Solar Impulse 2 :: Around the World!

Around the world with no fuel, using renewable energies, clean tech and solar energy.

It took 17 flights spaced over more than a year, with over 510 hours in the air to fly around the world on solar power alone.  The journey was 42,000 km long.  Twenty-two days were spent in the air.  11,000 kWh of solar energy were produced to power the flight.  The route spanned four continents, three seas, and two oceans.  And along the way, 19 world records were set.

The Dream

This was the flight of Solar Impulse 2, the dream of Bertrand Piccard, the famed Swiss balloonist.  In 1999, Piccard started with just the idea and nothing more. Piccard would need a plane that could fly on the power of the Sun alone.  He would need to build the team to manage it, raise the funds, build it, and fly it.  He would need to develop the vision not just as a personal challenge but as a global message about the environment, about zero-waste energy use, and about the future of mankind on the planet.  With that dream, he could find the partners.  Ultimately, even without one drop of gasoline, he was confident in his goal.

As with all dreams, at first he had no funding, no supporters, and no plan.  He did have perseverance and commitment to make his dream a reality.  From the start, he knew just that people would come together and make his dream a reality — if only he would lead the way.

Challenges like these were part of Piccard’s family tradition — in fact, the famous Star Trek character, Captain Piccard, was named after one of Bertrand’s relatives.  Yet, just like the fictional characters of Star Trek, no one man can do it all alone.  Thus, early on he partnered with another visionary, André Borschberg, who would also help him to pilot the journey.

In the 17 years that followed, the two men steadily developed his vision, gathered supporters and partners, undertook feasibility studies, and built a first airplane (Solar Impulse 1).  From there, they tested the concepts and proved that an all day-overnight to morning was possible.  Then they proved that intercontinental flight was possible by flying Solar Impulse 1 across the Mediterranean Sea.  Then, they made a transcontinental flight from California to New York.

With every flight, the two men set new records and gathered more support.  They then built Solar Impulse 2, the plane that would take them around the world.  Together and in the true pioneering sense, Piccard and Borschberg not only flew around the world, but also brought back the vision and a pioneering sense that is at the root of all aviation history and pioneering.

The Plane — Solar Impulse 2

A unique design emerged after years of work and design energy.  Technologies were selected, improved and even pioneered from scratch to make the mission possible.

The plane’s design was innovative — a very high aspect ratio wing ensured that the aircraft, something of a high tech powered glider, could ascend and fly long distances on minimal thrust and at low speeds.  Speeds was less important anyway because with the power of energy from the Sun, the plane could easily stay aloft for days at a time.  At night, stored power in batteries kept the engines running.

The wingspan of Solar Impulse 2 was 236 feet (72 meters), roughly the same as on a Boeing 747 Jumbo Jet.  A total of 17,248 photovoltaic solar cells lined the top of the wings and fuselage, lightened by amazing new technologies that reduced the cells to no thicker than a human hair, so as to save weight.  The plane’s empty weight, with the batteries, was just 5,070 pounds (2,300 kg).

Yet aerodynamic efficiency was such that the four engines could fly the plane perfectly — despite that together, the engines only produced a whopping total of 17.4 hp (13.5 kW).  Even with such limited power, the plane could fly as high as 28,000 feet (8,500 meters).  Often, they flew at less than 12,000 feet since the cockpit was unheated and unpressurized.  The pilot had just 3.8 cubic meters of living space, barely suitable for flights that could last days at a time.

Flight Operations

A team through and through, Bertrand Piccard shared the flying responsibilities with pilot André Borschberg, who traded off various legs of the journey.  Hundreds of others were involved in the development of the plane and over the years of the mission.

When the plane was flying, a team of dozens of engineers worked around the clock from mission control in Monaco to monitor the systems, manage the energy use, and take care of the pilot.  An autopilot system kept the plane on course while the pilot slept and inputs from the ground controlled the systems.  Top speeds were often just 25 knots — to cross the Atlantic Ocean from New York to Spain required a non-stop flight of over three days.

Ground Control and Handling

Ground handling could require up to 20 people, including those who peddled bikes behind the plane on landing to come in and grab the pylons mounted under the wings and fuselage to prevent damage as it slowed to a stop.  Guiding the plane into the hangar after each landing was an effort at manhandling it.

Another roughly 50 people supported other aspects of the flight, spanning the globe and covering everything from communications, maintenance, coordination and planning, systems monitoring, and the pilot’s health and condition.

The Route of Flight

The flight departed in April 2015 from Abu Dhabi in the UAE and returne 15 months later to the same point — arriving over the night of July 25/26, 2016.

The 17 legs of the journey were defined with stops at the following airfields:

  • Abu Dhabi, UAE
  • Muscat, Oman
  • Ahmedabad, India
  • Varanasi, India
  • Mandalay, Myanmar
  • Chongqing, China
  • Nanjing, China
  • Nagoya, Japan (unplanned)
  • Hawaii, USA
  • San Franscisco, California, USA
  • Phoenix, Arizona, USA
  • Tulsa, Oklahoma, USA
  • Dayton, Ohio, USA
  • Lehigh Valley, Pennsylvania, USA
  • New York, New York, USA
  • Seville, Spain
  • Cairo, Egypt
  • and finally, back to Abu Dhabi, UAE

Costs and Partners

The cost of the dream?  Just $170 million dollars — all of it raised from sponsorship and donations.  Many companies and entities contributed, such as ABB, Solvay, OMEGA, Schindler, Google, MoëtHennessy, Dassault, SunPower, Swisscom, Altran, Convestro, the EPFL, the European Space Agency and even the Government of Switzerland, among many others.  Many private individuals joined the effort as well, including Peter Diamandis, Chairman and CEO of the X Prize Foundation.

For the plane’s sponsors, the mission not only provided a welcome opportunity to engage in public relations, but also to develop new technologies that will ultimately make electric flight and solar-powered flight a practical, everyday reality.  The companies involved pioneered new ideas in solar energy and ever greater efficiency.  For instance, the specially-developed ABB engines operated at 97% efficiency — which compares favorably with the efficiency of jet engines, which are perhaps only 35% efficient.

Challenges and Setbacks

The flight was not predictable nor easy.  There were setbacks along the way.  Weather was always a key factor.  The plane was so lightweight and highly engineered that temperatures, turbulence, winds and weather were great hazards — a violent updraft could easily have snapped the plane in half.

Unsuitable atmospheric conditions kept the plane on the ground in China for many months, while the team sat frustrated waiting for a window of opportunity to make the long flight to Hawaii.  When it did come, it proved to be an illusion.

With deteriorating weather that developed after takeoff, the flight from China to Hawaii had to turn and make an unplanned emergency landing in Japan.  Even once the plane was on the ground, heavy rains and wind moved in.  The ground team, which had scrambled to race to Nagoya to meet the plane, quickly assembled the purpose-built inflatable hangar.  Despite that, the plane’s propellers were still damaged by the winds through the hangar walls.  That leg of the flight was a success nonetheless, covering 2,614.5 km over 44:10 hours of time and setting three new world records over the two days and two nights of flying.

Finally, when the plane left Japan, it suffered yet another setback.  A thermal overheating problem resulted in having to change the batteries in the plane while it was in Hawaii.  This resulting in yet another delay from July 2015 to April 2016 while the work was done.

From there, it was smooth flying.  Yet every flight was an adventure.  Even the final leg coming back to Abu Dhabi would test the limits of the team and airplane.  Conditions required that the team pioneer new ways of withstanding temperature ranges that were 5 degrees C higher than the aircraft’s design limits.  They did it, despite the reduced performance of batteries at those temperature ranges.

Even then, the plane’s final flight was, like every flight before it, still yet another test flight, made successful by the hard work of hundreds of members of the team that backed the plane’s journey.

In the end, the flight was successful, landing in Abu Dhabi, in the early morning hours of July 26, 2016. From dream to reality was just 17 years — a lifetime achievement that will never fade.

Looking Ahead

Ultimately, pioneering like that seen in Solar Impulse comes down to people.  Mankind is not advanced by any singular technology or any lone individual.  It takes a team of pioneers and dreamers to work together to engage in any pioneering mission. Where the dream starts with one, it ends with many — and for the benefit of all mankind.

Like the Wright Brothers and countless pioneers in aviation history who have come before, Solar Impulse has made its mark — thanks to those who had faith in the effort and in what it meant for the future.

Today, Solar Impulse represents a new and promising future of aviation.  A lot of work is yet to come, but future generations will look back on this moment and recognize that the next generation of flight started right here — with the big dream of one man.

All photos in this feature story were provided by Solar Impulse and are copyrighted by them.

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