[RyanN]

Originally Posted by ab500

Okay, so far in summary I've heard the following ideas:

-Lubrication - Hmm this definately could cut back on the friction on the balloons.

-Sabot Modification - (didn't see this one but it's a good idea) Right now what I've done to avoid breakage of the balloons is I've been creating rudimentry sabots out of plastic drinking cups. Basically my procedure is to place the cup in the barrel as far as it'll go, draw around it with sharpie, and then cut it odwn to size so it'll fit. I think there is a lot of room for improvement with this. Once I've fired the sabot and balloon out of the cannon the sabot has cracked on every side. This is telling me that most likely air pressure is escaping around the sides of it. Maybe a stronger material is needed.

-Longer Barrel - This is true although buying more 3" pipe is expensive. Once I get paid again I might go for it.

-Better Value - Solinoid valves with large diameters do get pretty expensive. If there is a reasonably priced one I'll go with it. Right now my cannon does make a honking noise which I attribute to the valve not being fully open but using a manual valve would remove the electronic control (which is a very important safety feature at this point)

-Angle of Firing - Yes 45 degrees is the ideal angle without wind resistence... 40ish is with it.... of course I've been firing somewhere between 30-45 using whatever angle can be obtained with various pieces of deck furnature.

-Weight of Balloons - I hope to get a balance and find the ideal weight for my cannon, I'm not sure how this will affect range.

Here's my plan of action for now:
-Next weekend I plan to build a stand for the cannon with more percise angle measurements (we also hope to motorize this stand at some point to do some very cool balistics)

-I will experiment with different sabots and balloon masses

-I will incrase the pressure up to 120psi.

-I will try some different forms of lubricant.

I would not increase the pressure for safety concerns. Although you already stated that you know the dangers of PVC, increasing the pressure will not help. I've posted before that a kid at school was charging his PVC potato cannon and it blew up in his face at 40PSI. This was the same tank that was on our t-shirt shooter before I revamped it last summer. PVC is dangerous and should not be used for storing air pressure, and certainly not anything above what you are already trying! Please at least put duct tape or something around the tank. Make a wooden box or something to go around it when it explodes.