double pilot vertical piston

[kydavies]

a while ago i was trying to wrap my head around the idea of modding my super cannon from a ball valve to a piston valve but because its already built it's kind of hard. so hears what i came up with a cross between a ball valve and a piston

[irisher]

Wouldn't that just be a chamber sealing piston valve?

[kydavies]

i have no idea what it is cause i really dont have any experience with piston valves

[Gun Freak]

That would be very hard to make functional, how would you make it seal? O-rings wouldn't work here.

[Technician1002]

For that type of valve to function, the piston must be much larger in diameter than the valve porting to provide a seal area to the cross flow much like a ball in a ball valve is larger than the port.

The chamber pressure will provide a side thrust on the piston causing increased friction (even ball valves do this some).

The worst problem with the design is the chamber pressure provides no pressure boost once the valve begins to open. This valve slowly opens as the pressure in the pilot drops and the gas spring slowly expands slowly opening the valve. Remember as the piston moves the gas spring as the volume increases, drops in pressure. You will have little need for much of a bumper.

These sliding valves are sometimes used in motorcycle carburetors where a full closed seal is not needed and the pressure is less than one Atm. They are not used as a high speed cannon valve and for good reason.

In your drawing, the 40 PSI area is way too small. In absolute pressure that is only (40 + 1 atm) 55 PSI. If it doubles volume (moves the same distance as it's volume) the pressure plummets to 27.5 PSI absolute or (27.5- 15) 11.5 PSI on the gauge. The pressure will be below atmospheric before it opens. (it won't open)

The idea shows you are thinking of options which is good. It was posted here for everyone to evaluate before you built it which is good. I would recommend learning the gas laws and become your own best critic to critique your own ideas.

Many of my wild ideas are proven to not work and are never built. Some of my ideas that work on paper are sometimes posted here and tossed around and something I missed gets identified. From there I build the best ideas. I have several plans on the drawing board. One is a full auto combustion design and another is a 2 stage air piston springer for supersonic launches.

[kydavies]

k thanks, looks like im back to the drawing board

[Crna Legija]

have you read this