“Flying UFO-shaped snakes” sounds like fodder for a late-night horror flick, but some snakes really do sail through the air and look like UFOs in the process, according to new research.
The study, published in the latest Journal of Experimental Biology, helps to explain how such snakes (in the genus Chrysopelea) can remain airborne for up to 100 feet in their Southeast Asia rainforest habitats.
The snakes launch from seemingly any position on a tree, flexing their ribs as they initiate a glide. They then stretch and flatten their bodies from a circle into an arched semi-circle.
“It looks like someone’s version of a UFO,” co-author Jake Socha of Virginia Tech’s College of Engineering, said in a press release.
The snakes launch themselves into air to move around their treetop home and to escape predators. They are mildly venomous, and prefer to take flight rather than fight.
For the study, Socha and his colleagues first watched the snakes in action. From afar, the snakes appear to be slithering midair.
“They look like they are swimming,” he said. “They turn their whole body into one aerodynamic surface.”
To determine what’s going on up close, the researchers used a 3-D printer to produce a rod with the same cross-section as the snake’s body. They then placed it across a tank filled with water that flowed over the snake-shaped bar.
Socha explained that, although water is much denser than air, it was possible for he and his colleagues to precisely recreate the air conditions experienced as the snakes fly. They flowed water over the model at a specific range of speeds. Those speeds ranged from about 8 to 20 inches per second.
Slightly tilting the snake model revealed that, at most angles, the snake’s body generated sufficient lift to account for the impressive gliding. When the rod was flat, however, turbulence created a suction-like force on the snake model, pulling it downward.
“Maybe the snake does hold part of its body flat at some point, using it as a mechanism for control,” Socha said, explaining that twisting the body while airborne could allow the snakes to fine tune the forces on their bodies for precise flight control.
The model, however, does not fully explain how snakes use their long bodies to stay airborne for so long.
“If you make a rough estimate of the lift to drag ratio for the real animal, it appears to do better than what we got from this study,” Socha said. “So even though this shape produced more lift than we were expecting, it doesn’t get us the glide performance that snakes can attain, giving us a hint that there is something in what the animal is doing aerodynamically that is not captured by the cross-sectional shape alone.”
The researchers plan to figure that out next. Once they fully unravel the snake’s technique, they plan to use it to design tiny aerial robots for search and rescue missions, reaching places that larger devices and humans could not otherwise go.
Photo: ©Jake Socha