designing my first pneumatic cannon

[wolfie22]

so i'm planning on building my first (full scale) pneumatic cannon. i want to build one that will shoot golf balls a distance of at least 1200 feet (400 yards). realistically, id like it to be more like 450 yards though. As this is my first real build, i was wondering if someone could help me come up with a good design, capable of this. thanks a lot!

Moderator edit by MrCrowley: Topic title. Topic titles are there for you to describe the topic

[Technician1002]

How did you choose that distance as a goal? Efficient designs seem to reach those distances well under 100PSI. Check the showcase or search for golfball cannons. Any well designed large port piston valve or burst disk cannon should fit the bill.

[Fnord]

I'd suggest looking for stuff by MrCrowley. He made a nice gb gun that shoots about 400 yards.

[MrCrowley]

Here's my instructable:
http://www.instructables.com/id/Golfbal ... That-Shoo/

I suggest using it as a guide only. Although it will tell you how to make a complete cannon, you wont have as good an understanding compared to if you build it yourself from scratch. I suggest doing a lot of research, design your cannon (with help from us if needed) and then start construction. My how-to should give you a few good ideas but try not to follow the whole thing step-by-step.

I'd also suggest checking out cannons by Technician1001 (look in his signature in the post above). As he said, it isn't too difficult to build a cannon capable of that distance. A 1.5" porting piston valve would have no problem as long as you have a decent sized chamber (3' of 2" PVC) and a long enough barrel (5' of 1.5" SDR 21 for example).

[BeaverRat]

Hey, I know this is your first post, but having a title of "help, please!" doesn't really convey what you actually need.

Anyway, a decent piston to use is Hubb's (it's in the wiki). I'm using a variation of it and I can send a golf ball 400 meters pretty easily...

[Gun Freak]

What the hell, I just posted an entire reply about a good setup but it dissapeared, did somebody delete it?
@beaverrat, it is very hard to get an airtight seal with that piston and I get a perfect check valve on my spool design piston. Hubbs on top, mine on bottom....

[wolfie22]

thanks for the quick responses. i chose that distance because i want to be able to reach the other side of a lake that is near my house. strange, i know, but its kind of become a build-off between my friend and i. i dont know too much about using 'piston valves', but i'll do my research. i'm trying to make it a simple design and build, but i will keep doing my research. thanks, guys.

[MrCrowley]

An 'advanced combustion' will give you the same, if not better, performance than a 1.5" porting piston valved cannon.

[Technician1002]

My 2 inch port piston launcher launched a golf ball just short of 400 yards on just 50 PSI. Use a large port if possible.

[jackssmirkingrevenge]

If size is not an issue, a large chamber and long barrel pressurised to 150 psi or so will give you the performance you seek even with a relatively cheap modded 1" sprinkler valve.

[wolfie22]

If size is not an issue, a large chamber and long barrel pressurised to 150 psi or so will give you the performance you seek even with a relatively cheap modded 1" sprinkler valve.

this sounds easier and more...my level. what kind of size are we talking. and is 150psi safe with usual pvc components?

[jackssmirkingrevenge]

this sounds easier and more...my level. what kind of size are we talking. and is 150psi safe with usual pvc components?

That's the idea, piston valves etc. are great but nothing wrong with an "entry level" sprinkler valve cannon that is just a question of putting store-bought parts together but will still give you the performance you need.

Off the top of my head, barrel length of 4-5 feet and a chamber volume 1-2 times that of the barrel should give you the performance you require, and it can be as simple as this:

[Technician1002]

Are you sure that size launcher can reach 400 yards? In testing my Marshmallow cannon with a golf ball barrel, it reached only 275 yards at 100PSI. I have my doubts that a compact 1 inch sprinkler valve launcher will meet the distance requirement.

Does anyone have measured distance for sprinkler valve GB launchers?

The 100 PSI GB shot was with a 1 inch valve launcher. The 50 PSI GB shot was with a 2 inch valve launcher.



With a larger chamber and longer barrel, it may gain the additional 125 yards needed to meet the goal. This is the launcher configuration that launched the 100 PSI shot. A compressor set to 100 PSI was used.

[jackssmirkingrevenge]

Tech, while your valve doubtless has the edge when it comes to efficiency, your chamber is fairly tiny and maximising this parameter will doubtless compensate for the relatively lower opening time of a sprinkler valve.

Of course a 1.5" or 2" sprinkler valve would allow you to do more with less, I suggested 1" to keep things on a low budget.

[Technician1002]

My question was will a 1 inch sprinkler valve flow enough volume to launch a golf ball that far even with a larger chamber and longer barrel. I was hoping someone who has built a sprinkler valve GB cannon would have some real data on the distance that has been obtained with a 1 inch sprinkler valve.

So the question remains, how far can we expect a 1 inch sprinkler valve launcher to shoot a golf ball. I'm thinking a larger valve may be required.

In the t shirt competition the flow of a 1.5 inch sprinkler valve and a 2 inch QDV with about the same size chamber was compared, both feeding a 3 inch barrel. The performance difference was huge.

Side by side testing 2 inch QDV VS 1.5 inch sprinkler valve with Chronograph.