Air pressure actuated QDV

[Labtecpower]

I made this design. do you guys think it will work?
I think the dead space may be too big.

The picture:



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The link:

http://yfrog.com/2gpneumaticqdvp

i hope to hear from you. If there are questions, ask me.

[jackssmirkingrevenge]

Isn't an "air pressure actuated QDV" a piston valve

I didn't quite get your diagram

[Technician1002]

Not in this case. It looks like the valve is blown forward to trigger it. I like it. The only downside is the double port required, one into the valve and one out to the barrel. This is an area of turbulence.

Is it possible to redesign it so the piston moves to the breech and directly opens the barrel? The trigger could be a pull cord and the reset would be a rod connected to the "pump" action to reset the piston.

Look at the drawing, the porting is a QDV spool valve. It is not a traditional piston valve where the barrel or chamber seal is smaller than the piston OD. The design is a 1:1 seat to OD ratio, a true QDV.

It is the first blow forward QDV I have seen designed.

Using air, I am playing with a blow back design to use in the 4 inch launcher. A sprinkler or other fast valve would port a blast of air between the piston and projectile moving both. The piston once unseated would behave like the mechanically triggered QDV and pop the rest of the way open. This is one way I am considering piloting the large 4 inch valve.

[Lockednloaded]

I can't see your diagram, but I have been designing a pressure activated QDV too. I hope this helps. All your really need is a dual action air cylinder for it to work

[Technician1002]

That design I have been considering, but with one difference. I have a single action cylinder with a spring return. It returns extended (piston reset) and pulls with air pressure. Only a single air connection to the air cylinder is needed. ( it only has one )

Coupled with a custom pop off shuttle valve, the set up could be full auto. 8) Applying pressure fires it, after the chamber is vented, the air cylinder supply is gone so it is vented too and self closes.

The air cylinder is 1 inch. It will fit in the breech of the 2 inch cannon right behind the piston. A blowgun between the chamber and cylinder will pilot it.

I've been too busy to tear apart my 2 inch to build this inside the stopper. I may build it inside the 2.5 inch cannon.

[Ranger]

I made something similar, the gun it self is a 3" chamber with a 1 1/2" sdr 21 golf ball barrel, QDV. Inside the stock is a 1/2" cpvc cylinder and a HDPE piston, a 3/16" steel rod runs through the stock and connects to the firing rid for the QDV piston. A blowgun connected to the chamber siphons a tiny amount of air and pushes the 1/2" piston, the firing rod moves building up momentum and then triggers the QDV piston.

Also inside the stock is a 1/4" ball valve for filling and a pressure gauge.

It works really good, so good that I'm having trouble finding a good bumper for the piston. It put a golf ball through 3/4" cedar plank at 50 psi, the highest I have taken to it 80 psi.











Did I beat every body to an air pressure activated QDV?

[Technician1002]

Did I beat every body to an air pressure activated QDV?

I think so. Sweet. Nice cannon. I hope the main piston is decoupled from the rod so the rod isn't getting a beating. Good luck with a bumper. It will need it. Try the inside of a dense foam football such as a Poof brand. The one I use in the ABS cannon sheds a little from wear, but is holding up well.

[Ranger]

Yes the main piston is disconnected from the rod. The 1/2" piston doesnt have enough power to move the main piston on its own, but when the 3/16" rod and 1/4" rod get moving it has enough force to unseat the piston. Right now I'm using knee pad foam for a bumper.