We recently reported on the historic flight of the Solar Impulse, the first solar-powered plane to fly through the night. Now another barrier has been broken. The Zephyr solar plane has flown nonstop for seven days.
Unlike the Solar Impulse, which carried a pilot, the Zephyr is an unmanned drone built by the UK defense firm Qinetiq. Drones have seen extensive service in Afghanistan and Iraq in recent years but are hampered by the need to return for refueling and thus losing sight of targets. Drones that never need to land have an obvious advantage. The civilian potential is obvious too, with researchers already thinking up applications for using them for scientific observation.
This development also marks another step forward for potential solar-powered commercial flight. The Zephyr has solar cells along its 22.5 meter (74 ft) wingspan that drive the propellers and fill batteries that are robust enough to power the plane from sunset to sunrise. Will we one day see solar-powered commercial flights? It may be a long way off, but considering the rapid pace of technological change, it’s unwise to say that anything is impossible.
The Zephyr is still in the air near the US Army’s Yuma Proving Ground in Arizona and its support team plans to leave it flying for another week.