Orion Entry Flight Control Modifications and Performance

The Earth return entry flight control system for the Orion Crew Module vehicle has matured to the level necessary for the program preliminary design review. This paper documents the current design of the control algorithm and numerous modifications and improvements implemented since the init ial conceptual control design. It addresses three distinct control regimes – exo -atmospheric operations, atmospheric guided flight, and touchdown orientation roll control while under the main parachutes. Control performance is evaluated by linear stabili ty analysis and time domain Monte Carlo simulation analysis. Control performance is measured against requirements metrics involving touchdown landing and orientation accuracy, propellant consumption, and maneuvering response. Parametric sensitivities af fecting control performance are analyzed including mass properties, latency, and aerodynamics. Finally, the results of a propulsion architecture trade study are discussed. A propulsion system design has been selected to meet control performance requireme nts while satisfying the vehicle mass and packaging constraints.