For 9 ears simplest scheme dynamically (and statically) balanced is this (120° between ears in every group)
pic.1
Each group is symmetrical and therefore balanced.
also every group can be rotated in any angle - symmetry is not broken
pic.2
and in this case - (imho) rotor is statically and...
>To have a dynamically balanced drum with 9 equally spaced/weighted ears
Hmm.. 9 = 3 groups x 3 ears at 60 degrees. this should work, because each group is symmetrical about the shaft axis. If the ears are shifted relative to each other along the shaft - this is not a problem if the shaft is...