[avmich]

> Are they? AFAIU the propensity for HTP to exothermically decompose was the main reason why it was abandoned in favor of IRFNA/NTO. I mean, if you're switching to something as nasty as NTO or IRFNA for safety reasons, whatever you're switching from has to be pretty bad!

I'm not sure the switch to IRFNA/NTO is for safety reasons. There is simplicity involved - you don't need catalyst with them. The components themselves are easier to get by and to store. They however have their own nasty properties regarding safety. Also historically nitric acid was initially used with turpentine, which is a hypergolic pair.

Here are some comments on safety.

https://yarchive.net/space/rocket/fuels/peroxide.html

[jabl]

> I'm not sure the switch to IRFNA/NTO is for safety reasons. There is simplicity involved - you don't need catalyst with them.

Yeah, good point, that's certainly an advantage.

> Here are some comments on safety.

> https://yarchive.net/space/rocket/fuels/peroxide.html

Coincidentally(?) those comments stop in the year 2000, when the Kursk put a dent in HTP enthusiasm. For a while at least.

Not that I have any good solution either. Seems all high performance liquid rocket fuels have some nasty downsides.

For small scale applications N2O + some light hydrocarbon like propane or ethane could be interesting. But that seems to be quite immature, so could be some showstoppers ahead in that path.