"Maple tree seeds (or samara fruit) and the spiraling pattern in which they glide to the ground have delighted children for ages and perplexed engineers for decades. Now aerospace engineering graduate students at the University of Maryland's Clark School of Engineering have learned how to apply the seeds' unique design to devices that can hover and perform surveillance in defense and emergency situations."
Students at the University of Maryland's Clark School Aerospace Engineering have solved the instability issues that have prevented successful development of unmanned aerial vehicles inspired by the flight of maple seeds. The hand-sized monocopter can "take off from the ground and hover, as well as perform controlled flight after its initial fall to the ground after being deployed from an aircraft. The device can also begin to hover during its initial descent, or after being launched by hand."
While the maple seed trades off altitude for rotation, the monocopter needs to ascent and hover. The key insight was separating stability and propulsion. The former is provided by a samara-like wing while propulsion is provided by a new curved component of the monocopter that maintains rotation.
The site includes a video clip of the monocopter in action.
Thanks to Micro-vehicle Imitates the Winged Maple Seed (Technology Review) for the pointer.