Discussed yesterday: Toroidal propeller allows a drone to operate more quietly (ll.mit.edu) https://news.ycombinator.com/item?id=34571569 https://news.ycombin

Discussed yesterday: Toroidal propeller allows a drone to operate more quietly (ll.mit.edu) https://news.ycombinator.com/item?id=34571569 https://news.ycombinator.com/item?id=34571569 (98 comments)