[Bryan Izatt]

...
As for the chart, sure, the two sets of data were completely different methodologies, but I think the result is indicative.  It doesn't jive with your preconception so you want to throw it out, but I think it is indicative.
...

Indicative of what? The addition of the Shiel data shows the slope for the ProV1 is steeper than for the Professional. Exactly my thesis.


I thought your thesis was that the ProV1 spun like a 2-piece ball of yore off the driver but spun like a Tour Balata or Professional off wedges.  The Shiel data says to me that the slope of the Professional and the ProV1 are virtually identical.  It says nothing about the slope of the old 2-piece balls.

Any other matching is meaningless. You don't know the conditions of the Lieberman data for low loft, or for high loft. So matching low loft points is meaningless. Matching high loft points is meaningless. The Lieberman data would simulate equal club head speed for all, whereas the other data has high club head speed for low loft, and low club head speed for high loft.


No, I don't know the test conditions of the Lieberman data, but then neither do you.  Given that, I wonder how you can assert that the Lieberman data was "equal club head speed for all".  It would have been a pretty silly test if he set up his experiment to shoot the ball at the plates with lofts that matched drivers through wedges and then shot the ball at each with the same speed.  How would that tell him anything about the spin rate off of the different club head angles in a real golf world where swing speed changes with the shorter clubs.  But, I'm sure when you get the whole article you can share with us the methodology of the test to prove your assertion that the same speed cannon was used on all.

[Bryan Izatt]

Re the Lieberman article, no I didn't find the whole article, just some snippets from Google books. Do share when you get the whole article.


I still don't get what specifically you mean by "characteristics" and "state".  Do you mean that you want modern balls to match the slope of the Lieberman line when fired at an angled metal plate, under whatever test conditions Lieberman had. 

Yes


That seems pretty silly since you don't know what the Lieberman test conditions were.


Would you allow them to have a greater slope of less slope or do they need to have exactly the same slope?

USGA regulations always have a fudge factor around a reasonable bound. Something along those lines would have to be worked out.

I think you'll find that Lieberman found that the slope varied depending on whether the plate was dry or grassy.  Do you want to factor in real world conditions in your slope.

USGA regulations try to avoid real world conditions. They did away with Iron Byron hitting balls outdoors,
because they couldn't control real world conditions (weather). Besides, the USGA has already worked on the grassy club face issue with their groove regulations.


I still don't understand how you think regulating the spin slope will affect distance or accuracy for professional players.

Clearly optimizing spin allows you to hit the ball farther. I believe that when you optimize a higher spinning ball, you have to reduce the effective loft of the club during contact. When you reduce the loft, the force component for applying back spin will decrease. The force component applying side spin will stay the same. The axis of spin will shift. The ball will curve more. Besides, that is essentially what many tour pros have indicated in layman's terms.


I take it you didn't graduate from engineering.     I think your understanding of the forces in a club/ball impact are kind of incomplete and flawed. 

You might find the Trackman article on spin interesting.  You should watch the video, it's instructive.  Their conclusion is that spin is the result of two main factors - clubhead speed and spin loft.  Other factors such as club design and ball design were relatively minor factors.  The Shiel data supports that conclusion.  There is little difference in the spin between the Professional and the ProV1 despite their difference in design and material.

https://blog.trackmangolf.com/spin-rate/

As to how much difference a higher spinning ball would make in distance for the optimized golfer, take a look at the trajectory calculator from the University of Sydney.  What's clear is that the optimal spin rate for maximum distance is inextricably linked to the optimal launch angle.  Spin and launch angle go hand in hand in determining optimal distance.  With lower spin you need higher launch and vice versa.  (see the Tuttleman article).

The trajectory calculator suggests that if a pro with a ball speed of 180 mph were to optimize his launch angle with 2500 RPM and then optimize the launch angle with with a spin rate of 3500 rpm he would lose a little over 10 yards with the higher spin.  But then again Trackman finds that if they adjusted their approach angle up a few degrees they'd lower their spin-rates and get more distance back.  Messing with spin is a very complicated matter and apparently has little to do with the ball.

www.physics.usyd.edu.au/teach_res/excel/golfball.xls


E.g., the Ryan Moore's comment doesn't say that, but I believe it implies that he believes players would have to dial back their swings with a ball that spun like the wound balata balls. My own experience is hitting TopFlites 300 yards with a 2 wood in the early 70s, while seeing Titleists balloon up and fall short. Couldn't control the Titleists with a driver without dialing the swing back. At the time I was a highly conditioned college BBall player that spent 8 hours a day during the summer tossing heavy lumber around in a sawmill so I had very strong wrists and forearms.


Are you sure you didn't drop any of the heavy lumber on your head in the '70's?   

 
What do you think would happen if a player opted for a higher spin ball for short game control?


As for using year-to-year changes in PGA Tour distances you forgot to include other factors that probably contributed to those year-to-year changes - some of the players changed; some of the courses changed; and, course conditions changed due to weather.  Not to  argue that the ball had nothing to do with the distance gains in that time period.  Obviously they did, but there were a lot of other factors involved too.  It presents a very complicated cause and effect analysis. 

Plot the gains before, and the gains after. You will probably find a small component that can be contributed to all the other factors. I believe the discrete jumps that happened at the event of introduction of the new ball, and optimization with the new ball will clearly dominate the results you see.

I think that spin is a lot smaller factor than many others.

I disagree.

[Garland Bayley]

...
I thought your thesis was that the ProV1 spun like a 2-piece ball of yore off the driver but spun like a Tour Balata or Professional off wedges.  The Shiel data says to me that the slope of the Professional and the ProV1 are virtually identical.  It says nothing about the slope of the old 2-piece balls.

If you look at your data plot of Shiel's results, you will see that the slope for the ProV1 is steeper than the slope for the Professional. I believe the Shiel actually expressed surprise in the video that wedge spin with ProV1 was so high.

The whole purpose of what i am proposing is to dial back from balls like the ProV1 with their steeper slope on the plot of face angle vs spin rate.

[Garland Bayley]

No, I don't know the test conditions of the Lieberman data, but then neither do you.  Given that, I wonder how you can assert that the Lieberman data was "equal club head speed for all".  It would have been a pretty silly test if he set up his experiment to shoot the ball at the plates with lofts that matched drivers through wedges and then shot the ball at each with the same speed.  How would that tell him anything about the spin rate off of the different club head angles in a real golf world where swing speed changes with the shorter clubs.  But, I'm sure when you get the whole article you can share with us the methodology of the test to prove your assertion that the same speed cannon was used on all.

The article I pointed to you gave the speed that all balls were fired at the angled surfaces. That is how I know. They use the same speed, because they are doing physics. Once the physics is understood, it can be applied to golf.

[Bryan Izatt]

No, I don't know the test conditions of the Lieberman data, but then neither do you.  Given that, I wonder how you can assert that the Lieberman data was "equal club head speed for all".  It would have been a pretty silly test if he set up his experiment to shoot the ball at the plates with lofts that matched drivers through wedges and then shot the ball at each with the same speed.  How would that tell him anything about the spin rate off of the different club head angles in a real golf world where swing speed changes with the shorter clubs.  But, I'm sure when you get the whole article you can share with us the methodology of the test to prove your assertion that the same speed cannon was used on all.

The article I pointed to you gave the speed that all balls were fired at the angled surfaces. That is how I know. They use the same speed, because they are doing physics. Once the physics is understood, it can be applied to golf.

Indeed it does say the same speed.  It would be interesting to see the full study because firing at the same speed doesn't seem to correlate to the real world difference in loft and swing speed.  One wonders what the purpose of the study was.  In any event the numbers of spin and loft seem irrelevant to this discussion.  We know that spin is a function of swing speed, amongst other things, in real world golf. 


It seems to me that mathematical modelling of physical phenomenon is always tested against empirical testing with real balls and clubs. 

[Bryan Izatt]

...
I thought your thesis was that the ProV1 spun like a 2-piece ball of yore off the driver but spun like a Tour Balata or Professional off wedges.  The Shiel data says to me that the slope of the Professional and the ProV1 are virtually identical.  It says nothing about the slope of the old 2-piece balls.

If you look at your data plot of Shiel's results, you will see that the slope for the ProV1 is steeper than the slope for the Professional. I believe the Shiel actually expressed surprise in the video that wedge spin with ProV1 was so high.

The whole purpose of what i am proposing is to dial back from balls like the ProV1 with their steeper slope on the plot of face angle vs spin rate.

Yes, the slope of the ProV1 is slightly higher.  The driver spin rates are virtually identical.  The difference in the wedge spin rates is statistically insignificant given the standard deviation. 


But, if you want to take the two slopes as absolutely true, then regulating spin so that the ProV1 slope exactly mirrors the slope of the Professional would require require reducing the ProV1 spin by 600 rpm off the wedge or increasing the spin by 600 rpm off the driver.


If you raise the driver spin to reduce distance and increase dispersion then there is an offsetting benefit in increased short game control -an unintended consequence, I guess.


How much distance loss would a 600 rpm increase in driver spin cause.  At 180 mph ball speed, (think DJ) about 10 yards if you optimize the launch angle for each spin rate. 


On the other hand you could increase the diameter of the ball by 0.04" (the size of the Top Flight Magna ball of years past) and achieve the same result, according to the trajectory calculator mentioned a few posts back.  And, it's easier to regulate and easier to test.


As a matter of interest, the trajectory calculator also projects that the small British ball would go 20 yards further than the current size ball.  It was 0.06" smaller than the current standard.


Perhaps that's the bifurcation required  - the Tour plays a modern Magna+ sized ball and the rest of us play a British sized ball.   

[Duncan Cheslett]

And, here for those interested in the difference between a current Pro V1 and a 1998 Titleist Professional is a link to a You-tube video of a comparison by Rick Shiels between the two using driver, 7 iron and wedge.  You can skip the ad after a few seconds.


https://www.youtube.com/watch?v=x6B6U0DflaY


Vis-a-vis the spin discussion, it is interesting to note that the modern Pro V1 actually spins slightly more off the wedge.  More interesting is that the Pro V1 doesn't spin any less off the driver.  The facts seem to contradict our past perceptions of the spin of the Professional ball.


There was little difference in the wedge distances and about 11 yards in carry distance with the driver.  There is no mention of weighing the Professional, but based on my personal experience there is probably a loss of 4 or 5 grams due to aging.  That would probably make the ball less resilient after 20 years.


The results are not much different from what I have seen in my own test in a sim with an old Professional that I have.  Shiels test is more rigorous than mine with better equipment for measuring the results.  And, of course, he swings much faster and hits it on the sweet spot more often than I do.   


   

One issue Shiels didn't address was that of possible deterioration of the wound ball while in its box for two decades.


Does a 20-year old golf ball perform as well out of the box as it would have done straight off the production line? Surely some elasticity will have been lost...

[Garland Bayley]

One issue Shiels didn't address was that of possible deterioration of the wound ball while in its box for two decades.


Does a 20-year old golf ball perform as well out of the box as it would have done straight off the production line? Surely some elasticity will have been lost...

Duncan,

Thanks for supporting what I have already mentioned here.

...
The relatively quick degradation of the balata balls is well known. I am sure the balls were not produced to be lighter, as that would be a self defeating exercise in ball degradation. Doing tests with old wound balata balls is a well known waste of time.
...

Note: Although the Professional 90 was urethane covered, it was still a wound ball, which was known to degrade.

[Erik J. Barzeski]

On the other hand you could increase the diameter of the ball by 0.04" (the size of the Top Flight Magna ball of years past) and achieve the same result, according to the trajectory calculator mentioned a few posts back.  And, it's easier to regulate and easier to test.

The larger ball would also be ever so slightly more difficult to hole (when putting mostly), and the hole would be correspondingly a tiny bit smaller.

I admire your stick-to-it-iveness, Bryan, in dealing with Garland's fantasy world.

One issue Shiels didn't address was that of possible deterioration of the wound ball while in its box for two decades.

Does a 20-year old golf ball perform as well out of the box as it would have done straight off the production line? Surely some elasticity will have been lost...

I wondered about that as well. Sure they were "new" in the sense that they had not been hit, but I wonder if he even weighed them. Perhaps one had absorbed water, or dried out slightly. Or the ball was simply less elastic and "bouncy" than before, when it was actually new.

[Garland Bayley]

...
You might find the Trackman article on spin interesting.  You should watch the video, it's instructive.  Their conclusion is that spin is the result of two main factors - clubhead speed and spin loft.  Other factors such as club design and ball design were relatively minor factors. The Shiel data supports that conclusion.  There is little difference in the spin between the Professional and the ProV1 despite their difference in design and material.

https://blog.trackmangolf.com/spin-rate/

i think you misunderstand the trackman video. As you can see from the plot you already posted.



Changing ball and subjecting it to essentially the same swing with the same club, one ball can spin half as much as another.

There is really no information in the Trackman video that every person who has asked, "why do players balls on TV stop quicker than my balls do?", and found the answer does not know. You hit the ball with more club head speed, and the ball spins faster, and stops quicker.

[Bryan Izatt]

One issue Shiels didn't address was that of possible deterioration of the wound ball while in its box for two decades.


Does a 20-year old golf ball perform as well out of the box as it would have done straight off the production line? Surely some elasticity will have been lost...

Duncan,

Thanks for supporting what I have already mentioned here.

...
The relatively quick degradation of the balata balls is well known. I am sure the balls were not produced to be lighter, as that would be a self defeating exercise in ball degradation. Doing tests with old wound balata balls is a well known waste of time.
...

Note: Although the Professional 90 was urethane covered, it was still a wound ball, which was known to degrade.

Duncan,


After doing some digging I'd offer the following nformation regarding degradation of wound balls that came from one of the USGA's groove studies 10 years back.


They had some COR and spin data from a test of a Titleist 384 Tour ball from 1987.  They replicated the test with the same ball 20 years later.


A result of the test was that the COR decreased by 2% to 8% depending on the loft of the strike.  The lower loft had the greater COR loss.


The other result was that the spin decreased from 9% to 23% depending of the loft of the strike. The higher loft lost less spin.


The implication, to me, of the relatively small COR loss is that when we see modern testing of old balls we should be aware that the Tour Balata/Professional ball speeds are lower than they would be if the ball hadn't degraded with age.  So, for instance, in the Shiel video the Professional ball speed would be as high as the ProV1 or higher if the ball had been recently manufactured.

[Garland Bayley]

...

A result of the test was that the COR decreased by 2% to 8% depending on the loft of the strike.  The lower loft had the greater COR loss.


The other result was that the spin decreased from 9% to 23% depending of the loft of the strike. The higher loft lost less spin.


The implication, to me, of the relatively small COR loss is that when we see modern testing of old balls we should be aware that the Tour Balata/Professional ball speeds are lower than they would be if the ball hadn't degraded with age.  So, for instance, in the Shiel video the Professional ball speed would be as high as the ProV1 or higher if the ball had been recently manufactured.

In other words, the would balata ball lost 23% spin when hit with driver.

I have always had the assumption that the high compression wound balata balls would be knocking up against the initial velocity limit. It seems logical to me that once manufacturers had gotten their balls to the point of needing a limit, it would be a losing business practice to produce balls that weren't knocking up against that limit.

[Bryan Izatt]

No, actually the lower loft was the equivalent of a 5 iron.  The study had no data points for a driver loft.


Unlike you, I'm surprised the initial ball velocity of a newly manufactured Tour Balata would be so close to that of a ProV1.  How would you account for the widespread belief that the 20 yard gain in distance was all about the ball when the two balls are launched with virtually the same initial velocity?  The trajectory calculator doesn't seem to suggest that whatever extra spin there is would account for that much extra distance if you optimize the launch angle for the spin.

[Bryan Izatt]

Garland,


Here is some more data to ponder in your spin universe. 


I've corrected the two end points of the Shiel data to reflect the age induced spin loss of the Professional ball used in his test.  The correction may not be accurate as the USGA study was based on the Titleist 384 Tour and not the Professional 90, but it should be indicative of the kind of spin loss that wound balls experience from aging.


I also added another real world test the USGA conducted with Tour Balata balls in 2006.  Six pros hit more than 600 shots with 5 and 8 irons and sand wedges similar to ones used in 1987.  The results are the average of the six pros - obviously there were variations in spin rates amongst the six.  Since there was no testing done of Tour Balatas in 1987, there is no age correction that I can apply.  The USGA tests imply that the Tour Balata lost less spin than the 384 Tour through aging. 


I left the current PGA spin figures from Trackman on the chart too.


The slopes all look remarkably similar to me given the confidence intervals of the tests.

[Garland Bayley]

...
Clearly optimizing spin allows you to hit the ball farther. I believe that when you optimize a higher spinning ball, you have to reduce the effective loft of the club during contact. When you reduce the loft, the force component for applying back spin will decrease. The force component applying side spin will stay the same. The axis of spin will shift. The ball will curve more. Besides, that is essentially what many tour pros have indicated in layman's terms.


I take it you didn't graduate from engineering.     I think your understanding of the forces in a club/ball impact are kind of incomplete and flawed. 
...

I wrote that based on intuition, not on any research into the matter.

How is my understanding of the forces in a club/ball impact are incomplete and flawed?

Can you slice or hook your wedge as much as your driver? Does not loft have a significant effect on the effect of side spin?

Looking into sideways curvature of flight I find some pertinent references.

From Wikipedia, "The curved path of a golf ball known as slice or hook is due largely to the ball's spinning motion (about its vertical axis) and the Magnus effect, causing a horizontal force that moves the ball from a straight line in its trajectory.[18]:§ 4.5 Backspin (upper surface rotating backwards from the direction of movement) on a golf ball causes a vertical force that counteracts the force of gravity slightly, and enables the ball to remain airborne a little longer than it would were the ball not spinning: this allows the ball to travel farther than a ball not spinning about its horizontal axis."
https://en.wikipedia.org/wiki/Magnus_effect

Although the following paper deals with side-spin from off-center hits on convex driver surfaces and not slices and hooks, it discusses the forces for back spin and side spin and curvature from side spin.
http://raypenner.com/golf-convex.pdf

...How would you account for the widespread belief that the 20 yard gain in distance was all about the ball when the two balls are launched with virtually the same initial velocity?  The trajectory calculator doesn't seem to suggest that whatever extra spin there is would account for that much extra distance if you optimize the launch angle for the spin.

I'm not sure the gain in distance was "all about the ball". Certainly most people recognize spring face, lighter clubs, larger sweet spots, etc. as part of the gain. However, the big jumps at the point of introduction of the new ball and optimization of the ball use point to the ball being the biggest culprit.

The trajectory calculator presumably calculates the distances using the same club head speed. I believe the tour pros are saying that a lower spinning ball (and bigger sweet spots (actually there is only one sweet spot, the performance degradation for missing it is less on the more engineered drivers)) allow the players to swing harder.

[Bryan Izatt]

Garland,

And one last set of data for your consideration.

In 2006, the USGA conducted a study of spin generation.  The purpose of the study was to gain a better understanding of the behavior of the golf ball in oblique impacts and also the effect of face treatments on the launch of the ball.  The report had extensive data from 1987 regarding spin.  As part of the study the USGA tried to replicate their own groove tests with wound balls conducted in 1987 to establish a benchmark to measure against modern balls (ProV1) and u-grooves.

The tests were carried out in a laboratory  using both Wilson club heads as well as plates with various face treatments (u-groove, v-groove, sand blasted and smooth).  The Wilson heads and the plates were affixed to an infinite barrier and a ball was fired at them at oblique angles.  The speed of the shot was 80 fps or 56 MPH.  This test is similar to the Lieberman experiment.  They tried one higher speed with limited data.  They also conducted a field test with six pros to provide a real world benchmark.

The 1987 benchmark was conducted with Titleist 384 Tour wound balls.  The USGA tried to replicate the 1987 tests but concluded that the 384 Tours had lost too much COR and spin to be useful.  They tested Tour Balatas and found that although they had lost some COR and spin relative to the 384 Tour that they would be a useful surrogate.

So, here are the results.  The Lieberman results are there although they seem out in left field - perhaps different test conditions.  The green dotted line and green solid line are the 1987 384 tour and the 2006 Tour Balata respectively.  The 2006 TB seems like a good surrogate for the 1987 TT384, lower spinning but the same slope.  The red and gold dotted lines are respectively a Pinnacle and a Spalding Tour Edition that were part of the 1987 test.  The blue line is the 2006 ProV1. 

Make what you will of the slopes.  Spin seems to me to be highly variable with club, ball, speed and swing and it would be hard to choose one spin slope as a desirable standard, hard to regulate and harder to engineer and with probably minimal effective distance loss.  But, good luck with tilting at the spin windmill. 

Oh, and by the way, the study found significant differences between u-grooves, v-groves, sand blasted faces and smooth faces.  Contrary to your previous post where you opined that grooves made no difference.



 

[Garland Bayley]

Bryan,

If you have links to the USGA reports, please post them.

[Bryan Izatt]

Garland,


The academic articles trying to explain the curvature of golf balls are beyond me mathematically and from a physics point of view and I graduated in Engineering Physics (a long time ago  ).  Try this article if you want a simpler version of why hooks and slices happen.  The answer is that it results from there being a difference between face angle and swing path causing a tilt in the spin axis.  And, yes, higher spin rates will increase the effect of a tilted spin axis.  Good luck if you can divine a mathematical model of the forces acting on the ball when it is struck.


https://mytrackman.com/.../4.../Get%20to%20Know%20Golf%20-%20FINAL.pdf


Why do drivers slice more than wedges - because there is a greater probability that there is a greater divergence between face angle and swing path with the longer, lower lofted club and the curvature is more obvious after 250 yards than it is after 100 yards.  Spin is no doubt in there somewhere.  But if it was a significant factor high spinning wedges should slice 3 or 4 times more than lower spinning drivers, and that doesn't happen in real life.


If you try the trajectory calculator, you can plug in whatever ball speed, spin rate, launch angle, and weather that you like to see the carry distance.  It doesn't deal with club head speed or sweet spots, it only deals with the flight of the ball depending on launch conditions.  Of course, hitting the ball off-centre on the club face affects the spin rate, launch angle, ball speed and spin axis.  All of those combined determine the flight of the ball.  But, continue your obsession with spin.


I do not have a link to the USGA study.  You can find it if you Google "interim report spin generation".  The first hit will be a PDF on the Japan Golf Association web site.  I've asked the USGA for the 1987 report but got no response so far.  Have fun with it - there are even some formulas in it to satisfy your academic physics cravings.   

[Erik J. Barzeski]

Why do drivers slice more than wedges - because there is a greater probability that there is a greater divergence between face angle and swing path with the longer, lower lofted club and the curvature is more obvious after 250 yards than it is after 100 yards.  Spin is no doubt in there somewhere.  But if it was a significant factor high spinning wedges should slice 3 or 4 times more than lower spinning drivers, and that doesn't happen in real life.

You're more right than wrong in the first half, and then not very right at the end…
https://www.youtube.com/watch?v=O-O-iyorOjo

Garland should stop calling it "side spin." There's really no such thing. There's just one spin, around the spin axis.

[Garland Bayley]

Why do drivers slice more than wedges - because there is a greater probability that there is a greater divergence between face angle and swing path with the longer, lower lofted club and the curvature is more obvious after 250 yards than it is after 100 yards.  Spin is no doubt in there somewhere.  But if it was a significant factor high spinning wedges should slice 3 or 4 times more than lower spinning drivers, and that doesn't happen in real life.

You're more right than wrong in the first half, and then not very right at the end…
https://www.youtube.com/watch?v=O-O-iyorOjo

Garland should stop calling it "side spin." There's really no such thing. There's just one spin, around the spin axis.

As a "science" guy, you should know that they scientists studying the phenomenon will model it with a tangential force vector in the vertical plane which they say provides back spin, and a tangential force vector in the horizontal plane which they say provides side spin. Then they calculate the combination of the two vectors to determine the axis of spin and how much spin there is. That's how science guys speak and model the world of golf.

[Erik J. Barzeski]

As a "science" guy, you should know that they scientists studying the phenomenon will model it with a tangential force vector in the vertical plane which they say provides back spin, and a tangential force vector in the horizontal plane which they say provides side spin. Then they calculate the combination of the two vectors to determine the axis of spin and how much spin there is. That's how science guys speak and model the world of golf.

No. You can break it down into vectors if you want, but doing so "first" is inaccurate. Most of the time when they conduct these tests they don't even worry about sidespin - they fire a ball at a plate or hit a ball with a clubhead or whatever with no real sidespin. A ball fired at a plate doesn't have sidespin by rule, almost, because the vectors are in whatever direction the plate is angled (typically it's angled upward, but there's nothing stopping them from firing a ball at a plate angled downward or to the left or right).

Spin is spin. There is no such thing as "sidespin." There could be a "sidespin vector" or a "sidespin component" but there's just one spin around an axis, which is either tilted or not. You can't "increase sidespin" without increasing overall spin, which may not even tilt the spin axis at all, and which would thus have a smaller effect than you might think on the overall curve of the shot (i.e. two balls with a spin axis of -8° and spins of 2200 and 3700 may not curve as differently as you'd think by only looking at the "side spin" vector).

[Garland Bayley]

...
Try this article if you want a simpler version of why hooks and slices happen.  The answer is that it results from there being a difference between face angle and swing path causing a tilt in the spin axis.  And, yes, higher spin rates will increase the effect of a tilted spin axis.
...

I know why hooks and slices happen. Lordy, I've hit so many I should have some idea.
The difference between the face angle and the swing path would be the cause of the tangential force on the horizontal plane, which causes the tilt in the spin axis.

[Garland Bayley]

...
Why do drivers slice more than wedges - because there is a greater probability that there is a greater divergence between face angle and swing path with the longer, lower lofted club and the curvature is more obvious after 250 yards than it is after 100 yards.  Spin is no doubt in there somewhere.  But if it was a significant factor high spinning wedges should slice 3 or 4 times more than lower spinning drivers, and that doesn't happen in real life.
...

I believe our scientist friends are telling us that with the wedge the tangential force on the vertical plane, which results in what is often referred to as back spin is much higher than the tangential force on the vertical plane from the driver. Think of how a ping pong player can slice by a ball with his paddle causing a lot of spin (wedge) vs. the ping pong player striking the ball with a paddle nearly at right angles to the ball path causing little spin (driver). Now add in the spin caused by the tangential force on the horizontal plane, which results in what is often referred to as side spin. If this tangential force is nearly equal with both clubs, then the tilt in the axis of spin it causes is going to be more with the driver than with the wedge. In all likely hood the longer shaft on the driver is going to make it harder to get the club face as square to the target line as with the wedge, so i believe that in all likely hood the "side spin" tangential force is going to be significantly higher with the driver than with the wedge.

And, you are right Bryan, I did not graduate with an engineering degree.

However, as an undergrad I did take Electrical Engineering courses as free electives for the easy A as opposed to taking humanities courses as free electives for a much lower grade.

[Bryan Izatt]

For your reading pleasure, here's a scientific article only 2 years old by a couple of Bulgarian researchers.


https://www.researchgate.net/publication/318276568_THREE_DIMENSIONAL_GOLF_BALL_FLIGHT


They do observe that golf ball flight is a "complicated area". 


Re your comments about forces, there are the forces that are part of the ball/club collision that launches the ball, and there are forces that affect the ball in flight.


In this paper about ball flight they postulate 6 degrees of freedom in 3 dimensions. 


It's worth keeping in mind that the forces and their direction of action is a mathematical construct to try and model a physical reality.  If you enjoy mathematical models of physical events then this paper will be right up your alley.

[Garland Bayley]

Re the Lieberman article, no I didn't find the whole article, just some snippets from Google books. Do share when you get the whole article.
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I read the paper. They tested both a clean surface and a grassy surface to determine where the spin rate crossed over. The spin rate for the 2 piece ball crossed over about 35 degrees angled plate, the balata at about 45 degrees. They had actually set up to do 55 degrees too, as their tables had an entry for that, but apparently when they determined the crossover lower than that they didn't collect the data for 55 degrees. They had mathematical models to predict the results. They stated that their mathematical models were always within 10% of the measured data.  I would note that they plotted their mathematical models, which showed an S shaped curve.

They fired the balls at the same speed, as was already noted. In the book, there was another paper where they fired the balls at the same speed at each of different angled plates, but it only reaction of the ball during the collision, and did not report spin rates.

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