Scientists at Stanford University now reveal that a recent quantitative analysis of hummingbirds shows that they generate lift more efficiently than even the best of microhelicopters. Could these findings actually lead to more futuristic robot flying vehicles inspired by the tiny bird itself?
It has taken 42 million years for the hummingbird to get where it is today. Humans have developed helicopters in a much shorter time span. Still, evolution may have something to teach science and mechanical engineers at Stanford University may be taking a page from the efficiency of the hummingbird itself.
A new study by David Lentink, an assistant professor of mechanical engineering at Stanford University, shows that the blades of new microhelicopters are almost as efficient as those of hummingbirds. Almost, but not quite.
Prox Dynamics Black Hornet
The experiment took samples from 12 different species of hummingbirds. The study measured airflow, drag and lift force at different speeds and angles. Lentink then compared the findings with those of the best of microhelicopters, like the ProxDynamics Black Hornet, which by the way is just about the same size of the average hummingbird.
The study showed that even if a hummingbird could spin its wings rather than flap them, it would still run twice as efficient as even the best of microhelicopters. While the Black Hornet was able to keep pace with the average hummingbird, the best of the species still ran 27 percent more efficient than the man-made substitute.
While the hummingbird did come out on top, still Lentink was impressed with the helicopter.
“The technology is at the level of an average Joe hummingbird,” Lentink said. “A helicopter is really the most efficient hovering device that we can build. The best hummingbirds are still better, but I think it’s amazing that we’re getting closer. It’s not easy to match their performance, but if we build better wings with better shapes, we might approximate hummingbirds.”
The experiment was also a great opportunity to revisit the issue of muscle power. A hummingbird’s muscles producing an amazing 130 watts of energy per just one kilogram. The average for other birds is just 100.
While the study did reveal how a hummingbird can maintain flight without actually moving any distance at all, it was not able to tell researchers how they can maintain constant speeds even in high gusts of wind. How they navigate through dense forest and change direction so quickly is also still anyone’s guess.
Lentink also believes studying hummingbirds can give researchers great insight into the importance of wing-span ratio. While the aspect ratio of most human-made aviation vehicles remains at 4.7, the ratio for a hummingbird is just 3.9.
“I want to understand if aspect ratio is special and whether the amount of variation has an effect on performance,” Lentink said. “Understanding and replicating these abilities and characteristics could be a boon for robotics and will be the focus of future experiments.”
Check out this remarkable video of the Black Hornet in action
…original content by PPE
Sources: The Royal Society