Modal Analysis of 1/3-Scale Yak-54 Aircraft Through Simulation and Flight Testing

摘要

This paper compares the accuracy of two low fidelity software packages at modeling a 1/3 scale Yak-54 RC aircraft. Two programs, Advanced Aircraft Analysis(AAA) and Athena Vortex Lattice(AVL) were used to develop a set of stability and control derivatives and subsequent state space models. Flight test data was analyzed using Math Works System Identification Toolbox for MATLAB to perform modal analysis. Results of identification are compared against low fidelity predictions and conclusions are drawn about the strengths of each program. Based on the results of this analysis both software packages provide similar results, however, AVL is slightly more accurate in predicting longitudinal dynamics as the natural frequency and damping ratio estimates of the short period mode more closely match that seen in flight for all flight conditions. AVL also predicts the natural frequency of the Dutch Roll mode on average with only 5% error, while AAA more accurately predicts the damping ratio of the Dutch Roll mode. AAA is also slightly more accurate at estimating the time constant for the Roll mode.