One of our central current research topics is aircraft drag reduction. All heavier-than-air aircrafts experience a considerable amount of drag stemming from lift generation even in the absence of friction, the so called induced drag. The drag power persists behind the wing in the form of trailing vortices which endanger following aircrafts especially near airports. This drag may be minimized by the use of special wing configurations like elliptic wings (e.g. WWII Spitfire) and aircrafts with very high wing spans (sailplanes). Further drag reduction can be achieved by modifying the wing tips as is the case for the well known winglet.