Drone with ion engines
The company "Technologies of Undefined" posted a video of a flight of prototype experimental drone with ion propulsion. Similar technologies have been used in space, and from the last decade without success, trying to adapt to fly in the atmosphere. Undefined stated goal is to 2024 to create a drone that can stay in the air for at least 15 minutes, thus creating noise less than 70 dB.
The principle of operation of ion thruster in this Dhron is to use a set of electrodes to create an electric field with a lot of stress. This allows you to ionize the air, releasing electrons from the molecules of nitrogen and oxygen, to guide them down to the ground. Created "ion wind", which lifts the machine upwards.
Silent Ventus
Alas, the shortcomings of the project is much greater than the benefits. First, it stated "quiet" yet to be achieved. Second, the duration of the flight while at times less than required. Thirdly, it is not clear how this design maneuvering, and how it will behave in the wind and bad weather. Fourth, there is no information about the payload. The drone Undefined looks too bulky and clumsy on the background of the commercial multicopter, and therefore its application in the urban environment also raises questions. It is possible that this "childhood diseases" and by the deadline or slightly later, the drone technology with ion engine will be modified and will be truly practical.