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How fast does an RCS thruster heat up if it's fired continuously? Will it stabilize at a maximum temperature? Does it need to be shut off before it melts itself? What would that temperature be if so? And how fast does it cool down once firing has stopped?

Let's assume a medium sized (100N?) UDMH+N204 thruster.

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  • $\begingroup$ Have a look at Aerojet Rocketdyne datasheets, The ability to reach steady state largely depends on the intended use of the thruster. Low duty cycle attitude control thrusters can get away with less material (less mass) because they won't reach steady state. Additionally, there is enough information given in the data sheets to be able to do some isentropic nozzle flow analysis and calculate a chamber temperature estimate $\endgroup$ Apr 29 at 14:51
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    $\begingroup$ Thanks, but doing isentropic nozzle flow analysis isn't really my thing. I just want a few rough numbers. $\endgroup$
    – Innovine
    Apr 29 at 15:31
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    $\begingroup$ Shuttle primary RCS thrusters could by flight rule be fired for up to 800 seconds in a contingency case with a 1,050 second firing possible. The limiting factor was the temperature of the Kapton insulation on the jet wiring. Unfortunately it never says what the temperature was, so posting as a comment. Bottom line, this was never a constraint on shuttle ops. $\endgroup$ Apr 29 at 22:40
  • $\begingroup$ The R-1E 110N (25 lbf) Bipropellant Rocket Engine from Aerojet Rocketdyne is specified for unlimited steady state firing. So it stabilizes at a maximum temperature and does not need to be shut off before melting. Of course there should be no barrier to radiative cooling of combustion chamber and nozzle. $\endgroup$
    – Uwe
    Apr 30 at 14:50
  • $\begingroup$ I found a bit akout the LM thrusters, they use film cooling so they don't get incredibly hot. Still, no numbers on how quick they cool down (but data on the heaters thresholds exist) $\endgroup$
    – Innovine
    May 1 at 8:44

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