Hi guys,
I’ve been trying to adjust the flight model of my aicraft, namely the aicraft is way too slow, even though I took the aerodynamic data for the planeperformance.xls file from the POH, so in theory the values should already be approximately right.
Here is what I’ve tried:
I’ve double checked the engine debug mode and saw that the engine’s power output is correct
I then figured the drag may be too high. I tried several different values for the drag_coef_zero_lift but noticed no changes whatsoever in the way the aicraft flies.
I have double checked that I resynced the aicraft editor after every change and that the values are actually saved properly in the flight_model.cfg.
Why is it that I notice no changes whenever I change the drag_coef_zero_lift?
What other parameters should I look into changing if I want the aicraft to fly slightly faster without increasing the engine power?
flight_model.cfg parameter tweaking is a real art in MSFS and it’s never as simple as a straight translation of available parameters from a POH into the sim as all the required data is never available in the exact form any given sim will need it. I don’t think it’s feasible to adjust a drag parameter looking at airspeed as that’s not the property the drag directly affects.
So essentially you stand a good chance of getting the dimensions, weights and CoG from the POH about right for your plane (check those in the sdk tools), maybe start with the aerodynamics parameters from another good similar aircraft and adjust from there (maybe you did this anyway).
Assuming your lift and drag parameters are about right (which would mean your glide ratio is about right but that’s tricky to measure engine-off in MSFS), then check what happens if you adjust the elevator trim. If the plane accelerates to a speed you’re happy with then perhaps a small elevator (or main wing) incidence adjustment will address your issue.
Depending on whether your plane has a fixed gear or not, another common error is the drag assigned to the gear could be totally out of whack (i.e. much higher than the zero lift drag set for the plane) and actually this is dominating your overall drag figure.
One of the SDK tools does a great job of showing you the a/c drag calculation in real-time to the extent you can see the drag going up due to movement of the controls (apologies I forget what that particular tool is called). The total drag will be the sum of a bunch of values including the zero lift drag figure, but you can quickly see if something else is dominating that figure.