The difference between Quad X and Quad H is that Quad H compensates for lack of torsional stiffness along the roll axis.
What if you rotated the Quad H config by 90 degrees so that the main torsional flex is along the pitch axis? Can you choose Quad X in this case?
I wonder if we can discuss more on this subject: how the lateral torsion affects the attitude controller quantitatively?
its just that h-frames tend to twist along the longitudinal axis, because they tend to have skinny center bodies. the h-frame motor rotations are such that a longitudinal twist would create a favorable control moment (instead of an adverse moment).
And how serious this issue causes bad effects to the attitude controller. I would love to know more for further analysing.
Thanks.
depends on how bad the twist is (e.g. how low the torsional stiffness). i have no idea what the effect on dynamic behavior is or if there are potential unstable modes. someone else can chime in here.