We haven't had an air travel post for a little while, so thought we'd go with a blast from the past to fill the void. NASA used to fly the Helios uninhabited aerial vehicle (UAV) (Just you just love TLAs?) about the place, until they lost it a few years ago in an "in-flight mishap." The 247-foot wingspan (greater than a 747 Jumbo Jet) were made of carbon fiber, graphite epoxy, Kevlar and other lightweight materials. 62,000 solar cells on the upper surface of the wing powered 14 brushless direct-current electric motors, which in turn spun lightweight two-blade propellers. This combination gave the the Helios a cruising speed in the range of 19 to 27 mph, "with takeoff and landing equating to the average speed of a bicycle", which is kinda fun because the landing gear was indeed mountain bike wheels! During its experimental flights the Helios managed "an unofficial world-record altitude of 96,863 feet and sustaining flight above 96,000 feet for more than 40 minutes." The idea was that such craft could be used for stuff like atmospheric sampling, imaging for agriculture and natural resources monitoring and suchlike. ::NASA Helios.