Solar-powered plane takes to the skies to set record

7 Jul 2010

At 6.51am today, a solar-powered aircraft, the Solar Impulse HB-SIA, took off from its Swiss base for a 24-hour test flight, aiming to be the longest and highest flight ever made by a solar plane.

André Borscherg, CEO and co-founder of the Solar Impulse project, was at the controls when the plane took flight from Payerne airfield this morning.

“For seven years now, the whole team has been passionately working to achieve this first decisive step of the project,” said Borschberg, as he got into the cockpit for a flight that’s expected to last until tomorrow morning.

Building on the HB-SIA prototype, the Solar Impulse team aims to build a second solar-powered aircraft (the HB-SIB), which will attempt to fly around the world. Solar Impulse’s main partners are Solvay, Omega, Deutsche Bank, while its official partners are Abtran and Swisscom.

Today’s flight

The HB-SIA plane first climbed to 7,000 feet in the test area around the Payerne military air field and then moved up to 10,000 feet above Lake Neuchatel.

Up until 7.30pm this evening the prototype plane will slowly ascend to an altitude of 8,500 metres while simultaneously charging its batteries in preparation for the night flight. Then, as evening descends, when the sun’s rays become too weak to supply the solar cells with energy (about two hours before sunset), the HB-SIA will start a slow descent to reach an altitude of circa 1,500 metres by 11pm.

The team anticipates that the plane will then continue flying until sunrise, using the energy stored in its batteries.

“The intention of this mission is to demonstrate the potential of renewable energy and clean technologies and to promote them amongst the public”, explains Bertrand Piccard, initiator and president of Solar Impulse. A psychiatrist and aeronaut, in 1992 Piccard won the first transatlantic balloon race (Chrysler Challenge). Then, in 1993, he captained the Breitling Orbiter 3, the first non-stop round-the-world balloon flight.

If everything goes to plan, the plane will land on Thursday, 8 July, in the morning.

Last Thursday, the Solar Impulse Mission Team had to postpone its first night-flight attempt due to a problem with the plane’s prototype telemetry transmitter that had broken down. This system enables the ground team to follow in real-time the flight mission and to monitor crucial parameters.

About the HB-SIA

– With a 63-metre wingspan, the length of the HB-SIA is 21.85m and it has a height of 6.4m. The plane has an average flying speed of 70km per hour and has 4 x 10 HP electric engines.

– It has a 1,600 kg take-off weight. The upper wing surface is covered with a skin of encapsulated solar cells, and the undersides of the wings with a high-resistance flexible film.

– It will capture the suns rays via 11,628 solar cells, each 150 microns thick, with 10,748 solar cells on the wings and 880 on the horizontal stabiliser. These particular solar cells have been selected for their lightness, flexibility and efficiency. And at 22pc, while their energy efficiency could be higher, the team said the additional weight would have penalised the aircraft during the night flight.

– Energy will be stored in the lithium polymer batteries. The accumulators needed for night flight weigh 400kg, equal to one quarter of the total weight of the aircraft.

Carmel Doyle was a long-time reporter with Silicon Republic