Improved Aeroprediction Code Part I Summary Of New Methods And Comparison With Experiment PDF Download

The NSWC Aeroprediction Code has been extended to angles of attack (AOA) greater than 30 deg. To accomplish this, several data bases were used to approximate the nonlinearities in individual missile component aerodynamics. Theoretical aerodynamic methods are used at small AOA. The new semiempirical model was applied to several configurations and the empirical constants adjusted to eliminate some of the errors associated with wind tunnel measurements of individual missile component loads. The new version of the code (AP95) was then pplied to several other missile configurations and estimates compared to data and other aerodynamic code calculations. Comparisons were made for Mach numbers 0.1 to 10.0 and AOA of 0 to 90 deg (not all data were available on any single configuration). In general, average accuracy levels of ±10 percent could be obrained for axial and normal force coefficeint and ±4 percent of body length for center of pressure, using the AP95. An exception to this was at AOA above 30 deg and at high supersonic Mach numbers, where nonlinearities caused by internal shock interactions were not accounted for. While these accuracy levels are very encouraging for a semiempirical code, improvements in the AP95 methodology could be made by additional missile-component wind-tunnel data at high AOA.