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Posted: Sun Nov 04, 2007 2:43 am
by Novacastrian
mtronic wrote:
Or people could combine prevention and protection - in addition to building safe cannons and using them safely (prevention of an accident), they should naturally use goggles and ear defenders (protection from an accident), in case something should go wrong.
This would happen in the perfect world....
Homer Simpson: "I'm the happy man from lolley pop lane" By the way i was being sarcastic

Posted: Sun Nov 04, 2007 6:26 pm
by nz_cannons
I used plastic soda bottles on my high powered water rockets a while back. Interesting thing about them. The clear ones I took to 140psi repeatedly (like 50 or more times) with no ill effect, even after flying up about 150 metres or more and then hitting the ground bottom first, pretty tough.

But, the brown coloured ones exploded at about 140-150 psi, they were crap. This might of been because they got hotter or something but they were filled with water which would have cooled them down so not sure huh. So best to use white lol I guess.

When they did explode, it was freakin loud, but didn't produce much shrapnel. Just bust and peeled apart really, and I don't think any small bits, if they did come off, would have much energy to do damage.

Posted: Sun Nov 04, 2007 7:34 pm
by ammosmoke
I have seen you know *cough* *pressure* *cough* *devices* *cough* and when the blow open, they just look like a peeled orange or something. No shrapnel I could see came off, the bottle just split open. A person even jumped on it to make it go off, with shorts on, and he just got wet. The bottle was just all curled up in a roll. This was a 2 liter coke bottle btw.

Posted: Tue Nov 06, 2007 11:37 am
by cannons-go-boom
Those waterbottle Rockets are fun...and mostly safe...lol

Posted: Tue Nov 06, 2007 4:09 pm
by jimmy101
MrCrowley is wrong.

Soda bottles are rated to at least 50 PSIG and most are rated to 100 PSIG or more to handle the extra pressure they might see when stored in a truck (or car) in the sun, which can easily reach 150F.

A can of Coke(tm) has a pressure of about 55 PSIG at room temperature.

There really isn't much of a safety issue for using soda bottles up to 50~100 PSIG. Many people have done it for spud guns. The water rocket folks regularly take their bottles to 120 PSIG (or more) then smash them into the ground (unpressurized). Even after several firings ruptures are very uncommon. Off hand, I don't ever recall seeing a report of a bottle failure in normal water rocketry.

Posted: Wed Nov 07, 2007 9:06 am
by cannons-go-boom
Yeah I usually take the rockets to about 120 - 135 psi.
So about 50 - 80 psi wont hurt. I could just switch out the bottle every now and then to be safe.