first coaxial plans

[jrrdw]

Wont that union hold the diaphram in one place? Thus not allowing it to move, keeping it from working?

[sandman]

the diaphragm is flexible so it can stretch, hence why sprinkler valves work

[jrrdw]

the diaphragm is flexible so it can stretch, hence why sprinkler valves work

Wont it be clamped all the way around? It has to let the pilot chamber vent.

[sandman]

Wont it be clamped all the way around? It has to let the pilot chamber vent.

a sprinkler valve is clamped all the way around
and when it vents the force stretches it back and allows the air into the barrel

[BigJon]

The diaphragm is accually a little bigger than the diameter of the union so it can move back and forth a little bit i think. Kinda hard to explain so sorry if you don't understand.

[Easterbunny]

would it be easier and peform better to make it a piston insted? somthing like an end cap with a rubber disk , bolt washer and a nut. put a couple of holes in the endcap for airflow. here

[BigJon]

If you use the piston method you won't need to drill holes in the endcap (piston) unless it is absolutely air tight. I also think a piston would be easier to make but thats just me.

[Easterbunny]

would this piston work?

[BigJon]

If you want a piston valve have a look at this since your chamber is 3"http://www.spudfiles.com/forums/3-piston-t313.html

[Easterbunny]

thank you, how much movment should i allow for it?

[sandman]

i think the formula is use 1/4 of the diameter of the piston

[MrCrowley]

Barrel diameter, not piston

[sandman]

wouldn't the Piston OD and the Barrel ID be the same thing?

[Easterbunny]

ok here is the updated plans, i hope to make the body tube removeable to service the launcher if it is nesscary with a pistion

[MrCrowley]

wouldn't the Piston OD and the Barrel ID be the same thing?

No otherwise the piston wouldn't work

And if the piston O.D = Barrel I.D wouldn't the piston go inside the barrel

The piston needs an exposed area that has pressure forcing it back, that's why pistons work so well.

So the O.D of the piston could be say 8cm and the I.D of the seat(barrel) could be 7cm.