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An idea for a semi-auto repeating design

Posted: Thu Aug 04, 2011 2:06 am
by evilvet
Idea:

A "standard" barrel sealing pneumatic, 20mm brass tee with a plastic piston, 15mm port. The current design is single shot but my air reserve is from a tethered 100 litre tank, feeding a 450mm x 20mm chamber.

If I port it via a solenoid valve that I control the dwell time on, once the port is closed the thought is that a second solenoid would open for say 5 seconds to re-pressurize the chamber for the next shot. Ammo feed would be a gravity or spring loaded tube mag.

Any thoughts from the group ?

Posted: Thu Aug 04, 2011 2:15 am
by Crna Legija
your could use a 3way valve, two birds one stone?

Posted: Thu Aug 04, 2011 2:34 am
by jackssmirkingrevenge
A three way valve would certainly simplify things, no need to calculate dwell time because if it isn't firing, it's filling.
Crna Legija wrote:your could use a 3way valve, two birds one stone?
Artist's impression, not sure how well it would work as you described it :-/

Posted: Thu Aug 04, 2011 3:00 am
by evilvet
True, but doesn't that mean my "chamber is now the entire HPA reserve ?
As I understand the three way concept once the port valve closed, the chamber valve is open ?

Sorry I cannot add a graphic right now (I am on site watching a server melt in slow motion) but what I was thinking was that the cycle would be:

*Reserve to chamber valve opens for 5 seconds, pressurizes firing chamber
*Reserve to chamber valve shuts
*Wait for firing opportunity
*Port valve opens, "bang"
*Port valve closes
*Reserve to chamber valve opens for 5 seconds, pressurizes firing chamber, decrements HPA reserve.

Can a 3 way do that ?

And so on and so forth

BTW JSR, that little bit of PaintShop is quite probably the sickest, most twisted, evil disgusting and downright funny things you have ever posted.
I love it :)

Posted: Thu Aug 04, 2011 3:15 am
by Crna Legija
Image

that's how 3ways work, the pilot there is a slide valve but any kind of 3way will work exactly how you want it.

Posted: Thu Aug 04, 2011 4:08 am
by jackssmirkingrevenge
evilvet wrote:Can a 3 way do that ?

And so on and so forth
Think of it this way:

A three way valve has three ports, which we will call A, B and C

There are two possible paths, AB (with C blocked off) and AC (with B blocked off)

A is connected to the pilot area of the piston

B is connected to your 100 litre tank

C is simply left open to the atmosphere.

At rest, the three way is in position AB. This means your reservoir is filling the launcher chamber.

When the trigger is pulled, the valve switches to position AC. This means the reservoir is blocked off, and is no longer filling the pilot and chamber, while the pilot is exhausted to the atmosphere, which fires the launcher.

Once the trigger is released, the valve goes back to AB, refilles the pilot and chamber and the cycle can be repeated.

Hope this is clear enough :)
that little bit of PaintShop is quite probably the sickest, most twisted, evil disgusting and downright funny things you have ever posted.
I'm sure I've done worse but glad it's appreciated ;)