Developing Robotic Birds

From a news story by
CNN San Francisco Reporter Don Knapp

September 8, 1999

After nearly a hundred years of powered flight, scientists are still trying to figure out how birds fly.

Researchers have learned that the slapping noise pigeons make when they suddenly take off is the sound of super charged lift. They call it the "clap fling" effect.

Here at S.R.I. International scientists try to duplicate the pigeons' thrust. A flashing strobe reveals the secret.

Scott Stanford, a scientist at SRI, says, "You're looking at the clap fling effect, where the two wings will come together and peel apart from each other, thus augmenting lift by drawing air from the top to the bottom."

This mechanical bug won't get off the ground but its flapping wings demonstrate a potential propulsion system for robotic birds: man-made rubbery muscle.

Roy Kornbluh works at SRI. "There, I'm turning the voltage on and off, and you can see when the voltage is on, the material is larger than when the voltage is off."

Super computers show high-speed airflows over supersonic aircraft.

But scientists have only begun to see how air flows at really low speeds.

Professor Max Platzer of the Naval Postgraduate School, says, "The flapping wing is generating a thrust, this way, this is the basic physics of the phenomenon."

It's pelicans - not pigeons - the Navy is looking at. The Navy is looking at the smooth easy flight of pelicans low over water -- called "ground effect." Researchers at the Naval Postgraduate School are trying to imitate the pelican's efficiency.

Assistant Professor Kevin Jones of the Naval Postgraduate School says, "By flapping the wings, symmetrically, we're in effect imitating ground effect. We now have the same feature a bird sees when it's flying over a ground plane."

An electric motor drives the flapping wings. Researchers here are working on ways to beam power to the tiny bird.

David Jenn of the Naval Postgraduate School says, "There's no battery inside of here, so we're going to set this inside the radar beam, and the energy is extracted from the radar beam and will be used to propel the rotor."

Scientists are learning it's one thing to build an airplane, but quite another to build a bird.

Additional notes:

The Notes: To really understand the project described in this article, it is important to know something about how things fly. Here are a few websites that will explain this to you. Also, there is a lot of information about birds on the Internet. Here are some selected sites with links to many other websites.

• How Birds Fly: Bird migration, navigation, and flight strategies
• What Makes an Airplane Fly? ALLSTAR-NASA Principles of Flight: This gives an excellent visual explanation of lift, thrust, drag, and other aspects of flight. This website explains many of the terms used in the news article.
• NASA Aero Design Team Online:This contains an excellent introduction to how airplanes fly, how birds fly, and other information.
• Aeronautics Glossary
• The K-8 Aeronautics Internet Textbook: This website has articles and information at three different reading levels. Here is one sample:
• How Birds Fly
• Plane Math is a website with a series of lessons and activities that explain flight. This is the lesson explaining lift: Lift Off
• Birding on the Web-Bird Links
• Bird Links: National Audubon Society
• Bird Song of the Week (Library of Natural Sounds)

 

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