Cleo is a donut-shaped drone with a single propellor in the center, which steers by changing the airflow direction, so its blades are entirely contained – and can’t be easily broken when the drone collides with something.
A IEEE notes:
It’s immediately obvious just how friendly this design is. It fits in a pocket without needing to be disassembled or folded, and there’s nothing externally fragile that you have to protect. It’s safe to hold, and so grabbable that you can snatch it right out of the air. Collisions with obstacles (including people) shouldn’t damage either the drone or whatever it runs into, and with all of the moving parts so well protected, it seems like it has to be much more durable than anything with exposed rotors.
As for me, though, when I saw it I had an instant acid flashback to … the Avrocar.
Fans of Canadian aerospace arcana will be familiar with the Avrocar. It was the invention of Avro Canada, a Canadian aerospace firm that flourished in the 40s and 50s by producing aircraft for military and commercial use. In the late 50s they began working for the US military on a disk-shaped flying craft that would hover in the air by venting exhaust out the bottom and sides. But the engineers could never figure out how to make it stable enough to fly more than a few feet above the ground, so the project was cancelled in 1961, and Avro itself soon collapsed.
The Avrocar is a fave of UFO military-conspiracy theorists, as you might expect. You can see the craft in action in this video – it’s thoroughly bonkers:
from Boing Boing https://boingboing.net/2018/02/15/donut-shaped-drone-that-isnt.html