I confess to some confusion here. Many have commented on the improved flight models of the new FSX aircraft and that's great. Many others seemed convinced that FS9 aircraft will perform better in FSX too. But, if the FSX flight dynamics engine has changed, that would mean that FS9 aircraft airfiles would require reworking to be compatible in FSX. All this seems to conflict with the general impression that FS9 aircraft are forward compatible with FSX.So what is the correct answer here? Will an FS9 aircraft ported over to FSX fly any differently in FSX? If so, why?

No differently, just more realistically.The numbers are pretty much the same, it's just that the aircraft react more realistically to wind changes etc, and the atmospheric effects such as thermals and up/down drafts are much better done in FSX.James

>No differently, just more realistically.>aircraft react more realistically to wind changes etc(snip)So the flight dynamics engine in FSX is the same as FS9.The environmental engine is more accurate.Is this correct?

I dunno about that; Flying helicopters at full realism in FS9 was mostly an exercise in futility, and it's a lot better in FSX. I haven't tried to stall or spin any of the default airplanes yet, though. Someone would have to do some side-to-side comparisons with the same airfile in both sims to see what the differences are.

>I dunno about that; Flying helicopters at full realism in FS9>was mostly an exercise in futility, and it's a lot better in>FSX. So we have one "no" and one "yes".:-/

Hi,The inputs appear to be exactly the same (although some have moved from the AIR file to the cfg file), but many feel that the interpretation of those inputs seems to be improved (or at least different). Whether this constitutes a "new flight dynamics engine" (highly doubtful) or a tweak of the previous one (very likely) is a matter for someone who knows more than myself. An MS blogger mentioned once that the FDE had a few improvements, but was not new.Hope this helps,--Tom GibsonCal Classic Propliner Page: http://www.calclassic.comFreeflight Design Shop: http://www.freeflightdesign.comDrop by! ___x_x_(")_x_x___

>>Many others seemed convinced that FS9 aircraft will perform>better in FSX too. But, if the FSX flight dynamics engine has>changed, that would mean that FS9 aircraft airfiles would>require reworking to be compatible in FSX. It doesn't necessarily mean that. It could conceivably be done without reworking.More variables could be allowed by FSX flight model--and naturally, an FS9 flight model would not have those variables. But, that is not a problem, as the sim could be programmed to sub in default values to allow the FS9 flight model to work in FSX.IIRC, this is exactly what was done several years ago. Either FS98 --> FS2000 or 2000 to 2002, can't recall.RhettAMD 3700+ (@2.5 ghz), eVGA 7800GT 256 (94.47), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 3-3-3-8, WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian