#70 Mini Helicopter

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 [1] the biological world for inspiration to build a scaled-down helicopter that could mimic the properties of full-size aircraft. The complex [2] 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 realized 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 [3] them to it. The seeds of trees such as the maple have a single-blade structure that [4] them to fly far away and drift safely to the ground. These seeds, known as samaras, need no engine to [5] through the air, thanks to a process called autorotation. By analyzing the behavior of the samara with high-speed cameras, Ulrich and his team were able to copy its design.