Gentlemen,
It seems there could be a problem regarding values FSX reports regarding world based accelerations (and/or speeds but it seems it concerns mostly accelerations). Apparently, it is not due to the way FSUIPC report them as far as they are mapped from the ACCELERATION WORLD X, Y and Z Simconnect values and some users using a direct Simconnect access already reported similar problems..See here
http://www.fsdeveloper.com/forum/showthread.php?t=23526
Some tests I performed (see graphs) using a standardized flight protocol for calculating reported averaged FS accelerations (eI) versus calculated accelerations from speeds (aI) over 250 ms intervals from FSUIPC mapped offsets show that:
- There are major discrepancies between calculated vs reported world X, Y and Z accelerations
- It is not the case for FSX body accelerations (at least Iy that was the one I tested)
- It is also not observed for FS9 using the same protocol and FSUIPC offsets
The reason for such discrepancies is still unknown. It could be due to some changes MS implemented for world reference axes but probably not to the way accelerations are aerodynamically defined. As so, I don't think we could imagine FSX reports an "acceleration of acceleration" as far as, AFAIK, this concept is still unused and physically unknown
Whatever it may be, any relationship between Vertical world based acceleration (FSUIPC 0x31C8) and G-force/G-load cannot be easily interpreted, considering ACCELERATION WORLD Y may not have the same meaning in FS9 and FSX. Additionally, we do not know how FS calculates G-Force as reported by SimConnect and FSUIPC but it certainly doesn't depend only on the vertical world acceleration but also on other forces that apply on other axes (for ex, a steep turn, or a longitudinal acceleration will increase it while vertical acceleration will still be 0). Consequently any comparison between G-Force / Vertical world acceleration in FS9 and FSX is probably not possible by now.
Detailed numerical results can be provided on request (email me for that)
Hervé Sors