Emerging Sustainable Technology, Design, Energy Efficiency, Renewable Energy and Appropriate Technology
Current solar airplanes are not designed to store energy and therefore have to land in cases of insufficient sunlight (clouds or night time). In so doing they mark the limits of solar energy. Other projects are seeking to fly remote controlled solar drones or hydrogen-powered airplanes. To demonstrate the formidable potential of renewable energies, Solar Impulse intends to place the bar much higher and have a piloted aircraft fly night and day without fuel.
But how do we succeed with a mission like this, when we know that with present-day technologies and performances, every square metre of photovoltaic cells can supply only 28 watts – the equivalent of an electric light bulb – to the propeller continuously over a 24-hour period? In other words, how can an airplane fly on the energy consumed by a supermarket window? It is impossible without a complete optimization of the airplane and without a drastic reduction in its energy consumption.
Only a machine of disproportionate dimensions (61 metre wingspan) and very light weight (1500 kg) will be able to fly sufficiently slowly (45 km/h) to operate off the available energy! The Solar Impulse engineers have therefore had to develop a totally new type of airplane, made possible by innovative technologies, in which everything is new, everything is different: aerodynamics, structure, manufacturing methods, type of propulsion, flight domain…
Via Inhabitat and Solar Impulse
( I would double check their assumption of solar cell output, 28 watts per square meter (?) Maybe averaged over 24 hours.)
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