Imagine a plane able to travel immense distances with no propulsion save the power of the wind. Such a capability, though unfathomable to most humans, has already been realized by the natural world in the unique capabilities of the Wandering Albatross. Without even flapping their wings, Wandering Albatross can travel 500-600 miles in a single day, fly the equivalent of eighteen round trips to the moon and back in a lifetime, and maintain speeds higher than 127 km/h for more than eight hours, all, achieved through the distinct skill of dynamic soaring.
Researchers have spent hundreds of hours studying the mechanics of dynamic soaring, but only recently did they discover its intricacies. Scientists already understood that an elbow-lock system allowed the albatross to keep its wings open at no energy cost. Though, researchers have now brought to light the method by which the wandering albatross uses dynamic soaring to fly great distances without flapping their wings.
With the assistance of high-precision GPS tracking, researchers found that albatross achieve dynamic soaring by a continually curving flight up and down that optimally adjusts to the wind. Wandering Albatross never fly in a straight line as they skim the water’s surface, ascend into the sky, turn leeward and descend back towards the water. This dynamic-soaring cycle has four major components: first, a windward climb; second, a turn from windward to leeward at the flight’s peak; third, a leeward descent; and finally, a curve from leeward to windward at the flight’s base.
By analyzing the total energy during the dynamic-soaring cycle, researchers were able to identify how dynamic soaring allows for sustained flight. The key is in the albatross’s change in direction. When the albatross faces windward, it loses much of its energy to drag and converts the rest into gravitational potential energy during the climb. This results in the minimum total energy during this period. The energy gain comes at the peak of the bird’s flight as it turns leeward. Following this turn, the wind exerts a propulsive effect throughout the descent that provides the albatross with a maximum total energy near the base of the descent. The albatross will inevitably lose energy in the turn back from leeward to windward, but because wind speeds are much smaller closer to the surface of the water, the albatross is able to achieve a net surplus of energy. This allows the Wandering Albatross to achieve the necessary power of 81.0 Watts for flight at 70 km/h that is required for its 8.5 kg body and maximum lift-to-drag ratio of 20.
Dynamic soaring offers incalculable lessons for the aeronautical community. Engineers at NASA are already designing a UAV based upon the Wandering Albatross able to stay aloft for months at a time. Dynamic soaring is truly a lesson in the unharnessed power of nature that humanity has yet to realize. Unlimited and omnipresent, the power of nature surrounds us, and humanity must learn to use it just as the Wandering Albatross and many others already have.
- Travels to the Edge Clip on You Tube
- Sachs, et al. Flying at No Mechanical Energy Cost: Disclosing the Secret of Wandering Albatrosses, PLOS One 7(9): e41449 (2012)
- NASA’s Dynamic Soaring on You Tube
- The Beauty of Dynamic Soaring on You Tube