ScienceTake | Bird in the Wind
ScienceTake | Bird in the Wind
Hummingbirds have a remarkable ability to hover in the midst of turbulence.
Big airplanes can power through turbulence, but for smaller planes like drones, shifting winds and air currents can cause more than discomfort. And hovering is particularly complicated.
That’s a problem that the has had to solve. The birds live on such a tight energy budget that they cannot afford to miss meals, so they must be able to hover, with their heads steady, while they feed on nectar, even in tough conditions.
They do it with a combination of wing and tail movements, according to Australian and American scientists who tested the birds in a wind tunnel with both a steady breeze and one that varied in intensity as much as 15 percent. Small drones can handle only about a 7 percent variation.
, a research fellow at RMIT University in Melbourne, Australia; at Harvard; and their colleagues used high-speed video to record how the birds managed turbulence in a wind tunnel.
The unscientific answer, as Dr. Ravi described it and the clearly shows, is that “the body is going crazy and the head is just incredibly stable.”
More precisely, as the in The Journal of Experimental Biology, the birds use their wings and tails to constantly correct for changing winds.
They change the position and motion of each wing independently as those wings beat 40 times a second. And they do it in the space of one wingbeat.
At the same time, Dr. Ravi said, the tail is making “constant corrective maneuvers.” The birds change the position of the tail and also how broadly it fans out, which intrigued Dr. Ravi. “The tail is such an understudied appendage of birds,” he said.
Flight mechanics in turbulent air is a new area of study, Dr. Ravi said, and it is already yielding insights that may be of practical use. A next step could be the design of a drone with a variable tail.