AlamHK

Thank you guys for advices. I tried to experiment on CD0 and CL0 in these few days and found that the modification led to dramatic change in the overall aerodynamics. Seems I have to give up in this complicated maths...

Thx for your reply, you're absolutely right about piston. But the case becomes different to jets.After passing the optimum altitude, the lift generated from the wings is not sufficient to keep the plane flying efficiently. Induced drag will increase more significantly. Thus the jet engines give extra power to overcome this and hence more fuel burn. Until the engines run to maximum rpm to yield the ceiling level, fuel burn surges when compared to that at optimum level.Taking PMDG 747 and you'll see the difference.Thank you anyway for your reply.

Hi guys, it's my first time to post here. Forgive me if i'm asking questions that have been asked before.Thanks to the avsim community, i've been flying with many fantastic freeware add-ons. But i've found that in general, the fuel flow always decreases with higher altitude, which is contradictory to real world datas. After passing optimum level, the fuel flow should increase.I looked into the air file but it seems too many parameters are linked to such a behaviour. Are there any guidelines or tips on modifying? Thank you very much.

I've just tried... I can struggle to FL360 with GW of 108k pounds, and even enjoy lower fuel consumption than at FL340. Seems the optimum level is not modelled in TM

just out of curious, after studying the performance file for Tinmouse in FSBuild, I found that no matter how heavy the plane is, it seems the fuel burn is always less when flying higher. So should I fly higher ignoring the weight?