Originally Posted by
BleedingOn
Interesting as always, fdr. Thank you. I have not come across critical temperature of a jet engine before wrt performance calculations. Where would I be able to find what it is for a Trent 1000 and is it variable or fixed?
Engines are generally rated for full thrust at "ISA+X" - where X is somewhere between 10 and 25 degrees C. Since ISA drops with altitude, the flat rate temperature will be less at altitude than at Sea Level. Above the flat rate temp, the max rating will decrease as a rate that gives a roughly constant EGT as the OAT increases.
It is also common that the flat rate for Takeoff - max five minutes (sometimes 10 minutes) is higher than for continuous operation - e.g. Takeoff might be IAS plus 20, but Max Con might be ISA plus 10.
I'm afraid I don't know what the numbers are for the Trent 1000 - your operations types should know (and it should be in the flight manual).