German test pilot Markus Scherdel steers the solar-powered Solar Impulse HB-SIA prototype airplane during his first flight over Payerne April 7, 2010. The propeller plane, with a 61 metres (200 feet) wingspan, is powered by four electric motors and designed to fly day and night by saving surplus energy from its 12,000 solar cells in high-performance batteries.  Wednesday's flight follows six years' work by 50 engineers and technicians led by Swiss adventurer Bertrand Piccard on the so-called Solar Impulse project. REUTERS