Nitromethane

[Ethanadams]

Could nitromethane be used for rocket fuel?

[Kryten]

Nitromethane, in terms of energy content, is worse than standard kerosene. What can give it an advantage in some situations is that it includes some of it's own oxygen, but that doesn't help you much in a rocketry situation as you're providing your own oxidiser anyway.

[Ethanadams]

Well I was lied to

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What about metallic hydrogen?

[Neywiny]

Wikipedia says: " It is a slightly viscous, highly polar liquid commonly used as a solvent in a variety of industrial applications such as in extractions, as a reaction medium, and as a cleaning solvent. As an intermediate in organic synthesis, it is used widely in the manufacture of pharmaceuticals, pesticides, explosives, fibers, and coatings." there is the one big problem which s that if it's used as a solvent, storing it will be harder, and also if it's "slightly viscous" the flow rates would drop preventing large amount of it to be burned quickly, so maybe as an upper stage but a first stage engine would require too much of it to store and keep flowing. On the other hand, it requires less oxidizer (can be used as a monop and is already used for rocket/engine applications so storing and pumping must already be figured out. There was a combustion velocity measured at .5 m/x vs lox/lh2 at 2,435 m/s, but I don't think they are measuring the same thing, and carbon monoxide is produced through nitromethane's combustion, which is a poison that can lead to harmful testing at full rocket capacity. Also it's a high explosive, meaning that it's dangerous to transport.

[Ethanadams]

For nitromethane or metallic hydrogen

[andrewas]

Metallic hydrogen hasn't been made yet, and we don't know if it exhibits metastability that may make it usable as a rocket fuel.

If it turns out to exist and be usable as a rocket fuel, it's energy density and pure hydrogen exhaust give it an isp high enough to completely change spaceflight.

Nitromethane is just another of thousands of chemicals that could be used as rocket fuel but dont have any advantages over existing fuels.

[KSK]

Nitromethane was a reasonable suggestion, if not that useful in practice compared to other fuels. I think somebody is either extremely optimistic or having a bit of a joke with you with the metallic hydrogen.

[Ethanadams]

I get lied to a lot about this stuff

[Scotius]

Do not worry, this forum and society is here to help. And we will not lie to you

[K^2]

If metallic hydrogen is metastable (MSMH), it is by several fold the best chemical rocket fuel we will have ever discover. That's a huge if, though. So far, none of the experiments that have claimed brief existence of metallic hydrogen have been capable to test any of its properties. So while there is some theoretical indication that it may be possible, there have been no experimental confirmation.

Nitromethane wouldn't give you great performance as a rocket fuel. There are far better rocket fuels available if you plant to launch something into space. But it might be a pretty good fuel for a hobby rocket with liquid fuel engine for a lot of the same reasons that make it a pretty good fuel for RC models.

[Stargate525]

If it turns out to exist and be usable as a rocket fuel, it's energy density and pure hydrogen exhaust give it an isp high enough to completely change spaceflight.

How is metallic hydrogen supposed to be used without oxidizer? Wouldn't the output be pure water?

[andrewas]

You don't burn it, you just let it decompose into normal hydrogen. That gets you an ISP of 1700 seconds, or a mass fraction to LEO of ~43% if I'm doing the math right. Depending on the properties of the stuff and how easily we can manufacture it in bulk, spaceflight might become almost as cheap and routine as air travel.

Edited February 28, 2015 by andrewas

[K^2]

Depending on the properties, it might make sense to use it as a very fuel-rich hybrid, using the ox flow for throttling. Otherwise, you are dealing with a solid booster with very little control. Of course, when the I_SP in question is on the order of several thousand seconds, it seems like a minor inconvenience either way.

[wumpus]

A better question would be nitromethane vs. [other] hypergolics. I remember reading that if there was a way hydrazine could be dangerous, it was (flammable, explosive, toxic, caustic, mutagenic, etc.). I assume that it has less Isp than those already used/in use, but might be something to consider.