I vaguely remember reading that the optimal dimple shape was hexagonal,
rather than round, like the standard golf ball. But the PGA tends to
be conservative in adopting such a radical change. I think spin is
more related to hooking or slicing because golf balls will always
travel further than a comparable spherical ball, without dimples, even
when struck by a machine. The question, for me, is do dimples create
eddy currents of air that reduces drag at slow airspeed? Second, what
is the optimal dimple size relative to the shape of the main body.
Chris

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

I've seen a video of that, but don't recall where. However, I believe
that
you have it backward--the flow detaches earlier (from the non-spinning
golf
ball) and reduces the drag.

I am not quite sure how that might relate to wings and propellers; but I
suspect that they (wings and props) are two radically different, and
possibly opposite, phenomena.

Peter

Ok, now you've done it. You are going to make me look this up...


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

http://www.aerospaceweb.org/question...cs/q0215.shtml
with a little math and some graphs

http://turb.seas.ucla.edu/~jkim/sciam/0197moinbox3.html
plots drag as a function of Reynolds number for a golf ball and a smooth
sphere - a good starting pont if you want to dimple your nosegear strut to
reduce drag - just figure you your own Reynolds number...

That's enough. Didn't find the picture I was looking for. But I see
references to both the reduction in wake and Magnus effect that converts
the
spin into lift. Apparently both contribute to the increase in range. (and
the drawings I've seen show the boundry layer staying attached longer as I
thought.)

--
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.


It looks like I misremembered as well, since all of them show the flow
remaining attached further around the dimpled ball. However, the
explanation of top spin under "How a Golf Ball Produces Lift" in the first
link does introduce a problem, since the result of Magnus Effect seems
(intuitively) reversed from the separation issue. The author's description
of the direction of lift is consistent with the description under "Hook and
Slice" which I know (regrettably) to be absolutely true.

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