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PCP Guns

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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PCP Guns

Unread postAuthor: maverik94 » Fri May 15, 2009 5:02 pm

I have heard of a kind of gun called a "PCP" gun. I looked it up on wikipedia and found out it stands for "PreCharged Pneumatic. However, I hav looked everywhere, google, spudfiles, spud-wiki, etc, an I have not been able to find any information about how these work. I am just curious about how they work and i was wondering if anyone knew anything about them, or had any usefull links. Thanks yall!
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Unread postAuthor: MountainousDew » Fri May 15, 2009 5:09 pm

I just did a quick search on Google and I found this:
http://airhog.com/about_airguns.htm
It says how they work, the velocity they can produce, and it mentions some advantages.
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Unread postAuthor: CpTn_lAw » Fri May 15, 2009 5:12 pm

PCP guns use a reservoir filled at high pressure (you're looking at 3000 psi for pellet/hunting rifles) and a hamer valve, each strike of the hammer let's a small amount of air at high pressure in the barrel, pushing the projectile at high speed ;)
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Unread postAuthor: far_cry » Fri May 15, 2009 5:38 pm

search for
talon ss
airforce condor
evanix ar6
you will see them on youtube
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Unread postAuthor: maverik94 » Fri May 15, 2009 6:00 pm

ok, I looked on that site MountainousDew, but I STILL DON'T UNDERSTAND HOW THEY WORK. (sorry, CAPS was on)
CpTn_lAw: Ok, well, I'd be interested in making one that would maybe be able to shoot 10 rounds on a fill, not a huge ammount like the commercial ones. Does anyone have diagrams on how they work?
far-cry, I have low-speed internet and can't watch youtube. sorry.
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Unread postAuthor: Gippeto » Fri May 15, 2009 6:27 pm

PCP airguns are roughly similar in function to those using co2.
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Unread postAuthor: jonnyboy » Fri May 15, 2009 6:48 pm

*Que a long rag post*

It's a hammer valve much like the ones we use. Think like hitting a schreder with a pin.
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Unread postAuthor: Ragnarok » Fri May 15, 2009 6:57 pm

jonnyboy wrote:*Que a long rag post*

No.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: mark.f » Fri May 15, 2009 8:14 pm

Ragnarok wrote:
jonnyboy wrote:*Que a long rag post*

No.


I like the way you think.
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Unread postAuthor: covey12 » Fri May 15, 2009 8:21 pm

just look at crosmans guns, they have a chamber that you pump up to 2000psi with there hand pump(which is really nice for spudguns), and it regulates each shot at about 900-1000 fps, this way you can have a repeater with no co2

http://www.crosman.com/airguns/benjamin/BP1K77GP
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Unread postAuthor: far_cry » Fri May 15, 2009 8:52 pm

maverik94 wrote: far-cry, I have low-speed internet and can't watch youtube. sorry.

why where are you from Syria :idea: :idea: cuz they the only country that have internet but very slow


her some pictures, if you didn't understand how this work
god may help you :oops: :oops:


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and



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Unread postAuthor: maverik94 » Fri May 15, 2009 10:33 pm

oh, that's simpler than I thought. Theoretically you could make a homemade mega-sized schrader valve, have a simple homemade spring loaded hammer...it's not so hard. One other question, when the hammer shoots forward and opens the schrader valve and shoots the air into the barrel, how does the schrader stop letting air into the barrel? Also, If I had a chamber say... 3/4" diameter and 5" long at 300 psi, how many shots would I get about? Thanks, that picture was very usefull Gippeto, where do you find those?
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Unread postAuthor: inonickname » Fri May 15, 2009 10:55 pm

Depends on your hammer weight and spring strength.

Ideally, the spring stops propelling the hammer just before it strikes the valve stem so that the kinetic inertia of the hammer is used to strike the valve stem, fighting the spring and air pressure behind it.

The kinetic energy is lost extremely rapidly, so the spring behind the valve stem and air pressure closes the valve extremely fast, meaning only a small burst of air is used.

On my micro repeater I used a spring that would be applying a very slight amount of pressure even after firing, but the air pressure behind the hammer valve was enough to keep it closed.

Here are some resources for you to look into:

Girandoni repeating airgun and pistol

Crosman multi pump valve

Airgun development (homebuilding, barrel rifling etc)

Simple tee hammer valve

The lighter your hammer is, the more shots. The heavier the hammer is, the stronger the shots. The stronger the spring, the stronger the shots. And vice versa.

Good luck, I too plan to build a PCP rifle to operate on anything from 100 psi to unregged CO2 (Soda Stream bottle, only non disposable source of CO2 here).

If you need any help just give us a buzz
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Unread postAuthor: maverik94 » Fri May 15, 2009 11:01 pm

Thanks for the links, I am considering making a little pcp pistol as a summer project. (it's almost here! :D ) I would be happy to get 10 shots out of it at 200 psi, do you think that's do-able? As for the help offer, if I run into trouble I may just take you up on that.
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"You can't be friends with anyone if you aren't friends with yourself."
"I'd rather be hated for who I am, than loved for who I'm not." -André Gide
Give me a lever long enough, and a fulcrum on which to place it and I shall move the world.
–Archimedes
Defeat is always momentary.
–Carl Denham

Current Project: None, I'm in Spudremission.
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Unread postAuthor: Gippeto » Fri May 15, 2009 11:07 pm

It's not so much the tension of the hammer spring that allows the hammer to knock open the valve, as the impact energy and momentum attained by the hammer. Mass of the hammer, spring tension, and distance traveled by the hammer all come into play. (Time to play with ggdt some more. :) )

Hammer mass and momentum , and valve spring tension, valve stem mass, pressure, also have an effect on valve dwell. This is how long the valve is actually open. Longer dwell = increased gas consumption, and MOAR power. (to a point)

After the shot, the hammer spring is essentially fully extended, and cannot overcome the spring in the valve. This, combined with the pressure in the valve, allows the valve to close.

It's not quite a schrader, but you are getting the basic idea.

There's no reliable way to calculate how many shots you will get out of that particular chamber. There are too many variables, just build it and find out.:D A wild arse guess (Literally pulled from. :lol: )...5 shots in 6mm caliber

I found that diagram and others online. Google is my friend. :roll:

Edit: Must learn to type faster. :(
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Last edited by Gippeto on Fri May 15, 2009 11:13 pm, edited 1 time in total.
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