Two veteran Swiss pilots are at nearly the midpoint of a round-the-world flight on the Solar Impulse 2, a solar-powered plane with a wingspan greater than a 747’s. Among other reasons for the huge wingspan is to make possible use of 17,000 solar cells that recharge the batteries that run the plane’s four engines.
They’ve so far flown, in six hops, from Abu Dhabi to Nanjing, in eastern China. The next, and longest flight, could take off as early as Thursday, from Nanjing to Hawaii. The first hops had a maximum of 20 hours in the air; this one will be 120 hours, with the pilot napping at intervals with instruments to wake him if anything out of the ordinary happens.
To keep the batteries charged, the plane flies at around 27,000 feet in the daytime for maximum charge, and then drops to around 3000 feet for the night. The plane has made a number of successful flights in the U.S. and Europe before; the RTW flight is the next step in showing a possible path to the future.
Photo: solarimpulse.com
