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Wednesday, August 18, 2010

Planes that land like birds

Airplanes require very long runways for landing. Birds, on the other hand, can land on telephone wires. Russ Tedrake from MIT and his student Rick Cory decided to see if they could make a plane act like a bird.

Regardless of whether planes are ascending or descending, they must keep their wings within only a few degrees of level. If they deviate too much from this angle, they go into a stall, which causes the plane to fall from the sky. Nobody wants that. But birds actually go into a purposeful stall each time they aim to land in a precise location. If engineers could precisely control stalling, then airplanes could be made to land on tiny areas just like birds. The trouble is that predicting exactly how air will flow around a plane during a stall has been extremely difficult. Tedrake and Cory developed their own mathematical model to do so.

So far, the team has successfully tested a foam prototype, for which Cory won Boeing’s 2010 Engineering Student of the Year award.

Here's a video clip of the model landing on a suspended string perch:

UPDATE: Because some people have not been able to view the video, here's a cartoon of the perching glider:


The glider is launched at a random initial speed that ranges anywhere from 6.0 to 8.5 meters per second (13.5-19 mph) and begins 3.5 meters (12 ft) away from the perch. It must then quickly decelerate to a near stop before making the point landing, by attaching a small hook under its belly to the perch. In order to slow down fast enough, the glider must orient its entire body to a high angle of attack, allowing it to exploit both viscous and pressure drag for braking. The entire maneuver last just a fraction of a second and is computer-controlled by varying the angle of the tail.

More videos and images can be viewed here.