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PostPosted: Fri Aug 10, 2018 10:09 am 
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the title says it all, i just need to fill this character limit now. but seriously why don't they?


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PostPosted: Fri Aug 10, 2018 10:39 am 
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low power the speed would not be very fast.
and it's called green gas but it's not really good for the environment. still Co2 emission.

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PostPosted: Fri Aug 10, 2018 11:47 am 
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Green gas is just propane with a different scent.

BB or pellets are heavier than most standard 6mm BB so it would be way less powerful.

Since the PSI difference. Green Gas or Propane is only like 115 PSI, where C02 is 840 PSI.


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PostPosted: Fri Aug 10, 2018 12:01 pm 
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leadslinger wrote:
Green gas is just propane with a different scent.

BB or pellets are heavier than most standard 6mm BB so it would be way less powerful.

Since the PSI difference. Green Gas or Propane is only like 115 PSI, where C02 is 840 PSI.


Wouldn't the propane be ignited like the tippmann c3 giving you suffice psi? C3 never took off due to size and safety concerns.

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PostPosted: Fri Aug 10, 2018 12:06 pm 
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jckstrthmghty wrote:
leadslinger wrote:
Green gas is just propane with a different scent.

BB or pellets are heavier than most standard 6mm BB so it would be way less powerful.

Since the PSI difference. Green Gas or Propane is only like 115 PSI, where C02 is 840 PSI.


Wouldn't the propane be ignited like the tippmann c3 giving you suffice psi? C3 never took off due to size and safety concerns.


Not sure.


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PostPosted: Fri Aug 10, 2018 12:15 pm 
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jckstrthmghty wrote:
Wouldn't the propane be ignited like the tippmann c3 giving you suffice psi? C3 never took off due to size and safety concerns.


Not for a small caliber. You can run paintball guns with efficient valves on less than 300 psi, that's around 3 times the weight of a typical 0.22" pellet but almost 10 times the surface area for the gas to push on. Burning propane at atmospheric pressure is not going to generate the amount of pressure you need for useful velocities with an airgun.


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PostPosted: Fri Aug 10, 2018 1:17 pm 
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PZAM wrote:
jckstrthmghty wrote:
Wouldn't the propane be ignited like the tippmann c3 giving you suffice psi? C3 never took off due to size and safety concerns.


Not for a small caliber. You can run paintball guns with efficient valves on less than 300 psi, that's around 3 times the weight of a typical 0.22" pellet but almost 10 times the surface area for the gas to push on. Burning propane at atmospheric pressure is not going to generate the amount of pressure you need for useful velocities with an airgun.


This is not my understanding. The c3 is shooting a .68 cal 50g projectile at around 280-300 fps. Why would it not be able to propel a 7-10g pellet to 500 fps? If you couldn't contain energy from the explosion then sure. In effect it would be a firearm and likely produce far greater velocities than 500fps and would require appropriate design to handle such forces. Once again only in my understanding.

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PostPosted: Fri Aug 10, 2018 1:42 pm 
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Air gun's and paint ball gun's don't work the same in a ....

airguns the air,co2,gas push directly on the pellet and it's very small. so higher psi needed.

paintball there is a different chamber with a much bigger surface area for the air.co2 to push on a piston that in turn moves 2nd leaver that propels the paintball out like pushing it out.
it's all in the law's of Hydraulics if I could write I would explain better but this works like a Hydraulics jack but backwards to get the speeds.

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PostPosted: Fri Aug 10, 2018 1:48 pm 
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Jimmy on the spudfiles forum had done some experiments with propane mixtures in a closed chamber: http://www.inpharmix.com/jps/Closed_Cha ... udies.html

The results were congruent with the calculated maximum pressure of 129 psi - nowhere near the kind of pressures you need to accelerate a 0.22" pellet to 500 fps within a reasonably sized setup.

Quote:
The c3 is shooting a .68 cal 50g projectile at around 280-300 fps. Why would it not be able to propel a 7-10g pellet to 500 fps?


While the pellet is lighter than the paintball, the gas has a much lower surface to push on (0.038 square inches vs 0.36 for the paintball) and so much less force is exerted on the pellet, which is disproportionately heavier in terms of the area ratios.

In order to get significant performance, you need to pressurize the propane so several times atmospheric pressure - at that point supersonic velocities are possible as in this example with a 10x atmospheric pressure propane/air mixture, but it becomes very hard to make a repeater.


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PostPosted: Fri Aug 10, 2018 2:09 pm 
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PZAM wrote:
Jimmy on the spudfiles forum had done some experiments with propane mixtures in a closed chamber: http://www.inpharmix.com/jps/Closed_Cha ... udies.html

The results were congruent with the calculated maximum pressure of 129 psi - nowhere near the kind of pressures you need to accelerate a 0.22" pellet to 500 fps within a reasonably sized setup.

While the pellet is lighter than the paintball, the gas has a much lower surface to push on (0.038 square inches vs 0.36 for the paintball) and so much less force is exerted on the pellet, which is disproportionately heavier in terms of the area ratios.

In order to get significant performance, you need to pressurize the propane so several times atmospheric pressure - at that point supersonic velocities are possible as in this example with a 10x atmospheric pressure propane/air mixture, but it becomes very hard to make a repeater.


So the charge is inadequate at 1x atmospheric pressure. Seems even the c3 pressurizes it's charge before ignition. As you have eluded to heat becomes an issue for multiple shots in a shorter time span.

Thank you for taking the time to explain.

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PostPosted: Fri Aug 10, 2018 3:30 pm 
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jckstrthmghty wrote:
So the charge is inadequate at 1x atmospheric pressure. Seems even the c3 pressurizes it's charge before ignition.


If you look at the diagram of its operation, the "pump" motion actually serves to make sure all the burned gasses are evacuated from the firing chamber"

Image

Quote:
Thank you for taking the time to explain.


Pleasure!


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PostPosted: Fri Aug 10, 2018 9:49 pm 
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PZAM wrote:
jckstrthmghty wrote:
So the charge is inadequate at 1x atmospheric pressure. Seems even the c3 pressurizes it's charge before ignition.


If you look at the diagram of its operation, the "pump" motion actually serves to make sure all the burned gasses are evacuated from the firing chamber"

Image

Quote:
Thank you for taking the time to explain.


Pleasure!



is this your drawing of a paintball or 6mm air soft?

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PostPosted: Sat Aug 11, 2018 4:48 am 
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FRANK wrote:
is this your drawing of a paintball or 6mm air soft?


Not my drawing, it describes the firing cycle of the Tippmann C3 paintball marker

Image

It operates on a similar principle to [url=https://home.howstuffworks.com/nail-gun3.htm]combustion nailguns
[/url] but instead of driving a piston, the combustion gasses propel the paintball directly down the barrel.


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PostPosted: Sun Aug 12, 2018 3:42 am 
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Discussion is interesting and deserves its own thread.
The topic of this thread is, "Why don't BB and pellet guns use green gas?"


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