Deployment Modeling of an Inclined Forward-Folded Wing

This paper develops and validates a three-dimensional deployment model for an inclined forward-folded wing, aimed at predicting deployment success under realistic flight and wind conditions. Unlike conventional two-dimensional folding mechanisms, the inclined forward-folded configuration enables efficient use of storage volume but introduces more complex spatial kinematics and aerodynamic interactions. To address this, a one-degree-of-freedom dynamic model about the deployment angle is formulated, incorporating torsional spring, pusher, gravity, friction, and aerodynamic hinge moments. The aerodynamic deployment moment is obtained from a database constructed by computational fluid dynamics analyses over a wide range of angles of attack, bank angles, and deployment angles, and it is coupled with the governing equation of motion. The resulting deployment prediction program is implemented using a numerical time-integration scheme and applied to various external wind conditions to determine the maximum crosswind magnitude for successful deployment. Its predictions are systematically compared with subsonic wind tunnel tests of a missile equipped with inclined forward-folded wings, showing good agreement in terms of deployment success and failure boundaries. In addition, the relative contributions of gravity, pusher torque, and aerodynamic moments to deployment failure are analyzed, providing practical guidelines for the design of reliable inclined forward-folded wing mechanisms.