Hypersonic Aircraft Performance Limitations Arising from Aerodynamic Control Limits

View Video Presentation: https://doi.org/10.2514/6.2023-2248.vid This paper describes how changes to the aerodynamic configuration of a general-purpose rocket propelled hypersonic aircraft impact its controllability over realistic missions. Aircraft style flight at very high speeds and altitudes requires close attention to: 1) operations at large flight-path angles, 2) high angles of attack to achieve necessary lift under low dynamic pressure conditions and the need for 3) high bank angles to mitigate tendencies for “atmospheric skip.” Seemingly stable aircraft may require supplemental reaction-control-jets if its Short-Period and/or Dutch-Roll rigid-body modes fall below fundamental time-domain limits. Other stable aircraft may prove to be uncontrollable using aerodynamic control surfaces alone when the Lateral Control Departure Parameter (LCDP) becomes unfavorable. We showcase these issues considering an “astronaut wings” flight flown by the famous North American X-15 rocket plane using both its baseline aerodynamic characteristics as well as variants with differing tail, control and/or wing configurations.