Undulating Skin Results In 50% Less Drag

If this technique can be adapted to gliders and other aircraft,
imagine the enabling effect it will produce:



http://technology.newscientist.com/c...-and-subs.html
Shape-shifting skin to reduce drag on planes and subs

* 13:30 16 April 2008
* NewScientist.com news service
* Colin Barras

Engineers have shown skin able to tune its wrinkles could cut
dramatically cut drag on submarines or planes (Image: IOP)
Engineers have shown skin able to tune its wrinkles could cut
dramatically cut drag on submarines or planes (Image: IOP)

Aircraft or submarines covered with an undulating skin able to
change at a flick of a button would experience 50% less drag than
conventional vehicles. This trick, which naturally occurs in
dolphins, is now being tested by human engineers.

Turbulence is the bane of engineers' lives. Chaotic air flow sets
up unstable vortices and patterns in gases and liquids, increasing
friction and drag.

Giving craft skin than can tweak its surface to impose order on
these currents could dramatically cut the effect of drag, says
Dimitris Lagoudas at Texas A&M University, US. Calming the chaotic
waves makes them interact less with the skin. "The particles in
the fluid stop "speaking" to the craft’s surface," he says.

Lagoudas and colleagues have worked out that wrinkling the surface
of a craft in the right way can cut problems. The surface must
assume the shape of the ideal ordered surface wave it is trying to
create, something that changes at different velocities.

Dolphin trick

It might seem counterintuitive to reduce drag by wrinkling the
surface of a craft, but nature provides a precedent. "Dolphins
induce their skin to wrinkle, so water won’t stick to them," says
Lagoudas.

After calculating that this approach would work, his team tested
designs for an "active skin" that shifts to ...

More...
http://technology.newscientist.com/c...-and-subs.html

On Apr 21, 12:57*pm, Larry Dighera wrote:
If this technique can be adapted to gliders and other aircraft,
imagine the enabling effect it will produce:

http://technology.newscientist.com/c...-shapeshifting...
* * * * Shape-shifting skin to reduce drag on planes and subs

* * * * * 13:30 16 April 2008
* * * * * NewScientist.com news service
* * * * * Colin Barras

* * Engineers have shown skin able to tune its wrinkles could cut
* * dramatically cut drag on submarines or planes (Image: IOP)
* * Engineers have shown skin able to tune its wrinkles could cut
* * dramatically cut drag on submarines or planes (Image: IOP)

* * Aircraft or submarines covered with an undulating skin able to
* * change at a flick of a button would experience 50% less drag than
* * conventional vehicles. This trick, which naturally occurs in
* * dolphins, is now being tested by human engineers.

* * Turbulence is the bane of engineers' lives. Chaotic air flow sets
* * up unstable vortices and patterns in gases and liquids, increasing
* * friction and drag.

* * Giving craft skin than can tweak its surface to impose order on
* * these currents could dramatically cut the effect of drag, says
* * Dimitris Lagoudas at Texas A&M University, US. Calming the chaotic
* * waves makes them interact less with the skin. "The particles in
* * the fluid stop "speaking" to the craft’s surface," he says.

* * Lagoudas and colleagues have worked out that wrinkling the surface
* * of a craft in the right way can cut problems. The surface must
* * assume the shape of the ideal ordered surface wave it is trying to
* * create, something that changes at different velocities.

* * Dolphin trick

* * It might seem counterintuitive to reduce drag by wrinkling the
* * surface of a craft, but nature provides a precedent. "Dolphins
* * induce their skin to wrinkle, so water won’t stick to them," says
* * Lagoudas.

* * After calculating that this approach would work, his team tested
* * designs for an "active skin" that shifts to ...

More...http://technology.newscientist.com/c...-shapeshifting...

Yesterday I was talking about something like this with my CFI and we
discussed the idea of dimpling an airplane like a golf ball. The
upper surfaces of the wings would remain smooth but the fuselage and
undersides of the wing would be dimpled to reduce drag.

"es330td" wrote in message
...
...

Yesterday I was talking about something like this with my CFI and we
discussed the idea of dimpling an airplane like a golf ball. The
upper surfaces of the wings would remain smooth but the fuselage and
undersides of the wing would be dimpled to reduce drag.

.................................................. .............................................

That only works on roundish things (helps keep the boundry layer attached as
you start around the back) and only for a limited range of reynolds numbers.
It won't work for your fuselage or the bottom of the wings.
Might work for round gear legs depending on the diameter and your airspeed.

Sailplanes do use "turbulator" tape to keep the boundry attached, but it is
applied only at specific locations.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
news:FuydnYfqHpzOvJDVnZ2dnUVZ_remnZ2d@wideopenwest .com:

"es330td" wrote in message
.
.. ...

Yesterday I was talking about something like this with my CFI and we
discussed the idea of dimpling an airplane like a golf ball. The
upper surfaces of the wings would remain smooth but the fuselage and
undersides of the wing would be dimpled to reduce drag.


There's tape you can get for airplanes as well. It's aplied to the upper
surface of wings, in fact, as well as struts and just about anything else
you care to stick it to, even props.


Bertie

"Bertie the Bunyip" wrote in message
...
"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
news:FuydnYfqHpzOvJDVnZ2dnUVZ_remnZ2d@wideopenwest .com:

"es330td" wrote in message
.
.. ...

Yesterday I was talking about something like this with my CFI and we
discussed the idea of dimpling an airplane like a golf ball. The
upper surfaces of the wings would remain smooth but the fuselage and
undersides of the wing would be dimpled to reduce drag.


There's tape you can get for airplanes as well. It's aplied to the upper
surface of wings, in fact, as well as struts and just about anything else
you care to stick it to, even props.


Bertie

"Maxwell" luv2^fly99@cox.^net wrote in
:


"Bertie the Bunyip" wrote in message
...
"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
news:FuydnYfqHpzOvJDVnZ2dnUVZ_remnZ2d@wideopenwest .com:

"es330td" wrote in message
news:991c8471-6955-4565-890e-167de27c4999
@m36g2000hse.googlegroups.co
m. .. ...

Yesterday I was talking about something like this with my CFI and we
discussed the idea of dimpling an airplane like a golf ball. The
upper surfaces of the wings would remain smooth but the fuselage and
undersides of the wing would be dimpled to reduce drag.


There's tape you can get for airplanes as well. It's aplied to the
upper surface of wings, in fact, as well as struts and just about
anything else you care to stick it to, even props.


Bertie






Snort!

God you're dummmmmmmm.


Bertie

"Bertie the Bunyip" wrote in message
...
"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
news:FuydnYfqHpzOvJDVnZ2dnUVZ_remnZ2d@wideopenwest .com:

"es330td" wrote in message
.
.. ...

Yesterday I was talking about something like this with my CFI and we
discussed the idea of dimpling an airplane like a golf ball. The
upper surfaces of the wings would remain smooth but the fuselage and
undersides of the wing would be dimpled to reduce drag.


There's tape you can get for airplanes as well. It's aplied to the upper
surface of wings, in fact, as well as struts and just about anything else
you care to stick it to, even props.


Bertie

Gee, I think I mentioned turbulator tape. Didn't I...

But of course, some MXwannaboi trimmed off my entire reply. Hmmmmm

Now, can you explain to the class what effect sticking this tape to "just
about anything else you care to stick it to," is going to have on drag?

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
news:vJSdnYfBN9CF2pDVnZ2dnUVZ_gudnZ2d@wideopenwest .com:

"Bertie the Bunyip" wrote in message
...
"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
news:FuydnYfqHpzOvJDVnZ2dnUVZ_remnZ2d@wideopenwest .com:

"es330td" wrote in message
news:991c8471-6955-4565-890e-167de27c4999
@m36g2000hse.googlegroups.co
m. .. ...

Yesterday I was talking about something like this with my CFI and we
discussed the idea of dimpling an airplane like a golf ball. The
upper surfaces of the wings would remain smooth but the fuselage and
undersides of the wing would be dimpled to reduce drag.


There's tape you can get for airplanes as well. It's aplied to the
upper surface of wings, in fact, as well as struts and just about
anything else you care to stick it to, even props.


Bertie

Gee, I think I mentioned turbulator tape. Didn't I...

Yes, but this stuff is different. it's perforated a-la golf ball as
opposed to the zig zag stuf they use on gliders.

But of course, some MXwannaboi trimmed off my entire reply. Hmmmmm


Oh brother.


Now, can you explain to the class what effect sticking this tape to
"just about anything else you care to stick it to," is going to have
on drag?



Well, the dimples form a very shallow turbulent layer that paadoxically
aids in the adherence of the boundary layer to the surface thus reducing
turbulence and as a result, drag as well.


Happy now or would you like me to call you a name as well?


Bertie

On Mon, 21 Apr 2008 16:57:03 GMT, Larry Dighera
wrote:


If this technique can be adapted to gliders and other aircraft,
imagine the enabling effect it will produce:



http://technology.newscientist.com/c...-and-subs.html
Shape-shifting skin to reduce drag on planes and subs

* 13:30 16 April 2008
* NewScientist.com news service
* Colin Barras

Engineers have shown skin able to tune its wrinkles could cut
dramatically cut drag on submarines or planes (Image: IOP)
Engineers have shown skin able to tune its wrinkles could cut
dramatically cut drag on submarines or planes (Image: IOP)

Aircraft or submarines covered with an undulating skin able to
change at a flick of a button would experience 50% less drag than
conventional vehicles. This trick, which naturally occurs in
dolphins, is now being tested by human engineers.

Turbulence is the bane of engineers' lives. Chaotic air flow sets
up unstable vortices and patterns in gases and liquids, increasing
friction and drag.

Giving craft skin than can tweak its surface to impose order on
these currents could dramatically cut the effect of drag, says
Dimitris Lagoudas at Texas A&M University, US. Calming the chaotic
waves makes them interact less with the skin. "The particles in
the fluid stop "speaking" to the craft’s surface," he says.

Lagoudas and colleagues have worked out that wrinkling the surface
of a craft in the right way can cut problems. The surface must
assume the shape of the ideal ordered surface wave it is trying to
create, something that changes at different velocities.

Dolphin trick

It might seem counterintuitive to reduce drag by wrinkling the
surface of a craft, but nature provides a precedent. "Dolphins
induce their skin to wrinkle, so water won’t stick to them," says
Lagoudas.

After calculating that this approach would work, his team tested
designs for an "active skin" that shifts to ...

More...
http://technology.newscientist.com/c...-and-subs.html

************************************************** ************
Didn't one or more of the America's Cup sail boats have something like
this in one of the last sail off's?

Big John

"Big John" wrote in message
...
...

************************************************** ************
Didn't one or more of the America's Cup sail boats have something like
this in one of the last sail off's?

Big John



They have tried a textured surface (more than a couple races ago) but the
rules were changed again to outlaw this sort of thing (along with surface
tension modifiers that you drip into the water at the bow).

I don't believe that the "shape shifting" idea has been attempted in real
life - But you are right, it's not exactly a new idea.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.