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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.


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Horizontal Launches

Discussions about water rocket powered cars, sleds or boats.
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DruJohnson
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Horizontal Launches

Post by DruJohnson » Mon Jun 20, 2011 12:53 pm

Hello,

My name is Andrew Johnson. I was wondering if I could get some help. I am currently working on a project in an internship at Haskell Indian Nations University. The project I am working on has to do with using radio controlled airplanes for remote sensing and first response rescue. We were thinking about using a platform sitting on a rope track with a water rocket attached to the bottom to help launch the planes. considering there will probably not be a suitable place for take offs in the areas we plan on using the planes. I was just wondering if there is anything different that we must do to have a successful horizontal launch.

Thank you,
Andrew Johnson



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U.S. Water Rockets2
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Joined: Wed Feb 07, 2007 12:57 pm

Re: Horizontal Launches

Post by U.S. Water Rockets2 » Mon Jun 20, 2011 3:57 pm

DruJohnson wrote:Hello,

My name is Andrew Johnson. I was wondering if I could get some help. I am currently working on a project in an internship at Haskell Indian Nations University. The project I am working on has to do with using radio controlled airplanes for remote sensing and first response rescue. We were thinking about using a platform sitting on a rope track with a water rocket attached to the bottom to help launch the planes. considering there will probably not be a suitable place for take offs in the areas we plan on using the planes. I was just wondering if there is anything different that we must do to have a successful horizontal launch.

Thank you,
Andrew Johnson
If you are using some sort of launch rail for your track, then you are almost certain to have no problems. The only caution you may need to consider is if the water level when horizontal is above the nozzle opening. If the water is too low then the nozzle will allow the air to escape before the water and you will not get the thrust.

Most of the time this is not an issue because the air coming out provides some initial thrust and this accelerates the rocket forward while conservation of momentum tries to keep the water stationary and this results in the water being forced to the nozzle end and coming out the nozzle. This accelerates the rocket even more and more water is forced back to the nozzle and keeps the rocket accelerating.

If you use a small nozzle then there is a chance that the water will not get pushed back enough, so you could simply tilt the rocket engine up a few degrees in the front and gravity will keep the nozzle submerged. If you are using a track then this would be fine because the track would hold the rocket at the angle and the rocket would still thrust down the track because the majority of the thrust vector would be in line with the track.

You will probably want to run some simulations of the rocket and plane with different rocket nozzle sizes and pressures to make sure that the thrust of the water rocket is not too large for the plane. Water rockets with large nozzles tend to accelerate very rapidly and may damage the plane. A smaller nozzle may be the ideal compromise.

Good luck!



DruJohnson
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Joined: Mon Jun 20, 2011 12:38 pm

Re: Horizontal Launches

Post by DruJohnson » Mon Jun 20, 2011 4:03 pm

Thanks. I will try that out.



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thampson
Current WRA2 Dragster Speed & Distance Record Holder
Current WRA2 Dragster Speed & Distance Record Holder
Posts: 232
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Re: Horizontal Launches

Post by thampson » Tue Jun 21, 2011 7:47 am

Andrew,

I answered in your other thread as well. try looking at our water rocket car on our website, lots of info for horizontal launches then remove the wheels and add some wings ;)

-todd-


HHWRSA
Hornsby Heights Water Rocket Space Agency
http://wrocket.hampson.net.au

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U.S. Water Rockets1
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Re: Horizontal Launches

Post by U.S. Water Rockets1 » Sat Jun 25, 2011 9:30 pm

DruJohnson wrote:Thanks. I will try that out.
Your application sounds really fascinating. This is the kind of use for water rockets that could really show off their utility. Good luck with this project!


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