TABLE OF CONTENTS Prior to the advent of digital computers, the accuracy of aircraft simulation was marginal due to the inherent limitations of analog computers. The digital computers opened up new horizons not only in the field of aircraft parameter estimation but also in the field of flight simulators.48 With the evolution of high performance modern aircraft and with the spiraling developmental and experimental costs, the importance of ground-based flight simulators and that of in-flight simulators increased continuously over the years. Simulators are increasingly used not only for pilot training but also for other applications such as flight planning, envelope expansion, design and analysis of control laws, handling qualities investigations, and pilot-in-the-loop studies. Many of these applications demand a high-fidelity flight simulator. The fidelity of a simulation depends to a large extent on the accuracy of the mathematical model and of the aerodynamic database representing the flight vehicle.
To arrive at flight-validated high-fidelity global databases for flight simulators, there are two viable approaches, 1) to verify, and if necessary, update the wind-tunnel predictions through incremental coefficients from flight data analysis, and 2) to generate a new database from flight data through a systematic system identification procedure starting from a basic six degrees-of-freedom model and extending it to include special effects like landing gear, high angle of attack regime, unsteady aerodynamics, ground effects, and engine-out effects. In both approaches the task is formidable and the process iterative, requiring model structure determination, and can be equally complex...
