water bottle rocket

Discussions about rockets, construction materials, adhesives, nozzles, nosecones and fin design.
brycenv
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water bottle rocket

Post by brycenv »

hi im brycen and i guess my teacher is making us build bottle rockets was wondering what i can do to make the biggest badassest rocket ever
is water and air best, is there liquids more compressible then water would that help also wondering about what you guys find to be the strongest bottles or best way to strenghten them im aiming for 140 psi im prtty sure he says thats as far as i can go although rules are made to be broken right also if a bottle explodes should i be worried about shrapnel or am i being a bitch suggestions appreciated thanks ~brycen :coffee:
skysaber89
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Re: water bottle rocket

Post by skysaber89 »

How long do you have to build? I would never recommend water bottles for water rockets, unless they are PET or really thick. If you don't want to do much in the way of reinforcing the bottle, then if you can manage to find some 24 oz bottles, those would be great. I have pressure tested them up to 200 psi ish and no explosion. They bulged to crap, and I would not recommend using those high pressures without reinforcement, but there is the option.

In my experience, if you are using just soda bottles, they don't necessarily explode and send shrapnel so much as the bottles will rip and tear themselves apart. They usually stay in one piece though. Only when there are external bits on the rocket, such as metal, or when the rocket is made from something like fiberglass or pvc will shrapnel become a major issue.

I would just stick with water and air, as exotic fuels get expensive. Air command has great tutorials on splicing bottles and reinforcing them on yo their YouTube channel.

Hope this helps
brycenv
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Re: water bottle rocket

Post by brycenv »

thanks for the tips man this week in class i created my secret labratory (pushed cubicles together to keep my secrets) everyone seems to be going for displacement, yet i feel a proper nozzle and somehow strenghtening a 1 litre bottle pepsi bottle. im thinking is going to be key in my build, do you guys have some sort of way of making a smaller nozzle as i feel if i can get the nozzle smaller my rocket is going to be powered for longer yet everything i try seems to shoot of my bottle at around 60psi, my friend showed me this picture on his iphone ( i stole his phone and emailed to myself) and he claims it will hold to 8 bar (i googled it 116psi!!!) wich is more then enough. yet i couldnt find anything on how to create it do you guys have any ideas?
thanks again ~brycen
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brycenv
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Re: water bottle rocket

Post by brycenv »

also what is a pet bottle and where can i find them, (if you dont mind sharing secrets) what bottles have you tested to 200 psi
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bugwubber
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Re: water bottle rocket

Post by bugwubber »

All plastic carbonated beverage bottles are made feom PET (polyethylenetetracholrate or something, there's a reason we say PET!.) Not all PET is formulated for high burst strength- such as juice and water bottles. If it originally held carbonated drink, you should be good up to 120psi for 2l. Smaller bottles go higher. I tested SMART WATER bottle to 150psi with no breakage but, it was deformed. Some cheap 2ls pop right at 120psi. Garden hose quick connects are the easiest method to make a smaller diameter nozzle and launch release mechanism. Polycarbonate florescent light covers are the best choice for altitude and can be launched with "full bore" nozzles on them.
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koutman
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Re: water bottle rocket

Post by koutman »

I found arrow head bottles hold around 170 psi but bulge a lot.
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Alien Space Agency
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Re: water bottle rocket

Post by Alien Space Agency »

bugwubber wrote:All plastic carbonated beverage bottles are made feom PET (polyethylenetetracholrate or something, there's a reason we say PET!)
Wait, I thought PET meant PolyEThylenetErephthalate? If its -tetrachlorate it should be PETC.
Just google it first to avoid clerical errors. :)

Cheers

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bugwubber
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Re: water bottle rocket

Post by bugwubber »

Yes, polyethylene terephthalate.
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bugwubber
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Re: water bottle rocket

Post by bugwubber »

Yes, polyethylene terephthalate.
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Alien Space Agency
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Re: water bottle rocket

Post by Alien Space Agency »

Oh, and by the way. Why are you aiming for such a high pressure? Are you aiming for a world record?
Nothing can stop a curious mind from inventing- Anonymous