Tom thanks i agree with you in the case that a model has at least half horizontal rudder fix and half movable, in this case you put the level ball on the fix part and you find the zero position later on you define and set the CG. But on my model the complete rudder is movable and in this case i suppose i need to find the correct zero position of the rudder first and in this case i need to start from the fact that incidence angle between rudder and wing is +1,5°. In this case i start to put wings at 1.5*° and in that position i put on 0° the rudder. From that point i am sure that between rudder and wings i have 1.5° and in that case i can define and fix the right CG. This is my point of view that is connected with the fact that the horizontal rudder is completley moveble. Thanks