Nonlinear System Identification Methodology Development Based on F-4S Flight Test Data Analysis.

The Naval Air Test Center (NATC) and Systems Control Technology, Inc. (SCT) have worked jointly to develop an advanced flight test data processing technique that supports an integrated flight testing procedure (i.e., extraction of test data for multiple test requirements from common flight conditions). This data processing technique is commonly referred to as system (or parameter) identification. Realization of this goal for an integrated flight testing procedure is dependent on the ability to identify nonlinear aerodynamic characteristics and propulsion system performance from flight test data. The identified models can be used to define performance, stability and control, and unaugmented airframe dynamic characteristics of the aircraft being evaluated. The need for improved modeling of aircraft aerodynamic characteristic has been, and continues to be apparent in numerous areas of technical and operational importance. Four such areas are: (1) flying quality military specification compliance testing, (2) training simulations, (3) design methods for specification of aircraft characteristics, and (4) the development of mission profiles that make optimum use of the airplane's capabilities. In general, there is a need for an improved understanding of an airplane's aerodynamic characteristics to support design improvements for increased cost effectiveness, expanded mission flexibility and enhanced operational safety.