Simulation-based design optimization of active-control rocket canards in subsonic flight

Rocket canards are small, vertical control surfaces located above a rocket's main rear fins, typically just below the nosecone, providing active-control maneuverability during flight. When an internal mechanism rotates the canards about their center relative to the rocket air frame, they achieve an angle of attack and produce a lifting force perpendicular to the airflow and tangential to the curvature of the air frame. This lifting force causes a moment relative to the rocket's center of gravity along both the roll and pitch axes, which can be used to stabilize the rocket mid-flight by providing corrective adjustments to the rocket's trajectory based on live avionics data. The larger the canards and the further the canards are placed above the center of gravity, the greater the moment generated from a given angle of attack, the greater their control authority over the rocket's orientation, and the greater their effectiveness in providing corrective adjustments. However, the addition of canard surfaces also inherently reduces the aerodynamic performance of a rocket by a factor determined by the size, shape, and position of the canards relative to the rocket body. Thus, a trade-off occurs between the aerodynamic performance of the rocket and the effectiveness of the canards smaller and lower canards have a greater aerodynamic performance and smaller corrective effectiveness while larger and higher canards have a smaller aerodynamic performance but greater corrective effectiveness. In this research, simulation-based design optimization methodology, which involves numerical simulation of rocket aerodynamic responses, meta-modeling techniques, and multi-objective optimization methodology, is used to obtain an optimum size, shape, and position of subsonic vertical-flight rocket canards for both aerodynamic performance and their active stability effectiveness.