1. I'm a developer on X-Plane, and I'm programming for the calculation of the aerodynamic moment exerted on the main rotor blades of EC120. My calculation is mainly based on the cyclic and collective feathering angles of the blades.

2. From "DataRefs", I've found "sim/flightmodel/cyclic/cyclic_ailn_blad_alph" and "sim/flightmodel/cyclic/cyclic_elev_blad_alph" which, I think, correspond to the A and B respectively in the feathering angle expression "-Acos(psi)-Bsin(psi)" where psi denotes the azimuth angle of the blade considered.

3. However, when I showed these values in X-Plane during a simualtion, even when I gave no commands from my mouse (I have controlled with my mouse and keyboard), these values are none zero, and change on their own.

4.Consequently, I've got confused. I'm not sure if they are the right choices and I can not find a reasonable explanation for this phenomenon.

I don't know how can I correctly get the feathering angles of the blades. Therefore, I pose my question here; hoping any one can help me on it. Many thanks for your kind help !