AeroVironment Global Observer

The AeroVironment Global Observer is a high altitude long endurance unmanned aircraft concept designed to act as a regional stratospheric satellite. Two aircraft flying at 55,000 to 65,000 feet could alternate over an area, relaying communications or watching the ground for up to a week at a time from above the weather. It had a wingspan of about 53 metres and was to burn liquid hydrogen in an engine driving four electric motors. A smaller prototype called Odyssey flew in 2005 on hydrogen fuel cells, and the full size aircraft first flew on 5 August 2010 and on hydrogen in January 2011. The first aircraft crashed in April 2011 and the Pentagon closed the development contract in December 2012.