Preliminary aircraft design: lateral handling qualities

Abstract

Handling qualities of airplanes can be improved by the use of an automatic control system (augmented stability control system), however, in the preliminary design phase it is sometimes better to implement suitable design changes. These changes can be performed according to iterative and trial–error procedures in order to get the required flight qualities. In the present paper a different approach to improve lateral handling qualities of aircraft is followed, based on necessary and sufficient conditions for the roots of the lateral characteristic equation to lie in prescribed region of the complex plane. As a result of this study, handling quality region of levels 1–3 can be visualized in the space of the physically relevant parameters. As an example, the vertical tail surface S_v and the dihedral angle Γ are chosen and the regions of levels 1–3 corresponding to some aircraft are shown in the ($\text{S}{}_{\mathrm{<mtext>v</mtext>}}\text{,}\text{Γ}$) plane.