Science

A new understanding of flying snakes may lead to advances in technology

Flying snakes are actually very gifted gliders, not unlike flying squirrels (Photo: Jake Socha, Virginia Tech)
Flying snakes are actually very gifted gliders, not unlike flying squirrels (Photo: Jake Socha, Virginia Tech)
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Flying snakes are actually very gifted gliders, not unlike flying squirrels (Photo: Jake Socha, Virginia Tech)
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Flying snakes are actually very gifted gliders, not unlike flying squirrels (Photo: Jake Socha, Virginia Tech)
There are three species of flying snakes, all belonging to the genus Chrysopelea, and all being found in the forests of Southeast and South Asia (Photo: Jake Socha, Virginia Tech)
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There are three species of flying snakes, all belonging to the genus Chrysopelea, and all being found in the forests of Southeast and South Asia (Photo: Jake Socha, Virginia Tech)
Flying snakes are able to flatten out their bodies after launching themselves from tree branches, proceeding to glide through the air for up to 100 feet (30.5 m) (Photo: Jake Socha, Virginia Tech)
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Flying snakes are able to flatten out their bodies after launching themselves from tree branches, proceeding to glide through the air for up to 100 feet (30.5 m) (Photo: Jake Socha, Virginia Tech)

So first of all ... yes, flying snakes do exist. Disappointingly, though, they don't have scaly dragon-like wings. Instead, they're able to flatten out their bodies after launching themselves from tree branches, proceeding to glide through the air for up to 100 feet (30.5 m). Recently, scientists figured out why that technique works as well as it does. Their findings could have some major applications for us humans.

There are three species of flying snakes, all belonging to the genus Chrysopelea, and all being found in the forests of Southeast and South Asia. They rotate their ribs in order to flatten themselves, and make an undulating side-to-side motion (as snakes will do) while gliding.

Jake Socha, a biomechanics professor at Virginia Tech, used tubing to build physical models of the snakes, which his team tested in a wind tunnel. Based on his observations of the real animals, it was expected that the models would experience more aerodynamic lift as they increased their angle of attack (i.e: the degree to which their nose was raised relative to the oncoming air flow), culminating in a sudden stall and drop. Instead, the researchers noted "lift increasing up to an angle of 30 degrees, a sharp boost at an angle of 35 degrees, then a gentle decrease."

There are three species of flying snakes, all belonging to the genus Chrysopelea, and all being found in the forests of Southeast and South Asia (Photo: Jake Socha, Virginia Tech)
There are three species of flying snakes, all belonging to the genus Chrysopelea, and all being found in the forests of Southeast and South Asia (Photo: Jake Socha, Virginia Tech)

Why was this the case? That's where Lorena Barba, an associate professor of mechanical and aerospace engineering at Washington DC's The George Washington University, came into the picture.

Working with research assistant Anush Krishnan, she created a computer model of the "wing" section of a snake's body. Using that model in computational fluid dynamics simulations, she observed the same lift phenomenon that Prof. Socha noted, known as a lift enhancement mechanism. In her case, however, she was able to "zoom in" on the flight surfaces, to better see exactly what was going on.

It turns out that at certain glide angles, curves in the animals' bodies create small whirlwind-like vortices in the surrounding air, essentially sucking the snakes higher. Barba still isn't clear on the role played by the side-to-side motion, but plans on using a computer model of a complete snake body to find out. She hopes that her findings could be put to practical use.

"It’s not wild to think that our understanding of the fluid mechanics of this particular shape could lead us to, for example, design a different type of air flow that is ideal for energy harvesting, or a wind turbine – or who knows,” she said. "You find applications in unexpected places."

On a related note, we've already seen improved wind turbines, undersea turbines and helicopter rotor blades that were inspired not by snakes, but by the hydrodynamic fins of the humpback whale.

A paper on the flying snake research was recently published in the journal Physics of Fluids.

Source: The George Washington University

7 comments
Captain Danger
There are snakes that climb trees Snakes that swim and Snakes on a plane and now Flying Freaking Snakes! This is not right! Is there no where I can be safe!
someguy
Then, Captain Danger, you have chosen the wrong alias name... ;) I don't think the vortices "suck" the snake up. I would think they merely prevent the flow from separating "early". This is a quite well-known phenomenon in low aspect-ratio wings and Deltas. One could make the case that the snake is indeed a "wing" with a VERY low aspect ratio... Not saying I'm right, but I feel that this might be part of the answer.
Arf
I would love to be walking through a jungle with an unsuspecting group and get to say "Now do watch out for the flying snakes!" The reaction would be priceless no doubt.
John in Brisbane
@someguy - sounds like you know a bit about aircraft :-) That was my thought too. It appears that they're getting more than twice the angle of attack that a normal straight aircraft wing can get - 37 degrees versus about 16 degrees. And without resorting to external devices like wing slats. Maybe they are working like a delta. I wonder if the rippling creates virtual delta conditions along the body? Delta wings of the sort used on the Concorde and Mirage fighter are the only way we humans can approach that kind of angle of attack.
Ian Mitko
stol airplanes have "vortex generators" that keep the airflow from separating from the wing as quickly. I assume that is the affect here. By keeping the pressure at a lower level above the snake than below it you are minimizing the rate of descent...but to say you are "sucking it up" is reductionist.
Bob
This is certainly out of my area of expertise but I suspect that the snake is getting a staggered bi or even tri wing effect. I would imagine that the cumulative effect will be quite different than considering the snake's body as just one wing. Having done a little free falling, I was quite impressed how tiny changes in an airfoil can have dramatic effects in direction and control.
someguy
One more thing, even though noone cares any more: The side-to-side movement might be for the snake to establish something like the high-sweep leading edge of a Delta wing, which ultimately is one of the main factors in the Delta wing's high AoA capability. By wiggling its body to the side, a swept "leading edge" is generated and the vortices can do their job. And of course this will make the snake "asymetric", which is why it has to do it in an "averaging" motion. You read it here first. You're welcome. ;)