* Astronomy

Lightweight wings for a high-flying kite
Tensairity elements made of air filled membrane assemblies, rods and cables have already made a name for themselves in the construction world as extremely light yet strong load-bearing structures. But is this new technology also suitable for use in the aerospace industry, for example to create novel wings for kites? Empa researchers are currently pushing back the envelope in this field, and are also demonstrating their first flying models.
Ultra light wing structures for kites are not just attractive for sport and hobby users but are also of interest to engineers, for example in applications such as towing kites which take advantage of wind energy to provide additional propulsion for diesel powered freighters, pulling them across the oceans. In this case the kites are intended to help shipping concerns to reduce their high fuels costs. They can also be used for other applications involving the exploitation of wind energy, one idea being to allow a kite to climb to a height of several kilometres, while up pulling a line wound around a drum. As the drum rotates to pay out the line, it can be made to generate electricity. When it reaches its target altitude the kites wing-area is somewhat reduced causing it to descend, following which it begins a new climb phase and once again generates electric power. This is a fascinating field of application for ultra light structures, because in order for the kite to utilise the winds energy efficiently it must have a large wing area.

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