Book Description

The 1998 (AP98) and prior versions of the aeroprediction code are based primarily on slender body and perturbation theories at low angle of attack and empirical constants that represent the nonlinear aerodynamics as a function of angle of attack, Mach number, aspect and taper ratio, and other missile geometric parameters. The primary data base upon which these empirical nonlinear constants were derived was based on the NASA/Tri-Service component data base taken in the 1970s. This data base was limited in body radius to wing semispan plus body radius ratios (r/s) of 0.5. A more recent data base taken by NASA and the former McDonnell Douglas Corporation, investigated other values of the parameter r/s of 0.25, 0.33 and 0.5. As a result of this new data base, the empirical constants in the AP98 were fine-tuned. This fine-tuning has shown the average normal force coefficient errors to be reduced by anywhere from 10 percent to over 40 percent on various missile configurations. The largest reductions in error were for configurations where the AP98 average accuracy was the worst. These new improved empirical constants will be a part of the next planned release of the aeroprediction code in 2002 (AP02). The AP98 average error on normal force coefficient of +/- 10 percent will therefore be somewhat better for the AP02.