Aircraft Design Using Constrained Bifurcation and Continuation Method

Abstract

A novel approach for conceptual aircraft design using constrained bifurcation and continuation method is presented in this paper. To demonstrate the approach, vertical tail sizing problem of a generic six seater, light, business transport airplane is addressed here. For sizing the vertical tail, stability analysis of the aircraft lateral-directional modes in straight and level, symmetric flight trims is carried out using constrained bifurcation analysis and continuation methodology. A full six degrees-of-freedom nonlinear mathematical model is used for modeling the rigid body flight dynamics of the aircraft; aerodynamic stability and control derivatives required for stability analysis are estimated using standard empirical relations available in aircraft design textbooks. Effects of center-of gravity change and altitude variation are also incorporated to cover a typical flight envelope for analysis. Stability parameters of lateral-directional modes, as characterized by the corresponding eigenvalues obtained from bifurcation analysis, are examined and compared with flying qualities specifications to arrive at an optimal vertical tail size that meets the handling qualities requirements.