Maple Seeds and Animals Exploit the Same Trick To Fly (via ScienceDaily)
The twirling seeds of maple trees spin like miniature helicopters as they fall to the ground. Because the seeds descend slowly as they swirl, they can be carried aloft by the wind and dispersed over great distances. Just how the seeds manage to fall so slowly, however, has mystified scientists.
In research published in the journal Science, researchers from Wageningen University in the Netherlands and the California Institute of Technology (Caltech) describe the aerodynamic secret of the enchanting swirling seeds.
The research, led by David Lentink, an assistant professor at Wageningen, and Michael H. Dickinson, the Zarem Professor of Bioengineering at Caltech, revealed that, by swirling, maple seeds generate a tornado-like vortex that sits atop the front leading edge of the seed as they spin slowly to the ground. This leading-edge vortex lowers the air pressure over the upper surface of the maple seed, effectively sucking the wing upward to oppose gravity, giving it a boost. The vortex doubles the lift generated by the seeds compared to nonswirling seeds.
This use of a leading-edge vortex to increase lift is remarkably similar to the trick employed by insects, bats, and hummingbirds when they sweep their wings back and forth to hover. The finding means that plants and animals have converged evolutionarily on an identical aerodynamic solution for improving their flight performance.
