High-Performance Soft Kite Technology State of the Art

Operation of the EnerKíte ram-air wing (15 August 2012).

Reinhart Paelinck

Research & Development – ReinART Flysurfer Kiteboarding R&D

Bredeweg 54 8420 De Haan

Belgium info@reinart.be www.reinart.be

High-Performance Soft Kite Technology State of the Art, Limits and Opportunities

Flysurfer Kiteboarding R&D - ReinART Recent technological developments in the kitesurfing

in-dustry may have an impact on how ground-based gener-ation Airborne Wind Energy (AWE) concepts perceive and use soft kites.

As kitesurfing is evolving to a complete sport, users ask for kites that make it possible to go out in nearly any con-dition. Light wind proves to be the incubator for tech-nological achievements. Hydrofoil and Formula kiterac-ing have pushed the limits in ram-air soft kite technol-ogy, asking for high L/D wings. Performant boards make it possible to go out when the kite can not yet sustain its own weight statically in the air, much like rigid wings. Ram-air kites are therefore not necessarily light. The frus-tration of dropping a kite in the water in these conditions has lead to the development of ultralight depowerable single-skin kites, such as the Flysurfer ”Peak” shown in the figure. In this design a minimal number of rib ele-ments are used to bulge the single-skin into a leading edge that induces the characteristic airflow around an air-foil and a lift-generating aerodynamic surface pressure distribution. The lightest weight per projected area of any kite has proven to be key to the ultimate light wind kiting. In practice, these are high performance successors to the classic Nasa Parawing.

System-bound, these single skin and ram-air kites have quite a limited depowerrange compared to inflatable kites or rigid wings. Therefore, possibilities to build ef-ficient yoyo-AWE systems with double- and single-skin

kites that retain their original shape in the retraction phase are quite limited. An efficient depowerrange comes in handy when the kitesurfer wants to jump as high as possible, a scenario that is much alike to the yoyo-phase in AWE. Therefore high L/D, high depower inflat-able kites have been developed. The aim of this presen-tation is to show the potential of soft kites in AWE by pre-senting the state of the art technology in these three soft kite categories. It gives an indication in which AWE system configurations it would make sense to use which kind of soft kite technology.

It discusses the limits of soft kite technology, in practical scenarios, production, lifecycle and scaling.

FlySurfer ”Peak” used for snowboarding (2013).