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3.JG51_Stecher
05-13-2004, 06:08 PM
I read this in an email forwarded to me. I thought some of you might find it interesting.

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Mimicking Humpback Whale Flippers May Improve Airplane Wing Design

DURHAM, N.C., May 11 (AScribe Newswire) -- Wind tunnel tests of scale-model humpback whale flippers have revealed that the scalloped, bumpy flipper is a more efficient wing design than is currently used by the aeronautics industry on airplanes. The tests show that bump-ridged flippers do not stall as quickly and produce more lift and less drag than comparably sized sleek flippers.

The tests were reported by biomechanicist Frank Fish of West Chester University, Penn., fluid dynamics engineer Laurens Howle of the Pratt School of Engineering at Duke University and David Miklosovic and Mark Murray at the U.S. Naval Academy. They reported their findings in the May 2004 issue of Physics of Fluids, published in advance online on March 15, 2004.

In their study, the team first created two approximately 22-inch-tall scale models of humpback pectoral flippers -- one with the characteristic bumps, called tubercles, and one without. The models were machined from thick, clear polycarbonate at Duke University. Testing was conducted in a low speed closed-circuit wind tunnel at the U.S. Naval Academy in Annapolis, Md.

The sleek flipper performance was similar to a typical airplane wing. But the tubercle flipper exhibited nearly 8 percent better lift properties, and withstood stall at a 40 percent steeper wind angle. The team was particularly surprised to discover that the flipper with tubercles produced as much as 32 percent lower drag than the sleek flipper.

"The simultaneous achievement of increased lift and reduced drag results in an increase in aerodynamic efficiency," Howle explains.

This new understanding of humpback whale flipper aerodynamics has implications for airplane wing and underwater vehicle design. Increased lift (the upward force on an airplane wing) at higher wind angles affects how easily airplanes take off, and helps pilots slow down during landing.

Improved resistance to stall would add a new margin of safety to aircraft flight and also make planes more maneuverable. Drag -- the rearward force on an airplane wing -- affects how much fuel the airplane must consume during flight. Stall occurs when the air no longer flows smoothly over the top of the wing but separates from the top of the wing before reaching the trailing edge. When an airplane wing stalls, it dramatically loses lift while incurring an increase in drag.

As whales move through the water, the tubercles disrupt the line of pressure against the leading edge of the flippers. The row of tubercles sheers the flow of water and redirects it into the scalloped valley between each tubercle, causing swirling vortices that roll up and over the flipper to actually enhance lift properties.

"The swirling vortices inject momentum into the flow," said Howle. "This injection of momentum keeps the flow attached to the upper surface of the wing and delays stall to higher wind angles."

"This discovery has potential applications not only to airplane wings but also on the tips of helicopter rotors, airplane propellers and ship rudders," said Howle.

The purpose of the tubercles on the leading edge of humpback whale flippers has been the source of speculation for some time, said Fish. "The idea they improved flipper aerodynamics was so counter to our current doctrine of fluid dynamics, no one had ever analyzed them," he said.

Humpback whales maneuver in the water with surprising agility for 44-foot animals, particularly when they are hunting for food. By exhaling air underwater as they turn in a circle, the whales create a cylindrical wall of bubbles that herd small fish inside. Then they barrel up through the middle of the "bubble net," mouth open wide, to scoop up their prey.

According to Fish, the scalloped hammerhead shark is the only other marine animal with a similar aerodynamic design. The expanded hammerhead shark head may act like a wing.

The trick now is to figure out how to incorporate the advantage of the tubercle flipper into manmade designs, said Fish.

The research team now plans to perform a systematic engineering investigation of the role of scalloped leading edges on lift increase, drag reduction and stall delay.

NOTE TO EDITORS: High-resolution photos of Duke researcher with test fins, and humpback whale shots are available at http://www.dukenews.duke.edu/images/fishfrank.jpg and http://www.dukenews.duke.edu/images/whale.jpg . For more information or to obtain a beta tape of the video news release, please contact Deborah Hill at 919-401-0299 x. 329. Preview VNR at http://quicktime.oit.duke.edu/dstudio/flipper.mov (high bandwidth) or http://quicktime.oit.duke.edu/dstudio/flipper_small.mov (low bandwidth)

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3./Jagdgeschwader 51
3./JG51_Stecher
www.jg51.com (http://www.jg51.com)

3.JG51_Stecher
05-13-2004, 06:08 PM
I read this in an email forwarded to me. I thought some of you might find it interesting.

-----------------------------------------------------------------------

Mimicking Humpback Whale Flippers May Improve Airplane Wing Design

DURHAM, N.C., May 11 (AScribe Newswire) -- Wind tunnel tests of scale-model humpback whale flippers have revealed that the scalloped, bumpy flipper is a more efficient wing design than is currently used by the aeronautics industry on airplanes. The tests show that bump-ridged flippers do not stall as quickly and produce more lift and less drag than comparably sized sleek flippers.

The tests were reported by biomechanicist Frank Fish of West Chester University, Penn., fluid dynamics engineer Laurens Howle of the Pratt School of Engineering at Duke University and David Miklosovic and Mark Murray at the U.S. Naval Academy. They reported their findings in the May 2004 issue of Physics of Fluids, published in advance online on March 15, 2004.

In their study, the team first created two approximately 22-inch-tall scale models of humpback pectoral flippers -- one with the characteristic bumps, called tubercles, and one without. The models were machined from thick, clear polycarbonate at Duke University. Testing was conducted in a low speed closed-circuit wind tunnel at the U.S. Naval Academy in Annapolis, Md.

The sleek flipper performance was similar to a typical airplane wing. But the tubercle flipper exhibited nearly 8 percent better lift properties, and withstood stall at a 40 percent steeper wind angle. The team was particularly surprised to discover that the flipper with tubercles produced as much as 32 percent lower drag than the sleek flipper.

"The simultaneous achievement of increased lift and reduced drag results in an increase in aerodynamic efficiency," Howle explains.

This new understanding of humpback whale flipper aerodynamics has implications for airplane wing and underwater vehicle design. Increased lift (the upward force on an airplane wing) at higher wind angles affects how easily airplanes take off, and helps pilots slow down during landing.

Improved resistance to stall would add a new margin of safety to aircraft flight and also make planes more maneuverable. Drag -- the rearward force on an airplane wing -- affects how much fuel the airplane must consume during flight. Stall occurs when the air no longer flows smoothly over the top of the wing but separates from the top of the wing before reaching the trailing edge. When an airplane wing stalls, it dramatically loses lift while incurring an increase in drag.

As whales move through the water, the tubercles disrupt the line of pressure against the leading edge of the flippers. The row of tubercles sheers the flow of water and redirects it into the scalloped valley between each tubercle, causing swirling vortices that roll up and over the flipper to actually enhance lift properties.

"The swirling vortices inject momentum into the flow," said Howle. "This injection of momentum keeps the flow attached to the upper surface of the wing and delays stall to higher wind angles."

"This discovery has potential applications not only to airplane wings but also on the tips of helicopter rotors, airplane propellers and ship rudders," said Howle.

The purpose of the tubercles on the leading edge of humpback whale flippers has been the source of speculation for some time, said Fish. "The idea they improved flipper aerodynamics was so counter to our current doctrine of fluid dynamics, no one had ever analyzed them," he said.

Humpback whales maneuver in the water with surprising agility for 44-foot animals, particularly when they are hunting for food. By exhaling air underwater as they turn in a circle, the whales create a cylindrical wall of bubbles that herd small fish inside. Then they barrel up through the middle of the "bubble net," mouth open wide, to scoop up their prey.

According to Fish, the scalloped hammerhead shark is the only other marine animal with a similar aerodynamic design. The expanded hammerhead shark head may act like a wing.

The trick now is to figure out how to incorporate the advantage of the tubercle flipper into manmade designs, said Fish.

The research team now plans to perform a systematic engineering investigation of the role of scalloped leading edges on lift increase, drag reduction and stall delay.

NOTE TO EDITORS: High-resolution photos of Duke researcher with test fins, and humpback whale shots are available at http://www.dukenews.duke.edu/images/fishfrank.jpg and http://www.dukenews.duke.edu/images/whale.jpg . For more information or to obtain a beta tape of the video news release, please contact Deborah Hill at 919-401-0299 x. 329. Preview VNR at http://quicktime.oit.duke.edu/dstudio/flipper.mov (high bandwidth) or http://quicktime.oit.duke.edu/dstudio/flipper_small.mov (low bandwidth)

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http://flygirl.dhs.org:8080/jg51/109sig.jpg


3./Jagdgeschwader 51
3./JG51_Stecher
www.jg51.com (http://www.jg51.com)

ImpStarDuece
05-13-2004, 06:27 PM
Sounds cool but i'm not really suprised at this. Water is a much denser medium than air (about 7 times i think) and so anything that has to propell itself through this mudium is going to develope a HIGHLY efficient method of doing it.

Anyone remember the ornithopter experiments conducted by MIT a few years ago? I think they were using blades/wings (or whatever it is an ornithopter actually uses) similar to those found on some types of penguin. Ran into some big ngineering problems trying to build anything bigger than a scale model though. Might have to do some digging up to find the article http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

"There's no such thing as gravity, the earth sucks!"

tsisqua
05-13-2004, 06:39 PM
Very interesting.

Did anyone else notice the name of the biomechanist is "Frank Fish"? http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Tsisqua

Agamemnon22
05-13-2004, 06:44 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by tsisqua:
Very interesting.

Did anyone else notice the name of the biomechanist is "Frank Fish"? http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Tsisqua<HR></BLOCKQUOTE>

Yup. To quote Bart Simpson
"The ironing is delicious"

SUPERAEREO
05-14-2004, 02:27 AM
The scalloped shape reminds me a little of the trailing edge of the wings in WW1 biplanes.

Interesting.

S!


"The first time I ever saw a jet, I shot it down."
Chuck Yaeger

GAU-8
05-14-2004, 03:49 AM
it took this looong??? i remember during the mid 80s when kneeboards went from a smooth bottom to a rough bottom...(all the rage then). for the same purpose.....for some reason the roughness actually created less drag, and better control in transition. (maybe less "stiction?" from the water tension on the surface?)

wow, guess surfers can have fun, and be intelligent.. who knew???

Hawgdog
05-14-2004, 04:35 AM
I remember watching this program where they studied the wings of a dragonfly of all things.
I think thats where they started messing around, scallops, mini-overlapping diamonds etc.

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When you get to Hell, tell 'em HawgDog sent you!

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Bansai Potato
05-14-2004, 05:21 AM
It has been known for ages that a rough surface creates a faster being than a smooth surface, at least in water anyway. Run your hand across the skin of a shark, it is like sandpaper, in all directions, yet sharks are amongst the fastest sea creatures. The reason they go faster for less effort is the fact that their rough skin breaks up the water flow that has direct contact with their surface, this in turn reduces the drag they face. They have a wake affect over their whole body, like prop wash i guess in the air, you fly through it and you get no lift and big problems because the air is so disturbed same as a sharks skin i suppose. Mother natures a clever old girl aint she

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