Flying Green with Solar Impulse

Early on the morning of May 2nd 2013, an airplane took off from an airport outside of San Fransisco, California for a flight to Phoenix, Arizona. Onboard the flight was one pilot and not a single drop of fuel. It was the milestone first leg of a planned trans-continental flight powered only by the energy of the sun in an airplane called Solar Impulse.

Check out all those landing lights!

Image © Solar Impulse | Revillard |

I have always been interested in things that are powered by alternative fuels and other 'green' sources of energy, and especially when it is used as a mode of transportation. So when I first heard that there was an airplane that would be travelling across the country powered only by the sun, I wanted to know more. The first Solar Impulse aircraft, carrying registration HB-SIA is a 4 propeller, carbon fiber creation with a wingspan as wide as a Boeing 747. Despite its seemingly large size, it weighs under 3,600 pounds. The upper surfaces of each wing are loaded with solar panels to provide all of the energy that the aircraft will need, while buried inside are roughly 800 pounds worth of batteries to provide power after the sun sets. You read that right, this solar powered plane is capable of flying at night. In fact, on the first leg, departure from Moffett Federal Airfield outside of San Francisco was just after 6:00 am while arrival into Phoenix wasn't until almost midnight.

This year's cross-country journey is just one step in a several years long project. Originally conceived in 1999, more than a decade was spent examining feasibility, securing funding, and in the design and construction of the plane.  In 2010, Solar Impulse began a series of test flights which included a marathon 26 hour continuous flight as a proof of concept during which 3 world records were set.  The summer of 2011 saw the first international flights from Switzerland to Brussels and then to the Paris International Air Show.

Solar Impulse 2012 Flight Route

The Spring of 2012 saw the first intercontinental flight of Solar Impulse.  Over the course of 2 months from May 24th to July 24th the aircraft flew from Payerne, Switzerland to Ouarzazate, Morocco and back.  The trip took nearly 182 hours to complete, over a span of 17 flights including several that had to return to their origin due to headwinds enroute that were too strong.  While in the process of completing the first leg of this intercontinental flight, the team set 2 world records for flight by an experimental solar-powered airplane, bringing the total number of records held to 5.  

Map of planned 2013 flight across North America.

Map of planned 2013 flight across North America.

That brings us to this year and the planned trans-continental flight across North America. To begin the journey, the aircraft was disassembled before being loaded onto a Boeing 747-400 Freighter operated by Cargolux.  After arriving at Moffett on February 21st of this year, HB-SIA was reassembled over a period of weeks before undergoing a series of test flights during the month of April.  Then came the start of the cross-country journey on May 3rd. Now, with the San Fransisco-Phoenix leg completed, the coming weeks will see flights onward to Dallas,TX, St. Louis, Mo, and Washington D.C, before ending the journey at New York's John F. Kennedy International Airport This journey is expected to take a few months, as there are long stopovers planned in each city visited for both technical reasons and to allow the public to get up close to this revolutionary piece of green aviation technology.  Arrival at JFK in New York is currently targeted for some time in early July. You can bet that we will be there for its arrival and to get an up close look.

So what's next for Solar Impulse? In 2011, construction began on a new, larger aircraft known as HB-SIB, which is breaking new ground in the technologies, materials and assembly techniques used.  Construction continues to move along today with the wing spar, a major structural component, just having been delivered yesterday.  The goals for that airplane currently include test flights to begin next year with an around-the-world journey currently planned for 2015.  That journey is planned to have flight segments several days long, allowing the aircraft to cross vast expanses of ocean non-stop.  Among the improvements being made in HB-SIB is an expanded crew cabin to allow the pilot to recline while they rest on a multiple day flight.  It should be very interesting to watch what the the Solar Impulse team can accomplish over the next few years and beyond.

Solar Impulse photos courtesy Solar Impulse. Maps courtesy Great Circle Mapper.