TABLE OF CONTENTS To solve motion Eqs. (4.417-4.419) and (4.459-4.461) for studying the stability (free response) or the response of the airplane to a given pilot input (forced response), we need to know the values of all the static and dynamic stability derivatives appearing in those equations. These derivatives can be determined either by analytical, semiempirical, computational fluid dynamics (CFD), or experimental methods. The analytical methods based on classical aerodynamic theories can be applied only to idealized wings and bodies. Aircraft configurations of practical interest cannot be analyzed using the classical aerodynamic theories. In view of this difficulty, several empirical/semiempirical methods have been developed over the years for evaluating the stability and control derivatives of aircraft configurations of practical interest. Datcom is one of the most widely used sources for estimating aircraft stability and control derivatives.7 It is a comprehensive compilation of all the available engineering methods for obtaining the stability and control derivatives of airplane-type configurations.
The modern CFD methods are capable of providing more accurate estimates of static and some dynamic derivatives. But, at present, the level of effort involved precludes their application at preliminary design stages. In view of this, the CFD methods are usually used at a sufficiently later stage in the vehicle design process when the configuration takes its final form.
The experimental methods for obtaining dynamic stability derivatives in ground-based test facilities 8-10 mainly consist of either forced oscillation or free oscillation technique wherein the test model undergoes an oscillatory motion...
