Rapid firing air cannon?

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
Luke31
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Sun Oct 24, 2021 3:59 pm

I am wondering how people build air cannons that seemingly have no air refilling time. Here's a couple videos showing some of them.




I don't see any air compressor anywhere, not even a large noticeable air tank like most potato guns. They act just like a paintball gun. Firing in quick succession.

I never understood how this is done exactly. My current plan to achieve a similar result was to use a high pressure air tank, and use that to fill up a 2nd air tank that will be used to shoot the cannon. But I don't think a 2nd tank is required with the right kind of air release control.
Theonepbs
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Sun Oct 24, 2021 8:02 pm

at the end of the mortar vid it clearly shows the crew

using a remote line with quick connect to a HPA tank or high pressure air tank which can be aluminum or fiber wrapped composite common to paintball

pressures range from 3000psi to 5000psi

5k is harder to find but 3k-45k are very common

these tanks are not cheap and have a 5 year hydrostatic test which has to be renewed every 5 years

the cool thing is you can now get a cheap high pressure compressor to fill these tanks for sub $300 and refill yourself

I would say if you don't mind the size of your tank

then look into diving pony bottles

same pressures much bigger tanks instead of 114ci hpa tank for paintball

a pony bottle is like 90 cubic feet @ 4500psi and the pony bottles are about the same price or less

pay attention to if it has a reg

and what the output is

high pressure typically is 800psi out

and low pressure output is typically 300

some can be adjusted some can not without a secondary regulator
Luke31
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Mon Oct 25, 2021 1:26 pm

After doing some research and thinking I realized how the principle of this probably works. There actually still is 2 chambers, high and low pressure, but the low pressure one is so small its not noticeable. Its like how there's 2 chambers in a paintball gun, the high pressure chamber (air tank) and the internal space in the paintball gun that's under constant output pressure, which acts like the 2nd low pressure "chamber".

So you could connect the high pressure air tank to the low pressure air tank with only 1 or 2 regulators in between them, and just have a valve between the low pressure chamber and barrel. You can then open the valve (thus firing the gun) and close the valve, and be ready for the next shot.

The only thing with this setup is if you leave the valve open after firing, the air will continually leak out, so you would have to be diligent about closing the valve right after firing.

The remedy this, you could use an auto closing valve, such as a solenoid valve, or you could still have a value between the high pressure chamber and low pressure chamber. You would just have to first dump air into the low pressure chamber, then close the valve between the high and low. Then open the valve between the low pressure chamber and the barrel.
Theonepbs
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Mon Oct 25, 2021 2:54 pm

seems they use a spring return ball valve with what looks to be a paracord loop as a trigger

very similar stuff https://alternativepaintball.com/paintball-goodies/
Luke31
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Tue Oct 26, 2021 12:48 pm

Theonepbs wrote:
Mon Oct 25, 2021 2:54 pm
seems they use a spring return ball valve with what looks to be a paracord loop as a trigger

very similar stuff https://alternativepaintball.com/paintball-goodies/
Their website appears to be partially down. There blog tab is empty, and there is no contact info on their contact page.

It looks like they were selling some stuff too, but there no way to buy anything. They were even selling a paintball mortar.
Theonepbs
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Wed Oct 27, 2021 1:58 pm

I have all there plans from many years ago before they sold the site i will look for them and post them if that's allowed since there out of business
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Thu Oct 28, 2021 2:39 am

You need to shut off the air feed or the recharge rate will effect the projectile velocity as the tank discharges. This varies on factors like ballast size and operating pressure. Smaller ballast needs higher psi but gets more efficient as you go. 800psi can be used in quite a small ballast and propel 25gram projectiles a couple hundred fps. With larger ballasts you can acheive the same velocities but at lower pressures. Fastest thing to fire off of is a giant tank that is at launch pressure. The faster the flow the better. Back to feed shut off, best way is to integrate the shut off seal into the piston or piston rod to close right before main valve opens to barrel.
Theonepbs
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Sun Oct 31, 2021 1:12 am

i have found the plans and will upload them shortly

I have been busy trying not to lose everything

but I wanted to post an update so your not left hanging

ill probably take pics of them and upload them that way it will be the easy way t save etc.

I also have a few others I may upload

like the PAC 6 ( the semi automatic )from xinventions and

the rapid fire six shooter potato gun from tech league

all companies and sites are now defunct so I don't see why this would be a problem
Luke31
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Sun Oct 31, 2021 4:55 pm

I noticed alot of info on air cannons on the web date back to 2000-2010. Similar thing with scenario paintball stuff like building tanks. Have the laws changed since then that discourages these things?
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Sun Oct 31, 2021 5:46 pm

No changes in the law but possibly interpetation . Our products were delayed to market for a number of reasons but mainly based on the aspect of their potential for self defense or police/military use. We were forced to get a class 10 Federal Firearms license as a manufacturer of destructive devices. There is no such requirement for them to be sold for paintball, airsoft, animal control, or even tear gas use. However, the ATF appears to be allowing air guns over .50 to be used for self defense now so we are getting back into the paintball and airsoft markets at the same time as we are launching our new police and military products. There are lots of "40mm" airsoft products and a few paintball, but I think we will be seeing a resurgence in large bore airguns and I am hoping to be a big part of that. Eclipse is finally getting back in the market this January. Other than just selling complete launchers we will selling kits and possibly stand alone valves.

Regarding tanks and air cannons in general, I think the enthusiasm waxes and wanes over time. Every time it seems to get better as new tech or techniques are tried by different builders. Events that allow them is another obstacle that may have played a role. Even fields allowing shot rounds has shrunk as most just use nerfs for indirect fire or against tanks. Insurance may be the culprit there.
Theonepbs
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Sun Nov 14, 2021 10:43 pm

alright i will start uploading some plans tonight is there any specific you want first
Luke31
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Mon Nov 15, 2021 4:34 pm

Theonepbs wrote:
Sun Nov 14, 2021 10:43 pm
alright i will start uploading some plans tonight is there any specific you want first
Thanks. I am most interested in the mortar.
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