<h2>AAS 95-336</h2><h2>An Evaluation of Energy-Sink Stability Criteria for Dual-Spin Spacecraft</h2><h4>V.  M. Ortiz and I. M.  Ross,  Dept. of Aero & Astro., Naval Postgraduate School, Monterey, CA</h4><h2> Abstract </h2>The very old problem of nutational stability of a dual-spin, quasi-rigid, axisymmetric spacecraft containing a driven rotor is revisited.  The purpose is to examine � by way of a numerical analysis � a revised energy-sink stability theory that accounts for the energy contributions of the motor.  An expression for the nutation angle is derived as a function of Hubert's core energy.  This equation is used to estimate the rate of convergence or divergence from a known equilibrium state whose stability can be predicted by the revised theory.  Mingori's model of a dual-spinner is used as a truth model.  Numerical simulations demonstrate that the time constants associated with the energy-sink model compare well with the truth model.<br><br>