Second test session today, delayed by the rain.
This gave me the time to read again the Bryan Hebert TTG ...
I flew with different battery positions but went back to the initial one.
The rudder is very sensitive, and I started to reduce the throw and adapt the expo.
I installed the battery as high as possible as recommended by BJ, and with the front CG knife edges on both sides don't require any rudder to elevator or rudder to aileron mixing.
Plane climb straight, and push slightly to the belly on the top of the vertical facing the wind when the speed decrease.
The downline need the usual throttle to elevator mixing.
I will continue tomorrow with the rudder and side thrust.