Flight Dynamic Analysis for Commercial Transport Aircraft Response to Severe Clear-Air Turbulence

Abstract

The main objective of this paper is to analyze the stability and controllability of a twin-jet transport in severe clear-air turbulence with sudden plunging motion in transonic flight. The clear-air turbulence is particularly difficult to detect and predict among all atmospheric disturbances, and yet affect the flight safety the most. To effectively analyze the performance degradation and variations in stability and controllability of aircraft encountering clear-air turbulence, the nonlinear, dynamic (i.e. time-dependent) aerodynamic models based on flight data are needed. In this paper, a numerical modeling method based on a Fuzzy-Logic Modeling (FLM) technique is used to estimate the unsteady aerodynamic models for a twin-jet transport by using the flight data from the flight data recorder (FDR). The stability and control derivatives to be presented can be calculated from these aerodynamic models. The results are analyzed to provide the mitigation concepts and promote the understanding of aerodynamic responses of the commercial transport aircraft in severe clear-air turbulence.