MIT scientists have unveiled the key behind the marathon flight of the wandering albatross, which can fly nearly 500 miles in a single day, with just an occasional flap of its wings. The albatross is one of the most efficient travellers in the animal world. The birds use their formidable wingspans, measuring up to 11 feet across, to catch and ride the wind.
Observers have noted for centuries that these feathered giants keep themselves aloft for hours, just above the ocean surface, by soaring and diving between contrasting currents of air, as if riding a sidewinding rollercoaster – a flight pattern known as dynamic soaring.
Now, engineers at Massachusetts Institute of Technology (MIT) in the US have developed a model to simulate dynamic soaring, and have used it to identify the optimal flight pattern that an albatross should take in order to harvest the most wind and energy. They found that as an albatross banks or turns to dive down and soar up, it should do so in shallow arcs, keeping almost to a straight, forward trajectory.
The new model will be useful in gauging how albatross flight patterns may change as wind patterns shift with
changing climate, researchers said. It also may inform the design of wind-propelled drones and gliders which could be used to perform long-duration, long-range monitoring missions in remote regions of the world, researchers said.
“The wandering albatross lives in the Southern Ocean, which is not very well-known. It is very hard to get there,
and there is a lot of wind and waves,” said Gabriel Bousquet, a graduate student at MIT.
“This is an important step forward to actually write algorithms for robots to be able to use the wind,” said
Bousquet, first author of research paper published in the journal Interface. The team’s project was inspired, in part, by contests of dynamic soaring, in which competitors launch gliders from atop mountains and track the speed of each glider as it dives down, soars up, then doubles back and dives down again in a loop, propelled by the winds.
“These planes, without any engines, can go over 500 miles per hour, in a loop. It sounds strange – how can you keep
pumping energy out of what looks like nothing?” said Michael Triantafyllou, professor at MIT. It turns out the gliders are given a boost by varying wind currents, researchers said. When a glider is launched from atop a mountain, high winds can act as a thruster, speeding the glider along until it reaches a sheltered layer of slower winds, whereupon it may reorient its flight direction before climbing back upward to the region of high winds.
The same wind-propelled phenomenon plays out in the flight of the albatross, Bousquet said, the only major
difference being that, rather than lofting down behind a mountain, an albatross soars over water.