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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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A bigger nozzle for WR-speed record.

Discussions about water rocket powered cars, sleds or boats.
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RaZias
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A bigger nozzle for WR-speed record.

Post by RaZias » Tue May 24, 2011 10:06 am

I was searching things about RC and in the RC-submarines section I saw this:

http://nitroradiocontrolledcars.com/pop ... e/pID/2155

The caps can make a connect system into a nozzle 90mm wide (there are even for 70 and 80 mm), this could allow the construction of a fast WR-dragster without adding several bottles to have more nozzles.
This would be nice for the speed record.

A bottle could even be cutted and molded to be glued to the a 90mm FTC tube.
Then it's just a question of reinforcing it with fiber-glass.


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RaZias
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Re: A bigger nozzle for WR-speed record.

Post by RaZias » Tue May 24, 2011 12:13 pm

Just to say that these caps are for sale at any on-line RC store that sells material for RC submarines, even WR rockets could have these big nozzles...althoug there would be a lot of drag.


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Brian
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Re: A bigger nozzle for WR-speed record.

Post by Brian » Tue May 24, 2011 6:50 pm

My test with 30mm nozzles show that the nozzle is too big to make full use of the air pulse. This is with a 1.75L rocket, the bigger the rocket, the nozzle. I would think that you would need a very large rocket to accommodate a 90mm nozzle!
Or a T-nozzle.


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RaZias
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Re: A bigger nozzle for WR-speed record.

Post by RaZias » Wed May 25, 2011 2:10 am

Brian wrote:My test with 30mm nozzles show that the nozzle is too big to make full use of the air pulse. This is with a 1.75L rocket, the bigger the rocket, the nozzle. I would think that you would need a very large rocket to accommodate a 90mm nozzle!
Or a T-nozzle.
I am thinking about a 4L WR-dragster at 230 psi with a 70-90 mm nozzle, the distance for a speed record is 50 meters so I wouldn't need an impulse for a large amout of time but only a big trusth with a small impulse.

I understand the problem you describe but I am thinking with 230 psi not 100 psi, anyway I still fear that even so what you say might happen.

...It will be like kicking a bottle or maybe I will just hear a big (230 psi) fart :shock:


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Brian
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Re: A bigger nozzle for WR-speed record.

Post by Brian » Thu May 26, 2011 5:17 am

I haven't had enough time to test the thrust of my nozzles but the air pulse doubles the velocity of the rocket. The air pulse is not as powerful as the water pulse but it is not pushing as much weight. I've been thinking of using a T-nozzle to restrict the nozzle after the water is gone to optimise the air pulse.
Only test will show how the 90mm nozzle will go.


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RaZias
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Re: A bigger nozzle for WR-speed record.

Post by RaZias » Fri May 27, 2011 2:20 am

In a WR-dragster I think it's needed an opposite of a T-nozzle, meaning that it should start slow to keep the car on track and then it would accelerate rapidly in at least 10 meters.


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U.S. Water Rockets1
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Re: A bigger nozzle for WR-speed record.

Post by U.S. Water Rockets1 » Sat May 28, 2011 10:26 pm

RaZias wrote:In a WR-dragster I think it's needed an opposite of a T-nozzle, meaning that it should start slow to keep the car on track and then it would accelerate rapidly in at least 10 meters.
This type of nozzle would be the best for a dragster. The large nozzle alone would provide too much acceleration all at one time and would be more like an explosive force than a thrusting force. A lot of the energy would be wasted as it would just dissipate. The gradual acceleration provided by a smaller nozzle would be more efficient but is not best for top speed.

Ideally, the acceleration should be gradual but increase to wide open throttle as approaching the maximum speed.


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Prodigy Rocketry
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Re: A bigger nozzle for WR-speed record.

Post by Prodigy Rocketry » Sun Nov 24, 2013 3:42 pm

Wow! I build real dragsters; do I really have time to build a water dragster? Well...................... :?: :?: :?: :?: :?:


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