Why does the axis follow the half angle rule?
Rotations are very different from translations.
For translations
pos = § vel (where § is the integral)
For rotations
q = § w q/2 (where q is the angular position and w is the angular velocity)
Thus to keep position (q) on LP (torsion = 0) velocity (w) must tilt out of Listing's plane by the half angle rule
