Researchers from the University of Virginia and Virginia Tech have published a study in Physics of Fluids exploring how flying snakes generate lift. These snakes can glide for long distances by undulating side-to-side, which allows them to quickly move from tree to tree. The researchers developed a computational model built from data pulled from high-speed video of flying snakes.
The model accounts for the cross-sectional shape of the snake's body, which resembles a frisbee. This shape is essential for understanding how the snake can glide so far. A frisbee’s spin increases air pressure below the disc and decreases it on top, lifting the disc into the air. To mimic that pressure differential, the snake undulates side to side, producing a low-pressure region above and a high-pressure region below and lifting the snake.
"The snake's horizontal undulation creates a series of major vortex structures, including leading edge vortices, LEV, and trailing edge vortices, TEV," said author Haibo Dong. "The formation and development of the LEV on the dorsal, or back, surface of the snake body plays an important role in producing lift.” The group also analyzed several other factors, like the angle of approach that the snake forms with the oncoming airflow and how frequently it undulates, to determine which impacted lift generation. Flying snakes typically undulate at a frequency between one and two times per second. Counterintuitively, the results showed that more frequent undulation than that decreases aerodynamic performance. The scientists hope this research will guide the development of more efficient flying robots down the road.
Flying snakes aren’t the only animals inspiring biomimicry studies. A recent study from Penn State University examined how the mechanisms of hummingbird flight could be used to provide insight for revamping aerial vehicles and flying robots.