CyPhy Wants to Set Drones Free by Tying Them to the Ground

The whole idea behind drones is that they fly free. Unattached to the traffic-clogged, obstacle-riddled surface, they promise to change the way we move our stuff and even ourselves. So it's strange to hear that one startup thinks the best way to fly drones is by tying them to the ground. In that tether, CyPhy Works sees a different sort of liberty: freedom from short-lived batteries. The typical commercial drone can stay aloft for 20 to 30 minutes.