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QDV Design?

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QDV Design?

Unread postAuthor: saefroch » Sat Sep 25, 2010 11:39 pm

I've been tinkering around with different piston hybrid designs, and this just came to me. I'm not sure what you could call a valve like this, but it's based on Tech's QDV, but "piloted" mechanically by a pop-off valve. I hope my diagram is fairly clear, and as this is clearly still theory, I have red arrows pointing to the two areas that would need to seal, maybe with female o-rings? Will this work? And assuming it would, what could one call it?

EDIT: Picture sequence explains the valve function in more detail, hope it now makes better sense. Thinking maybe an internal check valve in the main piston will solve the problem of pressure behind the valve slowing opening.

EDIT: All problems with the valve seem to be fixed... now I'm seeing this as a viable build with some very custom parts.

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Last edited by saefroch on Sun Sep 26, 2010 6:15 pm, edited 2 times in total.
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Unread postAuthor: Technician1002 » Sat Sep 25, 2010 11:56 pm

Servicing the seals would be a challenge. The air trapped behind the piston may slam it back forward. In a regular QDV, this area is vented with control rod hole.

I have toyed with a pop off pilot, but it would simply puff air in the small space between the piston and projectile to launch both into motion. Once in motion, the QDV would operate as if triggered any other way. :D

It may be easier to plumb a tube between a pop off valve and a hose barb on the side of the barrel. I've considered a variant for piloting a 4 inch QDV remotely with a 1 inch sprinkler valve.
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Unread postAuthor: Lockednloaded » Sun Sep 26, 2010 12:00 am

What about a conventional QDV, Pulled open by a two way air ram. To actuate the air ram, opening the valve, a directional pop-off (one that doesn't just vent into the atmosphere, but has an actual outlet) which lets the ar ram actuate when the mix has ignited... I'll draw up a diagram later, but It may work
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Unread postAuthor: saefroch » Sun Sep 26, 2010 12:03 am

Well (and theory this is) you could just slap some sort of check valve to the outside on the back of the piston area, that would solve problem #1.

What I was thinking for this idea (And I deeply apologize that I forgot about this when I drew up the design) is that you can do internally with just pressure and forces in a hybrid design, what the operator does for a normal QDV. The pop-off piston slides back in little bits, ignition, pop-off "pops", both from the ignition and the release of the extension air spring, and is really moving when it hits the front of the piston.

I'll have the diagram fixed at some point soon... I dragged myself out of bed to put this on Spudfiles.
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Unread postAuthor: POLAND_SPUD » Sun Sep 26, 2010 1:30 am

I think that this is simpler
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Unread postAuthor: saefroch » Sun Sep 26, 2010 2:15 am

I know what you're saying with the diagram, and what you are proposing is a practical answer to an purely intellectual pursuit. Therefore I disregard your design, though it is much simpler and has little overall performance difference, it is far less interesting.
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