It is said that "everything has a speed at which it will flutter, even a bowling ball". And that speed depends on the size and weight of the surface, and if the surface is a hinged one, the strength and rigidity of it's rigging.

With our models, the most effective cure (when you're lucky to have something left to cure) is to take the slop out of and stiffen the rigging.

When our models exhibit flutter, the first question to ask is, "was this model meant to fly that fast". The 3D models really are not. They've got huge surfaces and usually have very poor rigging design. The large servo arms and short surface horns guarantee that the rigging, no matter how slop-free has little chance. Mass balance can help them.

As for sealing the hinge gap, that's another one of our model airplane rules of thumb that needs to be last on the list, if at all. MinnFlyer has TWO (2) very excellent examples that too many people seem not to have understood. Seal a flag to the pole and it still flutters. Wings without ailerons flutter.

When our models exhibit flutter, your first correction (if you're lucky enough to have something to correct) should be to the rigging. Stronger and less slop. Do that and the next step is to consider if the plane was actually supposed to fly fast or not. If it has big surfaces? It wasn't. Stop doing it. Mass balancing will do wonders, but in today's ARF culture, you're probably not a builder, right? Well, it's easy, try it.