worked fine for me under pressure.

ilpug (author)jmlazer2012-10-22

until it doesn't...

nutsandbolts_64 (author)ilpug2012-05-11

The trouble is that 2 years ago, most of the PVC I used wasn't pressure-rated, add to that we didn't even have ABS piping. The thing is PVC is designed to withstand water pressure. Air is a completely different fluid to work with.

Someone should seriously get a blast shield and attempt to blow up PVC and ABS pipes rated for the same pressure. That should settle the argument.

ilpug (author)nutsandbolts_642012-05-12

I might do that at some point. Make two air chambers of equal volume, pressurize to the same pressure, and shoot them with something.

ilpug (author)nutsandbolts_642012-05-12

I might do that at some point. Make two air chambers of equal volume, pressurize to the same pressure, and shoot them with something.

Hard to show up on x- ray... Way to stop people from building it

T(M)^2 (author)2012-04-10

Privyet, comrades.

The question I have for you today is as follows: I am looking to build an air cannon with a 6.35mm(or 2.5in., for all of you ingloskiis who still use the English system) bore air cannon capable of launching a .5kg.(1.1023lbs.) projectile 200ft. at a 45° angle. For whoever wants to do the math, what modifications should I make to the specifications above?


de0509 (author)T(M)^22012-05-09

Not really doing much calculations, none actually, but because you are using a quite heavy projectile, you really need a lot of force. and your caliber is big. you need the ball valve to be big as well so as to not give much resistance for the air to flow. maybe try using a big ball valve or any other valves that release pressure fast. maybe 1 inch ball valve instead of 3/4. or maybe if you can use a tee so that 2 ball valves open together. that way, you have a 1.5 inch ball valve from combining 2x0.75 inch ball valve. just make sure they open at the same time. i.e. joining the two ball valve handles together maybe?
depends on the pressure you intend to use. if low, id suggest making the chamber part longer. if high pressure, i think the original should be ok. but that is to be just enough, you may want more power right? maybe double the chamber? keep note that this also increase pumping time.

T(M)^2 (author)de05092012-05-14

many thanks, de0509. I shall keep your advice on my mind and in my project.

sjoobbani (author)2012-05-09

This works pretty well with fire extinguisher cylinders as a pressure vessel too!

TygrFr3d (author)2012-05-09

30 PSI as a high average? If you are worried about it bursting, don't worry. I have taken a 3" chamber to 120 with no issues. And if you want good groupings, maybe have the ball valve open with a tension spring and a catch, so it will open fast, and at a consistent speed.

Turtlepwr (author)2012-05-09

The fire and danger is half the fun

sci (author)2008-09-01

How much safer would it be if you use schedule 40 PVC? what would be a safe air pressure?

ilpug (author)sci2012-05-09

If you used schedule 40 for all the parts, and assembled them correctly, a safe pressure would be about 80 PSI. That said, you can go much higher. A good rule of thumb is to take the pressure rating of the weakest pipe in the system (usually printed on the side) and divide that by 2 to get your maximium pressure

waycoobeens (author)2007-07-29

Where can you find that tire valve...honestly thats the only part i cannot find...the rest i just got from home depot

ilpug (author)waycoobeens2012-05-09

Old bike tires.

at advanced auto or other autoparts store.

codongolev (author)waycoobeens2008-07-09

a tire seriously, I got an old tire and ripped it out

I got mine at Ace hardware.(basically Ben Franklins)

Blardo (author)waycoobeens2007-08-12

A friend and I decided to build one of slightly different design, which also required a tire valve. We obtained ours by cannibalizing and old, broken BMX bike's front tire.

Hermes (author)waycoobeens2007-07-29

Try a car place like pep boy's. Also, you may want to check the lawn mower section at Home Depot as they may have some valves. ~Hermes

KNEX BUILDING IS FUN (author)2009-09-06

how much does this cost on average? also wat would i need to do to make the barrel bigger, would i have to chance anthing else besides the size of the barrel? also if i use this thing with about 15 psi could i hold it whiile i fire it?

by bigger i mean diameter

Technically, you could hold this while you fired it at 100+ PSI. The design of these guns is such that it makes firing while holding a bit awkward.

tulavatalo (author)2010-01-13

will this work with bigger pipe and bigger valve?

Lance Mt. (author)tulavatalo2010-03-11

 Maybe. You'd need a bigger Air Chamber though. I'd suggest bigger than the scale your increasing it at (ie, if you double the barrel diameter, 2.5x the Air Chamber.)

ilpug (author)Lance Mt.2012-05-09

Note that with bigger pipe, the pressure rating decreases.

LX_COCOS (author)2007-03-25

nice job but ive asked my dad for permission to do this but he says it could blow up in my face is this safe? if so how can i prove it to him any help apreciated

Hermes (author)LX_COCOS2007-03-25

If you use pressure rated pipe (generally about 150 PSI) and accurately glue your joints, this is a very safe design, far safer than the hairspray cannons. The recommended max of 30PSI that I have included is a fifth of what the cannon can take ensuring that it is very safe. As long as you follow the instructions, use pressure rated pipe, glue well, and don't over pressurize, this is far safer than a conventional lawnmower... ~Hermes

pufferfish9108 (author)Hermes2010-08-31


ilpug (author)pufferfish91082012-05-09

I would be very scared to use a cannon at 145 PSI.

kharosh1691 (author)Hermes2007-04-17

Hey there...I'm pretty new here, heh. However, I'm planning on building a potato gun this year for my science project. I couldn't come up with anything, however, one of my close friends suggested a potato gun. Consider me stupid, because I think I am many times, however...wot does a potato gun have to do with science? Am not a science person at all. Matter of fact, 'tis the subject I hate viciously. And I was going through a few sites, came accross this one and noticed that you knew wot you were talkin' about. I need some help. Am desperate, I'd say. Science fair is on May 14th, I'm sure I'd get it done before that, but I need all the help I can get... I've settled down to doing a potato gun as my science fair project. If you can help me, then talk with me here...But, I'm a new comer, and I'm very ignorant of technology and thinger...Ahem. So, I'd not know how/when to sign online. If you can help, I'd be much too thankful and you may email me at Your help would be very much appreciated and some weight off my shoulders. :sigh: - Kharosh

 2 years late, but nevertheless... -- Physics entails the study of motion, force, gravity, etc. A "potato gun" is a less formal way of saying a "Projectile Launcher". In physics, you study a topic specifically named Projectile Motion. See the correlation? Air pressure is built up (in this model), and you're monitoring the various forces exerted on the object leaving the barrel.


pasha.mostaghim (author)LX_COCOS2009-12-21

Tell your dad that the teapot in the kitchen could also blow up, the oven could explode, and etc. Nothing will happen to you if you don't set yourself up for it. Example? Looking down the barrel, even when its not pressurized, is stupid. I said the same thing to my mother, back when I made my first combustion (...explosion...) launcher, and she let me do it. I've switched over to pneumatic due to school regulations.


im going to quote you on that first line. somehow somewhere someday ill quote you

owwio (author)LX_COCOS2009-10-02

i have fired something alot like this at 120 psi with no problems.

de0509 (author)2012-05-09

Hello bro. the target here is consistency right? that means something needs to be done with the trigger because opening it manually doesnt always open the valve at a constant rate. my country doesnt see those sprinkler valves, so i designed an idea to just use rubber band and some ropes. it also uses moment of force or some would say torque. check it out

de0509 (author)de05092012-05-09

EDIT: but its an idea though. have A levels coming up this month, its my final year so cant do much stuff other than study. you can also use the moment principles as an add on to the science fair booth, let people learn some actual science right?

jamesbid123 (author)2012-02-17


blazer101 (author)2008-05-14

where is the cap you put the tire valve on?

blazer101 (author)blazer1012008-05-14

also, wont you need a PSI measurer

dog digger (author)blazer1012011-11-07

All on the bike pump, air compressor etc (author)2011-02-14

I always feel bad when people have to pump it up by hand, and not just hook it to an air compressor and have a fill time of 1 second +/- 0.5

About This Instructable




Bio: I am a filmmaker, student, and tinkerer. I love designig and building devices instead of purchasing them. Instructables is a great way to do that ... More »
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