Analytical Prediction of Trajectories for High-Velocity Direct-Fire Munitions

Abstract : An analysis of the velocity-time-range equations for direct-fire munitions has been performed. The analysis characterizes these munitions in terms of three parameters: muzzle velocity, muzzle retardation (or velocity fall-off), and a single parameter defining the shape of the drag curve. Using firing tables drag data for a variety of munitions, the expected range of values of the single parameter defining the shape of the drag curve in the supersonic flight regime has been determined. From the simplified analysis, many important flight characteristics can be determined. These include the velocity-time-range relationships, change in impact velocity due to change in muzzle velocity, gravity drop, change in impact location due to muzzle velocity and muzzle retardation variability, and crosswind deflection. The analysis shows that the muzzle velocity and muzzle retardation are the dominant terms defining these relationships. The shape of the drag curve is shown to be a higher-order effect which, in some cases, can be neglected. To validate these relationships, comparisons are made with numerical trajectory predictions for fielded direct-fire munitions using the measured drag data.