My First Pneumatic Cannon

[IMagius]

As the title says, this is my first cannon.

I built it to try and get a grasp of what's involved before moving up to a larger size of chamber and barrel. I have an "accomplice" who has almost unlimitied access to 600 psi rated 4", 6" & 8" heavy wall PVC, a dozen or so 2" sprinkler valves and a 100 acre farm to play on with the kind of beast one could build from those parts.

So here is what I built:
•Twin 2" x 48" sch40 280 psi PVC Chambers - with all the fittings it comes in at about 400 cubic inches.
•Barrel is 1.5" x 57" sch40 330 psi PVC
•1" Rainbird Sprinkler Valve
•Non Modified Blowgun
•Standard Tire Valve for filling

•Overall Length is 78"

The first thing I know people will think is that my Chamber:Barrel ratio (4:1) is well out or "norm" (1:1). You are 100% correct. According to GGDT - @ 80psi I am only running about 350 fps muzzle velocity. If I was to double thelength of the barrel, I could get much closer to 400-450 fps which would be an obvious improvement.

The logic behind my acceptance of a "lower performance" cannon is quite simple. Where I live (Ontario, Canada) a Firearm is described as:
•a barrelled weapon from which any shot, bullet or other projectile can be discharged and that is capable of causing serious bodily injury or death to a person
•A muzzle velocity of 152.4 meters (500 feet) per second or greater.

For that reason, I am keeping a fairly large safety zone between me & "the Law". I know I can run it up to 160 psi and still not exceed "the Law". Since I also collect real firearms, I don't want to risk losing the rest of my "toys". Better safe than sorry in this case.

Yes, it needs some paint and a proper piece of plywood cut for the Barrel Support, but I was in a hurry to test it out and some SM Blue was close at hand. It's a bit ghetto, but it's only temporary.

First "loaded" test was a 75 Gram Ice Slug at 15psi and 15 degrees barrel inclination. Result was 100 +/- feet down range.

Continued ramping up pressure and at 80 psi and 40 degree barrel inclination I achieved roughly 300 Yard down range.

Projectile had a lot of tumbling in the air so accuracy was not very good, but these were square cut cylinders of solid Ice so I wasn't expecting great accuracy - just a nice fit in the barrel with some acceptable mass for testing purposes.

All in all, I'm quite happy with the results.
My 10 yr old nephew was speechless with a grin from ear to ear

[jrrdw]

My 10 yr old nephew was speechless with a grin from ear to ear

Hahaha, having fun is what it's all about!

Feel free to post video's and damage pictures. What color are you going to paint it?

[iknowmy3tables]

you used sch40 for all your fittings, and used a moded sprinkler valve on your first pneumatic, your accomplice has taught you well

[IMagius]

Feel free to post video's and damage pictures. What color are you going to paint it?

No VidCam, so there won't be videos - but I think my Camera may take video ... I'll look into it.
When I get something to destroy, I'll defintiely take before and after shots.

Not sure on the color yet. Probably just a flat "military" green. Krylon for Plastic is my third best friend - right after Duct Tape and Tremclad.

you used sch40 for all your fittings, and used a moded sprinkler valve on your first pneumatic, your accomplice has taught you well

My accomplice taught me nothing 8) I owe everything I know about Cannon Design - specifically how to mod Valves and which pipe is preferrable - to this site. Some great "How To's" here that were invaluable. The accomplice is a Construction Foreman who happens to have access to left over pipe from road jobs when they are installing new Water & Sewer lines. He heard of Pneumatic Cannons and saw a vid of "punkin chunkin" and said to himself "I've got that size pipe, but in PVC instead of the steel.". He then passed the idea on to me and I said I'd research the idea and build it for/with him if he gave me access to supplies for one of my own as well.

What I want to build for myself is a Breach Loading Coaxial (4" Barrel - 8" Chamber) using Twinned 2" sprinkler valves on a recoil absorbing turrent mount. (I should probably see if I can doodle up a sketch of it in Autodesk one of these days and get people's opinion)

I'm a "jack of all trades" kind of guy - Building my own Hotrod from the ground - up so Modding a Sprinkler valve isn't all that hard once you see a couple pictures and understand the theory of how they work.
I've been doing Home Repairs for 20 years, so "plumbing" isn't new to me. sch40 is fairly easy to work with as long as you don't let go of the connections when you first glue them together. They need about 30 seconds of good pressure if you want a full depth connection due to the slight (almost immeasurable) taper inside the fittings.

I know most people aren't used to this concept but I prefer to learn before I build. I spent a couple weeks reading and learning on this site before I bought any parts or supplies. Then I raided the local hardware store.

[deathbyDWV]

Looks like a good cannon. Great job for your first

[Hubb]

I say you've done a mighty fine job with this, especially for a first. Have you considered a breech loader for it? A simple coupling breech loader can be made with just a small amount of effort.

Welcome to Spudfiles northern neighbor.

[Jack_Hogg]

Looks very good to me for a first.
I wish I has some white pvc tubing..
I hate the grey ugly pvc from europe...

But very nice cannon you got there mate

[IMagius]

I say you've done a mighty fine job with this, especially for a first. Have you considered a breech loader for it? A simple coupling breech loader can be made with just a small amount of effort.

Welcome to Spudfiles northern neighbor.

I thought about that, but for my First, I just wanted to get the fundamentals worked out.

The next step is to look into the various building design methods of breech loading and which will suit my purposes.

And thanks to all for the positive feedback!

[Hubb]

Check out the Hubb Library (in my sig). There is a ebook I put together called "Improving the barrel" and I have demonstrated several different methods of breech loading if you're interested.

[IMagius]

Already toured the Hubb Library - excellent collection of information! Thanks for putting it all in one easy to fin place.

I've got the pdf on my computer, just haven't read through it yet.

[jackssmirkingrevenge]

Not bad for a first effort, however the whole legal thing seems a bit silly:

•a barrelled weapon from which any shot, bullet or other projectile can be discharged and that is capable of causing serious bodily injury or death to a person
•A muzzle velocity of 152.4 meters (500 feet) per second or greater.

A 75 gram ice slug travelling at 200 feet per second has just over 100 ft/lbs of muzzle energy, about the same as a 22 rimfire round, and it is more than capable of "causing serious bodily injury or death to a person" - so fussing over whether you're exceeding 500 fps or not is a bit of a moot point.

It's also a question of whether the law defines launcher is capable of higher power, for example in the UK technically an airgun that generates a muzzle energy of 13 ft/lbs with 31 grain pellets is a firearm in the eyes of the law and needs to be licensed as it is capable of exceeding the 12 ft/lbs limit, and arguing that you only used it at 11 ft/lbs with 16 grain pellets is not a valid excuse.

Really though, I think it's a question of using it sensibly, if you're using it on your own property to destroy domestic appliances you're likely to be asked by any reasonable law enforcement officer if he or she could have a go, but if you're using it to shoot up your neighbour's car it will be a different story.

In short, you're breaking the law anyway, go ahead and crank it up 160 psi and solid projectiles FTW!

[cannonmaster]

for a first time with no help that is great. i know that i've gotten a lot of help from this sight and to me it is invaluable.