The sketching rules could have been utilized to
predict these features a priori. Here, the rules will be
used to glean insight into the migration behavior. In
general, the roots of 6(s) "track' the nonstationary roots
of q(s) (Rule 1). Both the roll mode and dutch-roll
mode migrate in synchronization with the complex
conjugate q(s) roots, which has positive effects on
dutch-roll damping and roll quickness. The q(s) roots
eventually break-in to the real axis near -2 Us. The roll
mode reverses direction and is pushed into the origin by
one of these roots. Additionally, one dutch-roll root
continues to follow the other moving zero to -00, and
the remaining dutch-root also moves to --, as it is an
excess root.