Prediction of Hinge Moment Coefficient for Nose-Mounted Canard Controls atSupersonic Speeds

摘要

The prediction of nose-mounted canard hinge moments in supersonic flow poses aunique problem for which the semi-empirical methods utilized in engineering-level aerodynamic prediction codes may not provide sufficient accuracy for preliminary design of the control actuation system. While providing accurate predictions of canard normal force, such codes generally cannot adequately predict canard hinge moments due to both their empirical nature and inability to address the local flowfield conditions on the rocket nose. It has been shown in this report that the local flowfield properties must be characterized to accurately determine the longitudinal center-of-pressure of the canards. A theoretical approach has been developed to predict normal force coefficient, longitudinal center-of-pressure, and subsequent hinge moment coefficient for nose-mounted canards. The method is based on shock-expansion theory and airfoil strip theory, and accounts for local flowfield properties, tip pressure losses, and body carryover effects. In contrast to aerodynamic code predictions, the theoretical method consistently estimates canard longitudinal center-of-pressure with a higher degree of accuracy, resulting in good agreement with experimental data for nose-mounted canard hinge moments at Mach 1.25 to 2.00.