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Michael Rehrnet


The idea of launching a plane by solar energy is not a novelty. A survey is given of the man-carrying solar-powered planes which have so far been realized. We have new materials today, and there are a lot of new developments in the area of solar cells, electronic controls and electrical engines. One of the biggest technical challenges is the realization of a high efficient, lightweight propulsion system with a flexible photovoltaic generator an the construction of an aircraft according to the following requirements: - selflaunchable with battery power, - climb with 2m/s to an altitude of min. 500m, - horizontal flight only with solar power, - payload 60 to 90kg, - structural strenght min. +4 / -2.69. It is possible today to combine available components to get a solar powered propulsion system for a lightweight sailplane and to design such a sailplane strong enough for rough air conditions and reasonable payloads. This is a big improvement compared to the solar powered predecessors ten years ago. But undoubtfully such a glider will not lead to sudden revolution in general aviation. On the one hand it will be expensive (at least double the price of a modern open class glider) and on the other hand the glide ratio of arround 40 at a speed of only 60 km/h is not very satisfying for today's glider pilots. The biggest advantages will result out of new developments in the field of solar powered propulsion systems, lightweight and flexible integration of solar cells and new design concepts for lightweight structural components. These could have a remarkable influence for the application of solar cells in a wide range of new fields.


Aerodynamics, Structures, Materials, Design

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