Help with large 3" cannon

[TG75]

I am needing some help designing an air cannon. It will have dual air tanks with a diameter of 4". The barrel will be 3". The length I was planning on having is 5 feet for the barrel and 3 feet for the tanks. I need it to be able to launch a baseball between 350 and 500 yards. Also, would I be able to accomplish this with a ball valve?

[RBurke83]

Possibly, you haven't supplied any relevant data in terms of pressure, or material. A baseball 500 yards is quite a feat. To accomplish that with just a ballvalve, you would need fairly high pressure and a much longer barrel to deal with how slow a ball valve opens. If I was going to guess, given the large projectile, you would prob be dealing with pvc, which means relatively low pressure. To overcome the low pressure design, you would need a huge chamber and a long barrel, probably much longer than 5 feet.

[RBurke83]

Sorry, for the double post, but in retrospect, thinking about how far 500yds is, I'm gonna say impossible with a ball valve.

[TG75]

Thanks for the quick reply, so what would you suggest for the valve?
Or what do you think the estimated range would be with my planned ball valve configuration?

[RBurke83]

I would have to say a piston valve would be the easiest way to get a fast and efficient valve. Most are built within a T fitting, allowing an over/under barrel/chamber design. You could use a ball valve to 'pilot' or trigger the piston valve. Check out this video by a fellow Spudfiles member and expert:



Watch it a few times like I did, it really is a great way to get a feel for piston valves.

[dewey-1]

You may get 250 yards with a 3 inch burst disc at 100 psi.

[mattyzip77]

500 yards is hard to get with a golf ball pneumatically nevermind a baseball.why do you need to launch a baseball so far???

[TG75]

I will look into using a piston valve. Is there some sort of formula for determining distance for air cannons? Also, it doesn't have to be 500 yards, I would even be fine with 250-300 yards.

[RBurke83]

I'm sure someone with a mathematical background would easily tell you how far a baseball fired at X angle and X speed would go. A baseball does present interesting problems as a ball leaving the barrel with no spin, I would assume, would act like a knuckleball pitch. Keep us posted what you come up with.

[TG75]

I am having a little trouble understanding the concept of a piston valve. Are there any tutorials for a larger valve, near my size of cannon?

[RBurke83]

[TG75]

Thank you, that cleared it up.

[RBurke83]

Hey dude, I randomly saw this on Random Cannon of all things, it seems to be what ur looking for as far as a design.

http://img531.imageshack.us/my.php?imag ... 203kf4.flv

http://img531.imageshack.us/my.php?imag ... 033ez5.flv

Spudtyrrant: "ty for you comment yeah i made the piston out of red oak so its nice and sturdy its very light only about 12 ounces i was trying to give the piston the largest amount of area possible for faster actuation i can put a soccer ball in front of the barrel @ 80 psi and dry fire and it will send the soccer ball a good 100feet"

Spudtyrrant:

barrel: 10ft 3" sch 40 approx: 850 ci

chamber:11ft 4" sch 40 approx: 1659 ci

valve: 4"tee 3" full porting piston valve 1 1/2" travel

pilot: 3/4 inch modded sprinkler valve with popoff(with string attached so it can be fired from a distance)

bumper: a plunger with holes cut in it for air flow

stand: made from an old wheelchair( will be replacing wheels) and dolly welded together well without further ado here she is:

[TG75]

Ya, that was around the size I am going to make mine. Except, is that big of a chamber needed for a cannon that big?

[RBurke83]

you could get away with a smaller chamber if you used galvanized steel chamber and higher pressures