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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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Water Rocket Car MkXI - The Green Hornet

Discussions about water rocket powered cars, sleds or boats.
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Brian
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Re: Water Rocket Car MkXI - The Green Hornet

Post by Brian » Tue Jun 01, 2010 8:48 am

a water rocket powered surface effect vehicle could be a better option. a ballistic trajectory would probable still be the best option.
the rear spoiler in the exhaust flow would be interesting but wouldn't work with water but probably air. i think that weight of the car would still be the best option because weight also helps with coasting.


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thampson
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Re: Water Rocket Car MkXI - The Green Hornet

Post by thampson » Tue Jun 01, 2010 8:56 am

Razius,

Here are some pics of the reinforced bottle I tested. This bottle is made up of

- 1 x 2L bottle (slightly shrunk)
- 2 x 2.25L bottles

The 2L and 2.25L have the same diameter, the 2.25L is slightly taller. I shrank the 2L slightly in hot water so the 2.25L would slide over the top of it. I cut one of the 2.25L bottles 1/3 from the top and the other 1/3 from the bottom and cut off the bottle throat. Then slid the 2.25L bottle without the top over the bottom section of the 2L carefully lining up the claws. The second 2.25L I had to cut a bit more of the throat away to fit it over the bottle throat flange (for want of a better word). The 2 x 2.25L bottles overlap a little in the middle. I just taped this down with fibre reinforced tape.

The next version of it I will grind of the flange of the 2L so that the throat section is more reinforced and use PL Premium to glue the bottle sections together.

Im quite sure the bottle had a lot more in it before bursting, I have a 300psi (working pressure, 1200psi burst pressure) hose on the way so once I have the testing setup strengthened I will up the pressure to see if I can get it to burst.

Here are the pics

-todd-
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RaZias
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Re: Water Rocket Car MkXI - The Green Hornet

Post by RaZias » Tue Jun 01, 2010 2:03 pm

For more ideas for that method you can always see:

http://www.aircommandrockets.com/home/ ... ingBottles


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Re: Water Rocket Car MkXI - The Green Hornet

Post by RaZias » Wed Jun 16, 2010 8:52 am

When you shrinked the 2L bottle did you did it with the cap on it or not ?


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thampson
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Re: Water Rocket Car MkXI - The Green Hornet

Post by thampson » Wed Jun 16, 2010 9:10 am

Razias,

I did it with the cap off

-todd-


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Re: Water Rocket Car MkXI - The Green Hornet

Post by U.S. Water Rockets1 » Sat Jun 19, 2010 11:12 pm

Has anyone ever tried to make a water rocket powered boat? There have been compressed air powered boats but the air doesn't have enough mass to get it moving. A water rocket engine with a small nozzle would be like a water jet motor such as on a jet-ski.


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Re: Water Rocket Car MkXI - The Green Hornet

Post by Brian » Sun Jun 20, 2010 1:01 am

I've been thinking if a small air compressor and pump could be put on the boat because the boats surrounded by its own fuel, water and air. after the rockets empty it automatically refills.


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Re: Water Rocket Car MkXI - The Green Hornet

Post by RaZias » Sun Jun 20, 2010 6:09 am

When I was thinking in WR-boats I just had an idea out-side the WR hobby that I was to expose here.

But I think someone with electronics know-how could steal this and make money from my idea....that is the sad point of internet :cry:

It would be a really could hobby, even better than any boat-toy :D

This forum won´t loose nothing if I kept secret because what I am thinking demands some "electronic know-how".


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Re: Water Rocket Car MkXI - The Green Hornet

Post by WRA2 » Mon Jun 21, 2010 4:01 pm

RaZias wrote:When I was thinking in WR-boats I just had an idea out-side the WR hobby that I was to expose here.

But I think someone with electronics know-how could steal this and make money from my idea....that is the sad point of internet :cry:

It would be a really could hobby, even better than any boat-toy :D

This forum won´t loose nothing if I kept secret because what I am thinking demands some "electronic know-how".
That is one of the advantages of the WRA2 and this forum. You wont be chastised for not "telling all". Even teams submitting record claims are not required to submit any technical details. If you invent a better mousetrap then you should be able to market it yourself or use it for a competitive advantage or you can share all if that is your choice.


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RaZias
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Re: Water Rocket Car MkXI - The Green Hornet

Post by RaZias » Sat Jun 26, 2010 5:11 pm

Thompson,

The concept of air amplifier I think it will work better with a big nozzle, try gluing a 30mm nozzle in a regular 2L bottle.
I think that the bigger the nozzle bigger will be the compression in the amplifier chamber and better will be the effect.
A 9mm will have little effect.

Anyway just saying that I will also try that concept. It´s a shame that I can´t make a 30mm quick-release, even doing the damn 22mm 0-ring I fail :cry:

Thank god for the quick-release...at least I can make a 9mm...


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Re: Water Rocket Car MkXI - The Green Hornet

Post by U.S. Water Rockets1 » Sat Jun 26, 2010 10:05 pm

RaZias wrote:Thompson,

The concept of air amplifier I think it will work better with a big nozzle, try gluing a 30mm nozzle in a regular 2L bottle.
I think that the bigger the nozzle bigger will be the compression in the amplifier chamber and better will be the effect.
A 9mm will have little effect.

Anyway just saying that I will also try that concept. It´s a shame that I can´t make a 30mm quick-release, even doing the damn 22mm 0-ring I fail :cry:

Thank god for the quick-release...at least I can make a 9mm...
The quick release mechanism doesn't work well once you start using custom profile nozzles or high pressures or both. We'd still be challenging AGR for the record if we had relied on quick releases instead of tailoring something specific to our nozzle.


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Re: Water Rocket Car MkXI - The Green Hornet

Post by RaZias » Tue Jul 06, 2010 7:45 am

Here is a Scram-jet rocket miniature that I have found on Internet.

Has we can see the air intake it´s made in a away that will have the lass drag as possible.
scramjet.jpg
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Re: Water Rocket Car MkXI - The Green Hornet

Post by RaZias » Tue Jul 06, 2010 8:04 am

Here is another design for the air-intake.
I hope one day a air augmentation design would work in a WR.
Image1.jpg
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Re: Water Rocket Car MkXI - The Green Hornet

Post by RaZias » Tue Jul 06, 2010 11:10 am

An example of a subsonic ram jet designed in the early fifties for use at the tip of a helicopter rotor. Notice that the inlet nozzle is not a Laval type (converging/diverging) but a simple subsonic expansion diffuser. Also note the exhaust nozzle is subsonic as well, a converging nozzle.

Source: http://airindustriesresearch.com/siram/ramdesigns.htm
subsonicram.gif
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