What Would the Ball Look Like Post Rollback or Bifurcation?

[Kalen Braley]

Jason,


Here's a couple videos that show the basics of dimpling and its effect on the ball.  Just change the dimpling, on the same ball, and the ball flies a lot shorter and less predictably if desired. This has been well studied and could be easily done.


https://www.youtube.com/watch?v=zZsvpw-JOO0
https://www.youtube.com/watch?v=fcjaxC-e8oY


P.S. I'm not suggesting a universal roll back, just a modified ball for top level professional play.

[Garland Bayley]

..., and I remain unconvinced that my golfing experience would improve if I was required to adopt your Flying Aardvark.

If you are looking for experience, I would suggest you give up golf, and take up scuba diving.

[Dave McCollum]

Jason,




P.S. I'm not suggesting a universal roll back, just a modified ball for top level professional play.

The position I've advocated for years.  Why change the ball because of a few guys that don't buy balls?  Nothing changes for the ball manufacturers except maybe the endorsements they pay to these same guys who could beat everyone else playing with dried fruits and nuts.

[Garland Bayley]

Jeff,


Swimming banned hi-tech suites


http://www.nytimes.com/2009/07/25/sports/25swim.html


In tennis each tourney uses its own balls.


https://www.nytimes.com/2016/09/04/sports/tennis/which-tennis-ball-is-in-use-it-makes-a-difference.html

Almost all motorsports have engines limited. So let's limit the engine of the club.

The NBA banned shoes from Athletic Propulsion Lab for providing an unfair advantage.
So let's limit ball propulsion.

[Kalen Braley]

Garland yes, more examples.


To me its simple.  Who do we want to be the masters of the game?  The equipment manufacturers/corporations or the duly appointed caretakers?


Its time the caretakers start weeding the garden, before the nutritional/worthwhile plants get choked to death.

[Bryan Izatt]

...............................

Bryan,

As it stands now the USGA does not even test for a spin rate. I think the only necessary addition is to set an arbitrary floor for the spin rate with the current tests. That gives us a baseline and another metric. Perhaps that spin rate could be tied to whatever presents the desired "roll-back" off the current testing maximum.

I am curious as to how many consumer golf balls fall well short of the regulated maximum performance standards. My guess is greater than 95%.

I really have no problem with professional athletes subsequently optimizing their swings and equipment around this new test. We seem to forget that optimization is applying a skill set to the sport at the highest level.

Most recreational golfers seem to practice to get luckier, not better, and success should be tied to the latter. That's why this equipment nonsense, to me, is the ultimate non-starter.

Kyle,


The USGA ODS Standard procedure establishes a standard set of launch conditions for the ODS test.  Spin is amongst the launch conditions.  The USGA does measure spin of balls in the conformance testing and the spin factors in to whether the ball conforms or not.  You can read the test procedure here:


https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf


I doubt any ball falls "well" short of the distance standard.  I do remember that when OHIO did the one ball (supposedly short) tournament that the anonymous ball used was in fact the Volvix Prospect - so maybe there was one that was shorter.  I imagine different balls work differently for different launch conditions but for the USGA ODS there are a standard set of conditions and I think that almost every ball today falls pretty close to the line under the standard conditions.  Do you have any balls in mind that you think are "well" short for you in your personal experience?

[Bryan Izatt]

Creating a ball with more spin will do little to the modern game. The ball started the lower spin movement but the clubs have brought the spin down dramatically in the last few years while still launching it high and being forgiving. I am seeing 7 iron spin readings that are more than a 1000 less rpms less than just 5 years ago. At this point, I just see them slowing the ball down. Equipment companies could over come a ball with more spin by just building even lower spinning setups for good players. The launch monitor can not be stopped. That is the modern tool that is most overlooked for distance gains.

Do you have a reference I could read on this information? How do players get their approach shots to stop reasonably if the spin is going down drastically? Or, is it that the modern 7 iron used to be called a 5 iron, and the 9 iron should be used to test the spin rate of the previous 7 iron?

Garland,


A thousand rpms is not a drastic reduction.  They stop reasonably, in part, because they hit the ball higher so the landing angle is larger.

[Bryan Izatt]

The back-and-forth in this thread is the same back-and-forth we get with every rollback thread. A vocal contingent insists the ball can simply be shortened, but can't even begin to articulate how...

Jason,


I'm baffled by this comment if you've read anything in this forum over the last two months.


I've only posted like 500 times its easily accomplished thru dimpling, and posted videos and layman links on the how.


Reducing distance on a golf ball is simple, Physics 101 kind of stuff...

Kalen,


I've looked at the videos you've posted.  Yes, dimples make a large difference compared to smooth balls.  Yes, asymmetric dimple patterns cause erratic flights.  All that is indeed aerodynamics 101.  You do know that the USGA ODS standard regulates symmetry of the ball , don't you.  So, you don't have to worry about those wildly bending left or right balls, or the Polara ball that flew too straight through dimpling.


Rolling back distance through dimpling regulation is not "easily" accomplished.  Doing it would be physics 999.  If you want simple, just increase the diameter or reduce the weight of the ball.  Both easily accomplished and easily measured and controlled.


I have read learned academic reports that suggest that deep dimples are better for longer balls.  Do you see any manufactures claiming they have deeper dimples?  No, because they've all figured out the optimal delth by now.


If you want to regulate dimples, would you prescribe the diameter, depth, pattern, shape and number of dimples?  Who would do the experimentation to determine what combination of these factors would produce the desired distance reduction and under what test conditions.  Would they linearly impact all swing speed players?

One quick anecdotal aside - I was playing a few days ago and lost my ball but found a TopFlite D2 Straight.  The D2, of course, stands for dual dimple.  So, I put it in play and my goodness, every drive was very straight.  That is until I chunked it into a lake.  But, what self-respecting golfer would use a Top-flight anyway?

[Bryan Izatt]

...
I'm pretty sure I've asked you this before, with no answer, but let's try again.  Can you please write out your spin regulation for me -concise and in plain English would be good.  And describe the test that the USGA could use to determine if balls conform to the regulation.
...

I have been specifying my regulation from the beginning. My English teachers and profs always said I was a poor writer, so maybe it is my fault for not getting it across. My Ph. D. advisor said my writing was to pithy for readers to decipher without excessive digestion.

There would be no minimum spin from the driver!

I believe there should be a linear relationship between club loft and spin rate. I.e., (using made up numbers for demonstration) if a ball spins 2000 rpm off of 10 degrees, it should spin 2500 rpm off of 20 degrees, 3000 rpm off of 30 degrees, 3500 rpm off of 40 degrees, 4000 rpm off of 50 degrees, 4500 degrees of of 60 degrees.
If a ball spins 3000 rpm off of 10 degrees, it should spin 3500 rpm off of 20 degrees, 4000 rpm off of 30 degrees, 4500 rpm off of 40 degrees, 5000 rpm off of 50 degrees, 5500 degrees of of 60 degrees.
If a ball spins 4000 rpm off of 10 degrees, it should spin 4500 rpm off of 20 degrees, 5000 rpm off of 30 degrees, 5500 rpm off of 40 degrees, 6000 rpm off of 50 degrees, 6500 degrees of of 60 degrees.

All of these produce a line with equal slope, which is why the simplistic numbers were chosen. It is not necessary for the same slope to hold for all balls, just that the data provides a linear relationship. My understanding is that ProV1 typically might spin 2000 from driver, and 9000 from wedge. This sort of bounds spin rates. So perhaps low spin balls would spin 2000 from driver to 7000 from wedge, and high spin balls would spin 4000 from driver to 9000 from wedge. Obviously more realistic numbers could be provided by someone more knowledgeable of the technology.

The test would need to test different swing speeds to verify the linear relationship holds for all swing speeds.

The club faces would all have the same type of surface area, probably without grooves.

There would have to be a regulation to state the slight variation allowed from true linear, because in practice you probably are not going to get exactly linear. Obviously I am not a physicist that can address the actual physical response to such testing.

The USGA would have to develop Titanium Tiger to conduct the tests.

Thanks for that. 


So, your impression at the moment is that the ProV1 is non-linear?  Or that it has a much steeper slope than what the old balata balls had?


You do realize that the spin imparted to the ball is the result of the properties of the club, the ball properties, and the properties of the swing.  Trying to control spin in some linear fashion through the ball alone seems to me to be a daunting to impossible engineering challenge.  The grooves on drivers are markedly different than on wedges. A player might have a +5° angle of attack with a driver and a -5° angle of attack with a wedge.  And, by the way, the stated loft of the driver is irrelevant - the loft that matters is the spin loft.  And on we go go.


What do you suppose the average driver spin rate is on tour.  It's certainly not 2000 rpm.  The faster you swing the more spin you impart, and those guys swing hard.  Also optimum flight of the ball depends at least partially on the spin rate - even the pros need some spin to create the lift force to keep the ball in the air.  At what spin rate do you suppose a ball balloons and loses distance?  Do you suppose that the difference between 9000 rpm and 7000 rpm on a full wedge shot would make a significant difference to a tour pro?


Certainly, the USGA can already measure spin rates and their effect on distance.  Now if you could only tell them what the ideal spin rate would be to dial back the ball they'd be all set.  The Tour pros wouldn't take long to retool to get the driver distance they're currently getting and sufficient spin to control iron shots.


Wouldn't it be infinitely easier to make the ball larger or lighter or both.  Either, by the way would probably drive spin up a bit.


For your contemplation, I plotted the average spin rate by club of PGA Tour players and LPGA players as measured by Trackman.  The LPGA players had no hybrid or 3 iron and used 7 woods instead.  Obviously there is variation in the loft of each club as different players use different clubs, so it's not a controlled experiment.  Clearly the irons are linear.  There is a discontinuity around the 5W, hybrid/7W, and 3I, probably because they are likely all in the same loft range but have different swing characteristics associated with them.  Draw whatever conclusions you like from the data, it seems to me getting to your linear spin model from driver to wedge is very unlikely.  Finding the driver spin rate that reduces the top end guys distance by 10%, or whatever, sounds like the search for the golden fleece.

[BCrosby]

Great stuff Bryan.  Thanks.


As you might already know, the debates over the first regulation of the ball circa 1920 ended up focusing on what you conclude above.  The easiest way (and perhaps only way at the time) to regulate the ball was to limit its size and weight. Interestingly, the R&A in those early debates wanted a 'floater' as the sanctioned ball (a bigger, lighter ball). The USGA objected and a compromise was reached as to max weight (originally 1.62 oz.) and minimum diameter (originally 1.62 inches).


The objections to the Haskell in 1902/03 were argued on a different basis. The argument then was over the material composition of the new American ball. But by 1920 everyone seemed agreed that rules about ball materials were impossible to draft. Any such rule would be take you deep into materials chemistry and no one wanted to go there.


The USGA and R&A now want to regulate balls through initial launch speeds. I am unclear of the relationship (if any) between ball size/weight and launch speeds. Or has it been addressed in the literature?  Note that machines to measure launch speeds did not exist in the early '20's. I think they first appeared later in the 1920's or in the 1930's. No?


Bob 

[Erik J. Barzeski]

The USGA and R&A now want to regulate balls through initial launch speeds. I am unclear of the relationship (if any) between ball size/weight and launch speeds.

It's not just initial ball speed, but initial ball speed plus the size/weight restrictions, etc. Given a ball of a certain size and weight, initial ball speed can fairly well predict how quickly it loses speed, and so on.

https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf

There's also a "launch" condition standard, which is where dimpling, aerodynamics, etc. come into play, and balls cannot fly beyond a certain yardage. So it's not like a manufacturer can make a ball that conforms to the size, weight, and speed parts of the ODS and Rules and Regulations, but through dimpling or something else, flies 350 yards when hit by the testing robot used in Phase II of the ODS testing process.

And to those suggesting Local Rules are bifurcation… please. We've had Local Rules for decades. They're worlds apart from actual bifurcation of the ball rules/regs.

[Garland Bayley]

Kyle,


The USGA ODS Standard procedure establishes a standard set of launch conditions for the ODS test.  Spin is amongst the launch conditions.  The USGA does measure spin of balls in the conformance testing and the spin factors in to whether the ball conforms or not.  You can read the test procedure here:


https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf

...

Bryan,

Thanks for the link.

"the spin factors in to whether the ball conforms or not."

My understanding is that they set up the apparatus to get the specified spin, i.e., they perform optimization, and not that they have spin factors to determine conformation.

[Kyle Harris]

Kyle,


The USGA ODS Standard procedure establishes a standard set of launch conditions for the ODS test.  Spin is amongst the launch conditions.  The USGA does measure spin of balls in the conformance testing and the spin factors in to whether the ball conforms or not.  You can read the test procedure here:


https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf

...

Bryan,

Thanks for the link.

"the spin factors in to whether the ball conforms or not."

My understanding is that they set up the apparatus to get the specified spin, i.e., they perform optimization, and not that they have spin factors to determine conformation.

Precisely, spin is only a factor in ensuring the ball and driver fit the launch parameters. A golf ball in their test is only conforming or non-conforming based on the distance it travels once the equipment has been calibrated based on those launch parameters. Therefore, the spin rate of the golf ball being tested is not measured.

[Garland Bayley]

Thanks for that. 


So, your impression at the moment is that the ProV1 is non-linear? 

That was the reason for its creation.

Or that it has a much steeper slope than what the old balata balls had?


You do realize that the spin imparted to the ball is the result of the properties of the club, the ball properties, and the properties of the swing.  Trying to control spin in some linear fashion through the ball alone seems to me to be a daunting to impossible engineering challenge.  The grooves on drivers are markedly different than on wedges. A player might have a +5° angle of attack with a driver and a -5° angle of attack with a wedge.  And, by the way, the stated loft of the driver is irrelevant - the loft that matters is the spin loft.  And on we go go.

Titanium Tiger would not vary her attack angle, and the club faces were specified to be grooveless and all the same surface.


What do you suppose the average driver spin rate is on tour.  It's certainly not 2000 rpm.  The faster you swing the more spin you impart, and those guys swing hard.  Also optimum flight of the ball depends at least partially on the spin rate - even the pros need some spin to create the lift force to keep the ball in the air.  At what spin rate do you suppose a ball balloons and loses distance?  Do you suppose that the difference between 9000 rpm and 7000 rpm on a full wedge shot would make a significant difference to a tour pro?

As I said, my numbers were made up to demonstrate line slope. I left it to experts to determine real numbers.

Certainly, the USGA can already measure spin rates and their effect on distance.

How So? They set their apparatus to produce 2500 rpm so all balls are tested under the same conditions. 

Now if you could only tell them what the ideal spin rate would be to dial back the ball they'd be all set.  The Tour pros wouldn't take long to retool to get the driver distance they're currently getting and sufficient spin to control iron shots.

Yes, but good luck with them hitting it straight at that distance with a ball that serves their short game.

Wouldn't it be infinitely easier to make the ball larger or lighter or both.  Either, by the way would probably drive spin up a bit.

Who cares about infinitely easier with today's technology.

For your contemplation, I plotted the average spin rate by club of PGA Tour players and LPGA players as measured by Trackman.  The LPGA players had no hybrid or 3 iron and used 7 woods instead.  Obviously there is variation in the loft of each club as different players use different clubs, so it's not a controlled experiment.  Clearly the irons are linear.  There is a discontinuity around the 5W, hybrid/7W, and 3I, probably because they are likely all in the same loft range but have different swing characteristics associated with them.  Draw whatever conclusions you like from the data, it seems to me getting to your linear spin model from driver to wedge is very unlikely.  Finding the driver spin rate that reduces the top end guys distance by 10%, or whatever, sounds like the search for the golden fleece.

[Bryan Izatt]

Great stuff Bryan.  Thanks.


As you might already know, the debates over the first regulation of the ball circa 1920 ended up focusing on what you conclude above.  The easiest way (and perhaps only way at the time) to regulate the ball was to limit its size and weight. Interestingly, the R&A in those early debates wanted a 'floater' as the sanctioned ball (a bigger, lighter ball). The USGA objected and a compromise was reached as to max weight (originally 1.62 oz.) and minimum diameter (originally 1.62 inches).


The objections to the Haskell in 1902/03 were argued on a different basis. The argument then was over the material composition of the new American ball. But by 1920 everyone seemed agreed that rules about ball materials were impossible to draft. Any such rule would be take you deep into materials chemistry and no one wanted to go there.


The USGA and R&A now want to regulate balls through initial launch speeds. I am unclear of the relationship (if any) between ball size/weight and launch speeds. Or has it been addressed in the literature?  Note that machines to measure launch speeds did not exist in the early '20's. I think they first appeared later in the 1920's or in the 1930's. No?


Bob

Not sure when speed measurement first existed.


Just for clarity the USGA and R&A already regulate Initial Velocity and Overall Distance.  These are two different regulations.  Ball distance has to do with initial velocity and launch conditions on the one hand and aerodynamics in flight on the other hand.  The Initial Velocity regulation deals with the former and the ODS deals with the latter.

[Bryan Izatt]

The USGA and R&A now want to regulate balls through initial launch speeds. I am unclear of the relationship (if any) between ball size/weight and launch speeds.

It's not just initial ball speed, but initial ball speed plus the size/weight restrictions, etc. Given a ball of a certain size and weight, initial ball speed can fairly well predict how quickly it loses speed, and so on.

https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf

There's also a "launch" condition standard, which is where dimpling, aerodynamics, etc. come into play, and balls cannot fly beyond a certain yardage. So it's not like a manufacturer can make a ball that conforms to the size, weight, and speed parts of the ODS and Rules and Regulations, but through dimpling or something else, flies 350 yards when hit by the testing robot used in Phase II of the ODS testing process.

And to those suggesting Local Rules are bifurcation… please. We've had Local Rules for decades. They're worlds apart from actual bifurcation of the ball rules/regs.

Erik,


It is possible that a ball could be invented that conforms to the initial velocity test but has dimpling or a more aerodynamic cover that would allow it to fly further, but the ODS standard would make it non-conforming as I understand it.

[Bryan Izatt]

Kyle,


The USGA ODS Standard procedure establishes a standard set of launch conditions for the ODS test.  Spin is amongst the launch conditions.  The USGA does measure spin of balls in the conformance testing and the spin factors in to whether the ball conforms or not.  You can read the test procedure here:


https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf

...

Bryan,

Thanks for the link.

"the spin factors in to whether the ball conforms or not."

My understanding is that they set up the apparatus to get the specified spin, i.e., they perform optimization, and not that they have spin factors to determine conformation.

Garland,


I think you are misunderstanding the conformance test.  As I understand it, they set up the test equipment to the standard launch parameters with the standard head and calibrate the machine  for launch angle, speed and spin using their standard ball (a 2 piece surlyn Bridgestone ball).  Once calibrated they test the new balls.  They don't optimize the machine for that ball.  Rather they measure the lift coefficient and the drag coefficient and use those to calculate the overall distance and whether it conforms or not.  The lift and drag coefficients factor in spin, I believe. 

[Erik J. Barzeski]

It is possible that a ball could be invented that conforms to the initial velocity test but has dimpling or a more aerodynamic cover that would allow it to fly further, but the ODS standard would make it non-conforming as I understand it.

That's what I (thought I'd) said. 

Balls have to conform to both parts. Engineers can't just make a ball fly farther via aerodynamics, because it's not just a ball speed test.

[Garland Bayley]

Kyle,


The USGA ODS Standard procedure establishes a standard set of launch conditions for the ODS test.  Spin is amongst the launch conditions.  The USGA does measure spin of balls in the conformance testing and the spin factors in to whether the ball conforms or not.  You can read the test procedure here:


https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf

...

Bryan,

Thanks for the link.

"the spin factors in to whether the ball conforms or not."

My understanding is that they set up the apparatus to get the specified spin, i.e., they perform optimization, and not that they have spin factors to determine conformation.

Garland,


I think you are misunderstanding the conformance test.  As I understand it, they set up the test equipment to the standard launch parameters with the standard head and calibrate the machine  for launch angle, speed and spin using their standard ball (a 2 piece surlyn Bridgestone ball).  Once calibrated they test the new balls.  They don't optimize the machine for that ball.  Rather they measure the lift coefficient and the drag coefficient and use those to calculate the overall distance and whether it conforms or not.  The lift and drag coefficients factor in spin, I believe.

On franklygolf.com Frank Thomas indicates the balls are tested at optimized conditions.

[BHoover]

If the ball is bifurcated, would it still look round?

[Bryan Izatt]

Kyle,


The USGA ODS Standard procedure establishes a standard set of launch conditions for the ODS test.  Spin is amongst the launch conditions.  The USGA does measure spin of balls in the conformance testing and the spin factors in to whether the ball conforms or not.  You can read the test procedure here:


https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3006-overall-distance-and-symmetry-test-procedure.pdf

...

Bryan,

Thanks for the link.

"the spin factors in to whether the ball conforms or not."

My understanding is that they set up the apparatus to get the specified spin, i.e., they perform optimization, and not that they have spin factors to determine conformation.

Precisely, spin is only a factor in ensuring the ball and driver fit the launch parameters. A golf ball in their test is only conforming or non-conforming based on the distance it travels once the equipment has been calibrated based on those launch parameters. Therefore, the spin rate of the golf ball being tested is not measured.

Garland, Kyle,


I think you misunderstand the test and how the data is used to determine conformance.  There are two devices used in the testing - a mechanical golfer that is calibrated at 120 mph to hit a standard ball at a standard velocity, launch angle and spin.  The second machine is the Indoor Test Range (ITR), basically two spinning disks that can launch a ball at any angle and spin rate and velocity down a 70 foot tunnel where the aerodymic performance of the ball can be measured.  If it helps, here are the pertinent sections of the test procedure.





They then hit the balls to be tested with the mechanical golfer and measure the launch angle, spin and ball speed. (and there are lots of detailed steps along the way)





The measured angle, speed and spin of the ball being tested are then used to launch the ball on the Indoor Test Range (ITR - basically two spinning disks).  The measured results of angle, speed and spin of the ball being tested will not be the same as the calibration ball.






During this test they collect data including launch speed and spin rate and then,





The measured spin rate of the ball being tested is used in the calculation of the lift and drag coefficients.  The lift and drag coefficients are then used in a mathematical calculation of distance to determine conformance of the ball with the ODS.







Perhaps this is more easily summarized and simplified by the USGA:


Today we still hit each brand of ball with the mechanical golfer, but instead of hitting the balls outside onto the range, we hit them into a net and measure their launch conditions off the clubhead (velocity, direction, and spin). We then use our Indoor Test Range (ITR) to precisely determine how each ball flies. The Indoor Test Range is a 70-foot long "tunnel" through which the balls are launched using a golf ball launcher that is similar to a pitching machine. The ITR allows the USGA to accurately measure the aerodynamics of a golf ball in flight. This information is used in a sophisticated computer program to accurately calculate driving distance of an actual drive. This "virtual" distance data is highly repeatable and not subject to weather variations.

I hope that helps your understanding.  There is no optimization going on in the test.  The spin rate of each ball being tested is measured and used to calculate the overall distance and conformance.

[Bryan Izatt]

Thanks for that. 


So, your impression at the moment is that the ProV1 is non-linear? 

That was the reason for its creation.

Or that it has a much steeper slope than what the old balata balls had?


You do realize that the spin imparted to the ball is the result of the properties of the club, the ball properties, and the properties of the swing.  Trying to control spin in some linear fashion through the ball alone seems to me to be a daunting to impossible engineering challenge.  The grooves on drivers are markedly different than on wedges. A player might have a +5° angle of attack with a driver and a -5° angle of attack with a wedge.  And, by the way, the stated loft of the driver is irrelevant - the loft that matters is the spin loft.  And on we go go.

Titanium Tiger would not vary her attack angle, and the club faces were specified to be grooveless and all the same surface.


What do you suppose the average driver spin rate is on tour.  It's certainly not 2000 rpm.  The faster you swing the more spin you impart, and those guys swing hard.  Also optimum flight of the ball depends at least partially on the spin rate - even the pros need some spin to create the lift force to keep the ball in the air.  At what spin rate do you suppose a ball balloons and loses distance?  Do you suppose that the difference between 9000 rpm and 7000 rpm on a full wedge shot would make a significant difference to a tour pro?

As I said, my numbers were made up to demonstrate line slope. I left it to experts to determine real numbers.

Certainly, the USGA can already measure spin rates and their effect on distance.

How So? They set their apparatus to produce 2500 rpm so all balls are tested under the same conditions. 

Now if you could only tell them what the ideal spin rate would be to dial back the ball they'd be all set.  The Tour pros wouldn't take long to retool to get the driver distance they're currently getting and sufficient spin to control iron shots.

Yes, but good luck with them hitting it straight at that distance with a ball that serves their short game.

Wouldn't it be infinitely easier to make the ball larger or lighter or both.  Either, by the way would probably drive spin up a bit.

Who cares about infinitely easier with today's technology.

For your contemplation, I plotted the average spin rate by club of PGA Tour players and LPGA players as measured by Trackman.  The LPGA players had no hybrid or 3 iron and used 7 woods instead.  Obviously there is variation in the loft of each club as different players use different clubs, so it's not a controlled experiment.  Clearly the irons are linear.  There is a discontinuity around the 5W, hybrid/7W, and 3I, probably because they are likely all in the same loft range but have different swing characteristics associated with them.  Draw whatever conclusions you like from the data, it seems to me getting to your linear spin model from driver to wedge is very unlikely.  Finding the driver spin rate that reduces the top end guys distance by 10%, or whatever, sounds like the search for the golden fleece.

Garland,

I think your various answers above are incorrect.  I have adjusted the PGA Tour spin rate graph above to be more accurately representative.  The version above I just plotted the spin rate against the club name.  It would be representative of spin vs loft if there was a consistent difference in degrees of loft between each club in the list.  That's obviously not the case so the graph misrepresents the slope.  To correct this I added a loft column to the table using TaylorMade M4 woods and P750 iron lofts as being representative of average tour players lofts (no idea if that is accurate but shouldn't be too far off).  The plot of spin vs loft is below.  The PGA Tour is pretty linear.  The LPGA has anomalies  at the 3W and 9I.  The tour guys largely use Pro V1's or equivalent modern balls.  So, your desire for a linear relationship appears to already be there.

All said and done, you might want to get off the spin soap box and try the weight or size one instead. 

[Garland Bayley]

Garland, Kyle,


I think you misunderstand the test and how the data is used to determine conformance.  There are two devices used in the testing - a mechanical golfer that is calibrated at 120 mph to hit a standard ball at a standard velocity, launch angle and spin.  ...

Got it. Spin is not a factor they measure to meet a regulation. Spin is a "factor" in the equations to calculate distance. I prefer parameter as the word for such a usage.

I guess I have to assume they have optimized the control balls, which would justify Frank Thomas saying they use optimization in the test. Or, perhaps Frank's test that they did not implement before he left USGA used optimization of the balls under test.

[Garland Bayley]

As I said, my numbers were made up to demonstrate line slope. I left it to experts to determine real numbers.

Garland,

I think your various answers above are incorrect. ...

What? You didn't believe I made the numbers up? You don't think experts could come up with realistic numbers?

[Garland Bayley]

Bryan,

Thanks for your effort in producing the graphs given. Where did you obtain the data?

The problem of course is that the graphs given don't come close to capturing data needed for the testing procedure that I specified at your request. In fact, showing linear at different club head speeds as your data does would seem to me to possibly demonstrate non-linearity for the specified test, thereby indicating the balls would fail my proposed test. The real crux would seem to show up in the 3 to 4 iron data that appears to transition (at about 25 degrees loft) to a steeper line for the other irons. This would seem to demonstrate how the balls are claimed to work. At lower lofts, the clubhead compresses deep into the ball and doesn't spin it as much. At higher lofts, the ball catches the outer layers and causes the ball to spin more absent the compression into the inner layers. The descriptions of how these balls work says to me they were designed to be nonlinear (a claim I made that you think is false).