Susceptibility of F/A-18 flight controllers to the falling-leaf mode: Nonlinear analysis

Abhijit Chakraborty, Peter J Seiler Jr, Gary J. Balas

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

The F/A-18 Hornet aircraft with the original flight control law exhibited a nonlinear out-of-control phenomenon known as the falling-leaf mode. This unstable mode was suppressed by modifying the control law. This paper employs the falling-leaf phenomenon as an example to investigate the applicability of linear analysis tools for detecting inherently nonlinear phenomenon.Ahigh- fidelity nonlinear model of the F/A-18 is developed for controller analysis using F/A-18 High-Alpha Research Vehicle aerodynamic data in the open literature. A variety of linear analysis methods are used to investigate the robustness properties of the original (baseline) and the revised F/A-18 flight control law at different trim points. Classical analyses, e.g., gain and phase margins, do not indicate a significant improvement in robustness properties of the revised control law over the baseline design. However, advanced robustness analyses, e.g., μ analysis, indicate that the revised control law is better able to handle the cross-coupling and variations in the dynamics than the baseline design.

Original languageEnglish (US)
Pages (from-to)73-85
Number of pages13
JournalJournal of Guidance, Control, and Dynamics
Volume34
Issue number1
DOIs
StatePublished - Jan 1 2011

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Nonlinear analysis
Nonlinear Analysis
falling
Susceptibility
leaves
controllers
Leaves
flight
magnetic permeability
Controller
Baseline
Flight Control
Controllers
Robustness
flight control
research vehicles
Nonlinear Phenomena
Aerodynamics
Margin
Fidelity

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Susceptibility of F/A-18 flight controllers to the falling-leaf mode : Nonlinear analysis. / Chakraborty, Abhijit; Seiler Jr, Peter J; Balas, Gary J.

In: Journal of Guidance, Control, and Dynamics, Vol. 34, No. 1, 01.01.2011, p. 73-85.

Research output: Contribution to journalArticle

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