2002 Version of the Aeroprediction Code (AP02)

Abstract

5.Dv,cpwo A%, -syAPI-08/03 ABSTRACT The AP05 code was evaluated when applied to configurations with boattails. Results of the evaluation indicated the AP05 predictions for normal force, center of pressure, pitch and roll damping moments needed improvement. As a result new and improved methods were developed and incorporated into the AP05 to be released as the AP09. Improvements include body alone lift characteristics for Mach numbers less than 2, low angle of attack improvements for roll and pitch damping for configurations with long boattails, incorporation of an improved boundary layer displacement model and refinement of several other existing methods. In addition, new methods were developed to predict nonlinear roll and pitch damping. Comparing the new and improved methods to existing experimental data indicated significant improvements in roll and pitch damping, normal force and center of pressure predictions compared to the AP05. However, validation of the AP09 code was not as complete as desired due to limited generic nonlinear roll and pitch damping data. Also, most of the available nonlinear dynamic derivative data has larger than desired accuracy boundaries due to model sting and wind tunnel wall interference issues. Weapons affected most by the new AP09 methodology are mortars, low drag bombs and projectiles in that order. However, the nonlinear dynamic derivative predictions affect all weapons. The AP09 is thus the most accurate and robust of the Aeroprediction Codes to date.

Prediction and Analysis of the Aerodynamic Characteristics of a Spinning Projectile Based on Computational Fluid Dynamics

“…The simulation results by Silton [5,6] and experimental data [10] show the same tendency with the lowest point reached shortly before Mach 1.0. Also, it was mentioned in [1] that the semiempirical Aeroprediction code AP02 [14] was not able to capture this peak in the transonic regime. Figure 10 shows the contours of the difference of pressure (P α=2:5 − P α=0:0 ) between two angles of attack for the calculation of the normal force coefficient derivative to investigate why the corresponding value (CLα) changes abruptly…”