I just reviewed the MSFS 2024 SDK info regarding the flight performance.cfg, and I have a number of questions/concerns. Although it states that this information has no influence on flight behavior, it supposedly can be used to check computed vs expected performance as well as to create flight plans. This makes me wonder if some of the information is indicative of what is actually going on within the MSFS 2024 physics model. Much of it is either incorrect, inappropriate, or just an approximation when applied to transport category airplanes (airliners and business jets).
For example, the “Notes on Takeoff Distances” is the only place in the SDK that I’ve seen values given for the rolling friction on wet and dry runways. As an IRL airplane performance engineer, we’ve never used different rolling friction coefficients for wet and dry runways for transport airplane performance. And the dry runway rolling coefficient we used is nearly half of the value shown in the SDK. Is this why we have to artificially increase the ground idle thrust of the engines at taxi speeds in order to get realistic taxi performance? And why it takes even more thrust in wet conditions?
Regarding use of this information for flight planning, the information provided does not appear to reflect regulatory requirements or operational usage (for example, use of reduced thrust/derates during takeoff, V1 speed selection, Vapp speed additives, etc.), and I have no idea where the identified safety margins came from.