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"...