When it's cold and humid, airplanes and huge wind turbines have the same problem -- they accumulate snow and ice, which disturbs the airflow over the wings or blades. On wind turbines, that accumulation can hamper the turbine's ability to produce electrical power and even stop the blades from turning. A Latvian firm, Aerones, has come up with a tethered industrial drone that is used to de-ice wind turbines, and this video shows how it's done:
The drone some 36 propellors (32 for lift, and four providing additional yaw control) and has two tether lines -- one of which supplies water that can spray at up to 100 liters per minute, and an electrical tether. This means that the drone can stay up as long as it needs to for cleaning tasks.
It's much safer than sending a crew up in a cherry picker, faster, and according to Aerones CEO Janis Putrams, the entire cleaning process could be done autonomously. The company believes that the tethered drones it produces have other applications including firefighting, human rescue, and sports applications -- can you imagine a 4K camera drone sitting in one spot for hours capturing a sports match?