Transonic Computational Fluid Dynamics Calculations on Preproduction F/A-18E for Stability and Control

Abstract

Computational fluid dynamics was used to predict the longitudinal and lateral/directional stability and control characteristics of an 8%-scale wind tunnel model of the preproduction F/A-18E Super Hornet at two transonic Mach numbers without any prior knowledge of existing wind tunnel or flight test data. The tetrahedral unstructured software system was used to generate and analyze grids during this computational study. The longitudinal stability and control characteristics of the aircraft were evaluated using three different horizontal tail deflections. Before evaluating nonzero horizontal tail deflections, coarse, medium and fine grids of the preproduction F/A-18E with a horizontal tail deflection of 0 deg were used in a grid resolution study to determine the grid density that was required to accurately calculate the forces and moments of the aircraft. The grid resolution study indicated that the medium grid was adequate at Mach 0.8 whereas the fine grid was necessary at Mach 0.9. The medium and fine grids with tail deflections of -6 and 6 deg were then generated and analyzed at Mach 0.8 and Mach 0.9, respectively, to determine the longitudinal stability and control characteristics of the aircraft. The lateral/ directional stability and control characteristics of the preproduction F/A-18E were evaluated using a range of sideslip angles for several different angles of attack at Mach 0.8 and 0.9. The computational results compared very favorably to the existing wind tunnel data.