The first solar-powered airplane. Solar Impulse Project
BySolar Impulse is a European long-range solar-powered plane project currently being undertaken at the EPFL.
The project is promoted by Bertrand Piccard, who piloted the first balloon to circle the world non-stop.
This project hopes to repeat that feat using only solar power.
The first aircraft (official name HB-SIA) is a one-seater, capable of taking off under its own power,
and intended to remain airborne for 36 hours.
Building on the experience of this prototype, a slightly larger follow-on design (HB-SIB) is planned to make
circumnavigation possible. Circumnavigation of the globe is anticipated to take 20-25 days.
Technical Data
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Wingspan 63m
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Weight 1,600 kg,
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Take-off speed 35 km/h
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Average flying speed: 70 km/h
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Motor power 4 x 10 HP electric engines
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Battery specific capacity: 220Wh/kg
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Solar cells: 11,628 (total area 200m?)
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Maximum altitude 8,500 m (27,900 ft)
Design Details
The plane is as wide as an Airbus A340. Under the wing are four gondolas,
each with a set of lithium polymer batteries, a 10HP motor and a twin-bladed propellor.
To keep the structure ultra-light, a customised carbon fibre honeycomb sandwich structure is used.
Photovoltaic cells on the upper wing surface and the tail generate electricity during the day.
This both propels the plane and recharges the batteries to allow flight at night.
The major design constraint of the project is the capacity of the lithium polymer batteries.
Over 24 hours, in the best conditions, the power train will deliver an average of 8HP (6kW),
roughly the power used by the Wright brothers’ Flyer in 1903.
First flight of Prototype
On 26 June 2009, the Solar Impulse was first presented to the public, in Du”bendorf, Switzerland.
Following taxi testing, a short-hop (350m) test flight was made on 3 December 2009. The pilot was Markus Scherdel.
“It was an unbelievable day,” Andre’ Borschberg, co-leader of the project team, told New Scientist.
“The airplane flew for about 350 metres and about 1 metre above the ground – the aim was not to get high but to
land on the same runway at a speed to test its controllability and get a first feeling of its flying characteristics.”
He added that the craft behaved just as the engineers had hoped. “It is the end of the engineering phase and the start
of the flight testing phase.”
