Cessna Citation X Aircraft Global Model Identification from Flight Tests

Abstract

During an aircraft development, mathematical models are elaborated from its characteristics, physical laws and modeler prior knowledge of the system. Once the aircraft built, those models (mainly linear models) are tuned with flight test recorded data. Regulation authorities define the precision needed for such models. The purpose of this paper is to build an aircraft global model complying with regulation authorities’ accuracy requirements with minimal prior knowledge of the system. A professional D level simulator has been used as a flight test aircraft. More than 1,000 experimental flight tests were made with numerous configurations in speed (140 to 240 kt), altitude (10,000 to 46,300 ft), mass (24,000 to 33,000 lb) and the center of gravity position (17 to 34 % of the mean aerodynamic chord). Aircraft’s global model is built by identifying linear models at flight points within aircraft flight envelop and the center of gravity limits. Those models are then interpolated to provide a linear model within all the aircraft flight envelop and the center of gravity limits. Linear model identification and interpolation provide accurate results for aircraft’s short period mode. To our knowledge, it’s the first time a study on this subject is conducted from flight test realization to model identification.