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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.


Hello Everyone. It is that time of year again. Time to approve changes to the competition rules for the new year.

You Can vote at:
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Need help with o ring size plesse

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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Hamby77
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Joined: Sun Sep 20, 2015 2:45 pm

Need help with o ring size plesse

Post by Hamby77 » Tue Oct 13, 2015 6:08 am

I built a launcher some years back with a one price pipe. I cut a groove into the pipe for the o ring to seat. I think I use 3/4 inch pvc. And now my o ring had final failed do to age. And I can't for the life of me remember what size o ring I used when I built it. :undecided: I do know that it only works with Pepsi bottles, not coke because the coke bottles are to tight. It has a Clark cable tie release on it. I real don't want to have to cut the launch tube in half to put a ring on. I just need to know what size I can slide down the tube to the groove to seal the bottle. I live in the middle of no where and will have to order one because the closet stores are 2hrs away. So any help would be greatly appreciated.
TH:



motorcyclepilot
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Re: Need help with o ring size plesse

Post by motorcyclepilot » Tue Oct 13, 2015 1:28 pm

I recommend you sand your launch tube down a bit so it fits more bottles. The o-ring will take up the slack and provide a nice seal for all of them. I believe you have a 1/2" launch tube, if you are launching 2-liter soda bottles.

As to a replacement, I believe you will find it in one of these kits: http://www.harborfreight.com/catalogsea ... t?q=o-ring

It's okay if you have to stretch the o-ring over the launch tube, so long as it fits in the groove you have cut and is thick enough to seal against your rocket.

Good luck!



Hamby77
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Joined: Sun Sep 20, 2015 2:45 pm

Re: Need help with o ring size plesse

Post by Hamby77 » Tue Oct 13, 2015 6:56 pm

TH: Thanks for the reply. And I do believe your right about it being 1/2 inch tubing DOH: I hadn't thought about sanding the tube but that's a great idea. Once again thank you.



Hamby77
WRA2 Member
WRA2 Member
Posts: 10
Joined: Sun Sep 20, 2015 2:45 pm

Re: Need help with o ring size plesse

Post by Hamby77 » Wed Oct 14, 2015 5:36 am

Would it be best to get SAE or metric sizes? And can any one please tell me right size I need. I know o rings come in different sizes. Out side and inside diameter and different #'s like #2 #3 ect. So I can simplify my buying. Sorry on a very strict budget here. Thank you very much in advance.



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