Chapter 9 - The Anatomy of the Wing

Abstract

A number of methods to size the wing of a new GA aircraft are presented. The chapter begins by the presentation of handy formulation to calculate various properties of trapezoidal surfaces, which is the most common planform shape for lifting surfaces like wings and horizontal and vertical tails. This is followed by the introduction of various concepts, topics, and methods for laying out the wing planform. These include aspect ratio, taper ratio, washout, and wing incidence angle. A detailed discussion follows to help the designer evaluate the pros and cons of typical wing planform shapes suitable for the new aircraft. In addition to the large number of different geometries presented, detailed information about the spanwise distribution of section lift coefficients is provided to help the designer realize their properties. Next, a number of methods to evaluate the lift and pitching moment characteristics of the wing as a 3-dimensional lifting body are provided. Then, a number of issues that have to do with wing stall characteristics and how to improve them are presented. Finally, in order to help the designer in realizing the properties of the selected wing planform and airfoils, a practical version of Prandtl’s Lifting-Line Theory is presented. It is a sophisticated numerical method that provides an initial of estimate of the wing’s aerodynamic properties. A software function, written in Visual Basic for Applications and intended for use with Microsoft Excel is presented as well, allowing the reader to get to work immediately.