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wip KRISS smg.

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: jhalek90 » Mon Sep 19, 2011 8:38 pm

Lockednloaded wrote:Sorry, I meant cloud chamber, mine feeds horribly, I'm trying to use 850psi.


850 psi. My pop of valve opens at 65-70psi.
So I'm sure you are dealing with a whole different set of parameters.

How tight of a fit is your barrel? Ive found that clouds feed much much better with a very tight barrel.

If I hold the barrel vertically, and drop a bb down the top then plug the top with my finger, the bb stops falling. it is a tight enough fit to create a vacuum. I think that might be your issue.

What caliber are you using?
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jackssmirkingrevenge wrote:I wonder... if you put flammable vapours inside a lady... could you get her to diesel?

POLAND_SPUD wrote:Anything is possible with the proper 3-way valve.
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Unread postAuthor: Lockednloaded » Mon Sep 19, 2011 8:54 pm

It's a very tight bore 6.02mm precision airsoft barrel, I think my problem could be solved by changing the position of the air input to agitate BBs better. What do you think?
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 20, 2011 1:14 am

jhalek90 wrote:The detent functions like a non adjustable spring/ball, as the latex tubing is slid over the outside of the barrel, it serves as a spring pushing the ball into the barrel.

I think my issue, and part of the reason i get such good feeding, is the super tight bore barrel. i cant see any light when i put a bb in it, and point it right at a light bulb. its VERY close to 6mm. probably like 6.01mm


This is my take on the problem with detents.

I might be persuaded to make a clear low pressure launcher to see if I can verify this data using high speed footage.
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Unread postAuthor: jhalek90 » Tue Sep 20, 2011 1:18 am

Jack, that's how I've always looked at it... A clear launcher and high speed footage would be fantastic. You could
Order a foot of clear PVC on eBay pretty cheaply.

@LnL. Do you have a detent? If so try it without the detent. See how that works. If not, I have the best luck with the air input being 90 degrees below the barrel. Also, my barrel sticks about 1/3 of the way into my chamber.
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jackssmirkingrevenge wrote:I wonder... if you put flammable vapours inside a lady... could you get her to diesel?

POLAND_SPUD wrote:Anything is possible with the proper 3-way valve.
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 20, 2011 1:44 am

jhalek90 wrote:Jack, that's how I've always looked at it... A clear launcher and high speed footage would be fantastic. You could
Order a foot of clear PVC on eBay pretty cheaply.


I can take the barrel from this and use a syringe as a BB chamber, hmmm...
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Unread postAuthor: Technician1002 » Tue Sep 20, 2011 2:00 am

JSR, the physics does not work as drawn.. Sorry.

The reality.

First BB enters the barrel and as it move into the barrel, air under pressure follows it in. Let's say it is a very low 15 PSI.

Second BB blocks the barrel. First BB does not "Stop due to vacuum". It begins to slow down when the air trapped between the 2 BBs expands out to double its volume at or 0 PSI. At double this new distance the pressure has now dropped below 1 atm to -7PSI and has most likely exited the barrel.

If the second BB enters the barrel before the first BB exits, the same mass of air is still between the two. As the space decreases, the pressure increases. The in barrel collision is highly unlikely. The 2nd BB won't acellerate enough with the rising head pressure on it.

I have done some low pressure shots to show the projectile rate of acceleration, and the much lower rate of deceleration on negative pressure.
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 20, 2011 2:10 am

Technician1002 wrote:JSR, the physics does not work as drawn...


The reality though is that in-barrel collisions with detents do happen:

Image

This is the only explanation I can think of at this point.
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Unread postAuthor: Technician1002 » Tue Sep 20, 2011 2:54 am

I think I have seen that photo before. I think that was a hybrid barrel and that is detonation damage.
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 20, 2011 3:45 am

Technician1002 wrote:I think I have seen that photo before. I think that was a hybrid barrel and that is detonation damage.


As the person who took the photo, I'm pretty sure it isn't ;)

Granted that particular one wasn't from a detent BBMG, but it's a phenomenon I've observed in various prototypes with an airtight detent, for example a shattered epoxy cast barrel at the muzzle end of my 3/8" HPA launcher, and barrel bulging is also the reason updates on this 3mm project stopped abruptly :roll:
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Unread postAuthor: jhalek90 » Wed Sep 21, 2011 1:13 am

I've never used metal bb's in a bbmg... But every time I build one with a detent, I always see shattered bb's
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jackssmirkingrevenge wrote:I wonder... if you put flammable vapours inside a lady... could you get her to diesel?

POLAND_SPUD wrote:Anything is possible with the proper 3-way valve.
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 21, 2011 2:26 am

Working on another hybrid cartridge at the moment but I will probably have time later to give that clear BBMG a go.
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Unread postAuthor: jhalek90 » Thu Sep 22, 2011 12:43 pm

Video:
[youtube]http://www.youtube.com/watch?v=QSSsHuD1wgg[/youtube]

also, i moved to a showcase topic... as this is now fully functional.
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jackssmirkingrevenge wrote:I wonder... if you put flammable vapours inside a lady... could you get her to diesel?

POLAND_SPUD wrote:Anything is possible with the proper 3-way valve.
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Unread postAuthor: evanmcorleytv » Mon Sep 26, 2011 7:07 pm

Looks GREAT bro!! Keep it up!!
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Unread postAuthor: mattyzip77 » Mon Sep 26, 2011 7:09 pm

Very impressive! Keep the videos coming!!!!
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Go Bruins!!!!
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