Hello,
I cannot seem to get the normalisation I want for the drag polar using the clcd_normalization_aoa_deg_low and clcd_normalization_aoa_deg_high parameters in the flight_model.cfg file.
It appears that the clcd_normalization_aoa_low parameter is capped in some way and cannot be set to lower than 0.
This is how it looks when set to 2.5 and 8.5 degrees.
It can clearly be seen that the normalization is aiming for a minimum drag coefficient for an AOA of 0°, when the minimum drag should happen around -5 degrees of AOA.
But when I set the clcd_normalization_aoa_deg_low to -5, this is what the normalisation process does look like (see below) :
As you can see, the drag polar looks very different, no longer matching the theoretical polar and my hypothesis is that the sim is locked from normalising drag for AOA lower than 0°, and that is the cause of incorrect drag.
If I try to fine tune and get the drag at 0° of AOA correct, then the sim will produce this polar :
Now, you can see the drag at AOA 0 is correct, but then diverges below the target theoretical drag since the sim appears to be centering the polar on the AOA 0, causing drag to be lower than it should be at positive AOAs, before matching the theoretical polar again at the defined clcd_normalization_aoa_deg_high of 8.5 degrees.
I believe this to be the root cause of why it is nearly impossible to get the drag to match the entire range of AOAs for an aircraft.
My question for the sim developers is the following : I know that the focus is now on MSFS 2024, but could you confirm or disprove my hypothesis? And if it is confirmed, could this be changed to actually have the sim normalise the drag to the defined parameters in the flight model file?
Thanks!