Winglet design

Boundary vortex and pressure distribution at the winglet

The aerodynamic design of a high-performance glider in the 50:1 glide ratio class is an extensive fine-tuning program. It is well-known that winglets can reduce the induced drag by shifting the tip vortex. They can also increase the efficiency of the ailerons, which leads to better flight characteristics. Yet an incorrectly designed winglet can absolutely ruin performance, especially at higher cruising speeds. The main design parameters are:

• Area
• Aspect ratio
• Twist-angle
• Cant angle
• Sweep

The winglets of the RS20 have been specially engineered for its wing shape and airfoil. VSAERO™ was used to achieve the optimum wing efficiency for all setups by carefully setting the design parameters. Care was taken not to overload the winglet and create suction peaks. Also in the area of the winglet root we found no separation problems. We achieved to design a winglet that increases low speed performance about approx. 5% compared to a wing without winglets.