Numerical Investigation of Different Airfoils at Low Reynolds Number in terms of Aerodynamic Performance of Sailplanes by using XFLR5

Wing design has a critical importance for sailplanes as well as for all the aircrafts in terms of aerodynamic performance. One of the important design phases of an aerodynamically efficient sailplane wing is selection of the appropriate airfoil. Airfoil selection of a wing design firstly requires performing aerodynamic performance analyses of different airfoils to compare according to determined requirements. In this study, numerical investigation of nine different airfoils was performed with the aim of comparison in terms of aerodynamic performance of sailplanes by using the general public licensed computer program XFLR5. Firstly, the airfoils which will be compared were selected from Eppler, Goettingen, NACA and Wortmann airfoil families. For the comparison of the airfoils, the two-dimensional analysis validation of the program was done with experimental data, and the airfoils were analyzed in two dimensions under the same validated analysis conditions. The analyses were performed at 2x105 Reynolds number and angle of attacks from -5 to 20 degrees. According to obtained results from the analyses, the airfoils were compared in terms of determined criteria which are thickness, maximum lift coefficient and its angle of attack, maximum drag to lift ratio, drag coefficient at maximum lift condition, pitching moment at zero lift condition and power factor.