Is anyone familiar with the chemical/thermodynamic properties of Otto II fuel (a monopropellant used in torpedoes)? It is composed of nitrated propylene gycol with a couple additives that make it non-explosive: https://en.wikipedia.org/wiki/Otto_fuel_II.

It is a stable, non-cryogenic, low vapor pressure, "shirt sleeves" chemical blend...not exactly benign, but not nearly as dangerous as hydrazine or even high test peroxide. It does not require a catalyst to burn. I have no idea what its ISP would be in a rocket thruster application.

As one of the gaseous products is hydrogen cyanide, it's not hard to understand why it's not commercially available. Can anyone shed some light on this propellant and why it is not used in spaceflight applications?

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    $\begingroup$ It's not mentioned in Clark's "Ignition!" (I searched "Otto", "dinitrate", and "torpedo" among other key words). I see that its combustion occurs when it's vaporized and heated (whereas peroxide and most other space monoprops are catalyzed); the required heater might be unsuitable for space applications. $\endgroup$ Commented Jan 5, 2018 at 22:06

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Otto fuel II has a specific impulse of 200 s, which is really low compared to solids at ~250 s, hypergolics at ~250 s and RP-1/LOX at 300 s.


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