The bird’s fingers are important for steering

Sunday, January 19th, 2020

Birds change the shape of their wings far more than planes do, and David Lentink, a professor of mechanical engineering at Stanford University, and his team explored this while creating their PigeonBot:

The researchers used common pigeon cadavers to try to figure out the mechanics of how birds control the motion of their feathers during flight. Scientists had thought the feathers might be controlled by individual muscles. But they learned that some aspects of bird wing motion are simpler than they expected.

Lentink says that several doctoral students realized that simply by moving the birds’ “wrist” and “finger,” the feathers would fall into place. When the bird’s wrist and finger moves, “all the feathers move, too, and they do this automatically,” he said. “And that’s really cool.”

The findings are some of the first evidence that the bird’s fingers are important for steering. The team replicated the bird’s wing on the PigeonBot using 40 pigeon feathers, springs and rubber bands connected to a wrist and finger structure. When the wrist and finger move, all the feathers move, too.

The researchers used a wind tunnel to see how the feather-and-rubber band design worked under turbulent conditions. “Most aerospace engineers would say this is not going to work well, but it turned out to be incredibly robust,” Lentink says.

They also pinpointed something interesting about how the feathers work together that helps most birds fly in turbulent conditions. At certain moments during flight, such as when a bird is extending its wings, tiny hooks on the feathers lock together like Velcro.

“These tiny, microscopic micro-structures that are between feathers lock them together as soon as they separate too far apart, and a gap is about to form. And it’s really spectacular,” Lentink adds. “It requires an enormous force to separate them.”

These tiny hooks are so small that they’re hard to see even through a microscope. Then, when a bird tucks its wing back in, the feathers unlock automatically, like directional Velcro. Separating the locked feathers makes an audible sound for most birds. The team published this finding in a separate paper in the journal Science.

It’s worth noting that the PigeonBot doesn’t incorporate something you might associate with birds’ wings – flapping. The designers were focused on incorporating the more subtle wrist-and-finger motions of the wings, so the bot appears to be gliding through the air while it’s in flight.

I guess Dune‘s ornithopters might not be so fanciful after all, and we might see a better human-power ornithopter, too.


  1. Bruce says:

    When I read Dune. I noticed Herbert never said the thopters didn’t rotate their wings as well as flap them. Helicopter ornithopters make more sense than just reprising Langley.

  2. Kirk says:

    Herbert wasn’t an aerodynamic engineer. I imagine he just wanted an exotic-sounding “thing” to throw in there, so that it sounded different. I remember reading that “thopter” thing, and going “WTF? How would that even work…?”.

    Thing to remember here is that what works in organic living context does not always do so well when it comes time to fabricate the damn thing in inert man-made materials. Witness the joys and humiliations of the poor bastards trying to replicate the hydrodynamics of whale and dolphin skin/blubber in covering our subs. The anechoic tiles we have to resort to are insanely expensive, prone to falling off, and mostly nowhere near as good as what whales and dolphins grow naturally for moving through the water. Same-same with the special suits for competitive swimmers–Those are crazy expensive and a massive pain in the ass to maintain.

    Until we’re bio-engineering giant birds, the most you’re going to do is emulate basic principles. I can only imagine what a huge pain in the ass it would be to have to maintain a set of artificial wing feathers for some ungodly mechanical bird, no matter how effective it might be in some applications.

  3. Alistair says:

    Ah, well, in defence of Herbert, the universe of Dune has arbitrarily advanced technology in many aspects; just no computers. Their bio-gene-tech, in particular, seems to be very advanced.

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