March 5, 2014
Flying Snakes Ride The Wind To Get More Boost
Brett Smith for redOrbit.com - Your Universe Online
The flying Paradise tree snakes of lowland Asia are renowned for their ability to glide from tree to tree and a new study in the journal Physics of Fluids has shown that these reptiles ride tiny vortices of air that give them a little extra boost.
The study expanded on previous research that showed the snakes get an extra boost of lift when facing the air flow at a certain angle.
“After experiments uncovered this, we decided to use computer simulations to try to explain it," said study author Lorena Barba, associate professor of mechanical and aerospace engineering at the George Washington University.
"Rather than fixed wings, animal fliers have flapping wings," Barba continued. "In the case of gliders, their small scale means they're always in a flurry of whirling winds. By understanding how they can be graceful and efficient under these conditions, we can in turn use that knowledge to create small flying machines that are equally graceful."
The research team is currently looking to include more factors related to the snake's actual gliding conditions into their computer simulations – such as the S-shape of its full body, instead of just using a section.
"This will be more difficult to do in a computer model, but it will probably reveal more about the complicated flow patterns snakes take advantage of to be such gifted gliders," Barba said.
In a study published in January, the same team of researchers described how the Paradise tree snake forms its body into an ‘S’ for extra surface area.
“They turn their whole body into one aerodynamic surface,” said Jake Socha, a biomechanics expert who was a co-author on both studies, adding, “they look like they are swimming.”
Published in the Journal of Experimental Biology, the study revealed that snakes flex their ribs as they launch – extending and flattening their body from a circular tube into an arched semi-circle.
“It looks like someone’s version of a UFO,” said Socha, adding it’s an unconventional shape for generating lift.
To analyze the aerodynamics of the S-shape, the study team used a 3-D printer to generate the very same UFO-like cross-section as the snake’s body. Next, the team placed their model in a tank filled with water that flowed over the snake-shaped bar. While water is considerably denser than air, it can be used to model the airflow passing across a surface at an array of speeds.
The team found that when the team tilted the model in the tank to a 35-degree angle, there was an immense spike in the lift produced by water flowing at higher speeds. More remarkably, when the model was positioned level with the flow, the fluid pushed it down. Also, when the team observed the water flowing around the model engineered with microscopic reflective beads, they could clearly see a vortex sitting beneath the level snake shape, sucking it down.
The researchers said twisting of the snake’s body in midair could allow it to fine tune the forces acting on their bodies – enabling more precise flight control.