Naturally, if you’re [Daniel Riley] of RCTestFlight, then you have to 3D print a few of them, and make a video covering a handful. Most famous of these is probably the toroidal propeller that ...

[PDF via NewAtlas] Inspired by some of the experiments with “ring wings” in the early 20th Century, researchers iterated on various toroidal propeller ... fabricated via 3D printing they ...