SpudFiles

Anybody know what size I should get for a 2" SCH 40 PVC cannon? I'm planning to fill it with water and I want it to be as thinwall as possible. (can stand launch but still explode easily on impact)

Rubber projectiles have a lot of friction. There's a reason water balloons usually require sabots. So a paper sleeve or something might be a good idea.

In my experience with latex tubing it'll expand about 800% in diameter. That's about 9 times the original diameter. So shoot for something less than 9 times smaller for a good fit.

Ah thanks, I was also just looking at the sites and saw the whole elongation at break factor (750% so your guess is pretty dead on).

Now to soon figure out my regulator situation.

Sorry for the double post, but how do you normally inflate them?

tie one end then fill like a baloon fill and tie other end

I'm worried that it won't fit over the faucet since its so small.

go to the neares dollar general and get a water baloon hose connector in the toy isle

Please note the weight of the water and the diameter you are using. A long projectile may have enough mass to build quite a bit of recoil in a 2 inch tube. At 100 PSI, the force between the projectile and cannon can be as high as 314 lbs. Often people not expecting that fill air cannons with water and pull the trigger, just to have them rocket out of their hands.
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I did that once with my marble rifle and it bruised my collar bone. Of course i was at 3 times the pressure but its still the same concept. Are you planning on using this for paintball? If not then a regular water ballon would probably be the best ammo.

You will also need a sabot as btrettel has mentioned, i reccomend a toilet paper tube or a dixie cup. They work really well.

Its going to be a short round, and its a mortar. I'm not exactly sure if a balloon will fit nicely into a 2" and still blow up on impact?

hey mishkan i did this with mine ( modified sprinkler) just DONT take it over 40 or 45 cant remeber or the ballon will burst what you want to do is
.....
take dixie cup or mc donalds water cup ( their free every time u go pick one up) cut 4 slides down the side every 1/4 all around the cup so the sides are in 4 parts...... but only cut half way down or 3/4 of the way

put a nicely fill balloon into the cup must fit snug or loosely then just stuff in the barrel

each cup will last about 4 to 7 shots before being riped apart

like i said before dont go above 45psi

here a link of me using mc donalds cup... in the start of the clip u can kind of see it... purple ballon
sorry bad video if u need i make another one

Was that 2" PVC? Anyhow I'm firing it at full velocity so I figured the latex would handle the acceleration a bit better.

All you need to do with water balloons is this:

1. Set your filled balloon in the middle of a paper towel

2. Roll it up like a burrito

3. Twist the ends closed

4. Load and fire!

I'd post pics, but I'm at AirVenture 2009 in Oshkosh, WI.

This method works well in most sprinkler valve designs, as the paper towel slides fairly easily in the barrel, and it also acts as wadding.

roboman wrote: I'd post pics, but I'm at AirVenture 2009 in Oshkosh, WI.

Off subject but, did you see the Airbus 380 In person?
I was hoping it would fly over but I didn't see it.
You are 15 miles south of my location.
Hope you had a good time at EAA.

dewey-1 wrote:

roboman wrote: I'd post pics, but I'm at AirVenture 2009 in Oshkosh, WI.

Off subject but, did you see the Airbus 380 In person?
I was hoping it would fly over but I didn't see it.
You are 15 miles south of my location.
Hope you had a good time at EAA.

Yeah, actually I did see it in person! It was incredibly huge...I heard it sunk into a runway at LAX, because it was too heavy for the tarmac!