Shark-inspired turbulators increase L/D X 3

Interesting research!
https://www.eurekalert.org/pub_relea...-uss020618.php

Will be interesting to see how and where this goes. You can take a bad airfoil section and make it better with vortex generators, but that doesn't mean this research will help already good designs.

Golf balls get better if dimpled, but that only works on spheres and cylinders, not wings, fuselages and tails.

Anyone else remember a previous iteration on a "sharkskin" for increasing laminar flow from back in the 80s? Even pictures in SOARING!

Steve Leonard

At 15:57 07 February 2018, Soartech wrote:
Interesting research!
https://www.eurekalert.org/pub_releases/2018-02/hjap-
uss020618.php

3M corporation has patents on several of these concepts. They own
the patent on V shaped grooves in the surface which was also
derived from shark skin research. I have a cousin who has worked
in the 3M thin film research department. There are a number of
these drag reduction applications that should work in theory. The
kicker is the adhesive used to bond these applications to surfaces.
To my knowledge, 3M has been sitting on these patents for quite a
number of years awaiting an adhesive that will withstand the
extreme temperature and friction variations to be able to safely
apply these types of films across a broad enough spectrum of
aircraft to make production economically viable. If 3M doesn't
have the right adhesives, then I don't know who does.. There is
also the problem of keeping these micro sized things clean and
undamaged by normal usage.

RO

On Wednesday, February 7, 2018 at 7:57:56 AM UTC-8, Soartech wrote:
Interesting research!
https://www.eurekalert.org/pub_relea...-uss020618.php

If this works so well, every swimmer would be using it. It was tried and was not very effective due to we do not have the right basic fish shaped body. We just now have the right tools in 3D printing to sub micron accuracy to explore this space. The limits now are in the minds of the designer, well not entirely. Simulation tools and iterative design methods could help.

Maybe we will see the molds to make our wings go from the aesthetically pleasing mirror finish to some new regime.

BTW...golf ball dimples reduce drag and provide better directionality, by creating a turbulent decoupling boundary layer. Shark skin could have similar properties, just on much smaller scales where the Reynolds numbers are important.

Cool concept, maybe not the "mass production" to go beyond small scale testing to 15M+ wing spans.
I believe currently, modern sailplane airfoils are laminar to about 90+%, the gains listed would gain very little likely diminished by the care to keep them working.
Yes, I remember the talk about doing similar in swimmer suits, lots of variables and cost.
Did it gain anything? I don't know.
Sometimes "thinking" you have an advantage MAKES an advantage.

Is it worth watching?
Yes.
Do I think it's a game changer for newer sailplane airfoils?
Nope.

Then again, I usually give up 10%+ just due to the "nut behind the stick", so this technology is not enough to give me a woody.

On Thu, 08 Feb 2018 08:50:35 -0800, BG wrote:

On Wednesday, February 7, 2018 at 7:57:56 AM UTC-8, Soartech wrote:
Interesting research!
https://www.eurekalert.org/pub_relea...-uss020618.php

If this works so well, every swimmer would be using it.

Quite so: in this quote from the article "demonstrated a new, bioinspired
structure that could improve the aerodynamic performance of planes, wind
turbines, drones and cars." the give-away word is:

'could'

I see this sort of article almost every week in New Scientist. You never
see a follow-up article, mainly because 'could' seems to mean:

"one of our MSc student's micro-scale experiments showed a 0.2%
improvement over current technology. With any luck it will work even
better after we've scaled it up to a usable size and we'll get a huge
grant to help us set up a spin-off company and sell stuff to the
military".

But, of course it usually doesn't work worth a damn when scaled up and is
never heard of again. For some reason the subject of the article is
usually going revolutionise aerodynamics or battery technology.

Sinha Technology wing surface treatment, anybody?


--

On Thursday, February 8, 2018 at 2:21:32 PM UTC-5, Kiwi User wrote:
On Thu, 08 Feb 2018 08:50:35 -0800, BG wrote:


Sinha Technology wing surface treatment, anybody?


--

Anyone know what ever happened. Seemed to be very active for about 2 years.
http://www.sinhatech.com/

Cold Fusion?

On Thursday, February 8, 2018 at 2:32:17 PM UTC-5, Papa3 wrote:
On Thursday, February 8, 2018 at 2:21:32 PM UTC-5, Kiwi User wrote:
On Thu, 08 Feb 2018 08:50:35 -0800, BG wrote:


Sinha Technology wing surface treatment, anybody?


--

Anyone know what ever happened. Seemed to be very active for about 2 years.
http://www.sinhatech.com/

Cold Fusion?

Drag reduction claims, when broken down to various components, showed the wing profile drag resulting from evaluation of data in the claims, to be below 0.
Snake oil.
UH

At 19:32 08 February 2018, Papa3 wrote:
On Thursday, February 8, 2018 at 2:21:32 PM UTC-5, Kiwi User
wrote:
On Thu, 08 Feb 2018 08:50:35 -0800, BG wrote:


Sinha Technology wing surface treatment, anybody?


--

Anyone know what ever happened. Seemed to be very active for
about 2
years.
http://www.sinhatech.com/

Cold Fusion?

No. I told them about the 3M patents and the problem with
adhesives to cover the broad temperature spectrum. I think he
was hoping to sell it for high altitude UAV applications among
others.

RO

On Wednesday, February 7, 2018 at 9:57:56 AM UTC-6, Soartech wrote:
Interesting research!
https://www.eurekalert.org/pub_relea...-uss020618.php

The title says it all, Turbulators. hese are devices for turbulent flows. Sharkskin, V-shaped riblets, mini vortex generators are all devices that can lower drag in turbulent flows, or delay separation for specific conditions. The airfoils of high performance gliders are designed to maintain as much laminar flow on them as possible, since the friction drag on the surface in laminar flow is far less than that of turbulent flow.

A mini VG, turbulator, or zigzag tape might be useful to eliminate a long-bubble separation where the flow transitions from laminar to turbulent, but modern airfoil design typically tries to avoid these bubbles, and thus makes those devices unnecessary.

Just use good laminar flow airfoils....