Discrepancy between performance stats listed, and actual performance?

[Guest]

This is after my first flight in the Bombardier Learjet in FS2004. The listed service ceiling is FL510, but trying to cross FL350, even at full power, I entered an interminable stall which devolved into an unrecoverable spin. I went through regular stall recovery procedures, but in the end knew I was going to plant it.This isn't the first time I've noticed discrepancies between written flight specs and the actual flying characteristics of the aircraft (particularly in cruising speed vs. when the overspeed indicator comes on). If anyone could help me, I'd really appreciate it.Mike

[Guest]

The service ceiling of the Lear45 is FL510, but not at MTOW (Maximum Take-Off Weight). Generally when trying to reach FL510, Lear pilots will cruise at a lower flight level until enough fuel is burned, allowing the now much lighter aircraft to climb to the next cruise altitude. This procedure is called a "step climb."In regard to the overspeed indicator, you are most likely flying over the maximum mach speed for that aircraft. Check the flight specs for cruise mach and set your autopilot to that mach number instead of setting is for IAS (indicated airspeed). The cruise speed listed is most likely TAS (true airspeed) which at high altitudes is much higher than your indicated airspeed due to the way the airspeed indicator works.Hope this helps.

[Guest]

Might be right about the fuel weight being the problem. As far as the using Mach, that is generally what I do use. But the listed VMO of the Lear is Mach .81. Even at Mach .68 the overspeed warning was sounding.Mike

[Guest]

The relationship between mach and altitude is often confusing. For example, M.81 at FL500 is about 190 knots IAS. At FL350, M.81 is pretty fast (490 kts IAS), and certainly over the Vmax of the Lear. For that matter, M.68 at FL350 is about 380 knots.I just tested what you say, and by taking all the fuel out of both wings and flying on the center tank only I was able to cruise at FL510 @ M.81 with no trouble. Try that and see what your results are.EDIT: By the time you start getting very high, you may have to back off your climb rate to about 500 fpm to keep your speed up.

[Guest]

Thanks for your help. Guess there are some things I still need to learn about the smaller jets. Ah, well. Figured I had too many hours with trans-oceanic 747 time, and tried something new. I'll work on it.Mike