Today is a historic day in aviation. Swiss businessman and pilot André Borschberg landed in Hawaii, USA after flying the Solar Impulse 2 plane for more than 4 days, continuously, from Nagoya, Japan. This flight has proven that fully solar powered aircraft can have infinite endurance (fly forever).
The Solar Impulse project is a Swiss one, with the intention of proving that long-range flight using solar powered aircraft is feasible. The project is privately funded and headed by André Borschberg and Bertrand Piccard. There were two experimental planes built, the Solar Impulse 1 (Si1) which conducted its first flight in 2009 and flew between multiple countries, and the Solar Impulse 2 (Si2) with a goal of circumnavigating the globe. Si2 started its flight on March of 2015 from Abu Dhabi in the United Arab Emirates, and has flown through Oman, India, Myanmar, China, and Japan finally landing today in Hawaii. There are still more flights scheduled for the US and south of Europe then finally back to Abu Dhabi.
Si2 is a revolutionary airplane, it is completely solar powered and can fly all over the globe. It was built to fly longer than any other plane ever made, that is why the engineers working the project had to rethink many technologies in aviation. The cockpit is designed to be highly ergonomic, to allow for piloting the airplane, sleeping, and relaxing since flights aboard Si2 can be days long. I am astounded by the wingspan of Si2; at 71.9 m (236 ft) it is on par with the Airbus A380, and wider than that of the Boeing 747. But, Si2 weighs 2.3 tonnes as compared to the A380 which is about 500 tonnes in weight. That is all thanks to advances in carbon-fiber composite technology. The entire planform area of the airplane is fitted with 17000 solar cells to collect 340 kWh of solar energy per day, this energy is stored in lithium polymer batteries that make up over a quarter of the airplane’s weight. These batteries power 4 burshless, sensorless, motors that generate 17.4 hp each.
I have been following the flight of Si2 on and off from March of this year, but recently I have been glued to solarimpulse.com since they have a very cool website that relays all telemetry and other data regarding the flight in real time. The latest flight, which was almost 5 days long over the Pacific ocean, captured me. As if the idea of one man, with the help of his team on ground, flying continuously for 5 days over the ocean was not amazing itself, André Borschberg was doing it only using solar power! I don’t know about you, but for me as an engineer this feels like a great achievement and victory for the human race. This is unquestionable proof that clean energy technology has gotten to the point where it is highly feasible for practically remarkable things. And it is not just thanks to one technology, but advances in solar panes, batteries, materials, electronics, and many other technologies are what allow for such a magnificent achievement. With this clear evidence, it is time for us to move towards energy sources that will allow us to have a clean future.
Yes the max speed of Si2 is 140 km/h, and it might not currently be the best solution to long-distance travel. But there are so many other applications in aviation that can operate in a similar fashion, leaving no footprint what so ever in adverse effect to the environment. And the same logic of technology advancement applies here; the work done in technical areas that allowed Si2 to set on its great journey needs to be continuously supported by governments and individuals for us to have a clean future.