Dutch roll is an unavoidable dynamic response, not a desirable
maneuver. It's no more useful than the phugoid. And no more
intentional.

You've never seen Dutch roll til you've seen it at high Mach. Quite
disconcerting @ 1.75 (at this speed, we're supposed to be going straight,
eh?).

On the subject of instability, what was the aerodynamic cause of the X-2's
departure and crash? Adverse yaw + minimal directional stability?

R / John