A solar-powered aircraft has this week been plying the skies around Moffett Field in San Francisco, California, as its inventors rehearse for their next ambitious move: a coast-to-coast sunshine-fuelled flight across the US.
Since 2006, Solar Impulse has been gradually ramping up the capabilities of its solar-powered, single-seat aircraft with a number of hops around Europe and Africa. The latest design of the 80-metre-wingspan plane, which has 12,000 photovoltaic cells peppered all over its wings and tailplane, charges batteries that power four electric motors.
It manages a speed of just 64 kilometres per hour so, although it can stay aloft for 36 hours, it cannot manage the coast-to-coast trip in one hop. It will stop over a number of times: at Phoenix, Arizona; at Dallas, Texas; at St Louis, Missouri (or Atlanta, Georgia); and at Washington DC en route to New York City.
That number of stops might make the flight sound easy – but past aviation greats have had stopovers too. Before the pioneer Charles Lindbergh flew from New York to Paris in his single-engine propeller plane Spirit of St Louis in May 1927, he checked out his new aircraft and engine with a coast-to-coast flight across the US from San Diego, California, where it was built, with a refuelling stopover in the city where his sponsors were based, St Louis.
Solar Impulse came out of a feasibility study at the Swiss Federal Institute of Technology in Lausanne in 2003, which suggested a round-the-world trip by solar airplane would become possible as solar cell power efficiency improved. The idea is not to suggest that aviation should switch to solar power, but rather to use the aircraft as a mobile showcase for solar cell efficiency.
Weather permitting, the coast-to-coast attempt should depart from Moffett Field on 1 May – with the round-the-world attempt slated for 2015.
(Image: J. Revillard/Solar Impuse)
Syndicated content: Paul Marks, New Scientist