Undulating Skin Results In 50% Less Drag

"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.

"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
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"Bertie the Bunyip" wrote in message
...
"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
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"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

"Bertie the Bunyip" wrote in message
.. .
"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.



Totally incorrect, Bertie Buttlick.

"Maxwell" luv2^fly99@cox.^net wrote in news:WSbPj.110302$Ft5.69371
@newsfe15.lga:


"Bertie the Bunyip" wrote in message
.. .
"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.



Totally incorrect, Bertie Buttlick.


Nope.


Bertie

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

...
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.


So if I stick this on my propeller (or "just about anything else you care
to stick it to," ) I am going to reduce 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.

On Mon, 21 Apr 2008 14:31:15 -0500, Big John
wrote in :

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

Is this it?


http://www.newscientist.com/article/...fect-skin.html
Researchers have known for years that fast-swimming sharks are
covered with renewable scales, called dermal denticles, that have
microscopic ridges. Just what these ridges did was a mystery until
the 1980s when specialists in aerodynamics developed a way of
smoothing turbulent flow using microscopic surface grooves that
are aligned with the movement of fluid. These grooves are called
riblets. "There are very close connections between riblets and
shark skins," says Kwing-So Choi, a mechanical engineer at the
University of Nottingham specialising in drag reduction.

Riblets work by making turbulence more ordered near the surface.
"They are like tiny fences that prevent the lateral movement of
turbulence across the flow," says Choi. While any lateral movement
is hindered, any flow that is parallel with the riblets continues
unabated. "If you optimise the size and shape of the riblets, a
drag reduction of up to 10 per cent is possible."

Riblets have already been tested in real applications. Their
biggest claim to fame was as a putative contributor to the sailing
coup in 1987 when the US won the America's Cup, the prestigious
yachting trophy. The American boat had a riblet coating on its
hull, a development that was later banned by race officials. Other
mariners have been slow to follow suit because riblets are easily
clogged by microscopic marine debris. A more promising application
is in aircraft, where fouling is less of a problem. Such riblets
are already in use on some commercial airliners.


It sounds different from the active skin in the more recent article.

"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in
:

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

...
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.


So if I stick this on my propeller (or "just about anything else you
care to stick it to," ) I am going to reduce drag?



Apparently. I have an article about it somewhere. the prop installation
was problematic and not STC'd for certified aircraft. It tended to peel,
apparently. They were featured in Sport Aviation a few years ago.


Bertie

Larry Dighera wrote in
:

On Mon, 21 Apr 2008 14:31:15 -0500, Big John
wrote in :

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

Is this it?


http://www.newscientist.com/article/...-secrets-of-a-
perfect
-skin.html
Researchers have known for years that fast-swimming sharks are
covered with renewable scales, called dermal denticles, that have
microscopic ridges. Just what these ridges did was a mystery until
the 1980s when specialists in aerodynamics developed a way of
smoothing turbulent flow using microscopic surface grooves that
are aligned with the movement of fluid. These grooves are called
riblets. "There are very close connections between riblets and
shark skins," says Kwing-So Choi, a mechanical engineer at the
University of Nottingham specialising in drag reduction.

Riblets work by making turbulence more ordered near the surface.
"They are like tiny fences that prevent the lateral movement of
turbulence across the flow," says Choi. While any lateral movement
is hindered, any flow that is parallel with the riblets continues
unabated. "If you optimise the size and shape of the riblets, a
drag reduction of up to 10 per cent is possible."

Riblets have already been tested in real applications. Their
biggest claim to fame was as a putative contributor to the sailing
coup in 1987 when the US won the America's Cup, the prestigious
yachting trophy. The American boat had a riblet coating on its
hull, a development that was later banned by race officials. Other
mariners have been slow to follow suit because riblets are easily
clogged by microscopic marine debris. A more promising application
is in aircraft, where fouling is less of a problem. Such riblets
are already in use on some commercial airliners.


It sounds different from the active skin in the more recent article.


It is and it isn't. The riblets on shark skins are more closely related
to vortex generators.



Bertie