| Themes > Science > Physics > Fluid Dynamics > Flying the flag for fluid dynamics > Aerodynamics > Selected Topics of Model Aerodynamics > A Close Look at Winglets > Prologue |
Most modern high performance flying wing aircraft with nearly elliptical lift distributions have vertical wing tip extensions, called winglets. Flying wings which use the bell shaped Horten lift distribution usually have no need for vertical fins. In 1992, the DLR Sailplane Symposium at Stuttgart saw a presentation from Mr. Waibel of the well known Schleicher sailplane factory. He presented interesting results from simple experiments, using a Volkswagen Golf (aka Rabbit), equipped with a winglet. This paper shows the results of numerical studies which were conducted to apply his findings to the winglets of tailless models. It is not the aim of this paper to seek information about the optimum winglet shape and its effect on induced drag, but to understand what happens in the region where the winglet joins the wing and why the reduction in induced drag can be spoiled by additional friction drag in this region. Thus we will concentrate on the boundary layer effects. The cover page of the 1992 «Competitors Achmer News» I found a detailed technical drawing of three tailless planes with winglets (it could also have been an explosion-sketch, as we call it in Germany, of the prototype flying wing «Delaminator») as shown in the title graphics above. The three tailless planes show interesting corners between the wing and the winglets, even an asymmetric layout, which might be optimized for left turns on the northern hemisphere. This drawing, which was very sketchy due to competition reasons, forced me into a more thorough investigation of this region of flying wing models. |
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