Piccard's Electrically Powered Solar Impluse Protype Completed

FUEL-FREE AIRPLANE UNVEILED
(http://www.avweb.com/eletter/archive...ll.html#196557)
The initial prototype of Solar Impulse

(http://www.solarimpulse.com/en/hbsia...44&idIndex=19),
a solar-powered aircraft that may fly around the world without
fuel in 2011, was unveiled last week in Switzerland by project
organizer Bertrand Piccard. The first aircraft has a wingspan of
almost 200 feet and will be used to test the basic science behind
the project. If all goes well, it will fly nonstop for 36 hours,
using solar power for its electric motors and charging batteries
by day and using the stored energy at night. As formidable as that
challenge might be, the ultimate goal is much more ambitious.




http://www.solarimpulse.com/multimed...en_5nov_07.pdf
A SYMBOL UNDER CONSTRUCTION
OFFICIAL SCIENTIFIC ADVISOR ENGINEERING PARTNER MAIN PARTNERS
After four years of research, studies, calculations and
simulations, the
Solar Impulse project has entered a concrete phase with the
construction of an initial
prototype with a 61-metre wingspan, referred to by its
registration number
“HB-SIA”. Its mission is to verify the working hypotheses in
practice and to validate
the selected construction technologies and procedures. If the
results are conclusive,
it could make a 36-hour flight - the equivalent of a complete
day-night-day cycle -
in 2009 without any fuel.
TWO AIRPLANES ON THE WAY Construction of the first prototype, the
HB-SIA, began in June 2007 and will last until
TO SUCCESS the summer of 2008. Test flights should start in autumn
2008, with the objective of
completing the first night flight in 2009. Another plane will then
be developed to
attempt to fly several 24-hour cycles consecutively, leading to
the first trans-Atlantic
flight in 2011, and then the first round-the-world flight.
HB–SIA’S MISSION This is a “basic” prototype airplane. The
instrument panel will be reduced to the
essentials, and with a non-pressurized cockpit it will be unable
to fly above 8,500 m.
It will be a first approach at optimizing the balance between
energy consumption,
weight, performance and controllability. The goal is not to try to
fly around the world
and indeed the HB-SIA is not built to do so.
The objectives at this stage a
• To validate the computer simulation results, the technological
choices and the
construction techniques.
• To test an unexplored area of flight: never before has an
airplane succeeded in
flying with these size, weight and speed characteristics.
• To store sufficient solar energy during the daytime to
demonstrate the feasibility
of a day-night-day cycle (36-hour flight).
EXAMPLE OF ENERGY EFFICIENCY 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 consum -
ed 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 every -
thing is new, everything is different: aerodynamics, structure,
manufacturing
methods, type of propulsion, flight domain…
A SYMBOL UNDER CONSTRUCTION
In some ways it looks like a large aircraft, in others more like a
glider. It has the
wingspan of the Airbus A340 and the wing load of paragliders and
delta planes. In
relation to its size, it must be eight times lighter than that of
the best existing glider.
This poses the problems of:
• constructing a structure with this wingspan and such a low
weight;
• finding the balance between stability and manoeuvrability, in
other words how to
make an airplane of this size and with such a low wing load
pilotable?
MODEL OF HIGH TECHNOLOGY The project will be successful only if it
can achieve performances which are still
unknown today, achieved by a combination of practical
experimentation and complex
computer simulations.
To achieve this, a multi-disciplinary team of 50 specialists from
six countries, based
in Dübendorf and Lausanne, assisted by a further roughly 100
outside advisers, are
pooling their very specific experiences to create the necessary
synergies. It is only
by combining the demands of the designers, equipment suppliers,
constructors and
pilots that an airplane can be built to such atypical
specifications. Research initiatives
have had to be undertaken and new solutions called into play in a
number of
sectors - conception, aerodynamics, energy efficiency, structure,
composite materials
and manufacturing procedures - both for each component
individually and for
the assembly as a whole.
An elegant example is the extreme precision achieved in the use of
composite
materials: for example stretching carbon sheet just a few tenths
of millimetres thick
over lengths of up to 20 metres. As the Project CEO, André
Borschberg, says,
“Anything that doesn’t break is potentially too heavy!”
The fragile solar panels also had to be flexible in flight. How do
we use cells as both
energy generators and wing surface, without breaking when the
airplane encounters
turbulence?
Of course, all this represents the management challenge of
bringing together
individualists who are as bold as they are creative, getting them
to work as a team
and motivating suppliers to move beyond their customary limits.
SYMBOL FOR OUR SOCIETY For Bertrand Piccard, the initiator and
president of the project, this airplane is the
symbol of the new technologies that our society ought to be
capable of rallying
behind it in order to economize the energy resources of our
planet.
Solar Impulse, in this sense, really means what its name says. The
sun provides the
energy, but the impulse to use it has to be transmitted to people
who are ready to
receive it and carry it further.
In any case, it demonstrates the importance of tomorrow’s
adventures being linked
to the search for a better quality of life.
Contact: For further information or requests for interviews,
please contact
Phil. Mundwiller on 0041 (0)79 570 14 94 /