August 05, 2014

Hummingbirds Outperform Tiny Helicopters


When it comes to flight, nothing can outdo Mother Nature, according to a new study, not even human engineers. When pitting hummingbirds against one of the world's most advanced micro-helicopters, researchers found that the birds' hovering capacity was 20 percent more efficient in comparison.


However, the "average Joe" or typical hummingbird was on par with the helicopter, showing "how far flight engineering has come."

The findings are published in the Royal Society journal Interface.

Researchers from Stanford University, Wageningen University, Eindhoven University of Technology, and the University of British Columbia studied the wings from hummingbird specimens stored in museums, looking for insight into how the blades of a tiny drone could fare against a hummingbird's wings.

They compared a 16-gram Black Hornet Nano Drone used for surveillance by the British army with 4-gram hummingbirds, the only bird capable of sustained hovering. Specifically, engineers focused on efficiency versus drag - the force opposing the upward force created when the birds flap their wings.


"Imagine a 4-gram bird," lead researcher Professor David Lentink, from Stanford University in California, told BBC News. "The forces they generate are tiny. As a result the drag of a hummingbird wing has never been measured accurately."

Researchers took the detached wings of the hummingbird specimens and put them into an apparatus called a wing spinner, using it to measure exactly how much flapping power was required to lift the bird's weight. In addition, they also used slow-motion recordings of the bird to measure the precise movement of their wings.

While the Anna's hummingbird species topped all others at 20 percent efficiency - meaning it required the least amount of power to hover midair - most hummingbirds performed around the same level of efficiency as the Black Hornet.

"This shows that if we design the wings well, we can build drones that hover as efficiently, if not more efficiently, as hummingbirds," Lentink told BBC.


"Clearly we are not even close to hummingbirds in many other design metrics, such as wind gust tolerance, visual flight control through clutter, to name a few. 

But if we focus on aerodynamic efficiency, we are closer than we perhaps ever imagined possible."

By Jenna Iacurci

With thanks to NWN