Development of a 6DOF Nonlinear Simulation Model Enhanced with Fine Tuning Procedures

This document describes the study of a conventional parametric modeling technique to be used for aircraft simulation in support of an Unmanned Aerial Vehicle (UAV) development program for glacial ice research funded by the National Science Foundation (NSF). A low cost, one-third scale Yak-54 RC plane is used as the research platform throughout this evaluation process. Using this geometric based modeling method, the aerodynamic derivatives are generated and are used to develop two state space linear models for both longitudinal and lateral dynamics so that the eigenvalue analysis can be performed. Parameter identification flight tests are conducted to identify the true open loop dynamics of the Yak-54, and the results are then used to evaluate the accuracy of the analysis results. A six-degrees of freedom (6DOF) nonlinear model is also developed using the derivative values, and its validity is investigated with the flight test data. The validation results reveal estimation errors in some of the predicted derivative values. A derivative tuning procedure is then introduced to refine the aircraft dynamics for each mode. The final results demonstrate that the derivative tuning technique is capable of improving the accuracy of the 6DOF simulation model, which gives very promising performance to duplicate the aircraft dynamics.