Undulating their bodies keeps flying snakes from tumbling out of control

How flying snakes glide by swimming through the air.

Flying snakes can glide as far as 78 feet (24 meters) without tumbling out of control because they undulate their bodies mid-flight, as if they were swimming through the air. This seems to be a specialized strategy to stabilize their flight rather than an evolutionary remnant of general snake behavior, according to a new paper in the journal Nature Physics. The work could eventually lead to a new, improved control template for dynamic flying robots.

Co-author Jake Socha of Virginia Tech has been studying these fascinating creatures for about 20 years. The peculiar gliding ability of these snakes-there are five known species, including Chrysopelea pelias and Chrysopelea paradisi-was first noted by a British scientist in the late 1800s, who observed one gliding through his tea garden in southeast Asia one day. But scientists had paid little attention to determining the precise physics and biomechanics at play until Socha published a 2002 paper outlining his preliminary findings on the fundamental aerodynamics.

Socha found that the snake will push its ridge scales against the tree trunk, using the rough surface to maneuver up to a branch. Then it dangles its body off the end of the branch and contracts sharply like a spring to launch itself into the air. The initial angle of inclination as the snake is hanging determines the flight path. To ensure maximum gliding distance, the snake will suck in its stomach and flatten its body, curving inward like a Frisbee to create lift, undulating its body in an S-shaped motion, which serves to increase the air pressure underneath.

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