I’ve experimented a lot with these values to see how much of a difference they

make. But now I wonder if there is a more scientific way to calculate these?

What values do I need to obtain in order to calculate them? If I don’t have

these values, can I estimate them? empty_weight_pitch_moi = ; Empty pitch

moment of inertia, Jxx (SLUG SQ FEET) empty_weight_roll_moi = ; Empty roll

moment of inertia, Jzz (SLUG SQ FEET) empty_weight_yaw_moi = ; Empty yaw

moment of inertia, Jyy (SLUG SQ FEET) empty_weight_coupled_moi = ; Empty

transverse moment of inertia, Jyz (SLUG SQ FEE

https://docs.flightsimulator.com/html/Content_Configuration/SimObjects/Aircraft_SimO/flight_model_cfg.htm

I also want to say that I am a complete beginner when it comes to model

aircraft. But I am trying with the limited data I have to improve an already

existing flight model.

This is from the CJ4 **Before** sim update 12: empty_weight_pitch_moi = 69403

; Empty pitch moment of inertia, Jxx (SLUG SQ FEET) empty_weight_roll_moi =

13434 ; Empty roll moment of inertia, Jzz (SLUG SQ FEET) empty_weight_yaw_moi

= 75997 ; Empty yaw moment of inertia, Jyy (SLUG SQ FEET)

empty_weight_coupled_moi = 100 ; Empty transverse moment of inertia, Jyz (SLUG

SQ FEET) This is from the CJ4 **After** sim update 12: empty_weight_pitch_moi

= 124220 ; Empty pitch moment of inertia, Jxx (SLUG SQ FEET)

empty_weight_roll_moi = 17781 ; Empty roll moment of inertia, Jzz (SLUG SQ

FEET) empty_weight_yaw_moi = 75997 ; Empty yaw moment of inertia, Jyy (SLUG SQ

FEET) empty_weight_coupled_moi = 100 ; Empty transverse moment of inertia, Jyz

(SLUG SQ FEET) Should I consider anything with this depending on CFD on or

off?

I can see this page:

https://docs.flightsimulator.com/html/Samples_And_Tutorials/Tutorials/Defining_A_Flight_Model.htm

I have set the numbers it gave me.

Yes there is an accurate/mathematical/scientific way - split the aircraft into

individual sections with own size and weight, and calculate MoI for each

section CoG, and then use parallel axis theorem to calc MoI for each section

at aircraft empty CoG. It’s a bit of work and very error-prone. A number of

approximation / average tools are mostly useless. MoI’s for MSFS are regularly

estimated too low.