Whale Flippers Make Better Airplane Wings

phreakmonkey writes "The bumpy, ridged surface on humpback whale flippers provide more lift, less drag, and exhibit better stall characteristics than traditional aircraft wing designs, according to Duke University, West Chester University, and the U.S. Naval Academy. This could help improve the design of airfoils used on everything from aircraft wings to underwater vehicles. The results were published in the May 2004 issue of Physics of Fluids and reported on Innovations Report."

Obligatory Douglas Adams...

[dustmote]

I don't think whales fly all that well, at least not according to Douglas Adams.

"I wonder if it will be my friend?" ***SPLAT*** :)

So Long and thanks for all the.....

[Anonymous Coward]

But you missed the opportunity to play off the fact that the researcher's name is, no joke, Frank Fish

dmanny

Re:Obligatory Douglas Adams...

[cammoblammo]

Don't forget that the trick is to distract yourself so you forget to fall. I don't know if whales would have any advantage over an aeroplane in this regard.

bumps

[OmniVector]

i'm not really an expert on the physics of aerodynamics but wouldn't bumps be completely contradictory to things like fluid dynamics? I can understand the whale flipper shape making a difference, but the bumps just seem like unnecessary drag.

Re:bumps

[M1FCJ]

Lift generated by a rotating body vs. lift generated by a rotating body generating turbulance. Interestingly enough turbulence helps. In high speeds laminar flows are not that good, in many aircraft sharp edges and slits on the wing are used to generate turbulance so that the shock wave won't be happening on the wing surface itself. It is not very good for lift. (When the aircraft is flying around 0.9M, the air flowing over the wing can move faster than sound).

Re:bumps

[MoeDrippins]

There have been a number of things where bumps (or otherwise non-flat/smooth) surfaces have helped aerodynamics; golf-ball dimples being the most recongizable example. If I recall correctly, some of the speed-skaters in the Olympics a few years back were wearing some whiz-bang body suit that had some "deformations" under the arms or somesuch for the same reason.

Here's one mention [tudelft.nl] of something related.

Re:bumps

[nomel]

I've been hearing this "put golf ball like dents to make more aerodynamic" for years upon years. I remember it back on beyond 2000 in the 90's. It amazes me everytime it makes it on the news...and not from a technological standpoint.

Wonder what's kept previouse people from using this idea. Maybe it's effects are neglible with all the other losses of an airplane?

Re:bumps

[ajax0187]

I would imagine it's just from a practical standpoint. An airplane wing can cause different effects depending on its airspeed (i.e. the most efficient airfoil shape at 150 knots is different than the most efficient shape at 1150 knots). Even though the dimples might create more lift at low airspeed, once you start approaching subsonic/supersonic conditions, the drag they produce would be more trouble then it's worth. And how exactly can you get rid of them? You can't (at least not at our present level o

Re:bumps

[Weh]

the strips on those suits are basically designed to 'trip' the flow so that it becomes turbulent (instead of laminar). Turbulent flow has more momentum which results in less pressure drag. The disadvantage of turbulent flow over laminar flow is that it gives more viscous drag.

Dimples in a golf ball are designed to increase the roughness so the amount of air being held to the surface of the ball is greater when the ball rotates. Higher air velocity (at the top) and lower velocity (at the bottom) create a pressure difference which gives lift.

Bumps are vortex generators

[Spamalamadingdong]

From the article [duke.edu]:

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 has been known to aerodynamicists for some time; there are vortex generators on many aircraft, including on the vertical stabilizers of many Cessnas (to improve the ability to resist turning forces during engine-out operations), on the leading edges of wings (to improve the attachment of airflow over the wings at high angles of attack and thereby increase the control effectiveness of the ailerons behind them), on the insides of the fan shrouds on the Boeing 757, and in other places.

This is not to say that this research doesn't show us anything we didn't already know, but it isn't exactly a huge revelation either.

Re:Bumps are vortex generators

[phreakmonkey]

Actually, I disagree. The increased low-speed handling (and higher angle of attack) characteristics of wings with vortex generators have been known for a long time. However, traditionally shaped vortex generators tend to increase drag, or at best leave it the same.

What appears to make this shape unique is that it actually increases the lift of the wing, increases the range of angle of attack (= lower stall speeds) AND reduces drag. This means it's more aerodynamically efficent overall, instead of trading one aerodynamic characteristic for another. (ie: increasing drag to lower the stall speed)

We haven't improved the overall efficency of wing design for some time. (That's why a 1967 Cessna 172 and a 2003 Cessna 172 have nearly identical wings.) This may change that.

- pm

A quibble

[Spamalamadingdong]

We haven't improved the overall efficency of wing design for some time. (That's why a 1967 Cessna 172 and a 2003 Cessna 172 have nearly identical wings.) This may change that.

I'd put that down to the requirements for FAA type certification rather than limits of knowledge or design. You can buy all kinds of flap- and aileron-gap seals and other cleanup hardware for Cessnas, but you can't get them installed at the factory. If the company doesn't find those relatively simple additions worthy of inclusion in

Reminiscent of Airbus trials with "shark skin"

[rv8]

Airbus was conducting trials many years ago with a covering that was striated like shark skin. They measured small drag reductions, but I haven't read anything about the concept in recent years. I suspect Airbus found that it was hard to keep the surface maintained properly.

http://www.spc.org.nc/coastfish/News/Fish_News/84/ Shark-skin-planes.htm [spc.org.nc]
http://www.bio.davidson.edu/Courses/anphys/2000/Tu scano/Applications.htm [davidson.edu]

Re:bumps

[BigBir3d]

A few things:

1. RTFA

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 delay

Re:bumps

[John Hasler]

That's what the whales thought too, but after a few hundred thousand years of experimenting they decided that it really does work.

Damn whale hunters

[AtariAmarok]

I knew it all along. The skies used to be filled with whales before the whale hunters forced them to hide under the sea. Go get 'em, Greenpeace!

Re:Damn whale hunters

[patrick.whitlock]

personally, im not happy when a bird shits on my car.... can't imagine what i'd be like to have it shit on by a whale

Did somebody mention...

[FlyingOrca]

flying whales? I guess I must be the last one.

(Don't get it? Look at my nick, fercrisake.)

Re:Did somebody mention...

[M1FCJ]

You must be flying with a C-5...

Golf Ball Dimples

[joelparker]

Bumps and dimples tend to make things fly more reliably, by letting small eddies of air whirl. The same effect can be seen in golf balls-- a golf ball with dimples (like all the ones today) will fly farther and straighter than a perfectly spherical one.

Why does a golf ball have dimples? [avkids.com]

Re:Golf Ball Dimples

[reinard]

Well I looked around on their site and there is no writeup on that.

I would be seriously surprised if you were correct. I think you're the one that beleives in an Urban Legend.

Re:Golf Ball Dimples

[Alizarin Erythrosin]

Try reading this then. [howstuffworks.com] I play golf occasionally, and when it's obvious that the dimples do something. If you're ever hit a good shot off the tee you'll notice that the ball trajectory isn't parabolic, it curves up before coming back down.

Re:Golf Ball Dimples

[MachDelta]

Bumps and dimples tend to make things fly more reliably...

Oh! So THAT'S why geeks are always thrown farther by the bullies!
Here I thought it had something to do with reduced mass, but nope - its all aerodynamics!

Re:Golf Ball Dimples

[Weh]

your statement that 'things with dimples' tend to fly farther is not really true. An aeroplane doesn't have many dimples does it? A golf ball flies further when it is rotating (in the right direction) since the air velocity at the top is higher than at the bottom (creating a pressure difference). The dimples serve to increase the roughness which increases the amount of air being acelerated/decelerated. It is exactly the same effect as a flettner rotor [montana.edu]

Experimentation?

[Dexx]

How, exactly, do you test something like that? Cessna with flippers? Drop whales from heights? Whale in a wind tunnel?

What conditions does this effect need?

[Retric]

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 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.

This sounds like the same effect that Honeybee's use, but I can't help but wonder what range of wind speeds this works for. My guess would be this is only useful for subsonic aircraft. Even if the effect were limited to say 1/2 the speed of sound there are plenty of aircraft that could benefit from this. If anyone can find a link which gives the conditions required for this effect that would be great until then I am going to assume it's not gong to work on a 747. Although some cessnas's might end up with bumpy wings.

Bumpy wings?

[Spamalamadingdong]

Most Cessnas are rivetted together, and already have bumpy wings....

What this says to me is that Ford may have had it more right than he knew, with the Trimotor. (The Trimotor's skins were corrugated with the ribs running parallel to the airflow.)

Re:Bumpy wings?

[thebigmacd]

Actually, the ridges parallel to airflow created huge amounts of drag. If they had corrugated the skin perpendicular to the flow of air, they could have used a lot less fuel and maintained more lift. Of course, to the untrained eye, parallel appears to be more logical than perpendicular but that is not the case. I have no accreditation to back up this claim. I read it way back when I was about 12, but I do understand it has to do with boundary layer separation.

Run a test on your memory, because....

[Spamalamadingdong]

You got it backwards. [aerodyn.org]

Squishy bits?

[sithkhan]

Just out of curiousity, are the bumps and nodes alluded to in the article made of flesh? Isn't flesh compressable? Would this not have an effect upon the properties of the foil in question? I think it would be difficult to replicate these qualities. but I am not an aeronautical engineer, nor am I a rocket scientist. I'm only a humble chemist.

Re:Squishy bits?

[WolfWithoutAClause]

Yeah, but provided you presquish it, it would behave the same way.

"Why yes I am a rocket scientist."- Werner Von Braun

Re:Squishy bits?

[Inominate]

The article says that the 'flippers' tested were made from polycarbonate, a decidedly solid material. So replicating it on a larger scale isn't all that difficult.

Clarification

[sithkhan]

Are the properties of the whale fins a result of the bumps and nodules? Do the nodules and bumps flex when subjected to the pressures of the fluids? If so, how would you replicate this in a man-made material? What composition would be required to have parts of the foil flex or compress/decompress to provide the results that a whale fin/fluke does?

Learning from nature

[Gallowsgod]

I think science could do well learning more from nature. After all, nature have perfected lots of designs over millions of years.

Take bats for instance, only after spending years inventing sonars and radars we humans discover these little creatures had used the same solutions for quite some time.

Ricard Dawkins' brilliant book The blind watchmaker [amazon.com] did a good job convincing me that we still have lots and lots to learn from nature.

Re:Learning from nature

[John Hasler]

"Learning from nature" is what science _does_.

Re:Learning from nature

[Gallowsgod]

"Learning from nature" is what science _does_.

I know that science learn a lot from nature. Perhaps I wasn't to clear on making my point.

I think science could be improved by learning even more from nature. The bat/sonar example I gave is one case I think illustrates this. AFAIK scientists did not learn how to build sonars and radars from nature. But they could have. The Wale flipper story is another example. We learned making wings from studying birds wings (I think?). It took a century of flying before

Re:Learning from nature

[NorthDude]

Just an observation, but I would think that 100 years between the point where we had been observing birds to make the first wing and the point where we observe whales to enhance them is pretty good. Because as you said, nature got millions of years to perfect those "design" so for us to do it in a couple hundred years is pretty good I think! :)

Biased?

[Anonymous Coward]

I don't know about you but a study like this reported by a guy named Frank Fish sounds a little biased. I would even go as far as to say it sounds a little fishy...ok maybe that was a little too far.

natural world...

[orn]

It continues to amaze me the amount of intellectual property that is lifted directly from the natural world. I see this pretty easily, I'm sure the corporate execs see it, I wish our government could see it.

There is so much yet that we have to learn about the world. It makes me wonder why protecting it isn't higher on the list of priorities for the human race.

TRIZ predicts this

[wjwlsn]

TRIZ is a step-by-step method for generating innovative solutions. That sounds stupid, I know, but bear with me. TRIZ is based on resolving contradictions between parameters... in classical TRIZ, there are 39 such parameters, mostly engineering focused. You have a contradiction when you have 2 parameters in conflict, where improving one of them makes the other worse. Your ideal solution would have BOTH improve.

Considering air flowing over an airfoil, I can see contradictions between lift (pressure, parame

As added bonus

[Felonius Thunk]

Whale flippers taste much better than airplane wings, too! A very useful side benefit for emergency landings. Despite all attempts, though, they do not in fact make very good kites.

So that's why the probe was looking for whales

[istewart]

It needed efficient atmospheric reentry vehicles. I guess George and Gracie told it to come back in a few hundred years and talk to their great-great-grandchildren.

Re:So that's why the probe was looking for whales

[Darth23]

One of the great plot hol- er, mysteries of our time hs been solved.

RTFR

[Garridan]

The report, that is: here [appliedfluids.com].

Free Willy

[Stevyn]

Well duh! Didn't anyone see that movie "Free Willy"? That whale jumped over those rocks and escaped to freedom.

But seriously though, it's good that researchers study animals because they have been perfecting flight and fluid motion for millions of years, where as we have been doing it for a hundred years.