Agriculture
Making the most of a meal
Got Milk? How?
Middle school science adventures
Amphibians
Newts
Toads
Frogs and Toads
Animals
Monkey Math
A Whale's Amazing Tooth
Not Slippery When Wet
Behavior
GSAT Mathematics Quiz, Teaching Math, teaching anxiety
Internet Generation
A Grim Future for Some Killer Whales
Birds
Kiwis
Vultures
Backyard Birds
Chemistry and Materials
Undercover Detectives
Gooey Secrets of Mussel Power
The metal detector in your mouth
Computers
New twists for phantom limbs
Play for Science
The hungry blob at the edge of the universe
Dinosaurs and Fossils
The bug that may have killed a dinosaur
Digging for Ancient DNA
South America's sticky tar pits
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
Flower family knows its roots
Coral Islands Survive a Tsunami
Pollution at the ends of the Earth
Environment
Whale Watch
Shrinking Fish
Bald Eagles Forever
Finding the Past
Of Lice and Old Clothes
Fakes in the museum
Ancient Art on the Rocks
Fish
Hagfish
Bass
Tilapia
Food and Nutrition
Building a Food Pyramid
Packing Fat
The Essence of Celery
GSAT English Rules
Adjectives and Adverbs
Capitalization Rules
Whoever vs. Whomever
GSAT Exam Preparation Jamaica
Tarrant High overcoming the odds
March 21-22, 2013: Over 43,000 students will take the GSAT Exam
Scotiabank Jamaica Foundation Grade Six Achievement Test (GSAT) Scholarships
GSAT Exams Jamaica Scholarships
2014 GSAT Results for Jamaican Kids
Results of GSAT are in schools this week
GSAT stars reap scholarship glory
GSAT Mathematics
Losing with Heads or Tails
Math and our number sense: PassGSAT.com
Deep-space dancers
Human Body
Attacking Asthma
A Fix for Injured Knees
Kids now getting 'adult' disease
Invertebrates
Spiders
Jellyfish
Praying Mantis
Mammals
Aardvarks
Bonobos
Moose
Parents
Expert report highlights the importance to parents of reading to children!
The Surprising Meaning and Benefits of Nursery Rhymes
Raise a Lifelong Reader by Reading Aloud
Physics
Speedy stars
Echoes of a Stretched Egg
The Particle Zoo
Plants
A Giant Flower's New Family
Assembling the Tree of Life
Fungus Hunt
Reptiles
Garter Snakes
Black Mamba
Rattlesnakes
Space and Astronomy
A Puffy Planetary Puzzle
Holes in Martian moon mystery
Sun Flips Out to Flip-Flop
Technology and Engineering
Riding Sunlight
Weaving with Light
Roll-Up Computer Monitors to Go
The Parts of Speech
Countable and Uncountable Nouns
Adjectives and Adverbs
What is a Verb?
Transportation
Robots on the Road, Again
Reach for the Sky
Flying the Hyper Skies
Weather
Either Martians or Mars has gas
Arctic Melt
Recipe for a Hurricane
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™