First Pneumatic Cannon PLANS

[GeekFreak]

I just bought my sprinkler valve today, and I think I'm going out to get the PVC parts tomorrow. I made a plan for it. Tell me how it looks (I know it's not perfect, but it's 1 a.m. and I'm lazy).

If you don't understand something, figure it out on your own, because you guys are all geniuses. Thanks in advance!

[inonickname]

Fine, except you want the sprinkler valve on the other side of the elbows to reduce deadspace.

[john bunsenburner]

Looks good. The barrel seems to be fairly big for the gun, maybe 1inch would be better(i am a fan of tiny bores like .22 but thats just me) also there will be alot extrap space the air will have to travle so putting the sprinkler up top(so it is lined u with the barrel) might be a better idea, depending on how large your hands are so you can trigger the valve. Also just to make sure, you do know the sprinkler will have to be moded to allow triggering by a blowgun.

[GeekFreak]

I actually just found 20' of 330PSI 1" PVC pipe. Do you think make a few chambers out of that could save me some money (I'm extremely tight on cash right now)? I was thinking since I wouldn't have to buy 2" bushings, 2" PVC, or 1-1/2 male adapters, I have a little moola left over. Any thoughts on 1" chambers?

[MountainousDew]

In my opinion, the barrel should have the smallest pipe diameter...
If you use 1" pipe for your chamber with a 1.5" barrel you are going to have a lot of performance loss, but since this is your first pneumatic, you won't know the difference...

I would use the 1" pipe for the barrel and 1.5" or 2" pipe for the chamber, this way you can launch marshmallows and your barrel will be smaller than your chamber...

[c11man]

1" chambers have a extreemly reduced volume. 1/4 that of a 2inch that is the same lenghth. so you defently would not have good preformace with a 2inch barrel, but if you had a 1inch barrel and a chamber equal or longer that your barrel you will get good preformace

[GeekFreak]

Here it is so far! The 1" PVC I found wasn't actually 330PSI, that was 3/4". I put the non-pressure rated 1" in (just to see what it would look like, without glue) and it looks about Schd 40 thickness, but it wouldn't be a good idea to use, right? Anyways, all I need now is 2" PVC, 1x1-1/2 bushing, a 2" PVC cap(I already have 1), a blowgun, a schrader valve, PVC Primer, and 2 2" couplings... Any ideas on the cost of all that? Thanks for all the feedback!

[GeekFreak]

If I have 2 2"x3' air chambers and I fill them to around 80 PSI, could I get multiple shots out of it? If not, what pressure would I need?

[Technician1002]

If I have 2 2"x3' air chambers and I fill them to around 80 PSI, could I get multiple shots out of it? If not, what pressure would I need?

To answer that question, the specifications on your valve will need to be known.

How fast does it open
How fast does it close
How long it it open
How fast is your flow while it is open
How will you limit the open time

These are important questions to understand the problem needing solved. Most of my air cannons completely empty the chamber in under 25 ms which is not very long. (0.025 seconds) A really large chamber with a valve that as low flow will not only limit the projectile speed, but may be able to close fast enough to retain some pressure.

A better solution may simply be a storage tank and a small chamber that is refilled after each shot.

[jrrdw]

If I have 2 2"x3' air chambers and I fill them to around 80 PSI, could I get multiple shots out of it? If not, what pressure would I need?

You don't have enough volume to get mutiple shots. Just to small.

[GeekFreak]

What size of chamber would you suggest for multiple shots? The only places I can use this is on my friends dock (where I can use an air compresor) or on a small island behind my house (no pumps available)

[Technician1002]

What size of chamber would you suggest for multiple shots? The only places I can use this is on my friends dock (where I can use an air compresor) or on a small island behind my house (no pumps available)

Control over the volume discharged from a small space with many variables in the valve is hard to predict. I simply use a small chamber and a external tank for refills. A modded propane or freon tank works, or for safety, a relatively inexpensive air storage tank from an auto parts place works fine. Calculate how much air you use in each shot and then you can size your requirements accordingly.

If you have a source for high pressure air, a tank and regulator can provide shots with the same pressure on each shot. Some people use CO2 and others use propane.

[GeekFreak]

I actually have a like, 50gal+ air tank... Think it would fit on a golf cart? Couldn't I just pressurize it really high and refill my chambers every shot?

[Technician1002]

I actually have a like, 50gal+ air tank... Think it would fit on a golf cart? Couldn't I just pressurize it really high and refill my chambers every shot?

Stay within the safety limits. A big tank failing .. Ugh.. 50 gallons should provide lots of shots from the small chamber launcher.

[GeekFreak]

I get a horrible image in my mind of that tank blowing up... Anyways, with a tank that size, I'm thinking I'd probably only need around 150PSI to get around a dozen shots (if not more?).