With the help of high-speed cameras and a computer model, US engineers have found that wave motion is vital to stabilize the flight of snakes that glide between tree branches. The discovery may help the development of new flying robots.
Many animals undulate their bodies to move on land or water, but the only vertebrates without limbs capable of doing so in the air are flying snakes (of the genusChrysopelea). Behind this ability there is a physical function.
The undulation helps stabilize the flight of these snakes, according to the study that engineers from the Polytechnic Institute and Virginia State University (Virginia Tech, USA) published this week in the magazineNature Physics.
Using cameras similar to those in some Hollywood movies, they recorded the movements of these reptiles at high speed. In this way they confirmed that they flatten their bodies to achieve lift - something that is already known - but also that during undulations their shape changes continuously as the horizontal and vertical waves produced by muscle contractions move.
The fact that the researchers identified the presence of a vertical wave while gliding in the air suggests that flying snakes use undulation for more than just moving horizontally in the air. To analyze the entire process in more detail, they built a computational model that simulated the flight of the snake with and without ripples.
The simulations reveal that when snakes are thrown and do not wave, they appear to 'roll' and fall a short distance away. However, when undulation is included, the landslides are more stable and the snakes go further. This is in contrast to other animals that use undulation only for power.
According to the study, “although the simulated landslides without ripples reached a certain horizontal distance, they are biologically unrealistic and fail due to instability of movement. On the contrary, the inclusion of the corrugation stabilizes the rotational movement and remarkably increases the sliding performance ”.
Bio-inspired flying robots
The authors suggest that these findings could aid the design of bio-inspired flying robots capable of gliding using the same mechanism: “This work shows that airborne undulation in snakes performs a different function than undulation known in other animals, and proposes a new template control for flying robots ”.
In a parallel article also published inNature Physics, researcher Jim Usherwood from the University of London publishes a very illustrative vignette of the process and comments: “Anyone who has ever made a paper airplane and has been disappointed when it goes out of control, hitting the ground, knows what It can be difficult to achieve proper fit and stability for planning. But somehow flying snakes know how to glide without falling. "
Isaac J. Yeaton, Shane D. Ross, Grant A. Baumgardner, John J. Socha. "Undulation enables gliding in flying snakes."Nature Physics, June 2020.