Researchers at ETH, Zurich, have been developing a distributed flight system comprising of hexagonal shaped single propellor robot units. Individually, each is unstable in flight. However by attaching themselves to each other in a myriad of configurations, the robots begin communicating and coordinating with each other in order to generate the appropriate amount of thrust, and thus result in level flight.

[image: ETH]

Update: Detailed write up at robohub by Raymond Oung, one of the developers.

[via ETH via hackaday]