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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.

Grandsons new launcher

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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Andrew Leigh
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Grandsons new launcher

Post by Andrew Leigh » Sun Aug 22, 2010 10:59 am

Hi,

here is the project my grandson and I have competed for his Science Fair project, he is 12.

We were lucky as we were able to use standard brass plumbing components. Starting at the top is the "gardena fitting" down into a one way valve then into a the 90 deg fitting which fortunately had a mounting foot with holes and then out to the air hose (fitting for hose not shown).

The holes in the corner of the mounting plate are for 6" nails which mount the launcher to the ground. We have four wedge type door stops for levelling and we are planning on putting a circular spirit level on the base to allow us to to set the launcher more accurately and perpindicular to the earths surface.

We had a 2l rockets up to 45 psi and found a leak at the hose fitting which needs modifying. The rocket has as a soft landing mechanism, a tennis ball which adds weight but works extremely well (we are not trying to establish an altitude record). At 45 psi we must have got a good 30m into the air, with the tennis ball removed the rocket gained what is estimated to be another 10m. We used about 500ml of water.

Found a nice hand pump which can go over 100psi, has a gauge and a pressure release button on the pump. What we have not fitted is a pressure release mechanism for the rocket which will be omitted as we do not plan on exceeding 60psi at launch. Besides we have run out of time. Version two will have it and it will be located in the current one way valve, not too sure how it will be done yet.

The rocket he built is hardly perfectly aligned but flies straight and true with the tennis ball nose cone and does not drift to far even in a brisk wind. With the tennis ball removed the rocket drifts significantly.

So far we have had not need for any additional guidance rods on the platform as the rocket apparently does not seem to need one.

Regards
Andrew
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RaZias
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Re: Grandsons new launcher

Post by RaZias » Mon Aug 23, 2010 12:50 pm

Your launcher is totally made of metal except the quick-release.

There was one rocketer whose plastic quick-release exploded after some launches.

Just put a metalic one, for safety.


Research and Development is the soul of WR

Andrew Leigh
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Re: Grandsons new launcher

Post by Andrew Leigh » Mon Aug 23, 2010 1:49 pm

Hi,

that sounds like very good advice which I will definitely follow, thank you.

Cheers
Andrew



Andrew Leigh
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Joined: Sat Aug 07, 2010 10:10 am

Re: Grandsons new launcher

Post by Andrew Leigh » Mon Aug 23, 2010 1:53 pm

Me again,

just a thought, the non return valve is 3/4" does one get the brass Gardena in 3/4"?

Cheers
Andrew



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RaZias
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Re: Grandsons new launcher

Post by RaZias » Mon Aug 23, 2010 2:04 pm

Andrew Leigh wrote:Me again,

just a thought, the non return valve is 3/4" does one get the brass Gardena in 3/4"?

Cheers
Andrew
I have already saw a brass Gardena with a plastic non return valve inside, but I don´t recommend using a non return valve.

Imagine that you want to abort the launch, so how you remove the air from the rocket ?

The best substitute to a non-return valve is to glue with epoxy a metalic tube to the quick-release, that tube should enter in the 9mm hole in the gardena male part.
Be carefull to check if the epoxy is not closing the air way, otherwise the air wont pass.

If you want to use anyway a non return valve the best way is to connect a "3 way tap" to a "non-return valve quick-release gardena", then they would be inserted at the middle of the tube.

So if you want to abort the launch you open the tap and the air will fly away.


Research and Development is the soul of WR

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