In regards to your earlier post: "Found another basic problem with jet engines.... Thrust increases linear with RPM !!!". I think you might be confusing the relationship between N1% VS throttle position with N1 % VS thrust. N1% VS thrust is not a linear relationship in real life and this is correctly modelled in X-Plane. This is in contrast to N1 % VS throttle position which is a relatively linear relationship as shown by your graph. I also did a little testing using XPFW's B733 IN X-Plane 9.