Solar Impulse 2, the
#RTW Solar Airplane

Solar Impulse is the only airplane of perpetual endurance, able to fly day and night on solar power, without a drop of fuel. 

The chances of succeeding at the first attempt to build a solar airplane capable of flying around the world were judged to be slim, so a more rudimentary prototype, HB-SIA, was first constructed. Lessons learned from this prototype are incorporated in Solar Impulse 2, the Round-The-World Solar Airplane.

#DISCOVERSi2

This revolutionary single-seater aircraft made of carbon fiber has a 72 meter wingspan (larger than that of the Boeing 747-8I) for a weight of just 2,300 Kg, equivalent to that of a car.

The 17,000 solar cells built into the wing supply four electric motors (17.5 CV each) with renewable energy.

During the day, the solar cells recharge lithium batteries weighing 633 Kg (2077 lbs.) which allow the aircraft to fly at night and therefore to have virtually unlimited autonomy.

Learn more about the challenges of building the Round-the-World Solar Airplane.

STREETVIEW: INSIDE THE HANGAR

Solar Impulse by Solar Impulse on Sketchfab

#Testflights

Whereas the prototype uses existing technologies, Solar Impulse HB-SIB requires the development of new materials and new construction methods. Solvay has invented electrolytes that allow the energy density of the batteries to be increased; Bayer MaterialScience is allowing the project to make use of its nanotechnologies; and Décision is using carbon fibers that are lighter in weight than any previously seen.

The first wing spar section was delivered to Dübendorf in March 2012. However, during the final test of this central part, the structure of the wing spar succumbed to the load and broke. The initial shock soon turned out to be an opportunity: the flight around the world had to be postponed which opened the door for going to the United States and completing the epic journey across America.

After the official presentation of Solar Impulse 2 to the public on April 9th, the airplane will be rigorously tested during 2014, and the Round-The-World flight will be attempted between March and July 2015.

Technical Datasheet

Solar Impulse 2's features, in short:

  • Batteries energy density 4 x 260 Wh/kg
  • Airplane Weight 2,3 tons
  • Wingspan 72 meter (236')
  • Solar Cells Thickness 135 micron
  • Solar Cells > 17,000
  • Cockpit Size 3.8 m3

ABU DHABI, MARCH 9, 2015

I’d never imagined that setting off to fly round the world would be so poignant. I’ve been dreaming about it for 16 years, ever since landing from my round-the-world balloon flight, and it’s hard for me to believe that the great day ...

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ABU DHABI, MARCH 9, 2015

I’d never imagined that setting off to fly round the world would be so poignant. I’ve been dreaming about it for 16 years, ever since landing from my round-the-world balloon flight, and it’s hard for me to believe that the great day has arrived. It's as if a new phase of my life is suddenly beginning.


We’d had a series of unexpected snags in recent days, including an electrical alarm just a few seconds before takeoff. Then Solar Impulse 2, flown on this first leg by André, disappeared into the mist. Unless it was into the tears that were blurring my eyes.


MUSCAT, MARCH 10, 2015

It is emotionally easier to be at the controls than on the ground. I'm finally in "pilot mode" to cross the Arabian Sea. And, as a bonus, to bring the first solar aircraft to Asia and break the world distance record. But already there’s a bit of nostalgia for the extraordinary welcome that the Omanis gave André the day before, dressed in white dishdashas, with colorful turbans and ceremonial daggers at the waist, contrasting with our prototype’s futuristic technology.

 

AHMEDABAD, MARCH 11, 2015

Vast bouquets of flowers, embroidered silk scarves laid one on top of another around my shoulders, the incessant crackling of blinding camera flashes: I am torn away in a split second from the cozy intimacy of my cockpit. There’s no room for doubt - I’ve arrived in India!


AHMEDABAD, MARCH 12, 2015

A mini-tornado shakes Solar Impulse’s tent and knocks the ventilation down onto the electricians’ workshop. Miraculously, Sébastien had left just a few seconds earlier. Danger doesn’t always come from where you expect it.


MANDALAY, MARCH 19, 2015

Seventeen years after my second, failed round-the-world balloon attempt, which ended in Burma, here I am on the approach to Mandalay airport. This time it’s a complete success. André tells me by radio to expect the most enthusiastic welcome ever granted either to Solar Impulse 1 or 2.

Behind me lie the Bay of Bengal and the Meghna Delta, where floodplains intersperse with meanders to create one of the most beautiful sights nature can offer. I flew at over 200 km/h thanks to one of my friendly jet-streams. And before me lies a country that rejoices in discovering that clean technologies and solar energy can be a source of social cohesion, peace and economic development.

It is night. My landing lights aren’t lighting up any of the pagodas. I'll have to wait till tomorrow to wallow again in the special aura of kindness and spirituality that once made such a deep impression on me...


MANDALAY, MARCH 30, 2015

I just love the unexpected gifts life brings.

Originally, I was supposed to take off at dawn from Mandalay and was looking forward enormously to flying over the local temples. The program was disrupted by the need to arrive earlier in Chongqing, and my departure was bought forward to 3:30 am, in inky blackness.

I was hardly airborne when illuminated pagodas swept away my disappointment. The spectacle fast became stunning, infinitely more beautiful than by day. Total darkness was punctuated with dozens of golden spots, each representing a temple glowing under floodlights. I fly north at low altitude up the Irrawaddy River, crossing Mandalay slowly. As slowly as possible…

 

SHANGHAI, APRIL 13, 2015

Solar Impulse is blocked by weather in Chongqing. Delays are accumulating. Our adventure is less easy than it’s seemed in recent weeks. André and I do one interview or talk after another in Shanghai for our partners. There’s no way you can tire of the amazing view of Pudong from our rooms in the Peninsula, where we are privileged to be invited to stay. The pace of growth in this city is frantic. For those who still had any doubt, the center of gravity of the world’s economy has indeed moved to the East.

Swiss Pilots Bertrand Piccard and Andre Borschberg Accomplished the Second Stop Over in China Before Embarking on the Historic Pacific Crossing

 Nanjing (China), April 21, 2015 – Solar Impulse 2 (“Si2”), the world’s most advanced solar-powered airplane and the first to fly day and night without fuel, landed successfully in Nanjing, People’s Republic of China, following a 20 day stay in Chongqing. With Bertrand Piccard at ...

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 Nanjing (China), April 21, 2015 – Solar Impulse 2 (“Si2”), the world’s most advanced solar-powered airplane and the first to fly day and night without fuel, landed successfully in Nanjing, People’s Republic of China, following a 20 day stay in Chongqing. With Bertrand Piccard at the controls, the solar airplane concluded the sixth leg of the historic trip around the world this evening at 11:28 pm local time China (3:28 pm GMT). 

My job as a pilot was relatively easy. The preparatory measures however proved challenging for our team of weather specialists and engineers from Si’s Partner Altran at the Monaco Control Center. We simulated all possible trajectories and exhausted all different strategies to get Solar Impulse 2 in the air; from defining pit-stops at airports along the route, to different speeds, altitudes and holding patterns. Throughout the entire process, the Chinese authorities have been unfailingly helpful and open to our ideas. We are amazed by the spirit of our team and the willingness of our partners to help us achieve our goal: The first Round-The-World flight without fuel” said Bertrand Piccard, Solar Impulse Initiator and Chairman. 

 This journey was also essential from a technical perspective as it was used to verify and fine-tune final elements in the preparation of the Pacific Ocean crossing scheduled for early May, pending favorable weather conditions. This last leg is bringing Solar Impulse one step closer to an aviation first – the next part of the circumnavigation will require flying five consecutive days and nights in a solar-powered aircraft to cross the Pacific, a feat that has never been accomplished before. 

 Commenting on the arrival in Nanjing André Borschberg said: 

 “Nanjing represents a turning point in the entire mission; this is where everything comes together for us as pilots after initiating the project 12 years ago. This is the moment of truth where all the technical and human challenges will have to be overcome. We now have less than a month to mentally and physically prepare for what will be Solar Impulse’s longest flight to date: a five day and five night journey across the Pacific Ocean from Nanjing to Hawaii.” 

Solar Impulse heads for Nanjing before crossing Pacific Ocean on its Round-The-World Flight

Chongqing (China) April 21, 2015: Solar Impulse departed for its sixth flight from Chongqing Jiangbei International Airport at 06:06 am (10:06 pm GMT [April 20th]), heading toward Nanjing Lukou International Airport in the People's Republic of China. ...

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Chongqing (China) April 21, 2015: Solar Impulse departed for its sixth flight from Chongqing Jiangbei International Airport at 06:06 am (10:06 pm GMT [April 20th]), heading toward Nanjing Lukou International Airport in the People's Republic of China. Bertrand Piccard is flying the solar powered airplane for an expected 14 hours across the country before arriving in Nanjing. Solar Impulse 2 (Si2) has been waiting patiently in Chongqing during the past three weeks for a suitable weather window to open - cloudy weather conditions and excessive crosswinds prevented an earlier take-off.
 
During the previous weeks, Solar Impulse meteorologists and simulation teams have battled with unfavourable weather circumstances to find solutions allowing a departure from Chongqing sooner rather than later. Strategies explored included alternative routes, possible pit stops and flying at various altitudes. While considering several possibilities, the Civil Aviation Authority of China (CAAC) was very supportive, collaborative and flexible, for which Solar Impulse is grateful.
 
Si2 departed from Chongqing, heading East toward the city of Fuling, located in the province of Sichuan. Bertrand Piccard will fly over the mountainous region just outside Fuling between 12:00 pm and 1:00 pm local at a cruising altitude of 3,700 meters (12,140 feet). Piccard will continue Easterly, crossing the longest river in Asia, the Yangtze River, after which flying North Easterly toward the city of Wuhan. The solar powered aircraft will pass over Chaohu Lake, one of the largest lakes in China at roughly 8:00 am local time. Piccard is expected to arrive in Nanjing at 8:00 pm (12:00 am GMT).
 
Si2 will remain in Nanjing for approximately 10 days, depending on favorable weather conditions, as a thorough check of the airplane is required before departing Nanjing to Hawaii (USA) for the Pacific Crossing which will last 5 days and 5 nights.


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