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Lithium+Fluorine+Hydrogen, why not?


RuBisCO

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  On 3/30/2020 at 1:30 PM, p1t1o said:

Its dangerous in that its a flammable rocketfuel yes, but what makes you say it is more dangerous - or more impractical - than a triple-fuelled rocket with fluorine and lithium?

 

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I did not say so. Reason is obvious. I compared hydrogen to methane and kerosine with liquid oxygen. Hydrogen is extremely cold (even compared to oxygen and methane) and causes hydrogen embrittlement which gives very strict restrictions to materials. Hydrogen is light which needs large tanks. It is exceptionally flammable (compared to normal fuels, of course exotic stuff like hypergolics or fluorine are even worse). Hydrogen flows through metals and other materials which makes storage and transportation bureaucratic and expensive. Etc. I do not believe that hydrogen will ever be significant fuel in any large scale applications.

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  On 3/30/2020 at 1:44 PM, Hannu2 said:

I did not say so. Reason is obvious. I compared hydrogen to methane and kerosine with liquid oxygen. Hydrogen is extremely cold (even compared to oxygen and methane) and causes hydrogen embrittlement which gives very strict restrictions to materials. Hydrogen is light which needs large tanks. It is exceptionally flammable (compared to normal fuels, of course exotic stuff like hypergolics or fluorine are even worse). Hydrogen flows through metals and other materials which makes storage and transportation bureaucratic and expensive. Etc. I do not believe that hydrogen will ever be significant fuel in any large scale applications.

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Yes, LH2 has its drawbacks, I shouldnt have gotten so hung up on hydrolox when I said 

 

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Cheaper and [much] safer to simply build a larger hydrolox rocket - and why wouldnt you?

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What I should have said was "cheaper and simpler to use a larger quantity of more conventional fuels than F/Li/H"

I meant to stress that I cant see any advantage with moving [from any given propellant] to F/Li/H when we have propellants which already work, for the sake of a few tens of Isps. 

Anyhoo, the OP question was "why not F/Li/H" and the given reasons ARE the actual reasons, for better or worse. It keeps blowing off bits of rocket scientist.

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Because 500-1000 ISP is not that interesting.  

First stage boosters can be big and cheap.  Deep space exploration can be done by high ISP non chemical energies.  

The only demand for super-exotic rockets will be for launching heavy payloads from Venus and things like that. 

Lithium and Florine are in high demand for molten salt fission reactors.  Oxygen and hydrogen are in extremely high demand in space.  An asteroid mining company will have no trouble selling those elements.  If they came out with a sodium - chlorine rocket with mediocre performance but cheap because it used an otherwise hazardous waste, that would be an attractive option for many moon and asteroid missions.

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  On 3/29/2020 at 4:04 PM, RuBisCO said:

Also why not ClF3

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Excerpt from Ignition about ClF3:

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