BTW, the last week or so, I've mostly been flying my new Tiger60. And noticed that it shows that tail wagging in the knife edge but not when straight and level. And realized the Tiger2 and Calmato Sport both do the same thing.

Guess that shows the vertical tail area is almost the right size, but not quite.

And all three of them produce a sound when in knife edge. My more aerobatic models don't seem to make that sorta deep, wind noise. Noise is energy, and I suppose it's signalling a significant amount of airflow separation somewhere. But it is worth noticing. And I've noticed the sound is steady, so doesn't appear to be associated with the hunting.

BTW, when a model shows an oscillation like that, on any axis, lots of modelers call it "hunting". It's like the model is hunting for the right direction. I only mention this because it's always struck me as funny. Very descriptive term, but funny.