This Drone On A Leash Could Guard Army Bases

Small drones are inefficient birds. They fly for short bursts of time, and get thrown about in the wind. That's not great for anyone hoping to use a drone as a hovering sentry, but there's a better way: tethers. Put a leash on a drone, and suddenly it's a flexible flying watchdog, able to peek up high and then recharge safely in its mechanical nest. This is Aerovironment's Tether Eye, a quadcopter promising 24 hour surveillance from a height of 150 feet, all in one tidy box.