@iampete @kd0aij
I begun to test the disk theory gain scaling on a non vectored dual motor tailsitter with max angle set to 80° and airspeed enable. The calculation gave me a value of 10 for the disk load parameter. I had to lower this value to 2 to get rid of oscillations. Low speed stability, medium lean angles or transitions are not affected so the overall result is very good.
About the plane: wingspan is 86cm, 1Kg, 25cm propeller, larges control surfaces, CG set to 4% static margin. This may be not obvious on the video but the recovery from medium lean angle (lets say 45°) require almost full elevon deflection which is very bad and I had expected a better result with this frame. Set the static margin to 0% improve things a lot but is not flyable in plane mode. I will try to implement a variable CG in the future.
This test was made with a freshly downloaded arduplane 4.1 firmware and I found a problem with tailsit_input, it seems to be broken, only copter style input is still working and the body frame roll is weird.