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N2O has been worked with very early on in the 40s and now again is seeing a resurgence. Is this interest merited, disregarding its apparent non-toxicity, and how well does it perform in an engine/general handling characteristics? This question is not concerned with the characteristics of mixed monopropellants of N2O nor with bipropellant systems.

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    $\begingroup$ @uhoh that could be a n2o mixed monopropellant which premix the n2o with fuel and then pass it over a catalyst. I didn't want to include it in the question because from what i've read it is liable to detonate (as you can imagine) and is infeasible on larger scales $\endgroup$
    – R. Hall
    Feb 9, 2022 at 5:18
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    $\begingroup$ Using my Chemical energy >= Kinetic Energy approach, I calculated we can put a cap of 197 seconds on $N_2O$ as monopropellant - anything more violates conservation of energy producing more kinetic energy than it had chemical energy available. $\endgroup$
    – SF.
    Feb 9, 2022 at 9:01
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    $\begingroup$ Re disregarding its apparent non-toxicity Why would you want to disregard the key reason for its resurgence? $\endgroup$ Feb 11, 2022 at 14:54
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    $\begingroup$ @Uwe Oxygen is dangerous and even toxic in high concentrations, yet it is not a banned substance. The dangers of dihydrogen oxide are well known, yet it too is not a banned substance. $\text C_2\text H_6\text O$ is highly toxic and results in about a hundred deaths per year in the US alone, and yet adults can easily buy it. Just because substances have a L50 dosage does not necessarily make those substances suspect. That said, some substances (e.g. hydrazine) are so extremely toxic that it is worthwhile to look for alternatives. $\endgroup$ Feb 14, 2022 at 5:20
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    $\begingroup$ @Cornelis Yes my fault was to use the page nitrous dioxide instead of nitrous oxide. $\endgroup$
    – Uwe
    Feb 14, 2022 at 14:25

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According to Science Direct:

Nitrous oxide (N2O) is considered a potential monopropellant for micro-thrusters applied in micro-spacecrafts as a result of its special properties, such as non-toxicity, self-pressurization, and self-sustaining reaction.

So, I would think yes if it is considered, but there are better options, such as, according to Wikipedia:

The most commonly used monopropellant is hydrazine (N2H4), a chemical which is a strong reducing agent.

This is most likely because it is more practical for some reason or another. The primary difficult with nitrous oxide however, making it very hard to use, if not impractical is stated by a a Harvard sub-site:

It has been largely overlooked due to the difficulty involved in maintaining reproducible catalytic decomposition

According all the referenced sites above, people are attempting to make N2O monoproellants that fix the from I just said. So, it is not practical currently, but may be in the future.

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    $\begingroup$ Note that the second linked article is from 2004, so about 18 years ago. A lot of work has been done on using N2O as a monopropellant since then. It is practical currently. $\endgroup$ Feb 11, 2022 at 15:04
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    $\begingroup$ Really? Then name a few rockets that use it? $\endgroup$ Feb 11, 2022 at 15:09
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    $\begingroup$ @Starshipisgoforlaunch "practical" doesn't necessarily mean "commonly used" $\endgroup$ Feb 12, 2022 at 2:44
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    $\begingroup$ Yes, but if almost nothing uses it, then it is probably not practical. @fyrepenguin $\endgroup$ Feb 13, 2022 at 0:23
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    $\begingroup$ This is the most recent article that I could find: sciencedirect.com/science/article/abs/pii/S0094576520307505 $\endgroup$
    – Cornelis
    Feb 16, 2022 at 11:32

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