Recent improvements in prediction techniques for supersonic weapon separation

The influence function method (IFM) has demonstrated a unique capability for accurately predicting store aerodynamic characteristics in an aircraft flowfield. To apply this method, one must know the force and moment influence functions of the respective stores involved. These are obtained from a separate "calibration" wind tunnel test where the forces and moments on the subject store are measured as the store is traversed through an oblique shock generated by a wedge or inclined plate. It was recently determined that these calibration forces and moments could be accurately predicted by the PANAIR pilot code, thus opening up the possibility for determining the required influence functions theoretically. This suggests that, in many instances, further economies in weapon separation testing are possible by using theoretically determined weapon calibrations. In addition, a procedure has been developed which combines PANAIR predictions of the parent aircraft flowfield with PANAIR store "calibrations." This process enables the calculation of supersonic store behavior without the need of any a priori experimental data, at a considerable cost savings compared to using the PANAIR pilot code to calculate the store forces and moments at every point in the traverse.