Agriculture
Growing Healthier Tomato Plants
Springing forward
Protecting Cows—and People—from a Deadly Disease
Amphibians
Toads
Poison Dart Frogs
Salamanders
Animals
Jay Watch
Little Beetle, Big Horns
Sea Lilies on the Run
Behavior
The Colorful World of Synesthesia
Night of the living ants
Flower family knows its roots
Birds
Birds We Eat
Falcons
Cassowaries
Chemistry and Materials
Sweeeet! The Skinny on Sugar Substitutes
Picture the Smell
Heaviest named element is official
Computers
Middle school science adventures
Two monkeys see a more colorful world
Secrets of an Ancient Computer
Dinosaurs and Fossils
Mini T. rex
Dino-bite!
Ferocious Growth Spurts
E Learning Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
Results of GSAT are in schools this week
2014 GSAT Results for Jamaican Kids
Earth
Weird, new ant
Challenging the Forces of Nature
Shrinking Glaciers
Environment
Animal CSI or from Science Lab to Crime Lab
Sea Otters, Kelp, and Killer Whales
Toxic Cleanups Get a Microbe Boost
Finding the Past
Digging Up Stone Age Art
A Volcano's Deadly Ash
Big Woman of the Distant Past
Fish
Dogfish
Great White Shark
Trout
Food and Nutrition
Allergies: From Bee Stings to Peanuts
Turning to Sweets, Fats to Calm the Brain
The Color of Health
GSAT English Rules
Whoever vs. Whomever
Problems with Prepositions
Capitalization Rules
GSAT Exam Preparation Jamaica
Mastering The GSAT Exam
Ministry of Education Announces 82 GSAT Scholarships for 2010
Scotiabank Jamaica Foundation Grade Six Achievement Test (GSAT) Scholarships
GSAT Exams Jamaica Scholarships
2014 GSAT Results for Jamaican Kids
GSAT Practice Papers | GSAT Mathematics | Maths
GSAT stars reap scholarship glory
GSAT Mathematics
Math of the World
Secrets of an Ancient Computer
How to Slice a Cake Fairly
Human Body
Opening a Channel for Tasting Salt
Running with Sneaker Science
Cell Phones and Possible Health Hazards
Invertebrates
Mollusks
Squid
Ants
Mammals
Pitbulls
Woolly Mammoths
Walrus
Parents
Children and Media
How children learn
Expert report highlights the importance to parents of reading to children!
Physics
IceCube Science
Extra Strings for New Sounds
Gaining a Swift Lift
Plants
When Fungi and Algae Marry
Pumping Up Poison Ivy
Tracking the Sun Improves Plant Pollen
Reptiles
Iguanas
Cobras
Geckos
Space and Astronomy
Planets on the Edge
Return to Space
Planet Hunters Nab Three More
Technology and Engineering
A Clean Getaway
Space Umbrellas to Shield Earth
Crime Lab
The Parts of Speech
What is a Preposition?
What is a Noun
Pronouns
Transportation
Charged cars that would charge
Seen on the Science Fair Scene
Robots on a Rocky Road
Weather
Catching Some Rays
Earth's Poles in Peril
Polar Ice Feels the Heat
Add your Article

Are Propellers Fin-ished?

If you've ever been to an aquarium or a zoo, you've probably admired the feisty penguins. They can squiggle through water faster than 10 miles per hour, turn on a dime, and leap onto shore, all in one smooth movement. Dolphins and seals can perform similar aquabatics. These marine animals are more than just fun to watch. They're also inspiring engineers to look for better ways of propelling boats. You never see a submarine do what a penguin can do, but wouldn't it be cool if it could? Propellers let ships travel in a relatively straight line over great distances. Today's engineers are trying to design vessels that can do a lot more than that. They want boats able to withstand stormy conditions that would shatter an existing craft. They want boats that can maneuver quickly in tight spaces. They want boats that can sense currents or waves and respond in a split second to hold their position. In effect, they want to reinvent the penguin—or perhaps the whale or fish. A penguin's flippers are a good starting point. All dressed up Propeller blades just spin. Penguin flippers do much more. A penguin's flipper is like a hard, stiff paddle covered with tiny feathers. It's shaped a bit like an airplane wing. A flipper can flap up and down, move forward and backward, and twist around at the joint where it's attached to the penguin's body. At the Massachusetts Institute of Technology, researchers are working on a new propulsion system for ships that mimics a penguin's flippers. Their artificial wooden flippers move a boat forward or backward by generating high-energy rings of spinning water. Other flipper movements steer the craft right, left, up, or down. The MIT team is now testing how various flipper movements affect a boat's motion, doing experiments in giant basins of water. The scientists envision using a pair of flippers in place of a propeller to move a boat along. More futuristic vessels could have as many as 50 flapping flippers, each one moving independently. But it'll take many more years of research before the Navy or anyone else can launch high-tech ships driven by flippers. A new kind of fin Flexibility also helps move things along in water. Marine animals such as dolphins and seals aren't made of stiff materials. They're squishy, like human skin and muscle. Flexible materials can store energy in ways that stiff ones can't. When a dolphin flexes its tail as far as it'll bend, it stores energy in its body—just like a stretched rubber band. When the tail slams down and straightens, this stored energy is released, and the dolphin shoots forward. Engineers at Nekton Research, a company in Durham, N.C., have designed flexible fins for an underwater vehicle to take advantage of such cycles of storing and releasing energy. The craft, called PilotFish, is shaped like a giant egg with four fins coming out of its waist. It's more than 3 feet long and weighs 350 pounds. PilotFish can't travel long distances quickly. Instead, maneuverability is its specialty. And it can get going in a fraction of a second. Moreover, unlike any other watercraft, it can stop almost instantaneously just by slamming its fins forward. "The thing looks like it hit a wall. It stops dead," says Chuck Pell, who helped design the fins. "The only other things that can do that are alive." PilotFish is designed to operate in water too turbulent for other craft. For example, it could be used to inspect the underwater portions of structures such as bridges and docks. A river's waves or current can easily overcome or carry away a propeller-driven craft before it can perform an inspection. In contrast, PilotFish reacts to its environment quickly enough to stay in place. If the craft encounters an unexpected object, it can immediately stop to avoid bumping into it. If a wave rolls it over, PilotFish can right itself before the next wave comes. To accomplish all this, PilotFish's fins generate huge forces. "You have to careful around it. You could break an arm," Pell says. He notes that he once ended up with a sprained wrist when a moving fin accidentally struck his hand. Whale watch For their size, humpback whales are surprisingly agile. This 50-foot, 30-ton animal can swim in a tight corkscrew pattern, sometimes less than 10 feet across. The whales do this not for fun but to capture a meal. They blow bubbles as they swim in this spiral pattern, creating a rising barrier around a cylinder of water. Tiny shrimp and small fish get trapped in the cylinder, and the whale simply swims up through the concentrated feast for its meal. Scientists have long wondered how humpbacks manage this feat. They've been particularly curious about bumps along the leading edge of a humpback's long, narrow flippers. To find out, researchers built two artificial whale flippers. One flipper had a scalloped edge, and the other was smooth. They then tested the two flippers in a wind tunnel. Although air is much less dense than water, it's still a fluid, and the researchers could adjust the air's speed so that it behaved like water rushing over a humpback's flipper. The scientists found that the bumps reduce drag and increase a flipper's lift so it behaves more like an airplane wing. This extra lift and reduced drag lets a humpback whale make sharper turns than other whales can make. Someday, engineers designing flippers or fins to drive boats and submarines might add bumps or scallops, too. Kayak flippers Artificial fins inspired by one marine animal, the penguin, are already available—though not where scientists might have predicted. They're in a foot-powered propulsion system for kayaks designed by engineers at Hobie Cat in Oceanside, Calif. Instead of paddling, you sit in the kayak and pedal with your feet. Your pedaling powers two flexible fins. At the start of each stroke, the fins twist and flex in such a way that they assume the shape of a propeller blade. A penguin's flipper flexes in the same way when the swimming bird wants to move itself forward. The fins move larger volumes of water than a traditional oar can yet require less energy to do so. This lets kayakers go farther and faster, without getting as tired as when paddling with oars. Hobie Cat's pedaled kayaks are leading the way in applications of nature-inspired flipper design. Other applications are bound to follow. Maybe someday you'll be able to go to an aquarium show featuring underwater vehicles, gliding gracefully, racing around rocks, and leaping out of the water to wow a crowd—doing what comes naturally to penguins and dolphins.

Are Propellers Fin-ished?
Are Propellers Fin-ished?








Designed and Powered by HBJamaica.com™