SUMMARYA three‐time scale singular perturbation control law is designed for a nonlinear helicopter model in vertical flight. The proposed control law is based on time scale decomposition and is able to achieve the desired altitude by selecting a desired angular velocity and the associated collective pitch angle of the blades. The stability of the system is performed by presenting a stability analysis for generic three‐time scale singularly perturbed systems, which allows to construct a composite Lyapunov function for the resultant closed‐loop system by using time scale separation and also providing mathematical expressions for the upper bounds of the singularly perturbed parameters that define the three‐time scale. Numerical results on both, the singular perturbation control strategy and the stability analysis, are also presented for the studied nonlinear highly coupled helicopter model. Copyright © 2012 John Wiley & Sons, Ltd.

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The need to investigate the static and dynamic stability for unconventional planes requires development of a code that automates the analysis for the airplane's stability performance. Flying wings are unconventional and challenging to analyze because they lack a tail to control the plane in the longitudinal and the lateral directions. With this motivation, an automated code was designed that was able to accurately predict the stability performance of flying wings.

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