Solar plane on final leg of intercontinental flight

The Swiss sun-powered aircraft Solar Impulse took off from south-western France on Tuesday on the final leg of its first intercontinental trip that took it from Europe to North Africa and back.

Solar plane on final leg of intercontinental flight
Photo: Solar Impulse/Jean Revillard

Pilot Bertrand Piccard took the plane up into the sky from an airfield near Toulouse on its journey back to Payerne in Switzerland, from where it left on May 24th for the Moroccan capital Rabat via Madrid.

The high-tech aircraft, which has the wingspan of a large airliner but weighs no more than a saloon car, is fitted with 12,000 solar cells feeding four electric engines.

Solar Impulse had to wait for a week in Toulouse for the right weather conditions. It departed Tuesday in a cloudless sky and was due to arrive in Payerne around 1800 GMT.

Once this final stage is completed, the 6,000-kilometre (3,700-mile) journey will be the longest to date for the aircraft after an inaugural flight to Paris and Brussels last year.

The flight was being live-streamed on, the website of the project run by Piccard, an explorer who has travelled around the world in a hot-air balloon, and fellow pilot Andre Borschberg, who took turns to fly the plane on its latest journey.

The trip was intended as a rehearsal in the run-up to a round-the-world flight planned for 2014 by an updated version of the plane.

The organizers said in a statement that Solar Impulse had now demonstrated the reliability of the technology it uses as well as its energy efficiency.

Solar Impulse made history in July 2010 as the first manned plane to fly around the clock on the sun's energy.

It holds the record for the longest flight by a manned solar-powered aeroplane after staying aloft for 26 hours, 10 minutes and 19 seconds above Switzerland, also setting a record for altitude by flying at 9,235 metres (30,298 feet).

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High flyer: Swiss firm H55 wins funds for new electric plane project

A Swiss firm co-founded by one of the key figures in the Solar Impulse project has won Silicon Valley funding towards developing electric aircraft.

High flyer: Swiss firm H55 wins funds for new electric plane project
H55 co-founder Henri Addor. Photo: Henri Addor

Sion-based company Hangar 55 (H55) has been awarded the first-round funding by US venture capital firm NanoDimension, company co-founder André Borschberg announced on Twitter on Tuesday.

An engineer and former fighter pilot, Borschberg also co-founded the Solar Impulse project which led to the first-ever round-the-world flight by a solar airplane – a multi-stage journey completed from 2015 to 2016 that garnered international headlines.

With his new project, Borschberg – along with fellow H55 travellers Sebastien Demont and Gregory Blatt – now hopes to develop and certify clean, safe and quiet electric propulsion systems that can be incorporated into other planes.

“With Solar Impulse the message was about perpetual energy – the ability to fly around the world using only renewable solar energy. H55, which has inherited the know-how acquired with Solar Impulse, will concentrate on the electrification of aircraft, what ever the source of that electricity,” Borschberg told Swiss business magazine Bilan.

H55 unveiled its first aircraft ‘aEro1’ in 2017: a relatively simple one-seat German-made Silence Twister aerobatic flyer fitted with batteries. It could fly for just an hour before those batteries needed charging. A newer version clocked up two hours, at a flying cost of just 3 Swiss francs an hour.

But as Borschberg explained to the science magazine Wired at the time aEro1 was unveiled, the goal is not to try and match Uber and its planned flying cars in terms of excitement.

Instead, the idea is to think small and “prove the safety” of the aviation systems developed so that they get the all-important nod from regulators, allowing new craft, for example, to be allowed to fly over populated areas.

And despite the inherit problems with battery-powered flight – a kilo of aviation fuel contains 30 times more energy than a battery equivalent –Borschberg believes the moment has come to move to electric aircraft.

This is not because he believes batteries are about to suddenly become a lot better, but because of the advantages electric flight offers in terms of both reduced CO2 emissions and in terms of allowing – at some stage in the future – for a complete rethink of airplane design.

Talking to Bilan, Borschberg also highlighted the potential safety benefits and lower maintenance requirements that could derive from developing planes with fewer engines than seen on current aircraft.