Drone On A Leash:  Orion 2 Tethered Mini-Drones Can Fly 24-Hour Shifts Small drones tethered to ground-based power stations offer theoretically limitless endurance-but risk overheating and vibration damage after many hours of flight. Now French company Elistair claims to have made a breakthrough: its Orion 2 drone can reliably remain aloft a full 24 hours.