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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.

Launcher abort valve silencer ??

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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thampson
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Launcher abort valve silencer ??

Post by thampson » Tue Oct 14, 2008 7:44 am

This might be a difficult one to answer but I thought I would pick the brains of the water rocket community on this one.

I have just put a ball value between my pump and a quick release to our launcher to use for launch aborts and to use in hydrostatic testing .. some pics of it are here http://wrocket.hampson.net.au/?p=498

I only get to do water rocket stuff when I find the time which is usually late at night in the garage. After testing the abort valve last night at 110psi I realized just how much noise it makes. The neighbors have a 3 year old and a 1 year old whose bedrooms are not too far away from our garage so the last thing I want to do is wake them at 12am.

Does anyone have a suggestion to muffle the sounds, I was thinking a roll of carpet but just wondered if others had come across this problem and solutions before ?

thanks
-todd-
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Re: Launcher abort valve silencer ??

Post by Tim Chen » Tue Oct 14, 2008 8:47 am

thampson wrote:This might be a difficult one to answer but I thought I would pick the brains of the water rocket community on this one.

I have just put a ball value between my pump and a quick release to our launcher to use for launch aborts and to use in hydrostatic testing .. some pics of it are here http://wrocket.hampson.net.au/?p=498

I only get to do water rocket stuff when I find the time which is usually late at night in the garage. After testing the abort valve last night at 110psi I realized just how much noise it makes. The neighbors have a 3 year old and a 1 year old whose bedrooms are not too far away from our garage so the last thing I want to do is wake them at 12am.

Does anyone have a suggestion to muffle the sounds, I was thinking a roll of carpet but just wondered if others had come across this problem and solutions before ?

thanks
-todd-
HHWRSA
I think maybe if you made a diffuser for the end of the hose. A large bucket of gravel with the hose in it for the air to diffuse into. Maybe if you put the hose end in a barrel of water that would make it just bubble out too.


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Re: Launcher abort valve silencer ??

Post by dongfang » Tue Oct 14, 2008 7:18 pm

Hi,

I think there are commercial silencers for compressed air too...

If you are old enough to have heard them: Ever noticed how the air brakes on old trucks made a lot of noise when released? Modern trucks are much better - they use silencers.

Maybe something as simple as a piece or larger diameter hose after the valve would work.

Haha, I once had a bottle explode in the middle of the night :) WHAMMO it went. But I never got any complaints.

Regards
Soren



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Re: Launcher abort valve silencer ??

Post by Bonami » Tue Oct 14, 2008 10:22 pm

dongfang wrote:Hi,

I think there are commercial silencers for compressed air too...

If you are old enough to have heard them: Ever noticed how the air brakes on old trucks made a lot of noise when released? Modern trucks are much better - they use silencers.

Maybe something as simple as a piece or larger diameter hose after the valve would work.

Haha, I once had a bottle explode in the middle of the night :) WHAMMO it went. But I never got any complaints.

Regards
Soren
Perhaps people assume it was thunderstorms?



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thampson
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Re: Launcher abort valve silencer ??

Post by thampson » Wed Oct 15, 2008 9:31 am

Thanks for the suggestions guys, gives me some areas to look into. I will see what I can come up with and post the results :)

-todd-
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Re: Launcher abort valve silencer ??

Post by RaZias » Thu Oct 16, 2008 5:23 pm

When I want to abort I unplug the compressor from the launcher.
It doesn´t make the BANG-noise because the air gets out by a bike valve (0.5cm).

So smaller the air exit, smaller the noise.

I know the sound you are indicating because that was the noise that happened when I launched a 110 psi rocket without water.
It makes a "BANG" because the the air would get out by the throath of the laucher that was a 20mm hole.

You should try a small air escape for the security valve.


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Re: Launcher abort valve silencer ??

Post by Tim Chen » Fri Oct 17, 2008 1:17 pm

RaZias wrote:When I want to abort I unplug the compressor from the launcher.
It doesn´t make the BANG-noise because the air gets out by a bike valve (0.5cm).

So smaller the air exit, smaller the noise.

I know the sound you are indicating because that was the noise that happened when I launched a 110 psi rocket without water.
It makes a "BANG" because the the air would get out by the throath of the laucher that was a 20mm hole.

You should try a small air escape for the security valve.
The bang noise you hear is probably the air exiting at supersonic speed and creating a sonic shockwave. A smaller hole restricts the flow and either causes it to come out at subsonic speed, or it will come out supersonic speed over a tiny area and create only a tiny shockwave.


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Re: Launcher abort valve silencer ??

Post by thampson » Fri Nov 14, 2008 7:53 am

Well guys here is what I came up with, I call it my "Hydrostatic Silencer Extension" .. :)

Its solves the problem quite well for what I need, which means I can pressure test at night and not soak the garage. This setup is not for burst tests just a pressure test prior to flight of the wrockets pressure bottles to test all fittings so I dont have to mess around on launch day.

[youtube][/youtube]

Just sounds a bit like a toilet flush now .. well a 120psi toilet flush that is ... :) .. hmmmm .. Im not sure this post is going where I intended it too ...

anyway thanks for the suggestions, hope this is of assistance to others.

-todd-


HHWRSA
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http://wrocket.hampson.net.au

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Re: Launcher abort valve silencer ??

Post by thampson » Fri Nov 14, 2008 7:59 am

hmm . .dont think that youtube link worked ... There is a writeup of this on my blog as well as the embedded video

http://wrocket.hampson.net.au/?p=600

-todd-


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Re: Launcher abort valve silencer ??

Post by Tim Chen » Fri Nov 14, 2008 1:06 pm

thampson wrote:hmm . .dont think that youtube link worked ... There is a writeup of this on my blog as well as the embedded video

http://wrocket.hampson.net.au/?p=600

-todd-
Hey Todd!

It looks like your idea worked! The small holes meter the air out slowly and the energy disperses less rapidly. Do you think you need to release it under water? It might just hiss if you did it in the open air. You could also try letting it go inside a pail of sand instead of water.

The water sounds like my Grandma's bathtub. Ha ha.

Thanks for the update!


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Re: Launcher abort valve silencer ??

Post by thampson » Sat Nov 15, 2008 11:37 am

Tim,

yeah worked pretty well, I found it was still quite quick, but not as quick as when the abort valve is open to the air.

I will give it a try in some sand and see how it fares, although its raining here at the moment so all the sand is wet .. might have to wait for the dry ;) will let you know how I go

Yeah it kind of sounds like a bath emptying or toilet flush .. so its no so suspicious :)

-todd-


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Re: Launcher abort valve silencer ??

Post by Tim Chen » Mon Nov 17, 2008 11:50 pm

thampson wrote:Tim,

yeah worked pretty well, I found it was still quite quick, but not as quick as when the abort valve is open to the air.

I will give it a try in some sand and see how it fares, although its raining here at the moment so all the sand is wet .. might have to wait for the dry ;) will let you know how I go

Yeah it kind of sounds like a bath emptying or toilet flush .. so its no so suspicious :)

-todd-
Hey Todd!

I thought a bit more about your system and I was wondering what would happen if you just used a long perforated hose for the release and left out the water or sand completely. If you had a 10 foot hose with perforations all along it the air would come out rapidly over a large surface area and not make much noise. Have you tried that method?


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Re: Launcher abort valve silencer ??

Post by air.command » Tue Nov 18, 2008 6:52 am

Tim Chen wrote:
thampson wrote:Tim,

yeah worked pretty well, I found it was still quite quick, but not as quick as when the abort valve is open to the air.

I will give it a try in some sand and see how it fares, although its raining here at the moment so all the sand is wet .. might have to wait for the dry ;) will let you know how I go

Yeah it kind of sounds like a bath emptying or toilet flush .. so its no so suspicious :)

-todd-
Hey Todd!

I thought a bit more about your system and I was wondering what would happen if you just used a long perforated hose for the release and left out the water or sand completely. If you had a 10 foot hose with perforations all along it the air would come out rapidly over a large surface area and not make much noise. Have you tried that method?
Nice idea Tim. Perhaps Todd could try one of the porous garden hoses intended for drip irrigation. (http://www.accentshopping.com/category.asp/CAT_ID/533) but not sure what it is pressure rated to.


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Re: Launcher abort valve silencer ??

Post by Tim Chen » Wed Nov 19, 2008 12:57 pm

air.command wrote:
Tim Chen wrote:
thampson wrote:Tim,

yeah worked pretty well, I found it was still quite quick, but not as quick as when the abort valve is open to the air.

I will give it a try in some sand and see how it fares, although its raining here at the moment so all the sand is wet .. might have to wait for the dry ;) will let you know how I go

Yeah it kind of sounds like a bath emptying or toilet flush .. so its no so suspicious :)

-todd-
Hey Todd!

I thought a bit more about your system and I was wondering what would happen if you just used a long perforated hose for the release and left out the water or sand completely. If you had a 10 foot hose with perforations all along it the air would come out rapidly over a large surface area and not make much noise. Have you tried that method?
Nice idea Tim. Perhaps Todd could try one of the porous garden hoses intended for drip irrigation. (http://www.accentshopping.com/category.asp/CAT_ID/533) but not sure what it is pressure rated to.
Thanks George. It helps that Mark is interested in Water Rockets too so we talk about them and bounce ideas off each other 24/7! We do a lot of brainstorming, so we have a lot of practice in thinking "outside the box".


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Re: Launcher abort valve silencer ??

Post by thampson » Thu Nov 20, 2008 11:10 am

hey guys,

been real busy this week. Will try to do some testing on the weekend or next week. I will post some results when I get them for you

cya
-todd-


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