Bernie: how is your new Kidney doing? Hope you are getting along with it in prime shape.
HStill
-------------- Original message --------------
> Pat and all,
>
> You lost me on the math, but I can read graphs pretty well. Back in the late
> 1930s, Spalding had Edgerton of MIT and a couple others of his staff do a
> lot of ultra high speed photography of Bobby Jones' and Jimmy Thompson's
> swings (Jimmy was the longest hitting pro at that time) as well as the
> swings of several ordinary golfers (Dad, who was a 2 handicap golfer at the
> time, and J. Victor East, who was considerably higher). From the information
> on these photos, acceleration and velocity were circle-graphed from the
> beginning of the downswing to the end of the followthrough.
>
> Without exception, the graphs show very little increase in velocity or
> acceleration after 40� from impact (about 7:30 with impact at 6:00) and a
> considerable drop in acceleration to 0 at impact...from about 2000> ft/sec/sec to 0 in the last 10�.
>
> In the better players, like Jones, the swing velocity has a very slight
> increase and acceleration is almost dead-flat from 7:30 and drops off late
> about 6:30. Poorer players velocity flattens sooner. It's interesting that
> comparing Jones' swing with a 2-iron and a wood, which incidentally are very
> similar swing patterns, clubhead velocity is about 12 ft/sec slower in the
> 2-iron. Maybe the effects of shorter club length and higher club weight?
>
> Bernie
> Write to: [EMAIL PROTECTED]
>
>
>
>
>
>
> ----- Original Message -----
> From: <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, October 14, 2004 10:32 AM
> Subject: Re: RE: ShopTalk: long drive
>
>
> > You're correct, if you assume that the force applied to the ball is not
&g! t; changing. There are many tour pros whose smash factors don'! t fit th e
> equations - pundits will say their clubs fail COR, but the data for many
> pros is similar to David D.'s. The equations don't work, and we know that
> they hit the ball on the center of the face.
> >
> > Baseball and golf are very similar in this respect - the force applied to
> the club (or bat) changes through the swing, and resulting ball speeds ARE
> different when clubhead (or bat) speeds are equal. It's not the same as the
> 'balls suspended by strings' collision, or the 'billard ball' collision -
> the force applied to the club is changing (increasing for a good player) as
> impact approaches.
> >
> > Answer this:
> > If the impact velocity for 2 players is equal and 1 has accelerated from
> the top and is coasting through impact while the other starts slowly and
> accererated through the ball, which one hits it further????
> >
>! > Or....
> >
> > If a moving car hits a stopped car at 35mph, will the collision be
> different if the moving car is accelerating to 35mph, coasting at 35mph, or
> decelerating from a higher speed??
> >
> > Again, I'm prolly wasting my breath with the 'expert' here.
> >
> > Pat K
> >
> > >
> > > From: "Childers, Tedd A" <[EMAIL PROTECTED]>
> > > Date: 2004/10/14 Thu AM 09:45:44 EDT
> > > To: [EMAIL PROTECTED]
> > > Subject: RE: ShopTalk: long drive
> > >
> > > Pat,
> > >
> > > I'm no physics expert, but I believe that the collision between a golf
> ball
> > > and a clubhead is represented by the conservation of momentum equation
> > > (M1V1=M2V2, in a perfect collision with no loss of energy), which is
> based
> &! gt; > on mass and velocity, not acceleration. Of course the! collisi on between
> a
> > > golf ball and a clubhead is not a perfect collision, as there are other
> > > factors involved (COR of clubhead for example), which makes the equation
> a
> > > bit more complicated (see equation below). Clubhead acceleration
> probably
> > > is a very important factor to measure to determine proper shaft
> stiffness
> > > (i.e shaft lab), but I believe that Dave T. is correct when he says that
> > > acceleration at impact has nothing to do with ball velocity.
> > >
> > > Tedd
> > >
> > >
> > >
> > >
> > > From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]
> > > Behalf Of The Kelley's
> > > Sent: Thursday, October 14, 2004 7:43 AM
> > > To: [EMAIL PROTECTED]
> > > Subject:! RE: ShopTalk: long drive
> > >
> > >
> > >
> > > David,
> > > You're welcome to follow both Dave T and Lloyd, both of whom 'know' so
> much
> > > about the golf swing.... The folks on tour have been measuring
> acceleration
> > > for many years, but according to Dave T (and hid 'bible' on the golf
> swing
> > > that many modern experts on this game threw in the trash years ago),
> > > acceleration has nothing to do with ball speed. Last I checked, basic
> > > physics says force = mass x acceleration, but I'm sure we'll see many
> > > reasons why this doesn't apply to golf.
> > >
> > > I guess I'd forgotten why I don't post here - the 'expert' (who has
> > > apparently never earned a dime in the golf business) is not woth my
> > > breath.....
> > > !
> > > Good luck in your fact finding - you seem b! oth inte lligent and open
> minded,
> > > both of which will allow you to make progress.
> > >
> > > Pat K
> > >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]
> > > Behalf Of [EMAIL PROTECTED]
> > > Sent: Thursday, October 14, 2004 2:19 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: ShopTalk: long drive
> > >
> > >
> > > In a message dated 10/13/2004 2:28:28 PM Pacific Daylight Time,
> > > [EMAIL PROTECTED] writes:
> > >
> > >
> > >
> > >
> > > At 07:50 AM 10/12/04 -0400, The Kelley's wrote:
> > > >You need to have acceleration information for each combination to
> evaluate
> > > >the data - I'd expect that! the longer shaft is allowing the player to
> > > >accelerate the clubhead a bit more as impact approaches than the other
> > > >drivers, thereby imparting a bit more force to the ball. I'll offer
> that
> > > >the 5g difference in clubheads in your test is not significant with
> > > >respect to the force imparted on the ball, as seen in the #2 and #4
> test
> > > data.
> > >
> > > Sorry, but I have to disagree with both assertions.
> > >
> > > The formula for ball velocity (ignoring centeredness of the hit and
> loft) is
> > >
> > > Vb = Vc*(1 + COR) / (1 + Mb/Mc)
> > >
> > > Ref: Cochran &Stobbs "Search for the Perfect Swing", but most of it is
> > > derivable from basic freshman physics.
> > >
> > > Note that there is no component! of acceleration at impact involved, and
> > > th! ere shou ldn't be.
> > >
> > > But the clubhead mass does make a difference, small but not completely
> > > negligible. The difference between 195g and 200g should be worth about
> > > 1/2%, or 1mph at the ball speeds involved.
> > >
> > > (BTW, those who look will notice that my numbers are very different from
> > > those that Lloyd just posted. We agree completely that mass matters and
> > > acceleration at impact doesn't, but disagree considerably on just how
> much
> > > mass matters.)
> > >
> > > Let's try out this formula for each of the drivers, to see whether
> > > something else is going on...
> > >
> > > driver 1 2 3 4
> > > >avg chs 142 148 148 150
> > > >avg bs 206 198 198 202
> > > >club length 50" 48" 48" 48"
> > > >spin ! rate 2100 2100 2200 2400
> > > >hd wt 200gr 195gr 195gr 200gr
> > > >launch a 11.5 12 12.5 12.5
> > > >hd vol 455cc 444cc 450cc 400cc
> > > >my smash # 1.45 1.33 1.33 1.34
> > >
> > > Let's assume that, for all four drivers:
> > > * The COR for the hit is 0.83, the legal limit.
> > > * The hit is in the center of the clubface.
> > > * The balls are all the same mass; we'll use 46g.
> > >
> > > Driver #1:
> > > Vb = 142(1.83) / (1 + 46/200) = 211mph (actual 206)
> > > Driver #2:
> > > Vb = 148(1.83) / (1 + 46/195) = 219mph (actual 198)
> > > Driver #3:
> > > Vb = 148(1.83) / (1 + 46/195) = 219mph (actual 198)
> > > Driver #4:
> > > Vb = 150(1.83) / (1 + 46/200) = 223mph (actual 202)
> > >
> > > So only drive! r #1 is anywhere near what the theory says it should be
&g! t; able
> > > to get. #1 is off by 2.5%, which is a pretty significant difference for
> a
> > > long driver -- it corresponds to ten yards or more for those guys. The
> > > other three drivers are only achieving about 90% of what the theory says
> > > they should. Something is wrong here, and something serious.
> > >
> > > Let's look at a few possibilities:
> > >
> > > (1) Are the assumptions correct? In particular, did somebody use impact
> > > tape to verify that all measurements were on centered hits?
> > >
> > > (2) Did somebody measure the COR of each driver using the type of ball
> used
> > > in the range tests? (I doubt it; the drivers were undoubtedly tested
> using
> > > the USGA pendulum test.) I know I disagree with Lloyd on lots of things,
> > > but his comment about a cl! ubhead/ball match is a real possibility. In
> 1998,
> > > Dick Helmstetter said in my presence -- and Alastair Cochran's as
> well --
> > > that they were looking at the opportunities for extra distance by
> matching
> > > balls to clubheads. Most of their effort was based on matching resonant
> > > frequencies, as Lloyd mentioned. Not at all an outrageous consideration.
> > >
> > > (3) Somebody mentioned a difference in loft or launch angle. That might
> > > make a substantial difference in distance, but the difference in ball
> speed
> > > would be small but measurable. The difference between 11.5 and 12.5
> degrees
> > > would be under 1/2%, or less than 1mph. So that isn't the problem.
> > >
> > > >Any ideas on what can be concluded from this data?
> > >
> > > My con! clusion is that there is some VERY significant difference from!
> ; test
> > > to test. I don't know if it's something about the club itself or how it
> is
> > > being swung (and impacting the ball), but this is not apples and apples.
> > >
> > > David, I know we've discussed this before (via private email) with other
> > > drivers. But those tests were a lot closer to the theory. Yes, they
> > > confounded the direction the theory says they should go, but they were
> > > closer. This is WAY off.
> > >
> > > DaveT
> > >
> > >
> > >
> > >
> > > Thanks,
> > > Dave and all that responded,
> > > Im sure that we are all a hold of a piece of the grail, there is no
> doubt a
> > > point of diminishing return and finding it is easier for some than most.
> > > For the acceleration data I believe Pat may b! e on to something.
> > > If you can imagine the acceleration curve as an upside down v and pick a
> > > clubhead speed such as 100 mph and imagine it at the peak of the V, and
> if
> > > you can further imagine that at just before the peak and just after the
> peak
> > > you have a clubhead speed of 99 mph I would expect that you would
> achieve a
> > > higher ball speed at 99 prior to the peak than you would after it.
> > >
> > >
> > >
> >
> >
>
>
> Pat and all,
>
> You lost me on the math, but I can read graphs pretty well. Back in the late
> 1930s, Spalding had Edgerton of MIT and a couple others of his staff do a
> lot of ultra high speed photography of Bobby Jones' and Jimmy Thompson's
> swings (Jimmy was the longest hitting pro at that time) as well as the
> swings of several ordinary golfers (Dad, who was a 2 handicap golfer at the
> time, and J. Victor East, who was considerably higher). From the information
> on these photos, acceleration and velocity were circle-graphed from the
> beginning of the downswing to the end of the followthrough.
>
> Without exception, the graphs show very little increase in velocity or
> acceleration after 40� from impact (about 7:30 with impact at 6:00) and a
> considerable drop in acceleration to 0 at impact...from about 2000
>
> In the better players, like Jones, the swing velocity has a very slight
> increase and acceleration is almost dead-flat from 7:30 and drops off late
> about 6:30. Poorer players velocity flattens sooner. It's interesting that
> comparing Jones' swing with a 2-iron and a wood, which incidentally are very
> similar swing patterns, clubhead velocity is about 12 ft/sec slower in the
> 2-iron. Maybe the effects of shorter club length and higher club weight?
>
> Bernie
> Write to: [EMAIL PROTECTED]
>
>
>
>
>
>
> ----- Original Message -----
> From: <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, October 14, 2004 10:32 AM
> Subject: Re: RE: ShopTalk: long drive
>
>
> > You're correct, if you assume that the force applied to the ball is not
&g! t; changing. There are many tour pros whose smash factors don'! t fit th e
> equations - pundits will say their clubs fail COR, but the data for many
> pros is similar to David D.'s. The equations don't work, and we know that
> they hit the ball on the center of the face.
> >
> > Baseball and golf are very similar in this respect - the force applied to
> the club (or bat) changes through the swing, and resulting ball speeds ARE
> different when clubhead (or bat) speeds are equal. It's not the same as the
> 'balls suspended by strings' collision, or the 'billard ball' collision -
> the force applied to the club is changing (increasing for a good player) as
> impact approaches.
> >
> > Answer this:
> > If the impact velocity for 2 players is equal and 1 has accelerated from
> the top and is coasting through impact while the other starts slowly and
> accererated through the ball, which one hits it further????
> >
>! > Or....
> >
> > If a moving car hits a stopped car at 35mph, will the collision be
> different if the moving car is accelerating to 35mph, coasting at 35mph, or
> decelerating from a higher speed??
> >
> > Again, I'm prolly wasting my breath with the 'expert' here.
> >
> > Pat K
> >
> > >
> > > From: "Childers, Tedd A" <[EMAIL PROTECTED]>
> > > Date: 2004/10/14 Thu AM 09:45:44 EDT
> > > To: [EMAIL PROTECTED]
> > > Subject: RE: ShopTalk: long drive
> > >
> > > Pat,
> > >
> > > I'm no physics expert, but I believe that the collision between a golf
> ball
> > > and a clubhead is represented by the conservation of momentum equation
> > > (M1V1=M2V2, in a perfect collision with no loss of energy), which is
> based
> &! gt; > on mass and velocity, not acceleration. Of course the! collisi on between
> a
> > > golf ball and a clubhead is not a perfect collision, as there are other
> > > factors involved (COR of clubhead for example), which makes the equation
> a
> > > bit more complicated (see equation below). Clubhead acceleration
> probably
> > > is a very important factor to measure to determine proper shaft
> stiffness
> > > (i.e shaft lab), but I believe that Dave T. is correct when he says that
> > > acceleration at impact has nothing to do with ball velocity.
> > >
> > > Tedd
> > >
> > >
> > >
> > >
> > > From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]
> > > Behalf Of The Kelley's
> > > Sent: Thursday, October 14, 2004 7:43 AM
> > > To: [EMAIL PROTECTED]
> > > Subject:! RE: ShopTalk: long drive
> > >
> > >
> > >
> > > David,
> > > You're welcome to follow both Dave T and Lloyd, both of whom 'know' so
> much
> > > about the golf swing.... The folks on tour have been measuring
> acceleration
> > > for many years, but according to Dave T (and hid 'bible' on the golf
> swing
> > > that many modern experts on this game threw in the trash years ago),
> > > acceleration has nothing to do with ball speed. Last I checked, basic
> > > physics says force = mass x acceleration, but I'm sure we'll see many
> > > reasons why this doesn't apply to golf.
> > >
> > > I guess I'd forgotten why I don't post here - the 'expert' (who has
> > > apparently never earned a dime in the golf business) is not woth my
> > > breath.....
> > > !
> > > Good luck in your fact finding - you seem b! oth inte lligent and open
> minded,
> > > both of which will allow you to make progress.
> > >
> > > Pat K
> > >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]
> > > Behalf Of [EMAIL PROTECTED]
> > > Sent: Thursday, October 14, 2004 2:19 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: ShopTalk: long drive
> > >
> > >
> > > In a message dated 10/13/2004 2:28:28 PM Pacific Daylight Time,
> > > [EMAIL PROTECTED] writes:
> > >
> > >
> > >
> > >
> > > At 07:50 AM 10/12/04 -0400, The Kelley's wrote:
> > > >You need to have acceleration information for each combination to
> evaluate
> > > >the data - I'd expect that! the longer shaft is allowing the player to
> > > >accelerate the clubhead a bit more as impact approaches than the other
> > > >drivers, thereby imparting a bit more force to the ball. I'll offer
> that
> > > >the 5g difference in clubheads in your test is not significant with
> > > >respect to the force imparted on the ball, as seen in the #2 and #4
> test
> > > data.
> > >
> > > Sorry, but I have to disagree with both assertions.
> > >
> > > The formula for ball velocity (ignoring centeredness of the hit and
> loft) is
> > >
> > > Vb = Vc*(1 + COR) / (1 + Mb/Mc)
> > >
> > > Ref: Cochran &Stobbs "Search for the Perfect Swing", but most of it is
> > > derivable from basic freshman physics.
> > >
> > > Note that there is no component! of acceleration at impact involved, and
> > > th! ere shou ldn't be.
> > >
> > > But the clubhead mass does make a difference, small but not completely
> > > negligible. The difference between 195g and 200g should be worth about
> > > 1/2%, or 1mph at the ball speeds involved.
> > >
> > > (BTW, those who look will notice that my numbers are very different from
> > > those that Lloyd just posted. We agree completely that mass matters and
> > > acceleration at impact doesn't, but disagree considerably on just how
> much
> > > mass matters.)
> > >
> > > Let's try out this formula for each of the drivers, to see whether
> > > something else is going on...
> > >
> > > driver 1 2 3 4
> > > >avg chs 142 148 148 150
> > > >avg bs 206 198 198 202
> > > >club length 50" 48" 48" 48"
> > > >spin ! rate 2100 2100 2200 2400
> > > >hd wt 200gr 195gr 195gr 200gr
> > > >launch a 11.5 12 12.5 12.5
> > > >hd vol 455cc 444cc 450cc 400cc
> > > >my smash # 1.45 1.33 1.33 1.34
> > >
> > > Let's assume that, for all four drivers:
> > > * The COR for the hit is 0.83, the legal limit.
> > > * The hit is in the center of the clubface.
> > > * The balls are all the same mass; we'll use 46g.
> > >
> > > Driver #1:
> > > Vb = 142(1.83) / (1 + 46/200) = 211mph (actual 206)
> > > Driver #2:
> > > Vb = 148(1.83) / (1 + 46/195) = 219mph (actual 198)
> > > Driver #3:
> > > Vb = 148(1.83) / (1 + 46/195) = 219mph (actual 198)
> > > Driver #4:
> > > Vb = 150(1.83) / (1 + 46/200) = 223mph (actual 202)
> > >
> > > So only drive! r #1 is anywhere near what the theory says it should be
&g! t; able
> > > to get. #1 is off by 2.5%, which is a pretty significant difference for
> a
> > > long driver -- it corresponds to ten yards or more for those guys. The
> > > other three drivers are only achieving about 90% of what the theory says
> > > they should. Something is wrong here, and something serious.
> > >
> > > Let's look at a few possibilities:
> > >
> > > (1) Are the assumptions correct? In particular, did somebody use impact
> > > tape to verify that all measurements were on centered hits?
> > >
> > > (2) Did somebody measure the COR of each driver using the type of ball
> used
> > > in the range tests? (I doubt it; the drivers were undoubtedly tested
> using
> > > the USGA pendulum test.) I know I disagree with Lloyd on lots of things,
> > > but his comment about a cl! ubhead/ball match is a real possibility. In
> 1998,
> > > Dick Helmstetter said in my presence -- and Alastair Cochran's as
> well --
> > > that they were looking at the opportunities for extra distance by
> matching
> > > balls to clubheads. Most of their effort was based on matching resonant
> > > frequencies, as Lloyd mentioned. Not at all an outrageous consideration.
> > >
> > > (3) Somebody mentioned a difference in loft or launch angle. That might
> > > make a substantial difference in distance, but the difference in ball
> speed
> > > would be small but measurable. The difference between 11.5 and 12.5
> degrees
> > > would be under 1/2%, or less than 1mph. So that isn't the problem.
> > >
> > > >Any ideas on what can be concluded from this data?
> > >
> > > My con! clusion is that there is some VERY significant difference from!
> ; test
> > > to test. I don't know if it's something about the club itself or how it
> is
> > > being swung (and impacting the ball), but this is not apples and apples.
> > >
> > > David, I know we've discussed this before (via private email) with other
> > > drivers. But those tests were a lot closer to the theory. Yes, they
> > > confounded the direction the theory says they should go, but they were
> > > closer. This is WAY off.
> > >
> > > DaveT
> > >
> > >
> > >
> > >
> > > Thanks,
> > > Dave and all that responded,
> > > Im sure that we are all a hold of a piece of the grail, there is no
> doubt a
> > > point of diminishing return and finding it is easier for some than most.
> > > For the acceleration data I believe Pat may b! e on to something.
> > > If you can imagine the acceleration curve as an upside down v and pick a
> > > clubhead speed such as 100 mph and imagine it at the peak of the V, and
> if
> > > you can further imagine that at just before the peak and just after the
> peak
> > > you have a clubhead speed of 99 mph I would expect that you would
> achieve a
> > > higher ball speed at 99 prior to the peak than you would after it.
> > >
> > >
> > >
> >
> >
>
>
