On Jan 9, China's first ton-class liquid hydrogen-powered vertical takeoff and landing (VTOL) drone completed its maiden test flight in Baoji, Shaanxi province. [Photo by Wang Peipei/For ...

that of carrying people and cargo from place to place in vertical take-off and landing aircraft (VTOL). It's not at all hard, though, to keep track of the ones that are in an advanced stage of ...