Pneumatic piston cannon help

[ThatGuy]

I am attempting to build my first piston cannon but have a question about the parts I want to use.

Parts:
-Chamber= 3" PVC, male/female coupler, Cap, 3" to 1.5" adapter
-Barrel= 1.5" PVC
-Piston= Gatorade bottle? (fits into 3" PVC pretty well and only leaves about .5cm between the walls of the Pipe)
-Exhaust- Blowgun?, Pressurized hose?

The 3" chamber will be 2 parts to allow maintenance. The hose will either connect to the back of the 3" cap or on the top of it (as in through the 3" PVC Pipe as well). The fill valve will be an industrial male quick-release on the blowgun trigger.

THE PROBLEM is I am not sure if a 3/8" hose will vent enough air to move the piston. Also will a Gatorade bottle cut in half with a rubber seal on the front work as a piston? I am trying to make this kind of like a M72 LAW rocket launcher or AT4 with the trigger being a small button on top, along with the male quick-release valve being connected to the trigger to fill it.

Any help or suggestions would be appreciated.

[pneumaticcannons]

The blowgun will not vent a piston with 0.5 cm of space between the walls. If you use o-rings( not on a gatorade bottle) You could propbably vent it moderatly quickly with a small pilot volume. If you can't make an o-ringed piston, why not just use a sprinkler valve as the pilot? Infact, that "small trigger" you wanted would could be as tiny as you want if you used electronic actuation.

[ThatGuy]

Well a sprinkler valve was plan B....
What If I made the chamber 2" instead and used a 1.25" cap as a piston? Do you think I would be able to use just the blowgun then?

[MrCrowley]

Nope, you would get pretty crappy performance. Go with at least a half inch ball valve but if you really want to have a trigger like a blowgun, use a 1" sprinkler valve modded with a blowgun as the pilot.

[jrrdw]

Nope, you would get pretty crappy performance. Go with at least a half inch ball valve but if you really want to have a trigger like a blowgun, use a 1" sprinkler valve modded with a blowgun as the pilot.

Yup!

[wyz2285]

if you really want to have a trigger like a blowgun, use a 1" sprinkler valve modded with a blowgun as the pilot.

Or a o-ring sealed piston