Taking flight. With a 385 ft wing-span, Stratolaunch is the largest plane in the world, but, until last Saturday, it had never taken flight. The brainchild of the late Paul Allen (he helped found Microsoft with Bill Gates), Stratolaunch soared effortlessly at 189 mph over the Mojave Desert. Eventually, the unusual-looking aircraft will soar to 35,000 ft as a sort of flying launchpad for satellite-bearing rocket ships. Allen would be proud.