How Do Snakes Fly? Just Ask Your Favorite Graphics Chip

A flying snake. Photo: Jake Socha

Jake Socha has been studying flying snakes since 1996, and he still doesn’t know exactly how they do it.

But he’s getting closer — thanks to the magic of 3-D printing and high-power computer simulations that use the graphical programming units, or GPUs, that now power everything from game consoles to supercomputers.

It’s a tricky thing to study. As his research collaborator, George Washington University Professor Lorena Barba, wrote in an abstract for an upcoming talk: “It would be hard to put a flying snake in a wind tunnel. So we are trying to put them in GPUs instead.”

Scientists have been living in an golden age of computer simulation, as they’ve discovered that these graphical processing units are good for more than speeding up explosions in Call of Duty. They are also great for certain types of mathematical work, such as simulating flying snakes.

The researchers have created two-dimensional computer models of the flying snakes, (pdf) but they’ve also done real-world simulations — using 3D printed components in water tunnels. Both show that snake-shaped objects would get a special aerodynamic pop should they tilt their bodies at 35 degrees as they drop from tree branches.

For the computer simulations, which were led by Barba and Anush Krishnan of the University of Boston, the researchers used a single Nvidia Tesla K20 GPU accelerator to simulate a two-dimensional cross section of the snake at a range of different speeds and angles of attack and then measure how that could provide lift. As it turns out, that 35 degree tilt provides more lift than one would expect, Socha says. “Its this spot where the lift really pops up,” he says.

Socha, a professor of engineering science and mechanics at Virginia Tech, has studied three species of these snakes — all of which live in southern Asia. They seem to use air travel as a kind of defense mechanism, flattening their bodies into an aerodynamic wing-like shape and then flinging themselves off of a tree. They drop fast and then even out in a kind of undulating and spooky s-like glide. They can easily cover 30 feet, if they drop from a tall enough tree.

Image L.A. Barba

Now that the first flying snake computer models have been built, the researchers hope to build more complex, three-dimensional simulations that will tell them more about how the motion of the snake affects things and whether the animal might be able to get additional lift by positioning the back part of its body behind the front — much like a bicyclist drafts the person in front.

Either way, the simulations are important steps toward understanding the flying snake. Scientists know about the snakes basic movements in the air, but there’s still a lot to learn Socha says. “The question I’m still most interested in is how exactly does the animal produce its aerodynamic force and how does it maintain control in the air.”

So why care about the flying snake? Socha says his work into this very novel type of flight could be applied to build a whole new kind of autonomous robots. “Maybe you can build a search and rescue robot that is able to get into cracks like a snake and go through rubble and emerge from the top of the pile and jump off and glide somewhere else.”

The Pentagon has already funded research in this area, by way of DARPA, the Defense Advanced Research Projects Agency. Slithering drone, anyone?

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