Hi, see the attached screenshot. I have a couple of questions:
Any idea why the FMS overspeeds the aircraft in cruise? Seems to always go 1-2 Kts above maximum causing the airspeed indicator to highlight red.
At what point does the FMS change from CLB to CRU mode? Is this something that happens after a period of stable altitude or is it something I can switch manually?
Thanks
The Longitude will fly at it’s MAX speed - it likes to go fast. It will hug that .84 Mach limit, and pop in and out of the red zone. Apparently this is true to real life.
The Engine indicator will show CLB for a while after reaching cruising altitude - it is showing the thrust LIMIT, not the mode. It is also true to life.
Appreciate your answers, thanks!
Can also go into Flight Plan > VNAV > Cruise and set a Pilot Defined Cruise and back off the default a hair. I’m at FL430 running M0.830 but it creeps up to .834
The instability is partly because the PID model (MSFS provides them) they use for everything, while a great device in itself (algorithm in this case), is not good for a dynamic system that changes behavior – the PID has to be tuned for some specific dynamic or else they tend to oscillate (or worse, diverge). Heavier planes respond differently than lighter planes so the PID is probably tuned for some medium weight with some median CG running at some median air density, etc and the further you get from there the worse the PID will perform. It’s also possible that they are not “properly” tuned at all since it is a Very Hard Problem – time delay processes (throttling up an engine) make it even harder.
