The "propellers" more or less look like the cylindrical drum in a standard push lawn mower with blades on it[1], but instead of blades it has fins. The drums co

The "propellers" more or less look like the cylindrical drum in a standard push lawn mower with blades on it[1], but instead of blades it has fins. The drums counter-rotated against each other, generating lift. Highlights of the engine design (from the article): * It is near silent * Low/Easy maintenance because of simple design. * Can carry a heavy load * Extremely agile (hover/fly/land/maneuver) * No expensive engine to produce Seems like all thumbs up stuff here, very interesting read. I think the biggest indicator to me that this would work is how simple the design is. Another cool highlight from the article: The forces on the blade pivots are understandably huge, and in initial testing it was found that all available bearings failed, so inventor Meinhard Schwaiger, who already has more than 150 patents to his name, knuckled down and invented (and patented) his own, near- frictionless swivel-bearing to cope with the stresses. [1] http://images.gizmag.com/gallery_lrg/d-dalus-revolutionary-uav-design-1.jpg http://images.gizmag.com/gallery_lrg/d-dalus-revolutionary-u...