Definition of CG and AERORP using wind tunnel data

[jean33-star]

Hi,

I have access to complete wind tunnel datas. They provide a complete characterization of the aerodynamic forces/moments experienced by the aircraft. The data are in the BODY frame, and moments are expressed at the balance resolution center. (I know the position of every important points of the aircraft).

I am wondering how to integrate these data into a JSBSIM model.

As I understand it, I have to:

• Define the CG at the known location for the aircraft (in the STRUCTURAL frame)
• Define the AERORP at the balance resolution center (in the STRUCTURAL frame)
• In the Aerodynamics section, define the axis of expression to BODY

But, should I also use something like this (seen in another discussion) ? :
<function name="aero/force/Lift_wbh" apply_at_cg="true">
or it is non necessary ?

I am very concerned about how the position of the CG affects the moments applied to the aircraft...

I look forward to your advice, I can provide you more details if necessary

JS

[seanmcleod]

I don't see why you would need to use apply_at_cg.

I am very concerned about how the position of the CG affects the moments applied to the aircraft...

What are your concerns?

This is the code that handles the position of the cg, which also moves as fuel is burnt off etc.

jsbsim/src/models/FGAerodynamics.cpp

Line 288 in 651ad3c

vMoments = vMomentsMRCBodyXYZ + vDXYZcg*vForces; // M = r X F