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Coaxil Design

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Coaxil Design

Unread postAuthor: octane89 » Mon Nov 05, 2007 8:58 pm

I haven't seen if anyone has donw a coaxil like this before, but in my mind it should work. I just wanted more cubic volume and like the simplicity of coaxil pistons so I did this. If anyone has seen one like this please post it, I'd like to see how it performs.
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Simple design, I just used 2" as an example.
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Unread postAuthor: benstern » Mon Nov 05, 2007 9:00 pm

Should Work.
However, that would be just way too much chamber volume.
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Unread postAuthor: Novacastrian » Mon Nov 05, 2007 9:03 pm

Depends how long he wants his barrel, or how fat.
I like it.
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Unread postAuthor: knappengineering » Mon Nov 05, 2007 9:03 pm

In theory it should work, but the extra volume is probably not necessary.
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Unread postAuthor: octane89 » Mon Nov 05, 2007 9:06 pm

benstern-But how would it propose a problem? I didn't really try to make it to scale either.

Ive been wanting to have a high volume cannon...bigger barrel, bigger chamber= farther distance.

I was going to try something like a 30inch chamber, and 4" diameter with is over 400 cubic inches. I just think too big sometimes though. As well as the fact I have to "one up" my friend.

edit- As far as a barrel, maybe a GB barrel or something around 1.5".
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Unread postAuthor: Novacastrian » Mon Nov 05, 2007 9:08 pm

It would make quite a good piantball shotgun :P
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Unread postAuthor: octane89 » Mon Nov 05, 2007 9:11 pm

I just gave up paintball-I do however have some paintballs left though.
Right now Im drawing up a breech loading design, which will probably end up to be too complicated but who knows.
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Unread postAuthor: bluerussetboy » Mon Nov 05, 2007 9:16 pm

my math might be bad, but wouldn't a single chamber of 3" pvc hold more than two chambers of 2"?
area of 2" circle = 9.8-10.0-ish
area of 3" circle = 22-ish

i'm too lazy to break out a calculator


not to mention less fittings
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Unread postAuthor: Pete Zaria » Mon Nov 05, 2007 9:17 pm

Sure it will work, but I see two problems....

It inherently creates a way-too-big C:B ratio, unless that's one of your design objectives, and,
It will restrict flow a lot. Connect the "secondary chamber" to the main chamber closer to the valve, the closer to the valve, the less distance the air has to go to exit out the barrel, and the faster it should be able to dump. Did that make sense?

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Unread postAuthor: octane89 » Mon Nov 05, 2007 9:19 pm

blue-Yes it would.
Two chambers of 2" ID at 30" long= 188 cubic inches
One 3" ID at 30"= 200 cubic inches
*roughly*
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Unread postAuthor: Lentamentalisk » Mon Nov 05, 2007 9:21 pm

The bottom chamber is completely unnecessary if you are going for a 1.5" barrel in a 4" chamber. A little sketchy rounded math to show:

1.5" volume:
(1.5/2)^2x(pi)x(length)=1.77x(length) sqr. in.
4" volume - 1.5" pipe (for simplicity we will say it has a 2" O.D.)
{[(4/2)^2x(pi)]-1.77}x(length)=10.80x(length) sqr. in.
Ratio:
10.80/1.77=6.1:1 C:B ratio

That is already HUGE!!!!!

hope this helps

edit: lol took me a long time to post. you all beat me
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Last edited by Lentamentalisk on Mon Nov 05, 2007 9:22 pm, edited 1 time in total.
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Unread postAuthor: octane89 » Mon Nov 05, 2007 9:21 pm

Yea it did. It's the same theory in a paintball gun. We would mod our bolts to let more air flow by removing some aluminium on the bolt cap, and tape part of the bolt to create less pilot volume.
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Unread postAuthor: LikimysCrotchus5 » Mon Nov 05, 2007 9:21 pm

well you could get somewhat more power with less chamber volume because it would be easier to get a higher presser. I would say to cut down on most of that extra chamber volume and make it a more of a handle rather than a big, bulky, unnecessary chamber.
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Unread postAuthor: octane89 » Mon Nov 05, 2007 9:29 pm

Pete- Something more like this? My previous post was refering to what you said too.



letamentalisk- Well it's not going to be a small cannon. Or at least I don't plan on it being one.
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Unread postAuthor: spudgunnerwryyyyy » Mon Nov 05, 2007 9:39 pm

Much better, But, you could reduce the length even more. The point of a coaxial is that it is small and compact.
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