Water balloon launcher questions

[oakman26]

I have built some 1/2" ball valve cannons to shoot paintballs and some custom foam projectiles. I have previously tried a 2" sprinkler valve cannon that shot 2" water balloons but this cannon was slightly impractical with bulk and air volume etc.
After that I've tried small diameter water balloons with the 1/2" ball valve cannons and a 1.5" barrel, this has been more successful.

My next project may be to build a 1.5" or 2" QEV cannon primarily to shoot sabot-ed (?spelling?) water balloons.

My current envisioned design is something like this.


1. is a 1.5" or 2" barrel

2. is a 1.5" air chamber

3. is a tee fitting with a smaller diameter female thread coming off the top

4. is a QEV

5. is the fill/ trigger.

6. is a support so a QEV wont have to support the barrel by itself.

Questions:

Are there QEVs that can fill from my chamber, so I can just have a trigger valve coming out the back of the QEV?

Are there QEVs that are readily available on the internet that thread into PVC or ABS fittings, I wish to purchase the pipe at a home improvement store and keep to a minimum of internet ordered parts.

Should I use a 1.5" or 2" barrel? 1.5 would consume less air and I have no problems with using smaller balloons (which I prefer with their strength compared to 2").

Is it okay to use a schrader valve if I fill from the chamber? Is it okay to use a schrader if I fill from 5.?

Just incase you're wondering this was the inspiration for the design

[MrCrowley]

Are there QEVs that can fill from my chamber, so I can just have a trigger valve coming out the back of the QEV?

You can poke a small equalisation hole in the QEV diaphragm and put a light spring behind the valve. Not too difficult to mod but you may trade-off slightly in performance. Has been done plenty of times before so try search the forums for a few cannon examples if you can.

Are there QEVs that are readily available on the internet that thread into PVC or ABS fittings, I wish to purchase the pipe at a home improvement store and keep to a minimum of internet ordered parts.

Yes, manufactured QEVs are quite common and can be found on sites like McMasterCarr in the US. They're generally available world-wide but can be quite expensive, especially above 3/4" in diameter. They are extremely common on this forum and come in many shapes, sizes, and designs. Search the pneumatic showcase section for "QEV" or "exhaust valve".

If you're sticking to under 125PSI, you may as well go with a 1" or 1.5" plastic sprinkler valve.

Should I use a 1.5" or 2" barrel? 1.5 would consume less air and I have no problems with using smaller balloons (which I prefer with their strength compared to 2").

A 1.5" barrel wouldn't "consume less air", the air wouldn't expand as much (lower the pressure) as in a 2" barrel. That being said, a 2" barrel provides more area for the air to act on the projectile, meaning more force. Depending on how you plan to launch the waterballoons, a bigger diameter barrel with lower pressure might be more suitable than a smaller barrel and higher pressure. A 1.5" barrel would be fine but you're going to have to used a sabot to launch the waterballoons either way.

You may want to check out:
http://www.spudfiles.com/spud-cannon-re ... 23256.html

Is it okay to use a schrader valve if I fill from the chamber?

Should be, provided you do the aforementioned mod. That mod may require some fiddling with springs and the like but it should work with a schrader I would think.