Dutch engineering students have developed RoboSwift, a bio-inspired morphing-wing micro aerial vehicle which flies like a swift. Like the real bird, this robotic one "will have unprecedented wing characteristics; the wing geometry as well as the wing surface area can be adjusted continuously." But unlike the real bird, RoboSwift, which will have a span of 50 cm and weigh about 80 grams, has been designed to spy on us. With its three micro cameras, it will perform surveillance missions lasting up to one hour on vehicles and people on the ground. The first RoboSwift is expected to fly in January 2008.
As you can see above, "RoboSwift can sweep its wings back and forth, changing the shape and the surface area. By doing so the airplane can fly more efficiently and more agilely than fixed-wing aircraft. The airplane is powered by means of a special propeller that folds during gliding to minimize air drag." (Credit: RoboSwift project) Here are two links to a larger version of this illustration and to other images and videos.
Here are more details about the morphing-wing design features of RoboSwift. "Morphing means the wings can be swept back in flight by folding feathers over each other, thus changing the wing shape and reducing the wing surface area. RoboSwift also steers by morphing its wings. Doing so, the micro airplane can perform optimally, flying efficiently and highly maneuverable at very high and very low speeds, just like the swift. The students found out that using only four feathers, much less than the bird uses, already provides the wing with sufficient morphing capacity; this feature makes actual production of the design feasible. Steering RoboSwift is done by asymmetrically morphing the wings. Sweeping one wing back further than the other creates a difference in lift on the wings that is used to roll and turn the micro plane in the air."
It's really interesting to note that the engineering team based the project on research performed by David Lentink, who works for the Experimental Zoology Group at Wageningen University and is studying the swift's flight characteristics. Did you know that "during its life, a common swift flies a distance that goes up to five times the distance to the Moon and back?"
This research work on swifts appeared on the cover of the April 26, 2007 issue of Nature under the name "How swifts control their glide performance with morphing wings" (Volume 446, Number 7139, Pages 1082-1085). Here are two links to the abstract and to the Editor's summary, "On the wing." Here is how it starts. "Gliding birds continually change the shape and size of their wings, tuning performance by means of morphology. Aerodynamic theory predicts that birds should adjust wing sweep to suit glide speed and now a more refined aerodynamic model has been developed, based on wind-tunnel data. The results reveal a remarkable degree of control: swifts can halve sink speed or triple turning rate by choosing the most suitable sweep.
Sources: Delft University of Technology, June 27, 2007; and various websites
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