Nell

Discussions about rockets, construction materials, adhesives, nozzles, nosecones and fin design.
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bugwubber
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Nell

Post by bugwubber »

Anyone do this yet?
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I'm thinking the weight might be a little high but still going to try it.
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Re: Nell

Post by anoymous »

Wait, I'm not so good at technology, so this is probably going to be wrong.
I have 3 guesses (most probable to least):
- some kind of water rocket with a reservoir (not shure how it would work)
- a water bazooka (idem)
-a launcher, but this is just a wild guess as I don't think it looks stable.
can you please give a description?
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Re: Nell

Post by bugwubber »

Nell is the historic first successful liquid fuel rocket invented by Robert Goddard. This is an adaptation for water rockets.

http://www.nasa.gov/centers/goddard/50t ... t.jpg.html

The original didnt fly very high and its control function was based on the flawed pendulum concept. But it proved liquid fuel works.
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Re: Nell

Post by anoymous »

Oh. This is the first time I ever heard of Nell.
With a little bit of research I found a very good image (even I understood it).
Isn't the structure very inefficient? As your nozzle is above the tank, The water wil hit the tank. This causes the rocket to decelerate. Or am I totally wrong?
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
- Albert Einstein

Sorry for malconstructions in my sentences, I am Belgian. And I was never good at making easy sentences.
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Re: Nell

Post by bugwubber »

Glad I could introduce you!

The sad irony is that the solid fuel pyro guys have made a working model.

http://www.fliskits.com/products/rocket ... l/nell.htm

I know there have been a couple water rockets done that put water in the top and had a pipe going down through the middle to the bottom to improve stability but this puts the nozzle on top.

Regarding the water blast, it won't be as bad as having a flat disc underneath to totally cancel out the thrust. However I'm thinking the column either has to come straight down or diffused into a spray or it might push the bottom off to the side.
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Re: Nell

Post by anoymous »

How were you going to pressurize it?
I think it will be difficult to pressurize trough the nozzle, as the system will be hindering the launch.
Will the water go into one of the tanks or into the combustion chamber?
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
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Sorry for malconstructions in my sentences, I am Belgian. And I was never good at making easy sentences.
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Re: Nell

Post by bugwubber »

Water only goes in the top bottle otherwise it could get trapped so here's where things get interesting. As long as I don't use foam, and don't pressurize to quickly, I could pressurize through a gardena quick connect in the upper nozzle. But there's a chance water or foam could get pushed into the pipe. So I'm considering a second quick connect at the bottom with a 1 way valve in it for pressurizing. Another idea would be to install a schrader valve at the low point to just act as a purge valve. I'm leaning towards the purge valve but haven't decided yet.
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Re: Nell

Post by anoymous »

bugwubber wrote:As long as I don't use foam, and don't pressurize to quickly, I could pressurize through a gardena quick connect in the upper nozzle. But there's a chance water or foam could get pushed into the pipe.
Maybe you could use a check valve in the pipe? Or would it make pressurizing the bottles impossible?
Also, after I posted my previous message, I saw the answer to my second question in your drawin. I forgot there was text above the volumes. :stars:
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
- Albert Einstein

Sorry for malconstructions in my sentences, I am Belgian. And I was never good at making easy sentences.
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Re: Nell

Post by bugwubber »

Well not a check valve but maybe a splash guard to make it harder for water to enter.
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Re: Nell

Post by anoymous »

And like this you Always learn... I never heard of it other than the ones on vehicles. I assume you mean the ones like on snorkels? That will indeed be better then a check valve.
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
- Albert Einstein

Sorry for malconstructions in my sentences, I am Belgian. And I was never good at making easy sentences.
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Re: Nell

Post by bugwubber »

I'll have to test these two water bottles first, otherwise this looks doable.
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Re: Nell

Post by anoymous »

I just checked the scheme again
Why do you use a tube from the bottom of the lowest bottle? Isn't it easier to connect the tube coming from between the two bottles with both bottles? (It will also weigh less)
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
- Albert Einstein

Sorry for malconstructions in my sentences, I am Belgian. And I was never good at making easy sentences.
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Re: Nell

Post by bugwubber »

anoymous wrote:I just checked the scheme again
Why do you use a tube from the bottom of the lowest bottle? Isn't it easier to connect the tube coming from between the two bottles with both bottles? (It will also weigh less)
Good question. Apart from maintaining the lines of the original, it can provide bracing to the bottom bottle and possibly act as a low point drain on the launch tower.
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Re: Nell

Post by anoymous »

How is it proceeding?
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
- Albert Einstein

Sorry for malconstructions in my sentences, I am Belgian. And I was never good at making easy sentences.
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Re: Nell

Post by bugwubber »

On pause for now due to other projects. These water bottles held all that my compressor could deliver- 150psi so looks like I can use them.
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