A mini helicopter modelled on flying tree seeds could soon be flying overhead. Evan Ulrich and colleagues at the University of Maryland in College Park turned to the biological world for inspiration to build a scaled-down helicopter that could mimic the properties of full-size aircraft.

Video: Maple seed helicopter

The complex design of full-size helicopters gets less efficient when shrunk, meaning that standard mini helicopters expend most of their power simply fighting to stay stable in the air. The researchers realised that a simpler aircraft designed to stay stable passively would use much less power and reduce manufacturing costs to boot.

It turns out that nature had beaten them to it. The seeds of trees such as the maple have a single-blade structure that allows them to fly far away and drift safely to the ground. These seeds, known as samaras, need no engine to spin through the air, thanks to a process called autorotation. By analysing the behaviour of the samara with high-speed cameras, Ulrich and his team were able to copy its design.

More of the story,
click image