Solar Impulse, the bird of the future
The aim of the Solar Impulse project is for an aeroplane to fly round the world day and night on no fuel, but powered only by solar energy. The objective is to demonstrate the immense potential of renewable energy sources and clean technologies.
Journey to the end of the night
Three months after an initial flight of 1½ hours, Solar Impulse passed a crucial milestone on 07 July 2010 when it flew 26 hours non-stop, thus allowing the aircraft’s ability to fly by day and night to be tested, with its 1200 photovoltaic cells recharging, by sunlight, the batteries required for flying at night.
However, that night’s experience was only a stage in the development of the HB-SIA prototype, which is now set to make a 36-hour flight to perform a complete cycle. At the end of the night the plane will not land but will continue its flight until the following evening.
It will then land with the battery charged which must be equal to that measured the evening before, thus demonstrating that the solar plane can fly indefinitely.
The team will then be ready for the next phase: the construction of a new craft, the HB-SIB, which will be larger and will have a pressurised 2-seater cockpit, designed for long flights.
On board, Bertrand Piccard and André Borschberg will then attempt to cross the Atlantic, followed by a trip around the world in five stages, planned for 2013/2014.
Featherweight
The aim of the Solar Impulse project is for an aeroplane to fly round the world day and night on no fuel, but powered only by solar energy. The objective is to demonstrate the immense potential of renewable energy sources and clean technologies.
For Solvay, the EPFL (Ecole Polytechnique Fédérale de Lausanne), the LTC (Laboratoire de Technologie des Composites et des Polymères), Bayer MaterialScience and all the other partners, the objective is one and the same: sharing their know-how in new innovative materials, high-performance plastics, optimising application processes and improving the so-called smart lightweight materials and existing processes in order to “demonstrate that progress and sustainable development are not mutually exclusive and can be viewed within the same perspective”.
An amalgam of technologies
To shed weight, the engineers opted for ultra-light plastic composite materials: the airframe, cabin and wings are made of a honeycomb structure weighing only 93 grams per square metre.
The 200 m2 upper parts of the wings are covered with a “skin” composed of 12,000 ultra-thin solar cells (150 microns thick), encapsulated and flexible enough to bear the inevitable stresses and deformation.
The plane’s lithium-polymer batteries weight 400 kg, recharged by the 200 m2 of solar panels, provide the necessary energy to keep the craft in the air during the night.
Another factor aimed at whittling down the weight is the altitude ceiling, which has been fixed at 8,500 metres in order to limit energy consumption and reduce the number of instruments on the flight instrument panel.
Solvay and Bayer join forces
No fewer than 11 polymers and products from Solvay, the main partner of Solar Impulse since 2004, are on board the solar plane and play a vital role, especially in energy management, the encapsulation of the solar cells and reducing the weight of the plane (for more details, read our earlier article.
Bayer, an official partner since March 2010, will bring its technical skills to bear on the next engines and flights, in the fields of high-tech polymer materials and lightweight energy-saving products. Its Baytubes carbon nanotubes, for instance, could enhance the performances of the batteries, with its rigid polyurethane foams insulating the cockpit and the engines …
What is a composite material ?
* a “composite material” is material comprising two materials of different natures. Composites with an organic matrix made from plastics (thermo-hardening or thermoplastic) constitute almost all the composites used at present (99%). The plastic matrix is reinforced with fibres of carbon, aramid, glass, etc.
MORE INFORMATION
www.solarimpulse.com
www.solvay.com/strategynew/solarimpulse/
www.bayer.fr/6-actualites?actualite=115
www.planetsolar.org/
www.turanor.eu
