Optimizing airfoil shape for small, low speed, unmanned gliders: A homemade investigation

Abstract

Motivated by an interest to increase the efficiency of static airfoils, the objective of this study was to optimize airfoil lift generation based solely on airfoil shape. Enhancing the lift generated by airfoils without flaps can lead to longer flight times for unmanned gliders and possibly reduce fuel requirements for ground and air vehicles (1,2,3). We employed a Bernoullian model of airfoil lift generation to predict an optimized wing shape which was then constructed and compared with five others in a wind tunnel. We assembled airfoils from Styrofoam and conducted experiments in a small wind tunnel, measuring air speeds with a handheld anemometer. Our Bernoullian model related lift generation to the ratio of surface areas above and below an airfoil’s chord, and because this ratio was maximized in our optimal airfoil, we predicted that this wing would generate more lift force than the other tested wings with lower ratios. However, we identified a variety of confounding variables including imperfections in wing constructions, turbulent airflow and air resistance within the wind tunnel, and low resolution of the anemometer, all of which contributed to unpredicted and unreliable results. Moreover, we concluded that our mathematical model was not rigorous enough to be generalized to a wider set of experimental conditions. Despite these shortcomings, our results did point to a correlation between airfoil shape and lift generation, and will allow for more informed, less error prone future studies.