Optimum Tail Plane Design for Sailplanes

Classical drag equations in a modern version were used to calculate the influence of tail modifications on the drag of a standard class sailplane. The profile drag which depends on the Reynolds number is included in the calculations. Minimum drag is compared with real drag for two lift coefficients. Some results have no clear tendency but low tail area and relatively low tail aspect ratio give some advantages. Optimum and real lift ratios between wing and tail plane are compared for the original sailplane.