Attitude dynamics of spinning rockets in space with internal mass motion

Models of spinning rockets in space with internal mass motion are developed and analyzed. Three of the models use simple combinations of particle masses and springs to represent the internal mass motion. Two more models use fluid mechanical representations. One fluid model uses inviscid fluid assumptions and has no damping in the resulting equations, while the other includes viscous effects. The research is motivated by nutation instabilities observed in a class of orbit transfer vehicles. It is hypothesized that the instability mechanism relies on the motion of liquid inside the vehicle.A linear stability analysis is used to evaluate each model. Sets of model parameters which permit instabilities are identified. While all models can exhibit instabilities, it was not possible to confirm an instability for parameters consistent with the flight data. Two of the particle models reproduce some aspects of the data.Additional findings include the identification of an equivalent particle representation for one of the fluid models. The equations governing the third particle model closely resemble those of the fluid models. Also, a degenerate case of the viscous fluid model provides a new approach for representing a class of spacecraft nutation dampers.