SpudFiles

Good evening all, I just joined this great site and I have a question.

Is there an optimum ratio for determining barrel length and diameter as compared to the air chamber size? I am thinking of using a 1 1/2" barrel and either a 3" or 4" air chamber. I am thinking of using a 6 to 8 foot long barrel and was wondering how big the chambers should be.


Thanks,



Bruce

well anywhere from a 1:1-4:1 ratio will be fine, make sure you use NSF-PW fittings, most hardware stores do not carry over 2" in PW, if you cant seem to find the fittings anywhere go to http://www.mcmaster.com http://www.plumbingsupply.com http://www.usplastics.com http://www.savko.com

I used a 4 inch chamber and a 1 1/2 barrel (good choice on barrel size) the chamber is a foot long and the barrel is only 4 feet long. I dont like longer barrels because they hit everything and hard to transport. Although longer barrels are much quieter (i like loud noises). When you construct your chamer use 4 inch pipe and make your barrel interchangable. I would make your chamber roughly around 2 feet if your going to have a 8 foot barrel. But if you choose to go with a 6 foot barrel i would use a 1 1/2 foot chamber. Hope i covered everything you need

PS: Ignore this post i thought that they were talking about combustions but i guess they werent.

pimpman from what you described you are talking about a combustion cannon, brachum is talking about pneumatics

Really, with a pnematic, the ratio is a matter of choise.
Once the chamber:barrel is about 2:1 , larger chambers barly help.
How are you going to have to fill this most of the time? That's the main question. If you are going to fill this with a 12v thing, I would go with a smaller chamber. On the other hand, if you have a nice air compressor, it's not too inconveinent to have a really big chamber. I have a 5'x4" chamber (with a 2" pipe down the center, it's co-axial) and it takes like 20 seconds to fill to 60 PSI. It, however, takes nearly a minute of good pumping to get it to 35 PSI with a hand pump.