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Help with large 3" cannon

Posted: Wed Mar 27, 2013 7:22 pm
by 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?

Posted: Wed Mar 27, 2013 7:42 pm
by 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.

Posted: Wed Mar 27, 2013 7:53 pm
by RBurke83
Sorry, for the double post, but in retrospect, thinking about how far 500yds is, I'm gonna say impossible with a ball valve.

Posted: Wed Mar 27, 2013 8:15 pm
by 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?

Posted: Wed Mar 27, 2013 8:35 pm
by 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.

Posted: Wed Mar 27, 2013 8:58 pm
by dewey-1
You may get 250 yards with a 3 inch burst disc at 100 psi.

Posted: Thu Mar 28, 2013 8:31 pm
by 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???

Posted: Fri Mar 29, 2013 7:01 pm
by 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.

Posted: Fri Mar 29, 2013 7:26 pm
by 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.

Posted: Fri Mar 29, 2013 10:12 pm
by 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?

Posted: Sat Mar 30, 2013 8:13 am
by RBurke83
Image

Posted: Sat Mar 30, 2013 9:31 am
by TG75
Thank you, that cleared it up.

Posted: Sat Mar 30, 2013 7:01 pm
by 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:

Posted: Sun Mar 31, 2013 9:15 am
by 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?

Posted: Sun Mar 31, 2013 9:28 am
by RBurke83
you could get away with a smaller chamber if you used galvanized steel chamber and higher pressures