Proof of Concept of an In-FIight Aerodynamic Model Identification Technique

This paper describes the development of an in-flight near real-time aerodynamic model identification (RAMI) technique. The model was based on flight data gathered from "2-3-1-1" alternating step manoeuvres with the NRC Falcon 20 aircraft. The aircraft was flown at ten thousand feet over a speed range of 150-225 knots. The air data systems were calibrated using a flush 4-hole nose-cone and DGPS technique. The installed data suite included parameters of standard aircraft inertial response, control parameters and air data pressure. The flight data was sampled onboard the aircraft's acquisition system, transferred to a high speed PC computer for analysis and display and was analysed using time domain (MMLE3) (Ref. 1,2) system identification techniques. This paper describes the flight test planning and execution, with emphasis on instrumentation and test input design. The CramerRao bounds for all derivatives were lower than 20% indicating that the final derivatives were robust. Excellent aircraft model fidelity was obtained using the time domain technique. The longitudinal and lateral model derivatives were estimated within 2 and 8 seconds respectively after the manoeuvre was completed.