https://tech.slashdot.org/story/16/0...-of-world-tour



"Solar Impulse flies without a drop of fuel, its four engines powered solely by energy collected from more than 17,000 solar cells in its wings. It relies on solar energy collected during the day and stored in batteries for electrical energy to fly at night. The carbon fiber plane, with a wingspan exceeding that of a Boeing 747 and the weight of a family car can climb to about 8,500 meters (28,000 feet) and cruise at 55-100 kph (34-62 mph)."

I had an opportunity to visit in during a stop, and then to come out in the night to watch it depart. It was fascinating, not the least in the use of four 18 horsepower electric engines.

As for not using a drop of fuel, the aircraft had a support team of 60 people following it around the world. The team used computers and equipment run by generators cooling units for the batteries during ground stops, burning a fairly large amount of diesel. The support team travelled on one and two aircraft, including an IL-76, around the world. While the Solar Impulse didn't technically burn petro fuels on it's flight, the effort certainly did.

Some very long legs, very slow going, and an impressive feat, as well as work of engineering in construction and application. I can't imagine operating that aircraft for those long legs on the oceanic segments, as they did. Well done.

Kind of funny how it is never presented this way and the general public now probably think electric passenger planes are only a couple years away. It was an amazing accomplishment, but had they used fossil fuels in the airplane to begin with much less fossil fuel would have been used (or corn gas).