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alkaline metal drives?

Posted by: TerraMrs - Sun Dec 21, 2003 6:51 pm
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alkaline metal drives? 
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Post alkaline metal drives?   Posted on: Sun Dec 21, 2003 6:51 pm
just a random thought i had a little while ago, but would a drive that used liquid sodium and liquid chlorine as fuel be a valid idea? i haven't looked up chlorine, but it's easy to keep sodium metal liquid (mp 360K or so) and the two reacting produces an obscenely large amount of energy, and has a completely harmless product (salt). while it is expensive to buy sodium or chlorine by itself, they are fairly easy to make with electrolytic cells. if a team built a couple big cells and had a big power supply, they could just buy salt and convert it into the fuel. anyone else have any ideas/comments on the thought?

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Post    Posted on: Mon Jan 12, 2004 5:11 pm
Na-Cl -reaction would surely provide a lot of energy, however the problem lies in the density of sodium; even though it would probably give plenty of thrust, the attained ISP would be very low.


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Post    Posted on: Tue Feb 10, 2004 3:53 am
The biggest obstacle to developing any type of engine is not the power that the fuel generates, but the fuel's specific thrust. Ammonium aluminate (a type of high explosive) and fulminate of mercury (another high explosive) are exceptional at generating power, as is the reaction between elemental cesium and water. However, their specific thrust is almost nil. Aluminum perchlorate, on the other hand, has a pretty high specific thrust -- it's used in the Orbiter's SRBs.

Note that I haven't said that an Na+ Cl- reaction would make a successful rocket fuel or not; I can't tell you right off the top of my head, although something about the reaction tells me it isn't. However, I might be able to come up with an answer fairly soon.

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Post    Posted on: Tue Feb 10, 2004 8:52 pm
yea, i was thinking that the density of sodium might prove troublesome, but it's not really all THAT dense in liquid form, higher than water of course but no where near mercury or something, and in terms of molar mass, 23 is less than many other fuels. chlorine may be too troublesome or not give much thrust, but weight/weight HCl may be good as a fuel with it, since the water will react as well, the biproducts are NaCl, H gas, which burns, and a little NaOH, and of course sodium and acid reacting produces an obscene amount of energy. sodium isn't too hard to keep in a liquid state also, since it's melting point is 80C i believe, plus if the heat was troublesome i can't see any reason, excepting the unknown factor of explosion risk :lol:, that a hybrid engine couldn't be used. obviously sodium will oxidize if exposed to oxygen, which could prove troublesome, but liquid sodium would be contained anyways so that would only have to be solved if a hybrid engine was used.


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Post    Posted on: Mon Feb 16, 2004 1:40 am
The biggest obstacle, if you're thinking about a ground launch, is that the exhaust products wouldn't be very nice.


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Post    Posted on: Mon Feb 16, 2004 4:01 pm
no, actually that's the neat part... the exhaust is just NaCl, though if it's HCl and water then you'll have some NaOH too, which isn't so nice. I suppose if the temperature in the plume is hotter than the boiling point of NaCl, which it would be in a big engine, then you might have trouble, but then again maybe not.


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Post    Posted on: Tue Feb 17, 2004 3:48 am
Who is going to let you pump thousands of gallons of chlorine into their neighbourhood? Nobody with a conscience would even let you do that over ocean.

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Post    Posted on: Tue Feb 17, 2004 8:45 pm
chlorine!=chloride
chlorine==highly toxic
chloride==harmless


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Post    Posted on: Thu Feb 26, 2004 4:21 pm
TerraMrs wrote:
chlorine!=chloride
chlorine==highly toxic
chloride==harmless


While we're in C++...

chloride!=harmless
ammonium chloride==high explosive, if I remember correctly
sodium chloride!=harmless
sodium chloride==mostly harmless

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Post    Posted on: Thu Feb 26, 2004 10:53 pm
spacecowboy wrote:
chloride!=harmless
ammonium chloride==high explosive, if I remember correctly
sodium chloride!=harmless
sodium chloride==mostly harmless


ok, chloride == mostly harmless, so does sodium ion.
ammonium chloride does == high explosive, but wouldn't form very much, and any formed would react on creation.
your last 2 lines == yes, mostly harmless, but salt as exhaust == not going to hurt anything at all.


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Post    Posted on: Mon Mar 08, 2004 5:00 pm
TerraMrs wrote:
spacecowboy wrote:
chloride!=harmless
ammonium chloride==high explosive, if I remember correctly
sodium chloride!=harmless
sodium chloride==mostly harmless


ok, chloride == mostly harmless, so does sodium ion.
ammonium chloride does == high explosive, but wouldn't form very much, and any formed would react on creation.
your last 2 lines == yes, mostly harmless, but salt as exhaust == not going to hurt anything at all.


Oh yeah? You're endangering the natural habitat of the ill-fated Rare Peruvian Tree Slug! By dumping that much salt on its last remaining habitat, you'll drive the species to extinction! :wink:

Actually, the dumping of that much NaCl on any one place is a fairly serious concern. Remember that we also have to take environmental effects into account. Good example: when the Roman army razed a city, they also salted the ground to prevent anything from growing there. Increase the salt content by just a very little, and you'll kill a whole bunch of stuff.

Your next response will be "Well, we'll just launch it right on the coast so that all the salt falls in the ocean. I mean, the ocean's already got so much salt in it that it can't hurt anything."

No offense, but you're wrong again. Saltwater is about 0.015% NaCl. You're talking about dumping tens of thousands of pounds of raw NaCl upon a stretch of water that's about a thousand square miles at the most. You do the math.

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Post    Posted on: Mon Mar 08, 2004 6:29 pm
yes spacecowboy is right, even large sea annimals like Sharks can't live in a diffrent salt environment, not too much, not too less... humens body can store and release, denie when too much or too less to some limitations, But a shark and many other annimals in the water can't...
A shark would just die within minutes when there is no salt... same when there is too much...
Vegetation would just die... too much Salt.. is a very dangerous thing for mother nature.

The best fuel would be, the one that just leaves only water or other "neutral" component as waste.
If this isn't possible... you may expect very soon groups of people standing with flags, chaining them to fences.... to stop useless vecations in space while killing annimals and vegetation...
Of course vecation isn't useless.. entertainment is needed to keep people happy... to let them develop more and to give them hope, but we should not do this at a too high cost for the future.

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Post different fuels   Posted on: Tue Mar 09, 2004 1:01 am
Well, all fuels are going to have an enviromental impact, no matter how small.

I think the best ones to use would be:

Liquid Oxygen and Liquid Hydrogen Combustion (SSMEs)
Oxygen and Hydrogen Combustion (hobby rockets)
H202 Catalytic Reaction (Armadillo's Peroxide Engines)
Closed System Nuclear Pebble Bed Fission (water is superheated by self-contained fission "pebbles", eliminating one of the problems with NERVA — leaving a radioactive exhaust trail)
Space Elevators :D
Railgun-assited launches
Ion Flow (microwave lightcraft)
Helium (balloon...)
Conventional Kerosene and Oxygen (not the best, not the worst, but it's what we're stuck with :))

Or my personal favourite for an ultimate space vacation:
Put someone in a spacesuit, put a parachute on them, drop them from 50,000 feet, have them deploy the parachute. Explode a nuke under them and send them into orbit ;).

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Post Re: different fuels   Posted on: Tue Mar 09, 2004 2:37 am
Zzap212 wrote:
Well, all fuels are going to have an enviromental impact, no matter how small.

I think the best ones to use would be:

Liquid Oxygen and Liquid Hydrogen Combustion (SSMEs)
Oxygen and Hydrogen Combustion (hobby rockets)
H202 Catalytic Reaction (Armadillo's Peroxide Engines)
Closed System Nuclear Pebble Bed Fission (water is superheated by self-contained fission "pebbles", eliminating one of the problems with NERVA — leaving a radioactive exhaust trail)
Space Elevators :D
Railgun-assited launches
Ion Flow (microwave lightcraft)
Helium (balloon...)
Conventional Kerosene and Oxygen (not the best, not the worst, but it's what we're stuck with :))

Or my personal favourite for an ultimate space vacation:
Put someone in a spacesuit, put a parachute on them, drop them from 50,000 feet, have them deploy the parachute. Explode a nuke under them and send them into orbit ;).


yea. every fuel has an environmental impact. yes, even LOX and Hydrogen. of course, the impact there isn't from the reaction but from the cryogenics needed. i think in terms of earth to orbit launches, any type of fission engine is completely out of the question due to the potential for an explosion, but a fusion engine would be great if we could make one that didn't give off radioactive exhaust.

as to the 'dumping salt' problem, my response isn't launch over the ocean, launch over white sands. there's tons of salt already there it won't hurt anything that isn't already critically damaged (not sure what could be damaged in some of the places out there. as to the 'tons of salt over 1000 sq. miles', yes it would dump alot over the places close to the launch site, but as the altitude increases the distribution because of atmosperic winds does too, so in the end you'll end up with a high concentration around your launch zone and low concentrations everywhere else. this might be a problem if you launched in certain areas, but i don't think there'd be enough for it to hurt anything really if you launched over the desert. the salt is coming out as a very hot liquid, not a solid, too so it won't just fall straight down.


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Post Re: different fuels   Posted on: Wed Mar 10, 2004 4:59 pm
Zzap212 wrote:
Or my personal favourite for an ultimate space vacation:
Put someone in a spacesuit, put a parachute on them, drop them from 50,000 feet, have them deploy the parachute. Explode a nuke under them and send them into orbit ;).


Agreed... Definitely the posh thing for those VIP trips to orbit... Call your local politicians and recommend this method. "You'll have to try it to understand it! It's insane!"

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