'Whale Tubercles" cut drag 32% on wings.

[freebeard]

By adding these you're necessarily increasing frontal area...

I think not. Plan area yes, frontal area no.

It would certainly complicate things like de-icing

https://spinoff.nasa.gov › Spinoff2007 › t_5.html
Deicing System Protects General Aviation Aircraft | NASA Spinoff
Typically, ice is removed from general aviation craft with either "weeping wing" liquid deicing systems or inflatable rubber bladders, called pneumatic boots, installed along the wings. Both of these methods have drawbacks, including the finite, limited effectiveness of the liquid deicers and the added weight and power usage of the boots.

[aerohead]

Originally Posted by Logic

My humble apologies; I misread that.


Statically; something 'Too good to be true' that is true... comes along every 30 years. (I like to look for these)
Despite the Cognitive Dissonance these Tubercles have caused in you; you're just going to have to get your head around the idea as the mounting body of evidence proving they work us undeniable and they are being adopted by industry.

Here's Harvard University:
"...Harvard University researchers have come up with a mathematical model that helps explain this hydrodynamic edge.
The work gives theoretical weight to a growing body of empirical evidence that similar bumps could lead to more-stable airplane designs, submarines with greater agility, and turbine blades that can capture more energy from the wind and water.

We were surprised that we were able to replicate a lot of the findings coming out of wind tunnels and water tunnels using relatively simple theory,” says Ernst van Nierop, a PhD candidate at the School of Engineering and Applied Sciences at Harvard. He coauthored the study with mathematics professor Michael Brenner and researcher Silas Alben..."
https://www.technologyreview.com/200...wind-turbines/

My memory is... selective at best. So when I said "Some Aero Engineer" I actually meant:
Frank Fish. A professor of biology at West Chester University.
You can read about how he discovered why whales have evolved these tubercles here:
https://www.theguardian.com/science/...lbehaviour.usa

I too grew up flying (GPL), repairing and building gliders (3 axis) and other small and experimental aircraft.
Winglets to minimize wing tip vortices were the 'talk of the town' back then and I was as surprised as you to learn (or not..?) about these tubercles.

But once you accept that evolution does not evolve things that don't give an advantage and that no matter how much wind tunnel time etc you have under your belt; you will never catch up with the time evolution has had; you may be more open to throwing some of what you thought you knew out the window!
Good luck!

As for seeing them at the airport:
As usual; there will be a 20 year hiatus while everyone waits for the patents to expire.

1) Your 'defense' of this technology is very 'telling.'
2) I invite you to revisit 'critical roughness.'
3) I invite you to dig out, from your reference library, the kinematic viscosity of air at standard conditions.
4) Since Rn 100,000 was provided in the research paper, we're free to reverse-engineer the wings velocity.
5) I ran numbers for a Piper Cherokee, with the Clark-Y 'Hershey-Bar' wing with dihedral, 6-foot chord.
6) At Rn 100,000, the aircraft velocity is 15-feet/second ( 10.27-mph )[ 10.129-knots ].
7) For a PORSCHE Taycan, of length= 195.4-inches, I calculated 3.14-mph velocity.
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7) I called my brother to confirm the flight data for the Cherokee we flew out of Van Nuys Municipal Airport, Southern, California.
* Our takeoff speed was 70-mph, @ zero flaps.
* One can nurse the Cherokee off the ground, in ground effect, @ 40-mph,zero flaps, if there are no collision hazards.
* For safety, and guarantee of rudder authority, in the case of a crosswind, or gust, the plane is landed @ 85-mph, on a 30-degree glide path, with 10-30-degrees flap. Reynolds number @ landing = 4,986,666.
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8) The PORSCHE Taycan, @ 100 km/h = Rn 9,887,037.
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9) I invite you to do your own math, with an aircraft and automobile of your own choosing, and see if, in the course of 'normal' flight or driving that, you experience Rn 100,000 for any significant temporal portion of the flight, or drive.
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10) You may also want to visit the SEARCH function over at the Aerodynamics Forum, and see if you can locate the dedicated thread on Humpback Whale tubercles we batted back and forth many years ago.
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11) At the time, Paul T. Soderman of NASA was kind enough to mail me a copy of his ' Aerodynamic Effects of Leading Edge Serrations on a Two-Dimensional Airfoil,' U.S. ARMY Air Mobility R&D Laboratory, Moffett Field, California, NASA Technical Report X-2643, September, 1972.
In this report he cites: ' The silent Flight of Owls, R.R. Graham, Journal of Royal Aeronautical Society, Volume 38, pp 837-843, 1934.
12) In April, 1974, Paul co-authored,' Investigations of Acoustic Effects of Leading-Edge Serrations on Airfoils, along with Alan S. Hersh and Richard E. Hayden, JOURNAL OF AIRCRAFT, Volume 11, No.4, pp 197-2002.
13) It appears that aeronautical engineering interest in bio-mimicry did not begin with whale-fin tubercles. And the research examined phenomena of interest not normally associated with 'aerodynamics.'
14) In the future, I'd appreciate if you address aerodynamic/ fluid mechanic materials at the 'Aerodynamics Forum,' where the SEARCH function can deliver you to our entire corpus.

[freebeard]

14) In the future, I'd appreciate if you address aerodynamic/ fluid mechanic materials at the 'Aerodynamics Forum,' where the SEARCH function can deliver you to our entire corpus.

Alternatively, one could click the Advanced link below the Search box and select Aerodynamics under Search in Forum(s).

[aerohead]

I'll try for a link.
https://ecomodder.com/forum/showthre...edge-1315.html

[Logic]

https://www.abmhydro.com/humpback-wh...ing-edge-tuber

[hat_man]

Not wanting to be the uneducated latecomer to this “discussion” but as for the “xxx years of evolution…” angle I do have a comment.

The evolution of these tubercles occur on an animal that lives its entire existence in the water, not in the air. Are we trying to say these tubercles would somehow be a benefit to thing’s (I don’t know……vehicles?) that only spend their entire existence moving through the air and not the water? Do we find these tubercles on birds or other similar animals that move through the air?

I assume there are similarities in aero dynamics and fluid dynamics, (I’m not smart enough to state this as fact) but are they the same? Do the findings of one directly apply to the other?

I can agree with evolution, but why didn’t “air creatures” develop these these tubercles if it cuts drag by that much? “Air creatures” would be able to fly faster and use less energy with tubercles, right?

Just my .02

[freebeard]

Do we find these tubercles on birds or other similar animals that move through the air?

Insects get pretty gnarly. But different animals may have no way to express the feature. A dragonfly's exoskeleton is malleable, but the flat wing structure may not be. Birds have feathers on their wing's leading edge that are active aero.

I assume there are similarities in aero dynamics and fluid dynamics, (I’m not smart enough to state this as fact) but are they the same? Do the findings of one directly apply to the other?

It's all one thing. The only difference is the Reynolds (no apostrophe) Number. A gnat swims in air like a fish does in water.

[hat_man]

I guess in a sense that’s my point.

If the evolution of tubercles is good (and aero and fluid dynamics being similar) then why don’t we see the same evolutionary process on “air creatures”? My assumption is that this evolution benefits only “water creatures” and not “air creatures”. And, somewhat by extension, this particular type evolution isn’t a benefit for vehicles that move through the air.

There’s always the exception to the rule (possibly insects with an exoskeleton), but if it doesn’t benefit birds, bats, etc., then how does it benefit vehicles?

[Logic]

Originally Posted by hat_man

I guess in a sense that’s my point.

If the evolution of tubercles is good (and aero and fluid dynamics being similar) then why don’t we see the same evolutionary process on “air creatures”? My assumption is that this evolution benefits only “water creatures” and not “air creatures”. And, somewhat by extension, this particular type evolution isn’t a benefit for vehicles that move through the air.

There’s always the exception to the rule (possibly insects with an exoskeleton), but if it doesn’t benefit birds, bats, etc., then how does it benefit vehicles?

You make a very good point hat_man.

At a guess I would say that birds etc have so much control over wing shape and angle of attack etc that evolution found tubercles not worth the trouble.
Then there's all the flapping too!

ie: Evolution found it difficult to justify 'lumpy' bone or musculature over weight savings and the convenience of being able to fold wings into a compact body hugging shape.

Then, thx to feathers, birds evolved an alternate way to keep wings flying , with low drag at high angles of attack:
https://ecomodder.com/forum/showthre...car-41629.html

Aircraft and cars don't have these considerations and the skin is a large part of their structural strength, making tubercles practical in their design.

NB freebeard's post and mine above it on page 1, where the car cabin sits where there would normally be an area of turbulence anyway in Tubercle theory, while airflow should remain more attached further back than usual, over the smooth surfaces.
That seems to be what Tuberlces do; keep flow attached for longer behind the 'humps', while turbulence starts were it normally would behind the 'hollows'...

I'm no expert either and am more interested in people keeping an open mind to new discoveries.
Especially one's that are easy to test for oneself, like the flappa-doodats linked above and even DBD.

[freebeard]

NB freebeard's post and mine above it on page 1, where the car cabin sits where there would normally be an area of turbulence anyway in Tubercle theory, while airflow should remain more attached further back than usual, over the smooth surfaces.

It' still page one for me, until Post #41.

I showed the Lotus Eleven, here's the Volkhart Sagitta. The whole cabin is a tubercle.



One of these rendered in fiberglass would drop right onto my 1971 Beetle floorpan. Do those front turn signal housings act as a fence or windsplit?