Book Description

This report documents the results of an experimental and computational investigation of a power-law elliptic cross-section projectile for increased maneuverability. Surface-pressure measurements and force-and-moment measurements have been conducted in the Tri-Sonic Wind-Tunnel (TWT) at the Aerodynamic Research Center (ARC) at the U.S. Air Force Academy. Flow visualization data were also obtained in the form of Schlieren photographs and surface oil-flow patterns during these test programs. Data were obtained at a Mach number of 4.2% over a range of Reynolds numbers (based on the free-stream conditions and the model length) of 12.47 million to 19.96 million over an angle-of-attack range from -11 to +11 degrees. The data from these wind-tunnel tests were compared with computations generated using the Cobalt code, which was run on the Beowulf cluster at the High-Performance Computing Facility (HPCF) at the ARC. It should be noted that the experimental and the computational parts of this investigation were conducted concurrently in a double-blind fashion. That is, the results from the experimental effort were not used to influence the way in which the results from the CFD effort were produced and vice versa. Free flight investigations were carried out at the U.S. Air Force Research Laboratory Munitions Directorate Aeroballistic Research Facility and were conducted at Mach numbers ranging from 3.0 to 5.0. The free flight experimental data consisted of nine free-flight projectiles launched within an instrumented facility. Additional computational work was again carried out via the Cobalt code at the flight conditions of the experimental facility. The results indicate good agreement between the experimental and computational data determined in this effort, as well as, with engineering level predictions. The free-flight data was limited to small angles of attack therefore high fidelity determination of the aerodynamic stability coefficients and derivatives was not possib7.