Aerodynamic Model Estimation and Analysis for a Jet Transport in a Landing Accident

Abstract

Nonlinear unsteady aerodynamic models for a jet transport in a flight accident in wind shear and heavy rain are established with a fuzzy logic algorithm. Modeling is applied to a set of Flight Data Recorder data. The results indicate that the fuzzy-logic modeling is capable of providing reasonable unsteady aerodynamics even in severe rainstorms. The fuzzy-logic models also provide a numerical aerodynamic database from which the aerodynamic coefficients under oscillatory conditions can be extracted to demonstrate the hysteresis effects. By analyzing the effects of time rate of sideslip from the unsteady model, it is found that the accident under consideration may be attributable to unstable yaw damping in sideslip motion and directional instability caused by unsteady aerodynamic effects. The latter, in turn, are induced by fast varying cross winds.