Aircraft.cfg file fixes for accurate range performance.

Over time, I've discovered that some planes fall way short of range values they should be able to achieve. One in particular, should have a range of almost 3000nm, yet I was out of fuel at only 600!

After some experimentation, I found that this can easily be remedied by editing the "fuel_flow_scalar" value found in the aircraft.cfg file, under the section "[GeneralEngineData]".

Below are changes you can make to make these few airplanes fly realistically - at least range wise! I have tested them many times, and they are very close to accurate - much better than the default values. Values shown are what should be in your cfg file. Simply change the current value to these proven rates. I'll add others as I find them.

Aircraft fuel_flow_scalar =
Curtiss C-46
0.1681
Dassault Falcon 50
0.63649
Convair CV-580
0.399888