I think most people know here that tuning large prop/low kV copters is a nightmare, and it is often impossible to achieve good results.
However, there is one idea which occured to me, that is to displace the CG vertically to increase rotational interia.
I always tried to design the frames so that the CG would be as close as possible to the motors in vertical plane, within about 2 cm, with arms being about 30 cm long.
The copters I have in mind have motors which, with props, and motor mounts, weigh about 500 grams at a distance of 30 cm from center. Now the battery weighs either 1.0 or 1.5 kg, and it could be easily displaced by about 10 cm. or more vertically. In terms of rotational inertia, that would increase it from anywhere 70 % to 150 %.
So the question is, if one does something like this, how would it affect tuning? Would it dampen oscillations which are so difficult to tune out with low kV motors and big props?
And another question is, if it is better to put the CG (battery) higher or lower than the center? What real effect would it have on the copter behaviour, safety, and tuning?