Dave,
Yes, I figured you'd correct me on that. :-) I looked at what I wrote and
thought 12/1000 is too small. Then, after the correction, I looked at an old
ball sitting on my desk which a friend remembered from the '60s (US Royal
with the inverted pyramids) in another e-mail discussion and realized it was
about that of my original 0.012" depth. My friend had been wondering about
what brand ball he played with "square" dimples, so I looked in my 90-ball
shag bag which hasn't been used more than a couple of times since I moved to
TN in 1970. Sure enough, there was one in there. Anyway, I'm sure dad told
me the 012...wherever the decimal point belongs. :-)
Bernie
[EMAIL PROTECTED]
----- Original Message -----
From: "Dave Tutelman" <[EMAIL PROTECTED]>
To: <ShopTalk@mail.msen.com>
Sent: Sunday, May 20, 2007 11:44 AM
Subject: Re: ShopTalk: Economic life of golf balls
At 11:17 AM 5/20/2007, Bernie Baymiller wrote:
Whoops! That number for dimple depth was supposed to be 0.12".
Gee, I certainly hope not! The original number your posted (0.012") is far
more likely. Consider:
(1) Your new number is 1/8". That's WAY too much for dimple depth.
(2) An article by a couple of Bridgestone engineers (see below) cites
0.2mm as typical for dimple depth. That would be 0.008", which is even
less than your 0.012" original estimate.
(3) Cochran & Stobbs "Search for the Perfect Swing" shows a graph of
dimple depth vs carry distance. It has a rounded maximum that shows little
difference over the range 0.008" to 0.012".
So I'd say your first estimate was the correct one.
About the Bridgestone article... It appears in the collection "Golf the
Scientific Way" from the early 1990s. It is by Tomita & Chikaraishi, and
is entitled "Effect of Different Dimple Patterns on Flight". Good article,
if you have an engineering or scientific background but no expertise on
aerodynamics or ball flight. Actually, that is the level of presentation
for most of the articles in that book.
Cheers!
DaveT
----- Original Message -----
From: <mailto:[EMAIL PROTECTED]>Bernie Baymiller
To: <mailto:ShopTalk@mail.msen.com>ShopTalk@mail.msen.com
Sent: Saturday, May 19, 2007 5:26 PM
Subject: Re: ShopTalk: Economic life of golf balls
Bob,
Don't know how much this applies today, but from a historical
standpoint...
When my dad was researching golf balls at Spalding & Bros. in the late
1930s, they tested many types of dimples and dimple depths. Spalding's
best ball at that time was the 100 compression Dot, tightly wound over a
liquid center with a balata cover. Dad told me the width and shape of the
dimple didn't seem to matter much, though an inverted tetrahedron was
slightly better for distance. The key to optimum ball flight was the
dimple depth, which was best at 0.012" (if I remember correctly). Dad said
that tests showed when a ball was hit about 25 times, it achieved maximum
distance because the edges of the dimples were slightly rounded off by the
pounding. That was worth about 5 extra yards. They experimented with a
"streamlined" dimple, but dad said it was so ugly that they decided it
wouldn't sell and never made any. When the dimple depth began to flatten,
the ball lost distance.
I'd guess that would still be true today, except today's cover materials
probably have more durable edges and it takes longer to "streamline" them.
I wonder how long they hold their distance myself.
Bernie
<mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED]
----- Original Message -----
From: <mailto:[EMAIL PROTECTED]>Bob Barrette
To: <mailto:ShopTalk@mail.msen.com>shop talk shop
Sent: Saturday, May 19, 2007 12:08 PM
Subject: ShopTalk: Economic life of golf balls
While everything is quiet, (not many posts of late) I thought I would pose
this question!
Has anyone, with a mechanical driving device (like Iron Byron), tested a
golf ball by hitting the same ball over and over, to determine after what
number of hits, does it starts to lose ball speed ?
My experience has been when playing the same ball for 2 rounds or more,
when I need to reach a par five in two, if I use a brand new ball, I seem
to get a much longer drive. Is it because a newer ball has not lost any of
its rebound properties, or is it just my imagination?
Would the makeup of different balls, ie. 2 piece, 3 piece, have different
results?
Inquiring minds would like to know!
Regards,
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