Application of Parameter Estimation to Highly Unstable Aircraft

Maine, Richard E. and Murray, James E. (1986) Application of Parameter Estimation to Highly Unstable Aircraft. Technical Report NASA TM-88266, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

This paper discusses the application of parameter estimation to highly unstable aircraft. It includes a discussion of the problems in applying the output error method to such aircraft and demonstrates that the filter error method eliminates these problems. The paper shows that the maximum likelihood estimator with no process noise does not reduce to the output error method when the system is unstable. It also proposes and demonstrates an ad hoc method that is similar in form to the filter error method, but applicable to nonlinear problems. Flight data from the X-29 forward-swept-wing demonstrator is used to illustrate the problems and methods discussed.

EPrint Type:	NASA Technical Memorandum
Keywords:	Aircraft stability, Flight test, Maximum likelihood estimates, Parameter estimation, Systems stability
Subjects:	(01 - 09) Aeronautics: (05) Aircraft Design, Testing And Performance Aircraft/Project: X-29
ID Code:	563
Deposited On:	27 January 2006
Additional Information:	15 pages. Prepared as AIAA Paper 86-2020-CP for presentation at AIAA Atmospheric Flight Mechanics Conference, Williamsburg, Virginia, August 18-20, 1986.