Optimal External Configuration Design of Unguided Missiles

A simple optimal external configuration design method is proposed that can be used in conceptual and preliminary design stages of an unguided missile development project. Cost and constraint functions are derived from the results of linear time-invariant aeroballistic theory (constant roll rate and forward speed, decoupled axial and transverse dynamics); therefore different phases of flight are examined separately. Curvefitting is used to reduce the number of trial cases and hence the work required to obtain aerodynamic and inertial data. Optimal configurations are determined by using a modified steepest-descent algorithm. A case study is presented in which the external configuration of an unguided light assault missile is optimized for free flight at low subsonic speed. Three cost functions related to stability, range, and warhead performance, respectively, and two inequality constraint functions related directly to stability and indirectly to dispersion are considered in the case study.