Thursday, January 28, 2016

Why some penguin feathers never freeze

These birds could inspire new ways to keep ice off of airplane wings

By Andrew Grant
January 28, 2016
Gentoo penguin
Gentoo penguins live in Antarctica. New research reveals that oil and tiny pores prevent water from freezing on the feathers of these birds. CHRISTOPHER MICHEL/FLICKR
Penguins in Antarctica survive in some rough conditions. Temperatures can reach -40° Celsius (-40° Fahrenheit). Winds can blow as fast as 40 meters per second (89 miles per hour). A drenched penguin waddling in such bone-chilling air would seem like a recipe for frozen feathers. Yet the birds don’t become popsicles. That’s because tiny grooves and an oily sheath on the feathers prevent some penguins from freezing, a new study finds.

Pirouz Kavehpour is a mechanical engineer at the University of California in Los Angeles. He and his colleagues studied feathers from gentoo penguins, an Antarctic species, under a scanning electron microscope. The jagged surface of the feathers was full of nano-sized pores. This subtle roughness forces water droplets to slide off rather than stay and freeze. The penguins also release preen oil from a gland near the base of the tail. A bird will use its beak to spread the oil over its feathers. That oil works as a water-repellent.

The Magellanic penguin lives in South America, in warmer climates than the gentoo. It has no pores on its feathers, the researchers found. And it secretes a less-repellant oil. Kavehpour reported his team’s new findings November 22 at the American Physical Society Division of Fluid Dynamics meeting in Boston, Mass.

Ice build-up on penguin wings may not be a big deal for most people. But icing on the wings of an airplane can bring down a craft. So Kavehpour hopes to exploit the birds’ deicing ways to design airplane wings that won’t ice up.


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