The Accuracy Study of the Stability/Control Derivative Estimates Derived from Flight Test Measures

Jung Hoon Lee, Principal Researcher, Korea Aerospace Research Institute, Daejeon, Korea

Abstract

The accuracy of estimated stability and control derivatives of a light aircraft from flight test data was evaluated. The light aircraft, named ChangGong-91, is the first certified aircraft from the Korean government in 1993.

The output error method, which is a maximum likelihood estimation technique and considers measurement noise only, was used to analyze the aircraft responses measures. The multi-step control inputs were applied in order to excite the short period mode for the longitudinal and the dutch-roll mode for the lateral-directional motion.

The estimated stability/control derivatives of ChanGong-91 were analyzed for the assessment of handling qualities comparing them with those of similar aircraft. The accuracy of the flight derivative estimates derived from flight test measurement was examined in engineering judgment, scatter and Cramer-Rao bound, which turned out to be satisfactory with minor defects.