Though the wing-flapping contraptions of early human flight haven't quite caught on, researchers think birds may still have something to teach us about navigating the air: how to land. MIT researchers have made a system that can bring a modified glider to an elegant bird-like stop, causing it to set down on its tail.
Russ Tedrake of MIT's Computer Science and Artificial Intelligence Laboratory and his student Rick Cory developed the computer model to bring a basic foam glider to a unique landing. The principle behind the plane's stop is the same one used by stunt planes--stall. When its wings tilt back, the plane loses lift and falls from the sky. Traditional planes don't use this method to land because the airflow is chaotic (see smoke visualization above) making it hard to predict how the plane will behave.
Birds come to a stop by tilting their wings back at sharp angles. This creates turbulence and large, unpredictable whirlwinds behind the wings. If an airplane pointed its wings up in this way, it would lose lift and fall out of the sky. But MIT researchers wanted to take advantage of stall--specifically, post-stall drag--to help a plane come to a controlled landing. [Popular Science]
Video after the break. Tedrake and Cory developed a computer program to control the glider with a steering motor attached to its tail. The program predetermined the best flight paths to bring the glider to a safe landing, and also how to correct or switch courses if it veered too far off the path.
For a range of launch conditions, they used the model to calculate sequences of instructions intended to guide the glider to its perch. . . . Cory and Tedrake also developed a set of error-correction controls that could nudge the glider back onto its trajectory when location sensors determined that it had deviated from it. [MIT]
They launched the 90-gram craft from 12 feet away from its landing wire, in winds between 13 and 19 miles per hour. Though they don't predict a passenger plane landing like this anytime soon, they think the technique might prove useful for flying robots that could perch and recharge their batteries on a power line. With more research, they might also make craft that use other bird strategies.
The researchers say they are continuing the research and will next be moving outside into real-world conditions. They also plan to explore the use of flapping wing vehicles as well as more typical propeller driven aircraft. [Wired]
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