Aerodynamic optimization of a biplane configuration using differential evolution

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.