Attitude dynamics of spinning rockets in space with internal fluid motion

A model of a spinning rocket in space with a particular type of internal fluid motion is developed and analyzed. A liquid is constrained to move in a narrow, annular channel which is centered about the rocket spin axis. The motion is governed by one-dimensional, shallow water surface waves propagating circumferentially about the channel. The rocket is modeled as a symmetric rigid body with axial thrust; center of mass motion of the liquid couples with the thrust to exert a torque on the system. The research is motivated by nutation instabilities observed in a class of orbit transfer vehicles. A linear stability analysis is used to evaluate the model; sets of parameters which permit instabilities are identified. While the model can exhibit instabilities, it was not possible to confirm an instability for parameters consistent with the flight data.