There's nothing in this piece that's actually quite a lie, interpreted
generously, but it stretches the truth frequently, and the overall picture
it paints is rather too rosy.
Yes indeed, nitrous can and has killed people including a good friend of
mine.
It's a monoprop, oxidizer and explosive all wrapped up in one big ball of
quasi stable juice.
Ken
On Tue, Apr 4, 2023 at 1:36 PM Henry Spencer <hspencer@xxxxxxxxxxxxx> wrote:
On Tue, 4 Apr 2023, Ben Brockert wrote:
https://payloadspace.com/transitioning-space-propulsion-to-a-nitrous-based-industry-standard/
For me it plays loose with the truth a bit too much in order to
strengthen its arguments...
For sure it's a bit, shall we say, slanted. "Storage pressures are
relatively low compared to other propellant types"; exactly which types
would those be? Compared to xenon, maybe, but nitrous isn't competing
with xenon. The modest Isp of nitrous-based combinations, combined with
big heavy high-pressure nitrous tanks, means that it simply can't give
really substantial delta-Vs. (Even a flight-weight nitrous tank can
easily weigh as much as its contents.) Xenon can.
Useful for some applications? Yes, I'd say so. The answer to all
propellant problems? Um, no. The article is carefully picking its
talking points, comparing nitrous's strengths to other propellants'
weaknesses, rather than doing a careful fair comparison.
(E.g., sure it can get cold without problems... but try getting it hot and
see what that does to your tank mass, given the way its vapor pressure
rises. "Typical operational temperatures of 14-95F" are by no means the
full story -- the outside air temperature at Kourou or Sriharikota can be
above that range, never mind the temperature inside a fairing. It's not
uncommon for people to require that a fully-fueled payload be able to
survive +50C = 122F on the pad or during ascent.)
“Propellant storage: N2O is a pure chemical compound. It does not demix,any
decompose, come out of solution, or crystalize. It does not degrade in
manner and is, therefore, theoretically infinitely storable.“about
Nitrous can be a pure chemical, but industrial nitrous that it talks
elsewhere in the article isn’t. Nitrous obviously decomposes...
Even pure nitrous ought to have some slight spontaneous decomposition rate
even at room temperature (although it's got to be pretty low if nobody's
noticed it). "Theoretically infinitely storable" is a bit overstated.
There's nothing in this piece that's actually quite a lie, interpreted
generously, but it stretches the truth frequently, and the overall picture
it paints is rather too rosy.
Henry