Author(s)

R. W. Derksen & A. G. Kraj

Abstract

This paper presents our work on designing a biplane configuration that has a minimum drag to lift ratio. This problem is a mixed optimization problem in that both discrete and continuous variables are used. Fourteen parameters were used to fully describe the biplane configuration and calculate performance. Performance calculations were based on Munk’s general biplane theory. Each wing required six parameters; airfoil profile type, span, tip and root chord lengths, angle of attack, and sweep angle. Two parameters were used to define the horizontal stagger and vertical gap between the two planes. The airfoil profile types were stored in an indexed database which allowed us to obtain the section’s aerodynamic characteristics. Our analysis showed that differential evolution found the optimum solution quickly. The characteristics of the resultant optimum solution will be discussed in detail, along with our observations of how the process needs to be adjusted for optimum performance. Keywords: aerodynamic design, optimization, biplanes, aerodynamic configuration. 1 Introduction The following sections will provide a brief review of the state-of-the-art of aerodynamic optimization. This will be followed by a discussion of the advantages and disadvantages of the biplane configuration. The introductory comments will conclude with the motivation for doing this work. 1.1 The practice of aerodynamic optimization A quest for performance has been a key component in the development of aviation from the start. A great deal of this was motivated by high performance

Keywords

aerodynamic design, optimization, biplanes, aerodynamic configuration.