Monster Pneumatic!

Just build a cannon and want to show it off? Post it in here.

Postby An Apple Pie » Fri Feb 02, 2007 4:34 pm

I second the nomination.
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Postby schmanman » Fri Feb 02, 2007 4:51 pm

two 16 foot long air chambers? how long does that take to fill (or how many cfm is your compressor?)
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Postby Arborman495 » Fri Feb 02, 2007 8:00 pm

That is awesome!!!!

I guess the beach is the ultimate firing range
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Postby clide » Fri Feb 02, 2007 11:33 pm

Very impressive cannon, if it is possible, a longer barrel would probably help out quite a bit.
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Postby daziv » Sun Feb 04, 2007 1:20 pm

Greetings,

I helped my brother build the above mentioned cannon. Some details for everyone on the valve. It's the main valve of an Anderson Greenwood pilot operated relief valve. 2" 300# inlet flange x 3" 150# outlet. This is the "old style" main valve and was available free. We worked around this since it's what we had. No way to reduce the restriction in the outlet and it doesn't matter since the flow is choked inside the main valve anyway. We didn't use the "pilot" and just configured it as a manual valve with the copper tubing and the two valves. When the upper valve opens, it dumps the pressure on top of the piston, which opens the valve. AGCO makes pilot valves as large as 10x14, but anything bigger than 3x4 or perhaps 4x6 will be very heavy.

Inside the valve is a steel cylinder "piston" which slides vertically. The area below the piston is smaller than the area above the piston, so the piston is normally held down against the flow of air that would try to come through from the receivers. Once the dump valve next to the pressure gauge is opened, the pressure on top of the piston is gone almost instantly and then there is a large pressure difference across the piston. This forces the piston all the way up in a small fraction of a second and the valve is then full open. Opening times are down in the milliseconds depending on size and pressure.

Here is a link. The valves pictured here are the "new main valve design" and you can see the "pilot" which is attached to the main valve. The pilot is a very small pressure relief valve itself and is pre-set to open at the requested pressure. When the pilot opens, it dumps the pressure on top of the piston as I described above and that then opens the main valve.

http://www.andersongreenwood.com/pilot_operated.asp
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Postby Navigator7 » Sun Feb 04, 2007 2:20 pm

Daziv,
Thanks for the post!


I dredge up a idea I had a long time ago:

We need a league, an Air Cannon League....the rules are: The cannon can be no bigger than that which can be safely and legally hauled on a double axle trailer by the largest pickup in production.

o Accuracy, distance and novelty classes.
o No explosive propellents.
o Forget the pumpkin...projectiles and materials design by the competitor. No limits.
o All components for firing contained on board the trailer.
o Pressure vessels built to ASME standards.
o 18 years or older.
o A handicap developed so smaller and larger or less expensive and more expensive can compete.
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Postby hi » Sun Feb 11, 2007 6:12 pm

you should paint it cammo, buy a used hummvee from the military, then drive down the freeway. really nice cannon.
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Postby skipatroller123 » Mon Feb 12, 2007 11:16 pm

great machine . now how can I make one that can be carried under my arm on a ski hill to launch a tennis ball 100 feet at -30 C
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