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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.

Just had a go.......

This forum is for new members to introduce themselves and tell us how they got started in water rocketry.
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fenrisulfr
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Posts: 10
Joined: Thu Aug 18, 2016 11:05 am

Just had a go.......

Post by fenrisulfr » Sat Aug 20, 2016 7:07 pm

Hi from the UK

Well not sure how I stumbled across water rocketry, may have been on youtube, but here I is.

I had a go at splicing a pair of 2Lt bottles today....... It didn't end well. I think the PU type caulk adhesive, I tried, was too high a viscosity. I managed a good heat shrink on one bottle to bring the bottles together, dry, but once the adhesive was on it caused buckling of the inner bottle as the 'glue' just rolled in places forming thick lumps. Looking at the various videos of splicing the adhesive used seems to be of a lower viscosity and in fact even looks much wetter to the eye and certainly spreads and works better than the rubbish I tried.

So after a second attempt, having cleaned the bottled down, I had a bad spasm and crushed the bloody bottles as it just wasn't going to work. I was already a bit annoyed as I had got a set of unbranded hose fittings from screwfix only to find the tap fitting didn't fit (My fault). This is solvable I just have to file the bottle threads down until it does and permanently fit it in place. Which is fine for a first go.

Now do I try splicing (though it seems the UK lacks a PL alternative of good or known repute or go for a Robinson fitting. My plans? Just to have a little fun. Go for a 4Lt as a start with a box fin as per USWR site. I dabble in electronics (analogue can't programme the new fangled stuff for toffee) I have a stirrup pump for my bike that has a gauge so I'm sort of partway there...... Not :BD:



skysaber89
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Re: Just had a go.......

Post by skysaber89 » Mon Aug 22, 2016 10:44 am

If you can find it, loctite brand marine epoxy has worked excellent for me. I've pressure tested the splice up to 150 psi, and it probably could have held more. It's a two part epoxy. It's very strong and rigid once it's cured. It may not be the best for water rockets, as the pl premium is good to allow for mild expansion to minimize the stress points. However, if you splice the bottles correctly and you don't use insane pressures, it will last for quite a few launches.

Also :W to the forum



fenrisulfr
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Joined: Thu Aug 18, 2016 11:05 am

Re: Just had a go.......

Post by fenrisulfr » Tue Aug 23, 2016 6:50 pm

Hi

Thanks for the heads up. 'If you can find it' Well so far it seems as rare as hens teeth! Even ebay is an import from US or AU........... The search for adhesion continues!!

Fen



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addstogether2
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Re: Just had a go.......

Post by addstogether2 » Sat Sep 24, 2016 6:10 pm

Hi,

Welcome to the Forum.

Re glues, whatever glue you use make sure you give it plenty of time to cure.

I once used a rubber based glue/construction adhesive and left it a week to dry but because it had to cure with air it failed badly. I left one of the splices for ages as I thought it was no good. On a whim I re tested it and it held pressure after that and it is still around today.

Al


Life is like riding a bicycle. To keep your balance you must keep moving.
"Albert Einstein"

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