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Old 07-14-2012, 11:24 PM #1
Colreb's Avatar
Join Date: May 2012
Location: Oxford, MS
Air Canon Breech fed system please help, comment, leave suggestions

Hey guys,
I'm needing to design a breech fed air cannon for my one day future tank. Here are the two cannons I have. I'll post pictures along with how they work, pros, cons, and changes I'd like to see made.
M1 LAW (Sprinkler valve)

Uses sprinkler solenoid valve. Air chamber fills to 100-115psi. Valve is set for 125psi. I also have added a pressure relief valve from Grainger between the air chamber and valve. To fire I have 2 9 volt batteries that are connected to two door bell switches that have to be pressed down to complete the circuit. I also have a male/male cable (not shown) that goes from the valve to my canon which arms the system. Plus I twist to open and close the valve. So there's no way this thing could accidentally go off.

It shoots far and fairly accurately
I also like the single burst of air
Lots of safety features

muzzle fed takes a pretty long stick to load the round
1 shot wonder
takes time to load. I currently use a Bell car air compressor that runs on a cigarette lighter.

What I'd like to see happen:
Constant air source
Breech fed
auto loader (possible upgrade)

A1 LAW (Pressure Washer)

This runs off a pressure washer handle I got from Lowe's for about $50. I drilled a hole in the pvc curved part to attach the pressure washer wand. It looks like a small hand saw. Then I used my old Spyder Compact 2000 standard tank adapter so I could use a tank on it. It's breech fed, but you have to take the barrel off and load the round from there. I got this idea from a friend, and we both got it from a guy from Viper's Twilight Zone VI. So it's more like an RPG not a LAW.

Constant air source
Breech fed

Range sucks
Not a lot of safety features
when you hold the handle down it's like water coming out of a hose and the rig freezes when I use co2.
Breech system requires the barrel to be taken off.

What I'd like to see happen:
Build a stored air source that fires a quick round without that extra leaking (water coming out of a hose) and then recharges
a few more safety features if necessary
RANGE!!! It really sucks compared to the other one. It's less than half!

Suggestions? Comments?

Please help!
Col. Reb


Last edited by Colreb : 07-14-2012 at 11:42 PM.
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Old 07-15-2012, 10:16 AM #2
Boom Master
Scenario Player
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Another attempt to use a pressure washer handle for a high pressure main valve. The range sucks once again... It appears that you cannot get enough flow rate to get the job done. One of several things are happening regarding flow rate.

1.. There isn't enough flow through the Air Supply CO2 tank pin valve or

2. There is not enough flow through the pressure washer valve.

3. The hose is the flow restriction.

The one with the least flow is the restriction. Of course, there is the possibility that neither have enough flow to get the job done. The GPM rating for pressure washers vary from 35-50 gallons per minute.

I have seen ONE post where the guy said he had some success but never posted a distance or chrono speed so I don't think he was too proud of his muzzle velocity.

He added an air chamber between the air supply and input of the pressure washer. That would suggest the flow restriction was the CO2 tank pin valve. Problem was he used hardware store 1" galvanized pipe rated 300 psi and put CO2 in it that could run as high as 1500 psi.... Maybe that was why we haven't heard from him.... But you could get some pipe and fittings rated for 1500 psi and give it a shot. (pun intended) His looked like 1" pipe about 5 inches long with the fittings on the ends adding a bit more.

Still, I have seen functional RPGs that have about the same port size as a pressure washer. Your basic plunger valve. It was on a commercially made RPG and was a HIGH operating pressure system running off CO2. That suggests this concept could be viable.

Does anybody know the air chamber volume of some of the other commercially made RPG that use CO2 or Air? That would give us a working point for what might work...

I always wondered if one of those OLD fashioned CO2 necks with an on off ball valve rather than a pin valve would work in a pressure washer. That is an 1/8" port opening. Problem is, I don't think you can buy one anymore. They were chronic leakers. I have one if anyone wants to give it a try. It leaks.
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You don't have to......

Last edited by Boom Master : 07-15-2012 at 10:20 AM.
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Old 07-30-2012, 10:19 PM #3
tmauriello's Avatar
Join Date: May 2004
Location: Indy, IN
 has been a member for 10 years
tmauriello owns a Planet Eclipse Ego
Hey there, I'm the guy who tried the pressure washer launcher! Still have all my fingers, but still get inconsistent results. One problem I noticed in testing is that the whole system gets cold after the first shot (100 feet) and then subsequent test shots are much weaker (50ish) My guess, is that it is best used as an emergency sidearm-rpg for shots under 50 feet.

Also, I got distracted building my "Boom Master-Style" launcher. All metal valve (the one you recomend) and used extinguisher chamber... (also like you recomend) That one shoots AMAZING! Got to use it at a scenario in July. It has a removable barrel with a simple breach load using a repair coupling. Set up for remote hpa... I'll get pics up soon.

So, my advice on your launcher is simple... follow Boom Master's other threads!
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