Unsteady aerodynamic modeling of a jet transport using flight-data-recorder data

To assess the effect of the unsteady aerodynamics on a jet transport that crashed upon executing an unsuccessful go-around operation, a fuzzy logic modeling technique is proposed to estimate the aerodynamic models using a set of data recorded by the digital flight data recorder.; The longitudinal aerodynamic models are assumed to be functions of the angle of attack, time rate of angle of attack, pitch rate, reduced frequency, sideslip, elevator deflection, stabilizer deflection, flap deflection and Mach number. The lateral-directional aerodynamic models are set up to be functions of the angle of attack, sideslip angle, roll angle, roll rate, yaw rate, lateral reduced frequency, aileron deflection, rudder deflection, and Mach number. Among these parameters, the reduced frequency, sideslip, pitch rate, roll rate, and yaw rate are derived from the recorded data. The Euler angles, accelerations along three axes, and other recorded flight data are first bias-analyzed by satisfying the kinematic relations to account for the measurement errors and noise. The force and moment coefficients are also calculated by satisfying the flight dynamic equations. The bias-adjusted data are then used to establish the general dynamic aerodynamic models using a fuzzy-logic algorithm with internal functions.; The identified fuzzy logic aerodynamic models are then employed to predict the stability and control derivatives along the flight path or in other flight conditions. The results show that low longitudinal control effectiveness and unstable pitch damping are possible at high flap angles and moderate angles of attack.; Finally, the identified aerodynamic models are integrated into a real-time flight simulation routine running on a PC. The simulation flight scenarios can be recorded by the simulation routine for later replay and plotting. It is demonstrated that the unsteady aerodynamic models in fuzzy logic form has the potential to be used on a real flight simulator.; More daily flight data collection and analysis are recommended for the future study to make the unsteady aerodynamic model complete. It is also recommended to apply the proposed technique to rapidly establish the dynamic aerodynamic models for other jet transports involved in flight accidents for engineering analysis.