Future high-mass missions to Mars, advancements in hypersonic aerospace vehicle design, and evolving science goals are stretching the performance capabilities of traditional entry systems. NASA’s Pterodactyl team at Ames Research Center has developed a novel yaw-to-bank control system for a non-traditional vehicle configurations, such as a Deployable Entry Vehicle (DEV), that can be folded and stowed. The approach provides vehicle stabilization, steering, and precise targeted landing. This control architecture is agnostic to control actuators and can be used with any aerospace vehicle with a strong dihedral effect and/or different guidance control variables.
This novel flightpath control system exploits the dihedral effect to control the bank angle of the vehicle by modulating sideslip. Exploiting the dihedral effect, in combination with significant aerodynamic forces, enables faster bank accelerations than could be practically achieved through typical control strategies, enhancing vehicle maneuverability. This approach enables vehicle designs with fewer control actuators since roll-specific actuators are not required to regulate bank angle.
The proposed control method has been studied with three actuator systems, Flaps Control System (FCS); Mass Movement Control System (MMCS); and Reaction Control System (RCS). FCS consists of a flap configuration with longitudinal flaps for independent pitch control, and lateral flaps generating yaw moments. The flaps are mounted to the shoulder of the vehicles deployable rib structure.
Additionally, the flaps are commanded and controlled to rotate into or out of the flow. This creates changes in the vehicles aerodynamics to maneuver the vehicle without the use of thrusters. MMCS consists of moveable masses that are mounted to several ribs of the DEV heat shield, steering the vehicle by shifting the vehicles Center of Mass (CoM). Shifting the vehicles CoM adjusts the moment arms of the forces on the vehicle and changes the pitch and yaw moments to control the vehicles flightpath. RCS thrusters are mounted to four ribs of the open-back DEV heat shield structure to provide efficient bank angle control of the vehicle by changing the vehicles roll. Combining rib-mounted RCS thrusters with a DEV is expected to provide greater downmass capability than a rigid capsule sized for the same launch.
The technology has several potential applications including aerodynamic bodies that require deployable control surfaces on articulating bodies; guidance and control of DEVs with high-precision landing of small payloads sent from planetary bodies back to Earth (e.g., biological samples landed near scientific facilities), and increasing down-mass capabilities to planetary bodies such as Mars reentry vehicles and precision space launch or ballistic munitions industry.