FIRST PUBLISHED IN POPULAR MECHANICS, OCTOBER 2008
An airplane systems engineer, a shower designer and a biologist walk into a Costa Rican rain forest.
“This is the neatest thing I’ve found this week,” says the airplane engineer, from Boeing, pointing to a cluster of daddy- longleg spiders gently oscillating on the trunk of a banana tree. “There must be some unique muscular elastic element in their legs sensing vibration and amplitude. There could be really important opportunities here for a low-energy sensor or mechanical actuator system.”
The group ambles on, stopping next at a 150-ft.-tall ajo tree with weeping vines and thick buttresses—the kind you might see in a natural history museum diorama. “These roots are circumferentially distributed, so the tree’s strong in any direction,” notes the shower designer, from Kohler. “These buttresses also have a nice gradient to the ground. When we want to reduce stresses in mechanical design, we try to gradually transform one shape into another—nature’s already done that here.”
This observation—that the natural world has spent 3.8 billion years honing elegant solutions to life’s toughest engineering challenges —provides the framework for the growing field of biomimicry. Inventors have long drawn ideas from the world around them. Now, advances in fields like nanotechnology allow them to probe natural processes more deeply. Armed with this insight, and motivated by an interest in sustainable design, engineers increasingly look outside the lab for inspiration.
To develop strategies for converting sunlight into clean energy, some researchers are studying photosynthetic bacteria. Others are examining how abalones, which build layers of calcium carbonate into extraordin-arily strong shells, might lead to a new generation of ceramic composites. Often, the natural model is there all along; it just requires taking a closer look: University of Exeter researchers recently discovered that reflectors used in new, high-emission LEDs serve a nearly identical function as the fluorescent patches on the wings of African swallowtail butterflies.
This past April, Boeing sent three of its engineers to Costa Rica’s southern Pacific coast to learn how biomimicry might be applied to aviation. The team chose to address a chronic problem with flying: the noise. Sound enters an airplane cabin from various sources— the engine, the air flowing across the aircraft, even the stow bins. Fiberglass blankets in the plane’s walls insulate passengers from both the bitter cold outside and some of this noise, but adding more would make the plane too heavy. Eliminating too much noise is also not ideal—consider what it would be like to hear the passengers’ every sneeze and cough.
Led by biologists from the Montana-based Biomimicry Guild, a consulting firm that also works with companies such as Nike, Interface and General Electric, the engineers are spending a week learning how to, if not exactly find the answer, at least ask the right questions. Thinking outside the standard academic toolbox is not intuitive for most engineers, says Dayna Baumeister, the guild’s co-founder. “Putting them in a rain forest brings them back to that childlike state of wonder and suddenly broadens their perspective to other ways problems might be solved.”
That principle seems to be at work the morning the Boeing engineers sit around a picnic table at La Cusinga, a lodge perched spectacularly on a bluff at the edge of a coastal rain forest. Behind them stretches the Pacific, where earlier the group kayaked through a maze of mangrove trees, contemplating desalination strategies.
“Whose survival depends on managing noise or vibration?” Baumeister asks them. “Parasites living on cicadas,” someone answers.
“Howler monkeys.”
“Spiders.”
“We have to look at the champion adapters,” Baumeister says. “What’s their secret? Let’s see if we can figure that out.” She begins reading an academic paper off her laptop. “This is really cool. Leaf-cutting ants produce high-frequency vibrations with a specialized organ. The high vibrational acceleration of the mandible appears to stiffen the material to be cut.”
“So by inducing a vibration into material you can change the physical properties,” muses engineer Bill Sanford. “Including conductance, possibly. Why don’t we change the conductance of the fuselage by shaping vibration to modify those values?”
The group continues to scan scientific abstracts. Cicadas and some birds, they learn, can actively shape the noise they generate— using mechanisms that could be valuable for managing airplane sound. A finding that bees are able to dampen sound by orienting their honeycomb a certain way proves compelling, too. In airplanes, the honeycomb shape is attractive for its high strength-to-weight ratio and so is used in many interior components. But it is currently oriented in a way that may help propagate sound, rather than deaden it.
One afternoon, the group snorkels around a nearby reef. Underwater, they hear a popping sound that calls to mind a child jumping on plastic Bubble Wrap. The source turns out to be a pistol shrimp, which deters predators by creating and then loudly collapsing an air bubble using a specialized claw. It remains unharmed by the noise, they later learn, because its brain blocks specific frequencies, effectively reducing the sound it perceives—not quite a noise-canceling headphone, but an intriguing strategy.
The outing inspires the engineers to look more closely at fish as well. The discovery that body slime not only helps reduce drag but also reduces the vibrations caused by passing waves has the group riffing on ways to modify an airplane’s outer coating to help attenuate sound.
Spiders, which are ubiquitous in the corners of the cabins and on trails around the lodge, also catch the engineers’ attention. Research reveals that they weave various thicknesses and levels of tension into their webs—both for structural reasons and so that the vibrations induced by an arriving meal will indicate what and where it is. If Boeing could pinpoint the places on an airplane’s panels that vibrate the most, the group reasons, they could build a complementary dampening structure on those nodes to minimize the vibration coming from them.
As they brainstorm ideas, Baumeister presses them to consider the fundamental principles behind each natural design. “Does it use benign manufacturing or water-based chemistry? Free energy? Is the system decentralized and distributed, with built-in redundancies?”
While the concepts that Boeing comes up with may be far-fetched in the real world of aviation, they are a start. “The difficult part will be making the transition from theory to practice,” says engineer Heidi Kneller. “But anything that not only encourages a new way of thinking but also opens up a new world of possibilities is a valuable tool.”
On the same trip, two engineers and a designer from Kohler grapple with the more universal, but no less perplexing, conundrum faced by eco-conscious bathers: In a world of water scarcity, how can the indulgence of taking a shower be reconciled with water conservation? The team flips through animal flash cards—the kind that pair a picture of the creature with an interesting fact about it. Soon, they are discussing the ability of whales and dolphins to release millions of tiny bubbles underwater from their blowholes. “Perhaps this unique method of inducting air can supplement water in a low-flow showering application,” one of the engineers notes.
After two days the Kohler team has made serious headway on designs for a low-flow luxury product that the company thinks it can actually develop. And by the end of the week, engineer Pete Kajuch finds himself rethinking the way he approaches design challenges. “Now I reach for a whole new set of inspirations,” he says. “I gravitate toward sustainable design first; I don’t just reach for the same metal and plastic.”
Back at Kohler’s headquarters in Wisconsin, a workroom has been filled with ecology books and displays. While the company can’t send every design team to Costa Rica, it hopes to re-create the effect of immersing them in a rain forest. After all, it sees the value in biomimicry—and how studying a tropical downpour could actually lead to the perfect shower.