over under air cannon

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
tape fist
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Mon Jan 19, 2009 2:07 am

dose the over under method of building and air cannon cause less sufficient power and if so is it noticeable?
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starman
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Mon Jan 19, 2009 2:29 am

Theoritically, but not really measurable in practice. The type and size of valve you use, piston, sprinkler, qev, ball valve, etc and chamber size and barrel length have much more to do with real performance.

BTW - sufficient = efficient
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Hotwired
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Mon Jan 19, 2009 3:29 am

No it's not noticeable from the viewpoint of a spudgunner.

Yes it is, in theory, not as good for compressed air to travel through a 180* bend as to flow straight through but...

1) All piston valves have at least a 90* turn in the gas flow when they are open, some can even be 180* turns so if you are using a piston valve you either have a ridiculous L shaped cannon or you go that extra 90* and have the chamber tucked in alongside the barrel.

2) A 4m long inline cannon or a 2m long over-under cannon. Same barrel, chamber and pressure, just that one is twice the length of the other and now can't fit in any of your storage rooms and for good measure is rather more bendy than the over-under as the barrel and chamber aren't supporting each other.


If you are using a valve such as a sprinkler valve or a burst disk it can be worthwhile making an inline cannon if the overall length isn't going to be too great anyway.
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