Hello Andy, a statically balanced rudder will eliminate flutter. Except the rudder is already around 85 grams. Even if you partially balanced the rudder, say around 70% of the mass, one would need about another 30 grams or so, concentrated on the very edge of the short dynamic balancer. Of course one may always add a longer moment arm but that would look silly

Another approach which I favor, is to remove the stock part and build one from balsa. It will weigh in at about 45 grams. The problem of flutter is exacerbated as the surface mass increases, both in terms of initiating it and in terms of the amount of load that transfers back into the stucture

rgds,

Mattk