Hummingbirds outperform advanced micro-helicopter

Scientists have found that the hovering capacity of hummingbirds is 20 per cent more efficient than one of the world's most advanced micro-helicopters.
Researchers found that in terms of the power they require to lift their weight the best hummingbird was over 20 per cent more efficient than the helicopter.
The "average Joe" hummingbird, however, was on par with the helicopter, showing "how far flight engineering has come", scientists said.
Lead researcher Professor David Lentink, from Stanford University in California, explained that the flight performance of a hummingbird - the only bird capable of sustained hovering - was extremely difficult to measure.

The drag of a hummingbird wing has never been measured accurately, researchers said.
Drag is the force opposing the upward force of lift that birds' wings generate by flapping.

Lentink and his team set out to determine if feathered hummingbird wings were more efficient - using less power to overcome drag - than the engineered blades of a helicopter of a similarly tiny scale.
He and his colleagues compared the birds' performance to an advanced micro-drone called the Black Hornet - a 16g helicopter used for surveillance by British troops in Afghanistan, 'BBC News' reported.
To make the laboratory measurements, they used wings from hummingbird specimens kept in museums.

The team was able to measure how much flapping power was required to lift the bird's weight by putting these detached wings into an apparatus called a wing spinner.
Lentink's colleagues at the University of British Columbia in Canada also made recordings of wild hummingbirds in flight, to measure the exact movement of their wings - which beat up to 80 times per second.
"By combining the wings' motion with the drag [that we measured in the lab], we were able to calculate the aerodynamic power hummingbird muscles need to provide to sustain hover," said Lentink.
One species - the Anna's hummingbird - was champion hoverer, performing much more efficiently than the helicopter. But on average, the birds hovering performance was "on par with the helicopter".

"This shows that if we design the wings well, we can build drones that hover as efficiently, if not more efficiently, as hummingbirds," said Lentink.
The findings are published in the Royal Society journal Interface.