To be frank, I'd be more trusting of sparse, but flight test derived, data, than I would be of wholly predicted data; there are too many times when the "predictions" guys say "but we didn't predict that" for me to be comfortable without some validation.
The aircraft modeling in XP is offcourse not only made by
entering known acf data into the sim and hope the flight model does the rest.
In fact, a big portion of the variables are unknown and impossible
to find out in many cases.
So, we use reverse engineering. This is based on real FDR data, manuals
and the good help of professionals like all of you on this site
We calculate and calibrate many key variables so we HIT the
real numbers while we still are WITHIN the laws of aerodynamics and the flight model of XP.
Don't worry, no "predictions" guys around here, we usually hit
the numbers we wan't to hit
btw, well said John_T
M