Okay, i've recycled kev's F-22 for my private(and personal) needs, i've made a dll for it usnig artlav's SC3 converter, for now though i would want it to be more realistic, i would want the engine to not fuction when it reaches a certain altitude (maybe 40-50km?), how do i impliment this?
The engine thrust depends basically on three factors:
absolute total pressure at the inlet
oxygen content in the air (Can be assumed to be constant until 50 km altitude).
temperature at the turbine
The first is pretty simple, the more pressure you press into the engine, the more thrust you gain. The second is sure also understandable, engines are designed for molecular oxygen, this gets rarer at higher altitudes. atomic oxygen or ozone is not that nice for engines. But implementing a molecular model of the atmosphere is pretty overkill.
The third is a soft limit: Most engine controllers throttle the engine down to prevent overheating of the turbine at higher speeds. Some older engines can be pushed at higher speeds and temperatures for a short time, but this will end in engine destruction eventually.
If you want to see a professional simulation for this:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.115.6961&rep=rep1&type=pdf
But I suspect, this is a bit overkill for your purposes. (But I just looked, it also contains C++ source code examples)
If you need more theory first:
http://www.grc.nasa.gov/WWW/k-12/airplane/ngnsim.html
