Wind Tunnel Tests on an Outer Wing Segment of the ASW-19X Sailplane

Abstract

At the Delft University of Technology Low Speed Laboratory (LSL) an investigation was conducted to determine the aerodynamic characteristics of an outer wing segrnent of the ASIW-19X sailplane. This sailplane is a Standard Class ASW-19B with a modified wing. New airfoils were designed such that just by adding material to the surface, the existing wing could be modified and tested in flight. Wind tunnel tests on an actual inner and outer wing segment of the original ASW-19B are described in a reference, and a comprehensive paper on the considerations, tests and results of the ASW-I9X research program - which led to an improvement of 5% in glide ratio over the entire practical flight speed range - is given in a reference. A special feature of the new wing is the applicatfon of pneumatic turbulators on the lower surface, a technique to reduce airfoil drag by avoiding pronounced laminar separation bubbles. Wind tunnel tests on the inner wing airfoil section showed a considerable drag decrease. At present, similar tests on an outer wing segment are described. In addition, tests with a tape with digged-in bunps instead of the pneumatic turbulators are described. Wool tufts filmed by a camera mounted on a sting on top of the fuselage indicated flow separation on the downward deflected aileron in circling flight. In the present investigation attention was given to this phenomenon.