Why don't wings have dimples?

"Peter Dohm" wrote in message
news

"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message
...
http://www.fi.edu/wright/again/wings...r/golf-01.html
description and a drawing...

...
So all of the articles agree on a couple of points, and appear to have
obtained the same photo for publication. However the Magnus Effect, while
well known to be true to every golfer (usually in a detrimental way)
appears
to be backward in some sense.

For the moment, this appears to have moved from my Solved Problems List to
my Unsolved Problems List.

Peter

Dunno, looked OK to me. If the ball is flying across your screen from right
to left think of an airfoil moving from right to left, low pressure on top,
circulation has to be clockwise in this view to accelrate the flow across
the top and decelerate it around the bottom -

"1877, British scientist P.G. Tait learned that a ball, driven with a spin
about a horizontal axis with the top of the ball coming toward the golfer
produces a lifting force. This type of spin is know as a backspin."

That would be clockwise in a view where the ball is moving from right to
left...

Note: Have you ever seen a drawing or wind tunnel picture where the object
was traveling from left to right or the air was moving from right to left?
How did we become so consistant?

--
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 com wrote in message
news:HvednScQQ67J5A3ZnZ2dnUVZ_oGdnZ2d@wideopenwest .com...


"Peter Dohm" wrote in message
news

"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in
message
...
http://www.fi.edu/wright/again/wings...r/golf-01.html
description and a drawing...

...
So all of the articles agree on a couple of points, and appear to have
obtained the same photo for publication. However the Magnus Effect,
while
well known to be true to every golfer (usually in a detrimental way)
appears
to be backward in some sense.

For the moment, this appears to have moved from my Solved Problems List
to
my Unsolved Problems List.

Peter

Dunno, looked OK to me. If the ball is flying across your screen from
right to left think of an airfoil moving from right to left, low pressure
on top, circulation has to be clockwise in this view to accelrate the flow
across the top and decelerate it around the bottom -

"1877, British scientist P.G. Tait learned that a ball, driven with a spin
about a horizontal axis with the top of the ball coming toward the golfer
produces a lifting force. This type of spin is know as a backspin."

That would be clockwise in a view where the ball is moving from right to
left...

Note: Have you ever seen a drawing or wind tunnel picture where the object
was traveling from left to right or the air was moving from right to left?
How did we become so consistant?



oops, didn't read far enough:

"The dimples also help in the generation of lift. By keeping the flow
attached, the dimples help promote an asymmetry of the flow in the wake.
This asymmetry can be seen in Figure 5. In this figure, the smoke shows the
flow pattern about a spinning golf ball. The flow is moving from left to
right and the ball is spinning in the counter-clockwise direction. The wake
is being deflected downwards. This downward deflection of the wake implies
that a lifting force is being applied to the golf ball."

This is inconsistant with my thinking and inconsistant with the top of the
ball moving towards the golfer as described earlier on the page...

--
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 wrote:


oops, didn't read far enough:

"The dimples also help in the generation of lift. By keeping the flow
attached, the dimples help promote an asymmetry of the flow in the wake.
This asymmetry can be seen in Figure 5. In this figure, the smoke shows the
flow pattern about a spinning golf ball. The flow is moving from left to
right and the ball is spinning in the counter-clockwise direction. The wake
is being deflected downwards. This downward deflection of the wake implies
that a lifting force is being applied to the golf ball."

This is inconsistant with my thinking and inconsistant with the top of the
ball moving towards the golfer as described earlier on the page...

--
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.



Somebody (NASA/University?) built a "tube wing" thing once.

The wing was a large dia tube mounted - well - like a wing.

The tube rotated - "leading edge" up to create a circulation effect.
(as the aircraft moved forward - no hovering allowed this area)

It worked, but drag was a real drag...


Just a suspicion that the lift vector of a golf ball changes in flight.

Any flight path deviation due to rotational lift vectors would be strongest
early in the flight, but decrease as velocity decays below Re(crit)(combined
forward motion plus rotational effects) and the path becomes more ballistic.

Also didja catch the "Happy Non-Hooker" ball?


Richard

cavelamb wrote:

...

Somebody (NASA/University?) built a "tube wing" thing once.

The wing was a large dia tube mounted - well - like a wing.

The tube rotated - "leading edge" up to create a circulation effect.
(as the aircraft moved forward - no hovering allowed this area)

It worked, but drag was a real drag...

Obviously they needed dimples on it...



A few years back I saw a TV show about a sailboat using he same
effect. It had big rotating column on the bow. I think the rotation
rate was adjusted to the windspeed and direction to keep the
thrust aligned astern.

--

FF

wrote:
A few years back I saw a TV show about a sailboat using he same
effect. It had big rotating column on the bow. I think the rotation
rate was adjusted to the windspeed and direction to keep the
thrust aligned astern.

I think a similar or perhaps the same boat was featured in Popular
Science magazine in the mid 1980s.

wrote:

cavelamb wrote:

...

Somebody (NASA/University?) built a "tube wing" thing once.

The wing was a large dia tube mounted - well - like a wing.

The tube rotated - "leading edge" up to create a circulation effect.
(as the aircraft moved forward - no hovering allowed this area)

It worked, but drag was a real drag...


Obviously they needed dimples on it...




I wonder if that was ever investigated....




A few years back I saw a TV show about a sailboat using he same
effect. It had big rotating column on the bow. I think the rotation
rate was adjusted to the windspeed and direction to keep the
thrust aligned astern.

"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message
news:LbydnT9K86ux5w3ZnZ2dnUVZ_tOdnZ2d@wideopenwest .com...
"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in message
news:HvednScQQ67J5A3ZnZ2dnUVZ_oGdnZ2d@wideopenwest .com...


"Peter Dohm" wrote in message
news

"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in
message
...

http://www.fi.edu/wright/again/wings...r/golf-01.html
description and a drawing...

...
So all of the articles agree on a couple of points, and appear to have
obtained the same photo for publication. However the Magnus Effect,
while
well known to be true to every golfer (usually in a detrimental way)
appears
to be backward in some sense.

For the moment, this appears to have moved from my Solved Problems List
to
my Unsolved Problems List.

Peter

Dunno, looked OK to me. If the ball is flying across your screen from
right to left think of an airfoil moving from right to left, low
pressure
on top, circulation has to be clockwise in this view to accelrate the
flow
across the top and decelerate it around the bottom -

"1877, British scientist P.G. Tait learned that a ball, driven with a
spin
about a horizontal axis with the top of the ball coming toward the
golfer
produces a lifting force. This type of spin is know as a backspin."

That would be clockwise in a view where the ball is moving from right to
left...

Note: Have you ever seen a drawing or wind tunnel picture where the
object
was traveling from left to right or the air was moving from right to
left?
How did we become so consistant?



oops, didn't read far enough:

"The dimples also help in the generation of lift. By keeping the flow
attached, the dimples help promote an asymmetry of the flow in the wake.
This asymmetry can be seen in Figure 5. In this figure, the smoke shows
the
flow pattern about a spinning golf ball. The flow is moving from left to
right and the ball is spinning in the counter-clockwise direction. The
wake
is being deflected downwards. This downward deflection of the wake implies
that a lifting force is being applied to the golf ball."

This is inconsistant with my thinking and inconsistant with the top of the
ball moving towards the golfer as described earlier on the page...

--
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.


I thought that I would be able to find a web site with the wind tunnel video
that I'm sure I've seen of this; however, for this evening at least, I must
admit that I have indeed struck out.

This is a subject that I would really like to understand; although I would
settle for a couple of good practical rules of thumb. If I happen to find
anything, I'll be sure to post it--or a link as appropriate.

Peter

Hopefully these links will help you somehow.

http://www.lessonexchange.net/Mech_E...rodynamics.pdf

http://library.thinkquest.org/10556/.../topics/22.htm

http://www.geocities.com/k_achutarao/MAGNUS/magnus.html

http://www.interactiveinstruments.co...CH%20PAPER.htm

http://mercury.pr.erau.edu/~hayasd87.../2004-06-23-W/

JP

"Peter Dohm" wrote in
t...

I thought that I would be able to find a web site with the wind tunnel
video
that I'm sure I've seen of this; however, for this evening at least, I
must
admit that I have indeed struck out.

This is a subject that I would really like to understand; although I would
settle for a couple of good practical rules of thumb. If I happen to find
anything, I'll be sure to post it--or a link as appropriate.

Peter

The Embry-Riddle link leads to someespecially fascinating discussion,
including that some efects of the dimples are related to Reynolds Number.
However, I clearly have a distance to go before understanding this
subject--even enough to safely apply any rules of thumb.

Thanks,
Peter

"JP" wrote in message
...
Hopefully these links will help you somehow.

http://www.lessonexchange.net/Mech_E...rodynamics.pdf

http://library.thinkquest.org/10556/.../topics/22.htm

http://www.geocities.com/k_achutarao/MAGNUS/magnus.html

http://www.interactiveinstruments.co...CH%20PAPER.htm

http://mercury.pr.erau.edu/~hayasd87.../2004-06-23-W/

JP

"Peter Dohm" wrote in
t...

I thought that I would be able to find a web site with the wind tunnel
video
that I'm sure I've seen of this; however, for this evening at least, I
must
admit that I have indeed struck out.

This is a subject that I would really like to understand; although I
would
settle for a couple of good practical rules of thumb. If I happen to
find
anything, I'll be sure to post it--or a link as appropriate.

Peter

Peter Dohm wrote:

The Embry-Riddle link leads to someespecially fascinating discussion,
including that some efects of the dimples are related to Reynolds Number.
However, I clearly have a distance to go before understanding this
subject--even enough to safely apply any rules of thumb.

Thanks,
Peter

"JP" wrote in message
...

Hopefully these links will help you somehow.

http://www.lessonexchange.net/Mech_E...rodynamics.pdf

http://library.thinkquest.org/10556/.../topics/22.htm

http://www.geocities.com/k_achutarao/MAGNUS/magnus.html

http://www.interactiveinstruments.co...CH%20PAPER.htm

http://mercury.pr.erau.edu/~hayasd87.../2004-06-23-W/

JP

"Peter Dohm" wrote in
. net...


I thought that I would be able to find a web site with the wind tunnel
video
that I'm sure I've seen of this; however, for this evening at least, I
must
admit that I have indeed struck out.

This is a subject that I would really like to understand; although I

would

settle for a couple of good practical rules of thumb. If I happen to

find

anything, I'll be sure to post it--or a link as appropriate.

Peter








It's a "stickyness" thing, Peter.

Air is sticky.

It sticks to surfaces.
That's what the boundry layer does.

With the tube rotating leading edge up, the air stuck to the surface of the tube
takes a free ride over the top! (maybe not really, but get the picture?)

Moving, the air attached to the surface exhibits a reduced pressure
(ohnoherewegoagain!)
Sucking the boundry layer down tighter in the process.

Note where the incomming air stream separates.

No rotation would be about centered.
But rotating UP pulls the separation point Down.

Circulation rules apply, and the trailing wake also has a downward vector.
(a result of the Lift Drag Vector)(which is probably not square with anything
but itself, and changes throughout the Lift phase of the flight).

The "Happy Non_Hooker" ball only had dimples in a band around the ball.
Line the band up vertically and smack it square - that's where it goes!
No Hook no slice, because the lift vector is only vertical.

The rules committie outlawed the Non-Hooker because (as they said) it took
the skill out of the game.




Having considered all the ramifications of this over the last few days, I'm
releived that I never took up the "sport"...