Ridges On Whale Flippers

It's surprising this wasn't discovered decades ago. On the other hand
wildlife will often sacrifice efficiency for some other goal.
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Reply to
Bret Cahill
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It was..
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Serrated trailing edges for improving lift and drag characteristics of lifting surfaces
Patent 5088665 Issued on February 18, 1992.
the apparatus includes a serrated panel having a plurality of span-wise, periodic indentations, and means for connecting the serrated panel to the trailing edge of the lifting surface. Preferably, the indentations form a plurality of saw teeth having 60° included angles between adjacent vertices, but other shapes of the indentations are possible.
Reply to
CWatters
You missed the crucial point of the OP. The serration are on the LEADING, not TRAILING edge!
Reply to
me
...
On the leading edge of a wing it's called (for Googling purposes) a "swept wing".
Reply to
kym
The bumps are on the leading edge of flippers, and that=92s not the way it=92s supposed to go.=94
...When you ride on an airplane, you don=92t see bumps on the leading edge of the wing... he did not see a flat surface that would produce smooth, aerodynamic flow...
...Drag and lift are familiar to anyone who ever stuck a hand out the window of a moving car. Hold the hand parallel to the ground and it will slice through the air. Cant it slightly and it will lift upwards. The amount of lift grows in linear fashion as the angle of attack increases=97up to a point. Too much and drag jerks the hand backwards.
This is how wings and flippers work. To maintain lift, we need to keep air or water flowing over the wing. Normally, wings allow an 11 to 12 percent angle of attack.
More than that and you lose the lift. What happens is not enough air is moving over the wing. The flow detaches from the surface of the wing and creates an eddy current. You lose the pressure differential between the upper and lower side of the wing and you stall...
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...the marriage of the born and the made. By extracting the logical principle of both life and machines, and applying each to the task of building extremely complex systems, technicians are conjuring up contraptions that are at once both made and alive. This marriage between life and machines is one of convenience, because, in part, it has been forced by our current technical limitations. For the world of our own making has become so complicated that we must turn to the world of the born to understand how to manage it. That is, the more mechanical we make our fabricated environment, the more biological it will eventually have to be if it is to work at all. Our future is technological; but it will not be a world of gray steel. Rather our technological future is headed toward a neo-biological civilization.
Nature has all along yielded her flesh to humans. First, we took nature's materials as food, fibers, and shelter. Then we learned to extract raw materials from her biosphere to create our own new synthetic materials. Now Bios is yielding us her mind-we are taking her logic.
Clockwork logic-the logic of the machines-will only build simple contraptions. Truly complex systems such as a cell, a meadow, an economy, or a brain (natural or artificial) require a rigorous nontechnological logic. We now see that no logic except bio-logic can assemble a thinking device, or even a workable system of any magnitude.
It is an astounding discovery that one can extract the logic of Bios out of biology and have something useful. Although many philosophers in the past have suspected one could abstract the laws of life and apply them elsewhere, it wasn't until the complexity of computers and human-made systems became as complicated as living things, that it was possible to prove this. It's eerie how much of life can be transferred. So far, some of the traits of the living that have successfully been transported to mechanical systems are: self- replication, self-governance, limited self-repair, mild evolution, and partial learning. We have reason to believe yet more can be synthesized and made into something new.
Yet at the same time that the logic of Bios is being imported into machines, the logic of Technos is being imported into life.
The root of bioengineering is the desire to control the organic long enough to improve it. Domesticated plants and animals are examples of technos-logic applied to life. The wild aromatic root of the Queen Anne's lace weed has been fine-tuned over generations by selective herb gatherers until it has evolved into a sweet carrot of the garden; the udders of wild bovines have been selectively enlarged in a "unnatural" way to satisfy humans rather than calves. Milk cows and carrots, therefore, are human inventions as much as steam engines and gunpowder are. But milk cows and carrots are more indicative of the kind of inventions humans will make in the future: products that are grown rather than manufactured.
Genetic engineering is precisely what cattle breeders do when they select better strains of Holsteins, only bioengineers employ more precise and powerful control. While carrot and milk cow breeders had to rely on diffuse organic evolution, modern genetic engineers can use directed artificial evolution-purposeful design-which greatly accelerates improvements.
The overlap of the mechanical and the lifelike increases year by year. Part of this bionic convergence is a matter of words. The meanings of "mechanical" and "life" are both stretching until all complicated things can be perceived as machines, and all self-sustaining machines can be perceived as alive. Yet beyond semantics, two concrete trends are happening: (1) Human-made things are behaving more lifelike, and (2) Life is becoming more engineered. The apparent veil between the organic and the manufactured has crumpled to reveal that the two really are, and have always been, of one being. What should we call that common soul between the organic communities we know of as organisms and ecologies, and their manufactured counterparts of robots, corporations, economies, and computer circuits? I call those examples, both made and born, "vivisystems" for the lifelikeness each kind of system holds.
In the following chapters I survey this unified bionic frontier. Many of the vivisystems I report on are "artificial"-artifices of human making-but in almost every case they are also real-experimentally implemented rather than mere theory. The artificial vivisystems I survey are all complex and grand: planetary telephone systems, computer virus incubators, robot prototypes, virtual reality worlds, synthetic animated characters, diverse artificial ecologies, and computer models of the whole Earth.
But the wildness of nature is the chief source for clarifying insights into vivisystems, and probably the paramount source of more insights to come. I report on new experimental work in ecosystem assembly, restoration biology, coral reef replicas, social insects (bees and ants), and complex closed systems such as the Biosphere 2 project in Arizona, from wherein I write this prologue.
The vivisystems I examine in this book are nearly bottomless complications, vast in range, and gigantic in nuance. From these particular big systems I have appropriated unifying principles for all large vivisystems; I call them the laws of god, and they are the fundamentals shared by all self-sustaining, self-improving systems.
As we look at human efforts to create complex mechanical things, again and again we return to nature for directions. Nature is thus more than a diverse gene bank harboring undiscovered herbal cures for future diseases-although it is certainly this. Nature is also a "meme bank," an idea factory. Vital, postindustrial paradigms are hidden in every jungly ant hill. The billion-footed beast of living bugs and weeds, and the aboriginal human cultures which have extracted meaning from this life, are worth protecting, if for no other reason than for the postmodern metaphors they still have not revealed. Destroying a prairie destroys not only a reservoir of genes but also a treasure of future metaphors, insight, and models for a neo-biological civilization.
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Reply to
Immortalist
| > It's surprising this wasn't discovered decades ago. | | It was.. | |
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| | Serrated trailing edges for improving lift and drag characteristics of | lifting surfaces | | Patent 5088665 Issued on February 18, 1992. | | the apparatus includes a serrated panel having a plurality of span-wise, | periodic indentations, and means for connecting the serrated panel to | the trailing edge of the lifting surface. Preferably, the indentations | form a plurality of saw teeth having 60° included angles between | adjacent vertices, but other shapes of the indentations are possible. | | Very funny Ads by Google, totally unrelated to the patent. I wonder if invalifts know what they are paying for?
The BAC 1-11 of the '60s had trailing edge "ridges".
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Reply to
Androcles
| | >| >> It's surprising this wasn't discovered decades ago. | > | >It was.. | > | >
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| > | >Serrated trailing edges for improving lift and drag characteristics of | >lifting surfaces | > | >Patent 5088665 Issued on February 18, 1992. | > | >the apparatus includes a serrated panel having a plurality of span-wise, | >periodic indentations, and means for connecting the serrated panel to | >the trailing edge of the lifting surface. Preferably, the indentations | >form a plurality of saw teeth having 60° included angles between | >adjacent vertices, but other shapes of the indentations are possible. | | You missed the crucial point of the OP. The serration are on the | LEADING, not TRAILING edge! |
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was the point again?
Reply to
Androcles
Howle was not surprised that the tubercles improved lift. =93The big surprise was that they increased lift without higher drag,=94 he said. =93Ordinarily, if you want more lift, you pay the price in drag. That was not the case here.=94The wind tunnel experiments enabled the team to develop CFD models that showed why tubercles delayed stall. They formed evenly spaced hills and valleys along the leading edge of the flipper. The rounded hills created vortices that they deflected into the valleys.Each valley was surrounded by two hills, and the vortices from each hill had opposite spins. When they mixed in the valley, they accelerated the flow of liquid to the back of the flipper. =93It was like what happens in a pitching machine in a batting cage,=94 Fish said. =93They have two large wheels spinning in opposite directions. When you put a baseball between them, it accelerates it very quickly.=94Ordinarily, the airflow over an airfoil separates from the surface when the angle of attack rises above 11 or 12 percent. The vortices, on the other hand, energized the airflow so that it adhered to the surface all the way back to the trailing edge. The result was more lift and less drag...
...=93The flippers act like wings, enabling them to bank and make turns,=94 Fish said. =93Why do they need tubercles? They have to cant at higher angles of attack to make the tight turn they need to concentrate their prey. If their flippers stall, it would be like going into a turn and hitting a patch of ice and being flung out tangentially. If they were to stall, the bubble net would be too large and their prey would get away.=94...
Reply to
Immortalist
Which explains why that Air France plane stalled and crashed into the Atlantic off Brazil.
It's WAY too late in the day for stuff like this to be coming up.
Bret Cahill
Reply to
Bret Cahill
The gains in efficiency are more than significant.
This represents a solid advancement in flight and propulsion.
Bret Cahill
Reply to
Bret Cahill
You're right I missed that.
But leading edge turbulators have been known about for even longer!
Reply to
CWatters
It would be nice to see a full blown study, Reynolds numbers, etc.
It may only work at lower speeds. Axial flow compressor blades don't have ridges yet they are already at 95% efficiency. If it does work at near sonic speeds, the higher angle of attack without separation may have some value reducing the number of stages of an axial compressor.
For adjustable pitch props it should increase the pitch range.
Bret Cahill
Reply to
Bret Cahill
Dear Bret Cahill:
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You are correct, you have to prevent shock formation on the leading edge.
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Seems to:
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just below mid-page, work done in the 1970s.
David A. Smith
Reply to
dlzc
That was for _trailing_ edges, not the leading front edge.
Reply to
John Stafford
Increasing the specific power of a gas turbine from 100 kW/kg to 120 kW/kg may be of dubious commercial value.
It may also have some application on sail design, i.e., a lot of pre formed battens for tacking more closely into the wind, etc. If so cup racers are already on it.
Powered para sail may be doing it without knowing it.
Bret Cahill
Reply to
Bret Cahill
Dear Bret Cahill:
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The winglets on the tips of commercial aircraft wings returned less than that, but it was still worth doing.
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> ... just below mid-page, work done in the 1970s.
Keels...
David A. Smith
Reply to
dlzc
That's pretty certain as a keel is providing horizontal "lift" tacking into the wind.
Reply to
Bret Cahill
Well we just blew at least a half dozen patentable inventions.
If you don't have the time to persue a patent always say, "don't know exactly how it would be done" so someone else can protect the invention.
Bret Cahill
Reply to
Bret Cahill
The real advantage may be each stage has a different size so reducing the number of stages reduces a lot of design work + 5-axis machining.
A shorter rotor would be easier to spin balance as well.
Bret Cahill
Reply to
Bret Cahill
The parasail's primary virtue, indeed the motive for inventing it, was to eliminate supports such as wood, composite struts, and so-forth. Check into the invention of the Jalbert Parasail (or parafoil) and the story of his life toward the final invention. I know the story well. He was my Uncle.
Reply to
John Stafford

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