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C:B for a pneumatic
Posted: Tue Feb 14, 2006 5:01 pm
by Rambo
I'm building a self recharjing pneumatic and I want to know what is there big diferense if the barrel is 50ml and tha ratio C:B 2:1 ; C:B 10:1; C:B 25:1;(or it dipends on the sheeels.) Is the shape critical?And what presure can a 0,5L sprite bottle withstand?I may post a diagram.
Posted: Tue Feb 14, 2006 5:18 pm
by boilingleadbath
Use the GGDT.
The shape is not terribly important.
Posted: Sun Oct 01, 2006 7:35 pm
by pyromanic13
could someone give me a link to GGDT? I always hear about it but have never seen it.
-thanks
Posted: Sun Oct 01, 2006 7:36 pm
by pyromanic13
rambo, whats you avatar?
Posted: Mon Oct 02, 2006 8:04 am
by rna_duelers
Just type in GGDT in google you will find it.
Posted: Tue Oct 03, 2006 11:40 am
by POS
can someone stick a number on that C:B ratio ? 2:1 ? more or less ?
Posted: Tue Oct 03, 2006 1:36 pm
by CpTn_lAw
it's very logical, that the bigger the ratio is (for example a 10:1) the more powerful your canon will be. The reason is that, the under-pressure air reserve is still almost the same when you projectile is leaving the barrel...that means that if you pump your ai tank to 150 psi, you will have 150 psi pushing the projectile down the whole barrel, the pressure loss is unsignificant.
On lower ratios, let's say 0.5:1 the pressure loss is very significant, making that your projectile is pushed by less and less air while it goes down the barrel. so, you make your pneumatic according to this, and you other criterias, and you'll get just fine.
Posted: Wed Oct 04, 2006 7:16 am
by rna_duelers
But there is a point were the larger ratio is to impacticle were by adding another 50cm of pipe will only make a gain of say 2m/s but i use a ratio of about 3:1 on my cannons works well.
Posted: Mon Oct 09, 2006 2:43 am
by brumby
is there an online version of the GGDT or is there a mac version?
Posted: Thu Oct 12, 2006 11:36 pm
by SquishY
What would be the most efficient and powerful ratio, or better yet make it a little easier for me and give the measurements. I have just over 5' of 4" pipe and almost 6' feet of 2" pipe, also when I get some 2.5" what lenght should it be for launching tennis balls and cola cans?
Posted: Fri Oct 13, 2006 1:55 am
by SquishY
Will a 5:1 be good, to get this ratio my chamber(30") would be longer than my barrel(24") which IMO would look pretty silly. How ever the way it looks isn't the idea, would this sling densely wrapped wads of duct tape and w/e will fit down the barrel a good distance with considerable power?