3 July 2007

Flight secrets of largest bird ever revealed

Agençe France-Presse
Using software originally written for helicopters, scientists have analysed the aerodynamics of the largest bird known to have taken flight – it was the size of a light aircraft.
Flight secrets of largest bird ever revealed

Extinct Argentavis magnificens is the world's largest known flying bird. It had a wingspan of seven metres and was about the size of a Cessna 152 aircraft. This illustration shows it soaring across the Miocene skies of the Argentinean Pampas six million years ago, much as condors fly today. Credit: Jeff Martz.

CHICAGO: Using software originally written for helicopters, scientists have analysed the aerodynamics of the largest bird known to have taken flight – it was the size of a light aircraft.

Argentavis magnificens cruised the skies above the Argentina’s grassy pampas about six million years ago, a soaring behemoth of a bird, dragging 63 kg in ballast.

But with little in the way of muscle to flap its wings and propel itself through the air, just how did the largest bird to ever take wing stay aloft?

flight simulator

That question has puzzled palaeontologists for decades, but in a study released today, U.S. researchers suggest that the now extinct Argentavis was essentially an expert glider, hitching a lift on thermals and updrafts.

“Once it was airborne, there was no problem. It could travel 200 miles in a day,” said geologist Sankar Chatterjee of the Museum of Texas Tech University in Lubbock, and lead author of the study published in the Proceedings of the National Academy of Sciences.

Chatterjee and a team of researchers analysed the aerodynamics of the ancient bird of prey by plugging information about its flight parameters into flight simulation software.

The analysis showed that the prehistoric aviator, like most large soaring landbirds, was too large to sustain powered flight, but could soar efficiently, reaching speeds of up to 108 kph in the right conditions.

Running start

Like modern-day condors, Argentavis would have relied on updrafts in the foothills of the Andes, or columns or pockets of rising air known as thermals over the grassy pampas where it hunted its prey, for lifting power.

In all likelihood, the bird would have circled upwards on a thermal and glided from thermal to thermal sometimes over long distances between its roost site and feeding areas.

Although it had a 6.5-metre wingspan, its 30-metre turning radius was short enough that it could keep circling within a thermal as it rose high to search the plains for its prey.

“The hardest part would be taking off from the ground,” said Chatterjee. “It would have been impossible to take off from a standing start. It probably used some of the techniques used by hang-glider pilots such as running on sloping ground to get thrust or energy, or running with a headwind behind it.”

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