hey ppl
iv taken off right, in any jet aircraft. I run through all the procedures and everything runs smoothly. Climbing is fine until i get above about 30000 ft. Thats when i lose power, the plane is in autopilot and the speed gradually decreases stalling the plane if i do not intervene.

Now it really annoys me when iv been orderd by ATC to climb to FL500 and i cannot get there

Any ideas?

Cheers
forfun

P.S. i doesnt have anything to do with the mixture, tried that already

Just as a rule of thumb the atmosphere is about half as dense at about 18,000 ft. as it is at sea level.   Above 30,000 ft. not only will the engines start to lose power due to the "thin" air but you also start to lose lift.  That combo will stall any jet aircraft if the operator is not carefull.  Vertical speed rates of under 1000 fpm usually will keep you safe but this may still be too much on some aircraft.  Trying to climb to FL500 is not pratical for anything but the Concord.  Even the Lears and Citations that are certified into the fifties really don't have any business being up there.  It just takes up too much energy and time to climb that high.  Time when you could be moving forward at a level cruise altitude. 

But hey that's what FS is all about.  Doing the unordinary.  One trick that some folks use in the real world is to level off periodically to build up speed before climbing to a higher flight level.  I heard a Lear pilot the other day on the radio tell the center controller that he needed to level off at FL370 for about 10 minutes to build up his speed before climbing higher.  You could always try that.

When you fly IFR, ATC will never tell you to climb directly to your desired altitude. They will ask you to climb to a lower one first, then when you reached that one, they will tell you to continue to your preferred alt.