Advances in Real-Time Aerodynamic Model Identification

Abstract

We describe the development of an in-flight, near real-time, aerodynamic model identification (RAMI) technique, for fixed-wing aircraft. This technique can be used to develop and validate an aerodynamic model to the Federal Aviation Administration AC 120 Level D flight simulator aerodynamic model criteria; and initial demonstrations of its capabilities are taking place on the National Research Council Falcon 20 research aircraft. As part of the RAMI development, innovative, self-contained software algorithms and hardware processing have been designed for onboard use. As well, novel hardware and software techniques are being applied to calibrate fundamental in-flight measurements, such as air data, in real time. The RAMI technique uses the 2-3-1-1 (alternating control input steps in seconds) maneuver, executed in each of the pitch, roll and yaw axes. These maneuvers are flown in flight conditions that span the entire flight envelope of interest. At each flight condition, the small perturbation stability and control derivatives (point model) are determined in real time. An automatic curve-fit process then combines the point models to develop a global aerodynamic model of the aircraft