An Implicit Approach to the Aerodynamic Calibration of Stores of Compressed Carriage Configuration

The Influence Function Method (IFM) was developed under Air Force contract (1,2)* primarily to determine the aerodynamic loads on a store in a non-uniform flow field, i.e., in proximity to an aircraft. The fundamental principle of the IFM requires that a store's influence coefficients be determined by analyzing the store's response to a known non-uniform flow. This process, referred to as store calibration, was initially demonstrated using experimental techniques to traverse the store in proximity to a known flow field generator in a wind tunnel, i.e., supersonic wedge. In the interest of economics, current practice involves the calibration of stores by analytic means using Computational Fluid Dynamics (CFD) type codes such as PAN AIR (3) or engineering methods such as IDL (4,5,6). Stores of compressed carriage configuration, i.e., folded wings or fins, do not lend themselves to analysis by theoretical codes such as PAN AIR or IDL, due to the complex geometry and resulting interference effects attendant with wings or fins folded. It was previously shown (7) that the influence coefficients for a store could be inferred from the coincident traverse data from another store in proximity to a flow field generator. This capability has been utilized to demonstrate the feasibility of calibrating stores of compressed carriage configuration to predict aerodynamic loads on those stores in a non-uniform flow field, such as in proximity to an aircraft, for the estimation of carriage loads and the analysis of store separation trajectories.