Orion entry flight control stability and performance

The Orion Spacecraft will be required to perform entry and landing functions for both Low Earth Orbit (LEO) and Lunar return missions, utilizing only the Command Module (CM) with its unique systems and GN&C design. This paper presents the current CM Flight Control System (FCS) designed to support entry and landing, with a focus on analyses that have supported its development. After Service Module (SM) separation, the CM FCS will provide spacecraft stability and control while following guidance or manual commands during exo-atmospheric flight, translational powered flight required of the CM, atmospheric flight supporting both direct entry and skip trajectories down to drogue chute deployment, and during roll attitude reorientation just prior to touchdown. Various studies and analyses have been performed or are on-going that support an overall FCS design with reasonably sized Reaction Control System (RCS) jets, minimal fuel usage, and appropriate commandfollowing with reasonable stability and control margin. Results from these efforts are included, with particular attention to design issues that have emerged, such as the struggle for sub-sonic pitch and yaw control without using excessively large jets that could have a detrimental impact on vehicle weight. Apollo, with a similar shape, struggled with this issue as well. CM FCS design and analysis planned for the future are also discussed.