But you made the statement that sealing a gap can CAUSE flutter. Please give us an explanation of how this can happen.
Don't need an explanation as I've seen it happen.
Guy at the field has a BIG ONE. Got gaps. It used to fly like a big one with gaps. Guy decides to make the airplane fly better and seals the gaps. First flight, flutter. What caused it? Sealing the gaps obviously. The theory? Who knows. It happened.
BTW, one of the first things they teach you about flutter, is that EVERYTHING has a flutter speed, even a bowling ball. Flags have been used forever by target shooters to indicate the wind speeds. When the flags starting being made out of lighter, slicker fabric they suddenly indicated the wind speed differently. Their flutter characteristics changed simply from better airflow or somesuch. So change the airflow over anything and it's flutter speed changes. ANY change can cause flutter. At a different speed.
Lighten up. This isn't a debate. It's still a discussion.