Computational Analysis of Drag Reduction Techniques for Afterbody/Nozzle/Empennage Configurations

Three-dimensional Navier-Stokes solutions were obtained for the external flow around three single-engine body-empennage configurations using the PAB3D code. These solutions were used to study afterbody drag reduction techniques. The configurations were solved at Mach 0.6 and 0° angle of attack and consisted of the following: (1) a baseline case for which experimental data was available, (2) a contoured modification based on the area rule, and (3) elliptic cross section modifications designed to take advantage of the favorable pressures in the tail stagnation regions. The area rule modification resulted in a 6.3% reduction in afterbody/nozzle drag and an 8.5% decrease in total aft end drag. While the afterbody/nozzle drag for the elliptic cross section case showed a 15.4% decrease from the baseline, the increased pressure drag of the tails resulted in a net decrease of only 1.1% for the body-empennage configuration.