Identification of a Full-Envelope Learjet-25 Simulation Model Using a Stitching Architecture

A full flight-envelope simulation model of the Calspan Variable Stability Learjet-25 was developed from flight data. The model is based on a stitched model architecture, which falls into the class of quasi-linear-parameter-varying models, and was developed using a series of discrete linear point models and trim data. Point models were identified from flight data at five different flight and loading conditions. A scaling method was used and validated to convert all identified point models to a common loading configuration. The quasi-linear aerodynamics from the models were then combined with trim data and the full nonlinear equations of motion to develop the stitched model. Through validation with flight data not used in the model development, the model was shown to accurately represent the aircraft dynamics within the normal flight envelope and be able to estimate the effects of weight and center of gravity variations. The paper provides a brief background of model stitching, lists the steps required to develop a stitched model from flight data, and then demonstrates how the steps are applied to the Learjet.