Fitting Factor Estimation for the Yaw of Repose Based Modified Point-Mass Trajectory Model

This study presents a fitting factor calibration method to enhance the accuracy and consistency of STANAG 4355 Modified Point-Mass Model trajectory simulations. Conventional approaches, typically based on Mach number or quadrant elevation, focus on matching only the impact range, whereas the proposed method fits the entire trajectory shape, including the maximum ordinate and its corresponding range at the trajectory apex. A new fitting scheme incorporating the yaw of repose and projectile velocity is introduced to reflect aerodynamic influences during flight. Calibration is performed using an interior-point optimization minimizing discrepancies with reference firing-table data, with the objective function explicitly considering four trajectory features: range, lateral deviation, and the altitude and corresponding distance at the trajectory apex. Validation results demonstrate that the proposed model significantly improves trajectory representation and impact accuracy compared with conventional methods, providing a more reliable and consistent simulation framework for future projectile system development.