The changing natural world at our doorsteps | Illustration and text by Patterson Clark
April 27, 2010
Maple samaras fly with one wing
In late April, the ground becomes littered with samaras, the winged seeds of maple trees.
With the right wind, the single-winged "whirlybirds" can carry the tree's embryos more than a mile.
From David Lentink
Two revolutions of a twirling maple samara, illuminated by a strobe light.
As illustrated at right, the leading edge of the seed's wing creates a horizontal tornado-like vortex above the wing surface. This creates a low-pressure area that sucks the wing upward. The mechanism was first described in 2009 by a team of scientists led by David Lentink at Wageningen University in the Netherlands.
Watch a slow-motion video of the phenomenon.
The RoboSeed Nano, right, is a micro-aircraft inspired by the devil maple samara. With a wing about three inches long, the tiny flier weighs less than two nickels do. A propeller spins the flyer around at 10 to 16 revolutions per second. In flight, the RoboSeed is much more stable and easier to control than are micro-helicopters.
Evan Ulrich has been developing the aircraft since 2006, a year after he began graduate studies at University of Maryland's Aerospace Engineering Department.
(Aircraft image from roboseed.com.)
SOURCES: Evan Ulrich; David Lentink, "Leading-edge vortices elevate lift of autorotating plant seeds," Science, 2009
Watch a video detailing the development of the aircraft pictured above.