Building a PCP pistol

[lloyd-ss]

I have  temporarily slowed on this while working on the Disco double tube project.
Velocity so far is around 600 fps with 77gn .312 bullets and 10" barrel.  The valve in this proto is very compact and I need to put a slightly longer barrel on it and see what happens, but I will try and get more velocity out of it with the 10" barrel, too.  That would be my preference.

She's in the rough.  My favorite part is the target grade trigger, LOL.   

[oldpink]

Funny thing, Lloyd, unlike nearly all of us here, you will probably be able to get this working and working very well from scratch.

[BenjiHunter]

Wow,that gun packs some serious punch !

[1377x]

i missed a bunch of cool threads while i was in the hospital for 3 months.this is really interesting
Lloyd have you worked on this project lately?

[lloyd-ss]

i missed a bunch of cool threads while i was in the hospital for 3 months.this is really interesting
Lloyd have you worked on this project lately?

Right now it is sitting in a clear plastic box (among several other clear plastic boxes) over one of my work benches.  It is looking at me wondering when I am coming back to work on it again. It is on the list..... and I think about it a lot.....  ..refining...redesigning..... if that counts??
Lloyd-ss

[1377x]

that counts!
it would have been bad to see this kind of post,
hmmm, now where is that pcp pistol project? oh yeah i scrapped it.

[venxxxxx]

any updates ?
How about convert a nail gun into a pcp pistol ?

[french falcon]

I'd LOVE to see it work Lloyd!
Best of all would be (I think) something along the lines of your e-valving system applied to a pistol..
Something compact, 6 to 8" barrelled which would leave space for a LDC,
caliber .32 or 9mm, for 0->25 yds shots. Would be an astounding hunting pistol.

[lloyd-ss]

This is still in the box on the shelf waiting to be worked on again.  The valve is not conventional and takes up very little length in the gun. I'd like to get it working reliably but there are still a few engineering challenges in it.

[french falcon]

Hi Lloyd!

 I bet it's along the lines of a monostable pneumatic operated valve, instead of the conventional poppet valve, which is an oscillating sytem by nature?
 I believe it's one of your greatest ideas in the development of your e-valve, to design along the principles of the industrial pneumatic operated valve, and prove it's fast enough for airguns. No more oscillating reactions from the valve, and an almost instantaneous pressure rise to the maximum value, which in turn maximizes efficiency - and minimizes pressure at the muzzle...

 Correct me if I'm wrong, but something CAN be designed with a return spring to close the valve, once it has been opened by the hammer strike?

[lloyd-ss]

Hi Lloyd!

 I bet it's along the lines of a monostable pneumatic operated valve, instead of the conventional poppet valve, which is an oscillating sytem by nature?
 I believe it's one of your greatest ideas in the development of your e-valve, to design along the principles of the industrial pneumatic operated valve, and prove it's fast enough for airguns. No more oscillating reactions from the valve, and an almost instantaneous pressure rise to the maximum value, which in turn maximizes efficiency - and minimizes pressure at the muzzle...

 Correct me if I'm wrong, but something CAN be designed with a return spring to close the valve, once it has been opened by the hammer strike?

With the e-valve, small solenoids used in very high speed industrial applications, with quick response time and almost perfect repeatability are the key.  I have found the Mac valves (no relation to Mac1 airguns) www.macvalves.com to perform well.  I am sure their are other equally as good brands, maybe even better. Considering that the dwell time needed to maintain consistent velocity across a 2000 psi range may run from (hypothetical)  2 milli sec to 5 milli sec with a required resolution of 20 micro sec, the fact that it functions at all is pretty amazing (to me anyway).  In actual application the mechanical lags are significant and the dynamics of the main HPA valve must be put into a push-pull situation with lead and lag varying across the pressure range, effectively preloading the main valve for fast opening and closing, while maintaining a fail-safe system such that any malfunction will close the main valve as the default mode.  It is easy to open the valve.  Closing it in a timely manner is the trick... and it is not easy.

Return springs, I think, can work in a balanced valve, but  I have never been able to master it.  If the valve is the least bit unbalanced and the HPA gets the upper hand, the return spring is at a major disadvantage.  The conventional knock-open valve, with the HPA functioning as the return spring is a pretty good design and I haven't seen much that is "really" different in a mechanical design.
Lloyd