RE: Is this loud sound flutter?
If you are experiencing flutter, it is probably coming from the elevators. The junky pushrod that comes with plane needs to be replaced with two straight metal pushrods running straight to the control horns and connecting just aft of the servo arm. This took care of my flutter problems for good.
P.S. just sold mine last week after 4 years of flying the snot out of it with a 32sx.