Water Balloon Cannons

Water Balloon Cannons

Ryan Bavetta
aka Bavetta
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We made these potato cannons early last year with the goal of being more compact than any of our previous models. They worked great for firing water balloons.

This is our most recent cannon - Cameron, Nick and I worked on it. We used this calculator to see how small we could make the reservoir and still get the distance we wanted. We made the barrel extra long and would cut it down if it was shooting farther than we needed (we wanted to hit the opposing dorm). As it turns out, they were overpowered (they can shoot things clear over the other dorm), but that is cool with us. We decided to leave the barrels at that length because they weren't all that big.

The barrel was 2" PVC, the tank was 4" and we used electronic sprinkler valves from home depot for the valve. To fill the tank we found a 1" to 1/4" pipe thread PVC joint that was perfect for connecting a quick-disconnect air hose connector to.

It fires water balloons! Cameron and Josue found that if you fill a regular sized balloon with water so that it is just small enough to easily fall down the barrel, it will fire and not explode in the air. We don't know how much it hurts to get hit with one of the flying water balloons and we don't want to find out. (It couldn't be much worse than getting hit by a water balloon from the other dorm in the eye, ya, it hurt for a while...)

The main problems we've found with this design:
- Not many, the design seems pretty solid so far. I wanted to put the valve on the reservoir side of the angle so that the cannon would have an overall smaller length, but Cameron and Nick wanted better 'heft'

I must add - PVC cannons can, and do, explode - so be safe and use the appropriate precautions. You are taking a major risk if you decide to build one.

By dstarks43	2006-03-21 19:36:02
would you please send me the insructions or blue prints of exactly how to make this, please, ive looked everywhere for the blueprints, no one will give them to me! please!

By potter	2006-03-23 14:44:08
he told you man its simple, the 2" is the barrel then the check valve w/release mechinism then a U into the 4"chamber with the air fitting. just watch your pressure as you fill the tank

By bavetta

2006-03-24 17:05:21

Ya, I don't know about blueprints, it's pretty straightforward. The dimensions don't matter all that much, although you can test them out on the calculator that I mentioned. As potter said, the only thing that can really get you in trouble is having the cannon explode, which happens if the PVC cracks or the tank is over-pressurized, so stick to somewhere under 60 or 70 psi to be safer, 100 if you feel more risky.

By cannon66

2008-05-15 20:42:41

Hey, i\'ve been researching all the air cannon sites and this one seems to be the best, i just built a reasonably large cannon with a 2\', 4\"dia. chamber, 1\" electronic sprinkler valve, and 5\', 3\"dia. barrel and i\'ve been testing it at 60psi. i rigged up a remote trigger and everything works well, except: the damn things gotta be the loudest f***ing air horn i\'ve ever heard! has nebody else had this problem?

By potter	2006-04-01 16:08:29
oh and for the guy who wanted blue prints i will draw some up in a few days (just got the new Autosdesk :)) and post a link to them here as long as bavetta doesn't mind

By bavetta	2006-04-01 16:56:22
that would be great

By trebuchet03

2006-03-23 21:07:54

I noticed in the second picture a box with some sort of planetary gearbox kit or something... Where did you find that? Cheapo drills eventually become an expensive source :P

--
Hehe... blueprints. No one will give 'em up because they most likely do not exist. Do the math at home to figure out the reservoir volume, barrel size and length etc. Then assemble it at the hardware store. Buy parts, glue and seal at home - let cure and then shoot whatever :D I made a rather large one awhile back with a modular barrel diameter - You just had to match the barrel size to the projectile that would be launched ;)

Just be careful. PVC does not fail nicely - it 'explodes' with sharp edges (ABS is a little safer in that regard).

By adambomb8857	2008-09-28 16:01:16
The solution for the dangerous shrapnel caused by a pvc explosion is to wrap the chamber in 1 layer of electrical tape, and then a few times in duct tape. it greatly reduces the effect and creates a safer potato gun.

By jdhawk	2006-03-24 13:29:16
those planetary gearboxes are electronic water sprinkler system valves. they're cheap and usually rated between 70 and 100psi

By trebuchet03

2006-03-24 15:59:29

Those are def. not sprinkler valves like the one for the cannons... I can't think of why a low pressure (relatively) sprinkler valve would even use gearing o.0 The box on the upper right of the picture is for the valve - I use that very same valve for my cannons (they cost about $12 and are rated for 80psi - I've gone higher without problems).

Look at the second picture in the plastic bin. I highly doubt it is part of the cannons... Looks like two or three of them....

By bavetta

2006-03-24 16:55:59

Ha, ya - those gearboxes were for a class I was taking at the time (2.007). They were part of a kit, so I don't know exactly where they got them, but I know a least one place you can get them is Robotstore.com, but they were plastic, and several people stripped the gears, so I'm not sure if I recommend them.

As for the sprinkler valve, it was from Home Depot. It is remarkably hard to find a solenoid sprinkler valve in the winter here in Boston - I called probably 20 lawn and garden and hardware type stores and no one had them in stock. Back home in California they are carried year-long, so that was a surprise to me. I eventually spotted them in a box about 20 feet up the shelves in Home Depot, and bought all they had.

By potter	2006-04-01 16:05:37
ok 2 things, how do you activate the 24 volt valve? and for you guys who like me couldn't find the valve heres a link. http://www.homedepot.com/prel80 /HDUS/EN_US/diy_main/ pg_diy.jsp?CNTTYPE=PROD_META&CNTKEY=misc %2fsearchResults.jsp

By bavetta

2006-04-01 16:55:39

For this cannon we never hooked up the solenoid to a power source, we just flipped the little manual override. We thought this was better than just flipping a ball valve because the manual valve that you flip on a solenoid valve triggers a secondary valve which switches at great speed. For past cannons, with the same valve, I just used a nine volt battery - believe it or not it triggered the 24V valve.

By trebuchet03	2006-04-01 21:52:59
Interestingly, I have had problems at higher pressures with the 9 volt.... a little over 3 bars and the solenoid just wouldn't pull -- used 12 volts (had a car battery on hand) it was just fine :D Luckily, I rarely 'need' to go any higher than that :P

By potter	2006-04-02 20:12:30
what if i linked 2 9V batteries in parrallel? I'm tring to keep this thing portable, its already 7ft long lol. im using CO2 to pressureize the chamber so i can use small tanks i want to link a button to the solinoid.

By trebuchet03	2006-04-02 22:07:13
I think you'll want it in series (but try just 9v at your operating pressure first).... -- Parallel: Amperage adds Series: Voltage adds

By potter	2006-04-03 13:27:49
your right, series it what i would need. thanks ill post a video link of the test fires later in the week

By potter	2006-04-03 13:31:52
oh and just an fyi for any one biulding PVC cannons you can find all the numbers you need for all calculations at www.charlottepipe.com they have all the Psi ratings for sch 40 and sch80 pipe 1/2" Diameter through 10"

By Minibax3

2006-04-06 21:30:52

Hello,

I am looking into making a cannon to shoot stuff, I was wondering how you came up with the Chamber:Barrel Ratio. I have read many extrememly conflicting reports of good Ratio's on other sites, some are 4:1 2:1 1.5:1. I do not agree with many of the ratio's as I think that would be obscenely large in some cases, and I was looking for some figures beyond chamber/barrel volume to work with. What did you use to figure out the transfered energy etc.

Thanks,

From a highschool newb

By bavetta

2006-04-08 19:56:20

We used the calculator then we halved the length and used that as our reference. It doesn't really matter a heck of a lot - the cannon will pretty much shoot things no matter what length the barrel is, but technically (with no losses) the length the calculator outputs is the optimal. I suggest checking out the excel spreadsheet and see how the projectile velocity varies with barrel length. As it turns out, you don't gain much over the last good length of the barrel, so it might as well be shorter - you should see how that works in the graph on the excel page.

By trebuchet03	2006-04-08 22:16:36
Just curious... how did you model it? I can picture a rather nasty differential equation to take care of variable pressure/time and variable length/time to get ds/dt... but I'm sure there's an easier way than that o.0

By potter

2006-05-06 07:07:34

Ok, after biulding a few of these i have dicovers a thing or 2:

1st, while the sprinkler valve is a great ideah and works ok, i owuld sugest using a plunger type solinoid. Diaphram solonoids like irrigation valves only allow an opening of about 1/4" even though the input and outputs are 1" this wastes valuble engery. Plunger type valves create the same size opening as there input and outout at the same speed of the irrigation valve.

2nd, eliminate the U in the gun this creates a delay in the air delivery to enough of an extent that with all other factors held constant (or as close as poss) hinders the guns distance by about 40 yards (avg over 20 shots with 130g potato) i found that by adding a threaded barrel you can break the gun down thus alloing for an inline tank eleminating the U

3rd, as a safety precaution wrap the gun in Duct tape from the tank to the valve, this greatly lessens the risk of ingery incase or an explosion (personal exp)

lastly i would like to know if anyone has tinkered with a more advanved typ of air cannon using a repeating bolt system, i stumbled across a blueprint for one the other day and im curious as to how exactly it works.

By root

2006-05-21 06:37:54

Have you came up with A good Plunger Valve?
Quite some time back I saw Plans for one, and thought I had saved them.( likely they are on a CD somewhere)
I Am working on recreating a water Cannon That I did as a prototype for my boss, before the 96 Atlanta Olympics. He gave me a sketch and I assembled a 4" pipe with a 2" pipe inside Attached was a regular sched 80 3/4 inch fountain nozzle, if I recall correct (its been over 12 years) it had to be filled via the nozzle and the air was supplied by a very small valve to the top of the reservoir.
end results was a really cool looking 3 foot pellet of water 40 feet in the air.

By Joe	2006-08-06 22:53:17
Hey If you got the time i want to ask a question. How do you build it? please respond

By tacobell_13	2006-08-26 21:50:37
DUDE, HAVE U LIKE SHOT ANY1 WITH IT?? JUST ASKIN.

By 0000HIM0000	2007-05-16 03:24:33
can you please tell me all the materials you used.. thanks

By jerry	2007-06-12 10:47:09
I made a water balloon canon just like this one but for some resoneit dosent work very well. can you send me a scematic of your gun for me to look at my E-mail adres is jerry_man_108@yahoo.com . if you could send me thous plans it would be grate Thanks Jerry

By turbo557	2007-07-12 13:36:00
i am working on a backpack design with a separate gun and air tank. the only problem i am experiencing is that i am having trouble activating the valve on my back to let air go through the tube into the gun if you can help it would be much appriciated email: superturboalix@aim.com

By jesse31415926	2008-06-30 23:38:00
I plan to build a cannon that can handle pressures up to 300 psi. From your experience, will it be possible to fire a balloon with out disintegrating it? Have you determined a pressure limit for a common water balloon? Also, have you guys ever attempted a cannon with a 3\" barrel? love the ingenuity

By Russell	2008-09-23 19:01:16
Guys can I purchase already assembled? thanks Russell spiderpig2@mac.com

By lin	2009-05-16 15:27:48
Hey, i need like the exact instructions on how tho make this cannon please. Its for a school project and it has to work in order for me to get a good grade. Can you help me? And tell me in a little bit more detail how to put this thing together? Such as precise measurements, where each item goes, and a list of items that i need. More importantly how high can the air pressure for this model go?

By lin	2009-05-18 17:43:35
Nvm mind guys, i went and figured it out on my own. I also made it way safer. Anyways... It works GREAT!