Mini Pnuematic Potato Cannon

[acanz]

http://www.zippyimages.com/31211.html

Check that out... I just built it out of boredom. Its a mini PVC potato cannon, made of 1" and 3/4" pressure-rated PVC and a 3/4" lawn sprinkler valve pnuematically modified to open alot faster. This program made for calculating the performance of a pnuematic potato cannon (which is extremely accurate - it is the standard for modeling pnuematic cannons and is usually accurate within 2-3 FPS when calculating performance) says the muzzle velocity is about 260FPS and muzzle energy is about 11.5 ft/lbs at 100 PSI. Not bad for something that I made in my garage and can be filled to 100 PSI with a few pumps of a bicycle tire pump, eh?

If anyone is interested, I can build you one like this for about $50, or more if you want a bigger one (but youll need an air compressor for some of the bigger ones). This is not a for-sale add though. Im not selling this one so if you want one or want more info on making one PM/email me.

By the way, that purple stuff is primer that helps the glue melt and bond the plastic better.

 

[Oldschooldeathwish]

I loved making those things a few years back.

 

[acanz]

http://www.putfile.com/media.php?n=cannon70psi (BIG - 3.63MB!)

Video of a grape shot against a railroad tie at 70 psi, and then a can shot twice by grapes at 70 psi.

 

[xsnrg]

How does this compare to the hairspray design? We used to be able to launch 2.5" potatoe plugs out of sight with a quick spray of whiterain into the chamber and a quick press of the grill-ignitor.

 

[SpeedyManiac]

My friend had one that used propane or white gas, can't remember which. We used to fire snowballs about 300-400 yards.

 

[acanz]

How does this compare to the hairspray design? We used to be able to launch 2.5" potatoe plugs out of sight with a quick spray of whiterain into the chamber and a quick press of the grill-ignitor.

It all depends on the size of the chamber and fuel. There is a limited amount of power that can be obtained from a combustion cannon like your talking about due to the fact that the combustable gas has a limit to the power it can create. It can usually create a maximum pressure of 60psi, while a pnuematic cannon can theoretically have a limitless amount of compressed air in it. In actuality, a pnuematic will usually use between 80-120psi based on how high its charged.

With two chambers of the same size, and both cannons at 60psi, the combustion will win as there is no valve to limit the flow of pressure. As the pnuematic cannon's chamber size is increased or the pressure is increased, the pnuematic will win.

Tell me if that made sense.

 

[Tony Eeds]

Not to be a wet blanket

http://www.lascofittings.com/supportcenter/compressedair.asp

 

[acanz]

I know that PVC isnt approved for use with compressed air, but hundreds of people have used it and as long as you stay well below the Sch.40/Sch.80 (220PSI/4??PSI) water pressure rating it <i>should</i> be fine.

A lot more info is avalible here - www.spudtech.com / http://forums.spudtech.com <--- you have to register to view the forums

 

[91KDX]

I dont want to put a damper on things, but I found out that the hairspray cannons are only good for like 40 or 50 shots. The PVC weakins from the flame and the chamber will explode. I throw my cannons out after 40 shots, I figure PVC isnt that expensive, they are easy to make, and I dont think its worth getting injured over. Just a little peice of advice.

Ben

 

[acanz]

I dont want to put a damper on things, but I found out that the hairspray cannons are only good for like 40 or 50 shots. The PVC weakins from the flame and the chamber will explode. I throw my cannons out after 40 shots, I figure PVC isnt that expensive, they are easy to make, and I dont think its worth getting injured over. Just a little peice of advice.

Ben

That is completely wrong. The flame is not hot enough and does last long enough to damage PVC at all. People have used propane which burns much hotter then hairspray and used their cannons hundreds of times with no weakening of the chamber walls.

 

[91KDX]

Well then, that was either some nasty hairspray or some crappy pvc?? I had the chamber blow on one of my cannons about a year and a half ago. it had like 60 rounds through it, and the when it ignited it cracked the pvc and burnt my hand alittle and made a loud bang. I dropped the gun and stepped back and I can remember thinking "what the hell am i doing?". I dont know, could have been some crappy pvc, or the pressure on the chamber was too much. I dont know, its just a warning.

Benjamin

 

[acanz]

You probably were using cellular core PVC. Its like styrofoam as a pipe, and would probably break as you said. If your going to build another, get Schedual 40 PVC. It is meant for pressure and will probably never break.

 

[Offroadr]

wussy stuff compared to our cannon :nener: