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Posted: Mon Nov 23, 2009 7:28 pm
by c11man
i dont understand the "revised" version i dont see a chamber

and all the c:b test you are using are not too much good for a pneumatic, those test are for a cumbustion, and those test gave the most efficency. for a pneumatic basicly the bigger chamber the better. but as you get above about 2:1 ratio the extra power is often not noticalbe

Posted: Mon Nov 23, 2009 7:56 pm
by julktyl
No worries, Techie.

c11man, thanks for pointing out that the tests were done with a combustion cannon, i didn't notice that. :? Thanks also for the chamber info. As for the revised version, the chamber was the "stock" of the gun since i thought the chamber had to be that small.

I've redesigned... once again... because I was making it way more complex than it had to be. I threw out the idea of making a piston valve, started from scratch, and this is what I came up with. Thanks to c11man's info on the bigger the chamber, the better for pneumatics, I'll have to make a bigger chamber.

Let me know what you think, and remember, that isn't the final chamber.

Posted: Mon Nov 23, 2009 8:01 pm
by jackssmirkingrevenge
That's more like it, get yourself a shock pump and at 400 psi it should be pretty impressive for its size.

Posted: Mon Nov 23, 2009 8:15 pm
by POLAND_SPUD
Burnt Latke's Chamber to Barrel Ratio Tests
yeah c11man is right, it's for combustions

also he is right that you might have used a larger chamber... your first chamber was too large but this one could be slightly larger... you should be fine with a 3" length of 1/2" pipe... esspecially if you want to use a longer barrel

of course it's completely up to you and the source of air that you have

I have to admit that in the past I was a big fan of c:b ratios smaller than 1:1... normally they were lower than 0.5:1

but now that I have a fridge compressor with a tank I don't mind using ratios close to 2:1 especially on a small bore launchers that don't use much air anyway

Posted: Mon Nov 23, 2009 8:22 pm
by julktyl
As a matter of fact, I'm looking at shock pumps as we speak. :D

Trying to find one for decent price, will be pretty much just like the beto shock pump you bought. 400 psi here I come!

Posted: Mon Nov 23, 2009 8:24 pm
by jackssmirkingrevenge
julktyl wrote:Trying to find one for decent price, will be pretty much just like the beto shock pump you bought. 400 psi here I come!
Excellent, shouldn't be hard to find a good one for not much $$$. You might want to move to a longer barrel in future too, it will make a considerable difference in power.

Posted: Mon Nov 23, 2009 8:35 pm
by julktyl
POLAND_SPUD, I'll see if i can find something along those lines for a chamber.

jsr, brake line is very easy to customize lengths. Sometime in the future I might do some tests similar to Burnt Latke's to figure out the optimal c:b ratio for airsoft BBs.

Posted: Mon Nov 23, 2009 8:43 pm
by jackssmirkingrevenge
Or you could download GGDT ;)

Posted: Mon Nov 23, 2009 8:51 pm
by julktyl
Ha so that's what that is. I've seen it mentioned here before but never bothered to look it up. Thanks a lot

Posted: Tue Nov 24, 2009 5:57 pm
by Techie
I've redesigned... once again... because I was making it way more complex than it had to be. I threw out the idea of making a piston valve, started from scratch, and this is what I came up with. Thanks to c11man's info on the bigger the chamber, the better for pneumatics, I'll have to make a bigger chamber.
that's EXACTLY what i was thinking it could be made. due to my stupid lack of parts(pretty sad as its just a few connectors) i couldn't build it.