helicopter cyclorotor mechanical principles propeller rotor Present quad cyclocopter Mechanism

 https://en.wikipedia.org/wiki/Cyclorotor

https://www.researchgate.net/figure/Present-quad-cyclocopter_fig1_301680815 

https://hackaday.com/2021/08/06/cyclocopter-flies-with-eight-spinning-horizontal-wings/

Development of a 100-gram Micro-Cyclocopter Capable of Autonomous Hover

Capable  Autonomous Hover Drones Autonomous Flight in Hover and Near-Hover for Thrust-Controlled Unmanned Airships 

https://www.suasnews.com/2012/02/hovermast-sky-sapience%E2%80%99s-autonomous-hovering-platform-makes-its-debut/

https://en.wikipedia.org/wiki/Unmanned_aerial_vehicle