Hey GTP, you can check it out here. It looks like the TSFC is increasing with the ALT for turbojet maintaining the constant speed or mach. I have tried both with speed and mach and every time went from 0 ft with the steps of 10000 ft and the TSFC has increased slightly, due to significant loss of thrust, which is compared to fuel flow reduction is much higher. Mathematically, TSFC is a ratio of the engine fuel mass flow rate mdot f to the amount of thrust F produced by burning the fuel:
TSFC = mdot f / F
http://www.grc.nasa.gov/WWW/K-12/airplane/ngnsim.html Well thats, what I have found out.
CHeers.
