- New Details are added to an analogy between orbital dynamics and the rotational dynamics of a flexible body. The radius vector, the instantaneous orbit normal, and the associated transverse vector are used to define a fictitious body frame. Euler-type rotational equations of motion are developed for the motion of this frame in the presence of arbitrary perturbation effects; in these equations, orbit precession appears as classical gyroscopic precession, and the variable radius effects appear as variable inertia or structural coupling effects. Euler parameters are employed to write regularized equations of motion. Asymptotic expansion and multiple time scale perturbation solutions are summarized for these equations, considering the second zonal harmonic as a perturbation.