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airsoft carbine build log 2.0

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: Demon » Fri Mar 26, 2010 6:18 am

Looks good. I too want to see it shoot


its not complete yet ...
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Unread postAuthor: jhalek90 » Sat Mar 27, 2010 9:51 am

PSI= pounds per square inch.

So, if you have a projectile with exactly 1 square inch of surface area , and 100 psi of air... your projectile will experience 100 lb of force.

But, if you went smaller bore.... say .25 sq in of surface area..... you would only get 25 lb of force on the projectile from the same 100OPSI of air.

This of course ignores all kind of other important variables, such as blow by around the projectile.... dead space.... ect.... but i think it should help you understand.

THAT it why higher FPS is easier with bigger projectiles, more surface area for the air to push against.
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POLAND_SPUD wrote:Anything is possible with the proper 3-way valve.
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Unread postAuthor: ONEWING » Sat Mar 27, 2010 10:41 am

True but it does assume the large diametre projectile is the same weight as the smaller one. Doesn't hold when comparing BBs for example, where the smaller they are the higher its surface area/volume(mass) ratio.

Also the quicker they are to accelerate the quicker they slow down. Thats one reason why sabots are used, high surface area in barrel and low upon exiting it.
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Unread postAuthor: Marffy » Sat Mar 27, 2010 10:34 pm

that looks real nice. I hope to see a diagram when you are done of how the thing works.
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Unread postAuthor: Jack_Hogg » Sun Mar 28, 2010 4:04 am

Here I made a video of my 580PSI gun. It's roughly 1" and has 1800 grain lead bullets. The avalible power is massive :)
So what jhalek90 said, "THAT it why higher FPS is easier with bigger projectiles, more surface area for the air to push against.", I really noticed that in my shots 8)
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Unread postAuthor: chinnerz » Sun Mar 28, 2010 5:23 am

damn it Jack, made me spit out my drink again...... stop putting that video up, or at the very least display a warning about the level of awesomeness this about the be expelled
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Unread postAuthor: Jack_Hogg » Sun Mar 28, 2010 11:12 am

Oh sorry for the boom chinnerz :D
I'll warn you guys next time :)
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Unread postAuthor: Demon » Sun Mar 28, 2010 12:38 pm

Well back on topic i have just fixed a pretty lame problem wich was that the gun triggered itself when it wanted without asking you ...

I reinforced the trigger mechanism and now its perfect ! I just need to make the bolt action ( anyway, muzle loading is pretty fast so its not a priority)

And i will take my time to make a nice stock .
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Unread postAuthor: chinnerz » Mon Mar 29, 2010 12:22 am

Jack_Hogg wrote:Oh sorry for the boom chinnerz :D
I'll warn you guys next time :)


:P well it was my bad, forgot i still had my pc connected to the surround sound system in the other room :P
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 29, 2010 2:33 am

Just to throw some data into the debate, using a schrader piloted piston valve and a 12" barrel I managed an average of about 650 fps with 0.25g BBs at 100 psi.
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Unread postAuthor: Demon » Sat Apr 10, 2010 7:45 am

Little update

I have managed to fix a leak with some epoxy, now, if i blow in the front of the barrel, no air escapes, wich was not the case before ...


ITS GETTHO !

seriously, its very powerful, but very gettho as well
i cant find a way to fix a scope attachement well enough ( i will work on that )

But its very accurate
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