A Model Stitching Architecture for Continuous Full Flight-Envelope Simulation of Fixed-Wing Aircraft and Rotorcraft from Discrete Point Linear Models

Abstract : A comprehensive model stitching simulation architecture has been developed, which allows continuous, full flight-envelope simulation based on a collection of discrete-point linear models and trim data. The model stitching simulation architecture is applicable to any aircraft configuration readily modeled by state equations and for which test data can be obtained. Individual linear models and trim data for specific flight conditions are incorporated with nonlinear elements to produce a continuous, quasi-nonlinear simulation model. Extrapolation methods within the model stitching architecture permit accurate simulation of off-nominal aircraft loading configurations, including variations in weight, inertia, and center of gravity, and variations in altitude, which together minimize the required number of point models for full-envelope simulation. The model stitching simulation architecture is applied herein to a model of a CJ1 business jet and to a model of a UH-60 utility helicopter. For both the fixed-wing and the rotorcraft application, configuring the stitched simulation models with 8 discrete-point linear models (4 point models each at two altitudes) plus additional trim data was found to allow accurate simulation over the full airspeed and altitude envelope. Flight-test implications for the development of stitched models from flight-identified point models are presented for fixed-wing and rotorcraft applications.