I was throwing around the idea of making an air cannon to play around with... designed to shoot nerf rockets or grapeshot.

My first cannon.



Stats:
20lb steel fire extinguisher rated to 585 psi (approx. 330 CuI) with a 1" male nipple MIG welded to the neck.
Steel 1" firing plumbing, brass 1/4" fill plumbing.
Modded Nelson sprinkler valve actuated by a shop blowgun.
Fill nipple threaded into the steel Tee.
160 psi pressure gauge
150 psi safety pop-off valve
2"x3' pvc barrel, modded for breach loading.
Max operating pressure is 140 psi

Not shown: regulator and fill hoses.

Max range at a 45 degree firing angle and 140 psi is approx. 400 feet, chronoing at about 160 fps with a nerf round.

Weighs a ton, horribly inefficient with the current barrel (max efficiency would require a 8'9" long barrel )

I've been thinking about lengthening the barrel a bit and mounting it on a turret or pedestal with a scuba tank nearby.
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Edited to add pressure rating of the pressure tank.

My 2nd cannon. sorry for the bad pics, my camera flash decides when it wants to work. I will get better pictures of it later.

Side View


Back view


Detailed plumbing view


Stats:
-3lb aluminum fire extinguisher (approx. 100 CuI) rated to 300 psi, with a 3/4" male nipple JB Welded to the neck.
-All brass plumbing, silver-ish parts are nickle plated.
-3/4" Main firing plumbing consists of a 3/4" QEV connecting the barrel to the chamber via a Tee.
-1/4" Triggering plumbing consists of a shop blow gun connected to a 1/4" QEV , connected to the input of the big QEV.
-1/8" tank fill nipple connected between the QEV and blowgun via a street Tee.
-160 psi pressure gauge (soon to be replaced due to a crack in the plastic casing).
-150 psi safety pop-off valve.
-15" overall x 2" pvc barrel, 12" effective length. (the last 3" are aesthetic).
-Max operating pressure is 140 psi.

Not shown: regulator and fill hoses.

How it works:
-The blow gun actuates the 1/4" QEV, which actuates the 3/4" QEV.
-The tank fill nipple allows me to fill the cannon and walk off, without worrying about depressurization of the cannon when I disconnect the fill hose.

Max range at a 45 degree firing angle and 45 psi is around 400 feet (no typo) with a nerf rocket chronoing at about 130 fps.

This weighs between 5 and 10 lbs, is extremely efficient due to a smaller chamber and using a QEV to fire.
Also gets around 10 fills from a 48/3k tank

Southpark got to shoot this one today, seemed to love it.
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Edited to enter info.

Sweet! I like your use of the shop airgun for firing.

Where are you getting your sprinkler valves from and what are they setting you back? I've been meaning to start a similar project of my own but haven't sourced valves yet.

SW

Cannon work great taken a few nerf rounds from the second at close range hits with some nice force Very well designed

Twinkletoes has done a bang up job with this thing. You have to see it first hand. I got to see it shot today... and then I got to shoot Ripper5 with it. Friking awesome bit of back yard mad scientist inventivness. Two thumbs up from me! Good work.... and thanks for posting the details.... I expect ShadoWalker and I will be cooking up a clone or two over the next months!

Your Lucky you got to shoot it ... i get shot at instead

That depends on what kind of valve you want.

My 1st cannon used a 1" plastic Nelson brand sprinkler valve. It requires some modification of the diaphragm to equalize pressures between the chamber and trigger. That cost me about $25 from Griffith's Plumbing 2 years ago, only recently modded and used it; and it opens fairly slow compared to a QEV.

My 2nd cannon used 2 QEVs and a shop blower. The blower triggered the smaller QEV which triggered the larger QEV, and no modifications are required to any parts. A QEV gets filled from the same port you trigger it from, a closer look at the plumbing picture will show you how that works. The 3/4" main cost me about $30, and the 1/4" secondary pilot QEV cost me about $20 from Fastenal.

QEV's are designed to be extremely fast to actuate because they are used on systems such as pneumatic cylinders and air brake systems; whereas a sprinkler valve is designed to actuate slowly in order to prevent water hammer on your houses' plumbing system.

Cost overall for Cannon #2 was about $120 for all the plumbing. The fire extinguisher was picked up from Sal-mart for $2 . PVC you can get from some stores like HH or any plumbing store for cheap or free if there are some broken lengths laying around.

Depending on your budget, I'd recommend going with the QEVs for the performance and efficiency. Average prices for the essential hardware are as follows:

QEV or sprinkler valve - $20-$35 depending on size (prices for QEVs are cheap up to 3/4" ports, 1" ports jump to about $120 each )
Safety pop-off valve (50-250 PSI, in 50 psi increments, non adjustable) - $20
Gauge - $15-$30 depending on pressure range
Shop blower - $7-$20
Assorted brass plumbing - $40-$100
-OR-
assorted cast iron plumbing - $20-$60

(I went with brass because I trust it more structurally, and it won't rust or shatter when dropped. It's worth the price to me.)

I'd recommend Fastenal for valves and Island hose and hydraulic for the plumbing, they stock just about every fitting you could possibly require. If you need anything ordered, I have an account with island hose so I can buy it at a discount of 15-25% off (or just make an account of your own, costs nothing).

Not with the 2nd one... Sean took the hit this time. if you had been at the field today, you could have shot it

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(I wouldn't have double posted, but I don't know how to add a quote to an edit and he 'ed in there as I was typing to SW)
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*EDIT* Gah, another Ninja here. I didn't think it took me that long to reply to SW.

Thanks SP, looking forward to seeing what you guys come up with. Looking forward to some cannon duels with you guys in the future.

Muahahahahah!!!!

Oh so many ideas....

Check Here for some info. A goldmine of information there.

It's nice and small but has the range and speed of the first one.

If we ever have another scenario game, you're going to have A LOT of fun with that second cannon. You can just act as a mortar team, keep 10 tanks with you and and a bunch of Chrony paint MAKE IT RAIN IN THE GHOST TOWN

Haha, could do. If I were to stay stationary, I'd lug around a scuba tank to the location. I'm also getting a surprising # of fills from a 12 ounce tank, but the darn Co2 keeps freezing the reg. I just have to stay with HP, I'm happy with that.

probly stating the obvious, but did you try keeping the tank upright when loading with CO2, otherwise it sucks in a lot more liquid.

Correct. Just too much volume flowing thru the reg.

That's much better than what I'd found so far. I'd seen sprinkler valves online for 85-150.00 a piece. I was wondering about using QEV's but hadn't gotten around to doing my research on them yet. Considering your results I'll have to give it some serious thought now. I was considering using a lever actuated globe valve but the QEV's sound like they might be simpler to implement.

What's the pressure requirement to trigger those QEV's?

And thanks for the tips!

SW

A globe valve has the best flow, but the slowest opening time. The positive to that is: they can withstand a couple thousand PSI; you can just hook up a 12ie or a Co2 tank and go. minimal cost for parts.

A QEV has no pressure 'requirement' to actuate, you just cut off the flow of propellant from the input, and trigger your pilot (ball valve, shop blower, etc.). I think mine operate with a 5 psi decrease in presure, so make sure you have NO leaks, or the results can range from a slow exhaust out the barrel to a regular firing of the canon.

I had a small leak between the pilot QEV and firing QEV, so I just had the air leaking out the barrel .

If you end up at midway next weekend, I can explain it to you better; I suck at written descriptions. I explain best with a physical model/diagram and word of mouth.

you can test fire it on me

That's a generous offer there Kyle, but it might be better to test it out on a man sized target

rob, where's the video of a 'kyle' flying across the landscape after being impacted by a slightly hot, not quite fully field-tested bazooka?

Youtube,


And im the Test target most of the Time anyway ussaly he shoots Pod's at me

Or that time he shot a 6 month old muffin at Tristan
I was disturbed to learn that Tristan ate the muffin afterwards.

(smashes head on Desk)

I thought that was a 3 week old muffin? We only threw them out the day before.

No, that tray of muffins was on top of the microwave in the back of the shop for at least 4-6 months. 4 months is a conservative estimate.

Tristan's reaction:
ahh, shot with a muffin
mmm, good muffin
somethings not right
crunchy and slimey don't go together
I swear something was moving!!

I see

Kyle's Reaction:
pwned.
what the.....
(giggles)
PWNED!
PWNED! x2!

I noticed we're getting a bit off topic...

only slightly, but it was really funny

it happens, i noticed too, were like Kids in a Toy Shop oh and i was wondering can you make a Cannon out of a Normal 45/4500 Tank???? that'd be cool to have strapped to your Back

He does use a normal tank, I don't know a whole lot about the cannon, but I believe that the fire extiguisher tanks are used as volumizers. This allows the cannon to use more low pressure air to launch the paintballs rather than shread them.

Yes, it *is* possible to use unregged pressure for a cannon. Just get an industrial powerwasher handle. I believe they're good for up to 4.5k psi. You wouldn't get a whole lot of accuracy with a nerf, or many usable paintballs, though.

i kinda wanna make a Shotgun like Thing with it

5Barrels
1 Paintball in Each barrel
Attempt to bunker someone

pretty interesting idea, but is it really practical?

if you're only going to get one shot per load, might as well just load up one or two hundred. Grapeshot is pretty effective.

well it'd be Fun to try

Took a shot in the leg on Sunday, in the padding on the pants.

From about 30 feet away, on a padded part, it feels like 2x a paintball hit on an unpadded part. Shot with a nerf rocket.


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hahahhahah

Unless I lengthen the barrel and/or increase the operating pressure, I'm going to just stick with nerf rockets. Paint preforms horribly at 45 psi and a 12" barre, barely going 30 feet. A 30" barrel may work better, We'll see next weekend.

Are you going Friday? there's a group booked (pro D day for schools)

I'll bring that green laser pointer for your phantom.

Im Coming Down too

and i have somthing for his Phantom too

Nope, working on friday. I'll be there on saturday, and I'm going to vic on sunday, so I'll only be there for a few hours. Make sure that pointer has batteries, Yes?