Ramjet tidbits

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leo
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Re: re: Ramjet tidbits

Post by leo » Sun Jan 22, 2006 8:12 pm

Zippiot wrote: soot burns because it isnt pure carbon. things that burn are part hydrogen, hydrocarbons burn. if you remove the hydro part there is nothing flammable left. think about the best things to burn: gasoline (hydrocarbon) alcohol (hydrocarbon). now think about things that burn "pure": hydrogen. carbon is the unburnable part that is left behind after a reaction, if there isnt anything except hydrogen all that comes out of the reaction is water.

your wrong, for example; metals burn, try lightening steel wool no hydrogen involved.
You only get soot because there is a to low temperature and/or to les oxygen.
The thing what’s leftover if you burn something is ashes. Which are mostly oxides and salts who were already present or formed in the burning process.

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re: Ramjet tidbits

Post by Zippiot » Sun Jan 22, 2006 8:34 pm

burn was the wrong word i guess. but does metal (except magnesium and a few others) burn like hydrogen phosphorus sodium and potassium? elements that are unstable are on the sides of the periodic table correct? most metals are smack dab in the center.


i do gotta question, wut temp does salt melt at? rock salt to be exact
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re: Ramjet tidbits

Post by Zippiot » Sun Jan 22, 2006 9:04 pm

i admitt defeat. the mythbusters has p[roved me wrong

under special circumstances (highly oxygenated environment) carbon will burn slowly but completely

they used it as part of their fuel in the big hybrid rocket, but they also said that it is the only element from the project that they were doing, that can withstand the heat. my "assumption" isthat the oxidizer burns up before it gets to the nozzle made of graphite, so the graphite wont burn from lack of O2.

this is straight from the disc channel please drop the subject now i admitt im wrong
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re: Ramjet tidbits

Post by Mark » Sun Jan 22, 2006 9:47 pm

Presentation is Everything

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re: Ramjet tidbits

Post by Zippiot » Sun Jan 22, 2006 9:56 pm

anthracite, sounds menacing, i must have it!!
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re: Ramjet tidbits

Post by Bruno Ogorelec » Mon Jan 23, 2006 10:09 am

Zippiot, I think you have made a wrong turn somewhere. You had better recheck your facts. Yes, soot burns. Carbon burns. It does not burn easily or readily, but it can burn, producing carbon dioxide and carbon monoxide.

Carbon fiber is NOT made out of graphite, which is not fiber and does not come in fibrous form. Graphite is a soft mineral you can scratch with your fingernail.

Fibers for carbon fiber composite materials are produced by burning organic fiber -- originally cotton, later various polyacryllic fibers. The modern techniques no longer employ burning but curing at very high temperatures in inert atmosphere. The proces removes everything but carbon from the structure. The resulting carbon matrix is impregnated with resin to make what we call 'carbon fiber'.

[edit]
Sorry, I just saw other people making corrections. Mine looks superfluous.

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re: Ramjet tidbits

Post by Zippiot » Mon Jan 23, 2006 2:50 pm

i said i admitt defeat, i got a few things crossed u r correct about that.
last time i trust the internet, ha
the carbon fiber i had used was a carbon graphite hybrid, 1 direction is carbon fiber the other direction of the weave is graphite. i asked the man wut was the difference he said nothing.
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re: Ramjet tidbits

Post by Najm » Mon Jan 23, 2006 2:53 pm

Cant a ramjet be made out of aluminium?
If the flame is concentrated in the center and enough air for cooling is flowing around the ramjet, the aluminium shouldnt melt.
[Zippiot wrote:]
i do gotta question, wut temp does salt melt at? rock salt to be exact[/quote]

Melting point of rock salt is 800 degree C.
but what are u going to do with it , it cant be used for making a ramjet.

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re: Ramjet tidbits

Post by Zippiot » Mon Jan 23, 2006 2:56 pm

aluminum melts quite readily, i mean it will melt within seconds without proper cooling. if you look at the maggie muggs project it is held together by epoxy, which melts at 800f, aluminum melts beyond that i believe but once it starts to burn it burns...

i think i can make a salt crystal large enough to use as a nozzle for a small ramjet im doing i was wondering if the salt will take the heat.
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re: Ramjet tidbits

Post by larry cottrill » Mon Jan 23, 2006 3:34 pm

Zip -

See if you can get some sodium silicate, aka 'water glass' - it used to be used for repair of laboratory glassware. It dissolves in water to form a "clear" paste, which dries fairly fast. It is not terribly strong, and the dried material would have to be handled as you would glassware. There WILL be some shrinkage, no matter what "ceramic" type material you use.

Another material would be "fire clay", which would be excellent - but, you would have to know someone who could kiln fire it, like pottery. Again, you would need to carefully oversize it, so the hardened dimensions would be right. This is one of the best materials you could possibly use - it is used to make crucibles for metal casting.

Of course, these materials are ancient. There's probably some "space age" ceramic you could find that might be as good or better. Probably more expensive, though. I have a whole little jar full of little packages that say DO NOT EAT, from shoe boxes and other packaging. Those are all sodium silicate powder or crystals. I save it because it is such excellent "glue" for attaching insulation material to pulsejet-powered projects.

L Cottrill

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re: Ramjet tidbits

Post by Mark » Mon Jan 23, 2006 4:11 pm

I put several coats of waterglass or sodium silicate on a paper towel tube section, I was attempting a small jam jar device. It didn't work very well, the substance when lightly propane torched for example, just flew off like popcorn. I even let the waterglass dry for a week before testing it.
Has anyone tried heating boric acid powder, it melts and then forms a puffy stiff strandy souffle, one might liken it to space shuttle tile? Mixed with other ingredients, it might be good for something.
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re: Ramjet tidbits

Post by Zippiot » Mon Jan 23, 2006 4:34 pm

actually i am great friends with the local highschool ceramics teacher. his clay melts at 2500 farenheit i believe, hes got buttloads of extra sititng around but im not sure if he will fire it, mostly because he says thigns have to be thin to be fired. the nozzle might be just too thick, even though there will be a big hole thru the middle.
actually i finished a abg of jerky and there is a tiny vile of sodium silicate. not nearly enough but i'll save it
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re: Ramjet tidbits

Post by Zippiot » Tue Jan 24, 2006 5:57 am

i did check...my friend with the welder is gone so i needed help with "out there" ideas. never heard of kitty litter, thats the first thing ima try....now how do i get it from my neighbor without seeming weird
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Re: re: Ramjet tidbits

Post by larry cottrill » Tue Jan 24, 2006 1:40 pm

Ben wrote:Many builders use very simple things, like "kitty litter". It can be pressed around a form in situ to make quite passable nozzles, and doesn't ablate nearly as much as you might think.
I'm sure Ben means the "clumping" variety of litter (which almost all of it is, nowadays). I think this is similar to the structural/landscaping product known as "Volclay", which expands slightly when hydrated - it's used to seal up cracks in concrete, etc.

There must be many clay products that can be used, even clays that normally "require" kiln firing. Even cheap "greenware" clay from a hobby/craft store would probably work. Again, the main design problem with any ceramic is that you have to expect some shrinkage during drying.

L Cottrill

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