Rapid Aerodynamic Parameter Identification on a Large Transport Aircraft

Abstract

Flight testing of new aircraft designs is a challenging task in terms of time and costs. Tests have to be conducted in a careful and controlled manner, as flight characteristics may not be known exactly in all parts of the envelope. Rapid identification of the aerodynamic properties in-flight could help to detect any discrepancies to model predictions at an early stage and make flight testing safer. This paper introduces a software tool called RAPIT which identifies aerodynamic parameters during flight. It is based on an existing frequency domain parameter identification method using recursive Fourier transformation. After extensive ground testing, RAPIT was installed on board of an Airbus A320 research aircraft and flight tests with excitation maneuvers were conducted. Only the standard A320 flight test instrumentation was used for the parameter identification. The identification process was monitored on a laptop display which allowed optimizing the maneuvers. Comparison of the identified aerodynamic parameters with values derived from a model based on a-priori information showed good agreement and demonstrated the successful application of rapid stability and control parameter identification to a modern large transport aircraft.