Spin off of mats vs grass, what is the technical cause?

[clevited]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

 

The same effect happens if we place one of those impact decals on the face of an iron. The grooves very much matter from a clean lie, despite some rumors and theories to the contrary.

 

It's also the reason that a hard cover golf ball will launch higher and spin less with a wedge... vs a soft cover ball.

 

Sure, so is this effect happening as well with the surface the ball sits on?

[cxx]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

Where is the soap? On the counter top that the plate is moving on? On the plate?

 

I put a single drop on the table and placed the ball on the drop. None on the frisbee golf disk or anywhere else on the ball. The friction between the disk and the ball should be the same, only the friction between the ball and the table changed.

 

That's funny. I wouldn't have imagined that there would be much friction between the table and the ball to begin with. Especially with the hit low on the ball, forcing the ball upwards and inducing spin. I would have thought that the surface analogous to the club face was the edge of the frisbee and reducing friction between the frisbee and the ball would have had the largest impact on the trajectory and spin.

[Cwebb]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

 

The same effect happens if we place one of those impact decals on the face of an iron. The grooves very much matter from a clean lie, despite some rumors and theories to the contrary.

 

It's also the reason that a hard cover golf ball will launch higher and spin less with a wedge... vs a soft cover ball.

 

Sure, so is this effect happening as well with the surface the ball sits on?

 

I don't believe so. An iron hit from tee (all else equal), will spin a little more than a shot from the turf. A tee would represent about as little surface friction as possible

[clevited]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

 

The same effect happens if we place one of those impact decals on the face of an iron. The grooves very much matter from a clean lie, despite some rumors and theories to the contrary.

 

It's also the reason that a hard cover golf ball will launch higher and spin less with a wedge... vs a soft cover ball.

 

Sure, so is this effect happening as well with the surface the ball sits on?

 

I don't believe so. An iron hit from tee (all else equal), will spin a little more than a shot from the turf. A tee would represent about as little surface friction as possible

 

This was what I had always thought, but this little experiment just showed the opposite. This is why I brought this subject up. I don't think anyone actually knows for sure what is happening. Too many variables. I would love to make a very controlled test with a phantom camera to try and capture it. I have been trying to imagine it all in my head regarding what happens when striking a ball identically but off different surfaces. Is it a mechanism that makes the ball slide up club face rather than bite and spin, is it more of a bar of soap squirting from out under your foot effect, is it something else? Someone on here has to have the means to capture this definitively?

[cxx]

There is the possibility that there is no difference between the two cases in your experiment. Since the force applied to the ball is to a large degree away from the countertop surface, the friction component, which depends on the force normal to the countertop, is negligible.

[clevited]

There is the possibility that there is no difference between the two cases in your experiment. Since the force applied to the ball is to a large degree away from the countertop surface, the friction component, which depends on the force normal to the countertop, is negligible.

 

That is entirely possible but just little at home experiments alone seem to show something happens. I just have a theory or suspicion as to what might be happening. There are some other ones in here as well that may be the true story. Idk for sure, it is just something that nobody seems to have pin pointed. I should just sit down and math it out with a good old free body diagram to see if that reveals anything but that is less fun and doesn't necessarily reveal any hidden dynamic mechanisms that may or may not be occurring.

[ThinkingPlus]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

Apriori it is non-obvious to me that the coefficient of friction between the soap and ball and table (3 surfaces participating) would be lower than between the ball and table.

[clevited]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

Apriori it is non-obvious to me that the coefficient of friction between the soap and ball and table (3 surfaces participating) would be lower than between the ball and table.

 

Maybe its not and my original thought is possibly true? If I pull the ball with a string taped to it, it definitely pulls easier on the soap than the bare table but that isn't necessarily true in a highly dynamic situation like striking the ball. If the opposite is true and perhaps the viscosity of the soap makes more friction, than that would make much more sense to me.

[Cwebb]

I don't believe so. An iron hit from tee (all else equal), will spin a little more than a shot from the turf. A tee would represent about as little surface friction as possible

 

This was what I had always thought, but this little experiment just showed the opposite. This is why I brought this subject up. I don't think anyone actually knows for sure what is happening. Too many variables. I would love to make a very controlled test with a phantom camera to try and capture it. I have been trying to imagine it all in my head regarding what happens when striking a ball identically but off different surfaces. Is it a mechanism that makes the ball slide up club face rather than bite and spin, is it more of a bar of soap squirting from out under your foot effect, is it something else? Someone on here has to have the means to capture this definitively?

 

I'm leaning strongly towards it being the fact that during an iron strike from a mat, the sole bounces or "skips". This doesn't happen from real grass....but does a bit from a hard pan lie. It prevents the continued down and through AOA of the head....and I believe it can happen when the ball is still interacting with the face, even when the face touched the ball first

[ThinkingPlus]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

Apriori it is non-obvious to me that the coefficient of friction between the soap and ball and table (3 surfaces participating) would be lower than between the ball and table.

 

Maybe its not and my original thought is possibly true? If I pull the ball with a string taped to it, it definitely pulls easier on the soap than the bare table but that isn't necessarily true in a highly dynamic situation like striking the ball. If the opposite is true and perhaps the viscosity of the soap makes more friction, than that would make much more sense to me.

At the very least you have constructed a more complicated scenario. The soap might be forming a bit of a film coating the ball as it spins. Could be lots going on or nothing, but complicated enough to make simple assumptions/conclusions perilous.

[clevited]

Just to summarize, no soap on table, ball went lower and spin slightly more than with soap. I compared frames where ball diameter just gets entirely outside of paper. Was almost identical for each non soap and each soap test. I only did this the 4 times.

 

Btw, this shows exactly opposite of what I thought. Seems less friction between ball and surface produces less spin and higher launch but its not exactly a proper test. It just shows a difference in ball behavior given only a change in its friction with the surface it is on.

 

I found it surprising and interesting to say the least.

Apriori it is non-obvious to me that the coefficient of friction between the soap and ball and table (3 surfaces participating) would be lower than between the ball and table.

 

Maybe its not and my original thought is possibly true? If I pull the ball with a string taped to it, it definitely pulls easier on the soap than the bare table but that isn't necessarily true in a highly dynamic situation like striking the ball. If the opposite is true and perhaps the viscosity of the soap makes more friction, than that would make much more sense to me.

At the very least you have constructed a more complicated scenario. The soap might be forming a bit of a film coating the ball as it spins. Could be lots going on or nothing, but complicated enough to make simple assumptions/conclusions perilous.

 

Yeah I understand, I will see if I can think of a more clear way to test this with less variables. It was a quick thought and easy to set up so I thought I would see what happens. I obviously had to make some assumptions.

[clevited]

I don't believe so. An iron hit from tee (all else equal), will spin a little more than a shot from the turf. A tee would represent about as little surface friction as possible

 

This was what I had always thought, but this little experiment just showed the opposite. This is why I brought this subject up. I don't think anyone actually knows for sure what is happening. Too many variables. I would love to make a very controlled test with a phantom camera to try and capture it. I have been trying to imagine it all in my head regarding what happens when striking a ball identically but off different surfaces. Is it a mechanism that makes the ball slide up club face rather than bite and spin, is it more of a bar of soap squirting from out under your foot effect, is it something else? Someone on here has to have the means to capture this definitively?

 

I'm leaning strongly towards it being the fact that during an iron strike from a mat, the sole bounces or "skips". This doesn't happen from real grass....but does a bit from a hard pan lie. It prevents the continued down and through AOA of the head....and I believe it can happen when the ball is still interacting with the face, even when the face touched the ball first

 

Could very well be all there is to it, don't know for sure.

[clevited]

Just did experiment again and lubricated table with a very thin layer of oil. Not enough to flow or attach to ball or get on disk. I need to better edit the videos but initial observations are that I got the opposite behavior to happen, in other words the behavior I suspected. I think i would need a much much better and more controlled method to determine if the theory I have holds any merit or not. All I seem to show is that "perhaps" there is some impact of turf surface friction on the spin and launch angle of the ball.

[howellhandmade]

Enjoyable discussion. I’ve never worried about spin off of mats, because in the golfing hierarchy of needs I never get to it. Mats, to me, are so much more forgiving than turf that a fantastic range session from mats means bupkis when I get to the course. If I hit a shot a little fat on a mat, the mat bounces the clubhead up into the ball. If I hit a shot a little thin, the mat holds the ball up firmly instead of deforming like turf would do. Mats are such an inferior and incomparable surface to turf that I only hit off them in desperation. Like all f0c41ng winter.

[Trap Junior]

I am interested if a 3 wood off the mat (off the deck) spins or launches different to a 3 wood off the deck off grass. This is important to know when getting a fairway wood when trying to get good spin numbers . Ideal is 3200-3600 but is that the same for grass and mats????

[Stuart_G]

The same effect happens if we place one of those impact decals on the face of an iron. The grooves very much matter from a clean lie, despite some rumors and theories to the contrary.

 

It's more accurate to say the friction between the ball and the face matters. Still not enough to conclude how much the grooves play a factor in that amount of friction. The tape could also just be reducing the friction compared to a raw steel face with no grooves.

 

 

I'm leaning strongly towards it being the fact that during an iron strike from a mat, the sole bounces or "skips". This doesn't happen from real grass....but does a bit from a hard pan lie. It prevents the continued down and through AOA of the head....and I believe it can happen when the ball is still interacting with the face, even when the face touched the ball first

 

The head wouldn't actually need to bounce or skip to reduce the spin. A full rebound ins't really necessary, just some deceleration of the downward motion of the head while the ball is in contact with the face would be all that's needed.

 

Apriori it is non-obvious to me that the coefficient of friction between the soap and ball and table (3 surfaces participating) would be lower than between the ball and table.

...

At the very least you have constructed a more complicated scenario. The soap might be forming a bit of a film coating the ball as it spins. Could be lots going on or nothing, but complicated enough to make simple assumptions/conclusions perilous.

 

And also, I doubt it's really much of a factor but if you really want to get nit-picky, one also should consider the surface tension of the higher viscosity soap (or oil) which could, in theory, could potentially be adding resistance instead of reducing it.

[clevited]

Yeah that issue very well could be Stuart. I changed tactic and wiped a very thin layer of oil onto the surface such that it didn't flow or get on everything. Set a clean ball on it and did a couple more videos. Opposite effect occured so perhaps the soap did mess with results. You can see the soap cling and follow the ball in the videos.

 

I will try and post my other videos. They just didn't turn out quite as well as the others for following and measuring what happened. Some frames got dropped during recording it seems.

[clevited]

Ok, edited my videos and grabbed a screen shot to more clearly show the difference. The image on the left is with an oiled counter top, and the one on the right is cleaned and dry counter top. For both tests, I cleaned the ball with soap and water and let dry. I also cleaned the disk and then didn't touch the edge that contacted the ball so I didn't introduce any skin oil. I marked a spot where I would start to push the disk so I started from the same distance each time. I did my absolute best to make identical pushes of the disk and I was pretty happy with how well I controlled that, it is however a variable I would need to control to get a more accurate result.

 

Anyways, what I show is what I expected to see this time. I saw lower launch higher spin with the oiled surface, and higher launch lower spin with the dry surface. I am guessing my other tests with the soap were not very representative of what I was trying to test. The viscosity of the soap could have hindered spin (you can see the soap stretch out to stay attached to the ball for a frame or two in the videos).

 

I hope to do some better tests just to try and capture a difference in ball flight given only surface friction changes. I hope to do enough controlled tests to show a consistent behavior if there is one. These couple of tests I did were just quick and dirty to tell me if there is even potentially anything to it. It seems there may very well be, but I can understand any skepticism.

 

Edit: Just to state my case better for this idea of a surface friction causing at least part of the issue that is seen when hitting off mats. When the ball is struck, motion is induced into the ball and it travels at an upward angle. Immediately however upon being struck, there has to also be an initial rotational motion induced in the ball. My thought is that the friction of a grass lie is significantly less than the friction of a mat lie. What I think happens is, the mat prevents some of the intital rotation of the golf ball and it tends to then pop upwards more and with lessened spin than a ball struck off a lower friction lie.

[cxx]

Ok, edited my videos and grabbed a screen shot to more clearly show the difference. The image on the left is with an oiled counter top, and the one on the right is cleaned and dry counter top. For both tests, I cleaned the ball with soap and water and let dry. I also cleaned the disk and then didn't touch the edge that contacted the ball so I didn't introduce any skin oil. I marked a spot where I would start to push the disk so I started from the same distance each time. I did my absolute best to make identical pushes of the disk and I was pretty happy with how well I controlled that, it is however a variable I would need to control to get a more accurate result.

 

Anyways, what I show is what I expected to see this time. I saw lower launch higher spin with the oiled surface, and higher launch lower spin with the dry surface. I am guessing my other tests with the soap were not very representative of what I was trying to test. The viscosity of the soap could have hindered spin (you can see the soap stretch out to stay attached to the ball for a frame or two in the videos).

 

I hope to do some better tests just to try and capture a difference in ball flight given only surface friction changes. I hope to do enough controlled tests to show a consistent behavior if there is one. These couple of tests I did were just quick and dirty to tell me if there is even potentially anything to it. It seems there may very well be, but I can understand any skepticism.

 

Edit: Just to state my case better for this idea of a surface friction causing at least part of the issue that is seen when hitting off mats. When the ball is struck, motion is induced into the ball and it travels at an upward angle. Immediately however upon being struck, there has to also be an initial rotational motion induced in the ball. My thought is that the friction of a grass lie is significantly less than the friction of a mat lie. What I think happens is, the mat prevents some of the intital rotation of the golf ball and it tends to then pop upwards more and with lessened spin than a ball struck off a lower friction lie.

 

That's funny I would have thought that the mat, especially an old hard one, provided less resistance than grass, assuming we are not trying to take a divot out of the mat. Take a look at these short shots producing different ball flights. http://www.aroundhawaii.com/fitness/how-to-hit-the-low-spinning-wedge-shot/ The floater (2nd high speed video looks like using the bounce type shot) has some grass between the face and ball while the spinner is pretty clean. The water content of the grass reduces spin if it gets between the face and the ball. You don't get that on mats.

 

A reasonable strike sends the ball on an upward angle on the plane of the path and the normal (the d-plane). It's usually closer to the normal than the path. I would think that the upward motion would significantly reduce any friction forces between the mat and the ball. The idea of hitting down on the ball and forcing the ball down is not real. It's a behavior modification tool that instructors use to get students to produce a solid strike on the ball from a descending blow. The face angle of the club ensures that the ball moves up.

 

Let me add that I don't agree with all that Kelvin says, but he has some excellent footage and points out the complexity of the ball strike.

[clevited]

Ok, edited my videos and grabbed a screen shot to more clearly show the difference. The image on the left is with an oiled counter top, and the one on the right is cleaned and dry counter top. For both tests, I cleaned the ball with soap and water and let dry. I also cleaned the disk and then didn't touch the edge that contacted the ball so I didn't introduce any skin oil. I marked a spot where I would start to push the disk so I started from the same distance each time. I did my absolute best to make identical pushes of the disk and I was pretty happy with how well I controlled that, it is however a variable I would need to control to get a more accurate result.

 

Anyways, what I show is what I expected to see this time. I saw lower launch higher spin with the oiled surface, and higher launch lower spin with the dry surface. I am guessing my other tests with the soap were not very representative of what I was trying to test. The viscosity of the soap could have hindered spin (you can see the soap stretch out to stay attached to the ball for a frame or two in the videos).

 

I hope to do some better tests just to try and capture a difference in ball flight given only surface friction changes. I hope to do enough controlled tests to show a consistent behavior if there is one. These couple of tests I did were just quick and dirty to tell me if there is even potentially anything to it. It seems there may very well be, but I can understand any skepticism.

 

Edit: Just to state my case better for this idea of a surface friction causing at least part of the issue that is seen when hitting off mats. When the ball is struck, motion is induced into the ball and it travels at an upward angle. Immediately however upon being struck, there has to also be an initial rotational motion induced in the ball. My thought is that the friction of a grass lie is significantly less than the friction of a mat lie. What I think happens is, the mat prevents some of the intital rotation of the golf ball and it tends to then pop upwards more and with lessened spin than a ball struck off a lower friction lie.

 

That's funny I would have thought that the mat, especially an old hard one, provided less resistance than grass, assuming we are not trying to take a divot out of the mat. Take a look at these short shots producing different ball flights. http://www.aroundhawaii.com/fitness/how-to-hit-the-low-spinning-wedge-shot/ The floater (2nd high speed video looks like using the bounce type shot) has some grass between the face and ball while the spinner is pretty clean. The water content of the grass reduces spin if it gets between the face and the ball. You don't get that on mats.

 

A reasonable strike sends the ball on an upward angle on the plane of the path and the normal (the d-plane). It's usually closer to the normal than the path. I would think that the upward motion would significantly reduce any friction forces between the mat and the ball. The idea of hitting down on the ball and forcing the ball down is not real. It's a behavior modification tool that instructors use to get students to produce a solid strike on the ball from a descending blow. The face angle of the club ensures that the ball moves up.

 

Yeah I am not comparing this at all to how a flyer lie works, I mentioned it a while back as a way to look at the behavior of a ball off a mat vs grass. A nice fairway or tee box lie is all I care about regarding this little thought experiment. I am not considering grass getting between the ball and the club nor mat material getting between ball and club. I am merely suggesting that right when the ball is struck, the ball both starts on an upward angle and it starts to spin, both at the same time. If there is low friction between the surface and the ball, I hypothesis that it will come out lower and with more spin than when their is higher friction.

 

A way to kind of visualize this is to take a basketball, put it on a grippy surface, hold the ball still with one hand and slowly try to slide your hand underneath the ball. The ball doesn't want to start to rotate or go forward, it wants to pop up. If you take the same ball and place it on a piece of paper on your same surface and then slowly try to slide your hand underneath it, the ball will want to go forward and rotate. I think this same mechanism occurs in that tiny amount of time that the club impacts the ball.

 

Another little tidbit that might add a little credibility to my idea (or just make more questions), comes from a video I saw. It is a Titleist video and they show many slow motion shots with a driver being swung by a robot. They show several shots of it hitting a ball off a typical wood tee and one where it is struck off of a rubber tee. You can clearly see the ball get grabbed by the rubber tee and spin noticeably less than any of the shots off a wooden tee. You can even see the tee edge deform as the ball is struck. The edge stays in contact with the ball for a significant amount of time and "seems" to reduce backspin. This I feel might be a more extreme example of what also occurs during a shot off a mat. The wooden tee in this case would be more representative of a shot of grass, and the rubber tee, a shot off of a mat.

 

Edit: Do you think you can fix that link? I copied and pasted it and it worked but a working link would be even better I'd think.

 

Edit 2: I should add that I don't think the amount of spin reduction or loft increase is equal for every club in the bag. I would imagine that it is worse with certain clubs and perhaps hardly noticeably with others. I am of course though not saying my hypothesis is true, but from all of the little tests I have tried to do the past couple of days, it seems possibly true.

 

Edit 3: I looked at those videos again. To me the grass in the first video plays no role in the results of the shot. I don't think it gets between the club and the ball. This to me would be a standard shot as done by a robot and how I would try and test my theory off of both a grass and mat lie. The second video shows clearly what happens when the ball hits higher on the face and a person uses club bounce. With my idea I am not saying that a shot like that isn't also part of the issue. There are many little things that can add to the common problem of lower spin off of a mat. I am proposing that identically struck balls will see a difference off of a mat vs off of a grass lie due to friction alone. Personally, when I get ball first, I get lower spin off a mat that off of grass which I have only ever measured by hitting pitch shots onto a putting green. Off a mat, significantly more roll out than off the grass when I felt I hit them just as cleanly.

[cxx]

Ok, edited my videos and grabbed a screen shot to more clearly show the difference. The image on the left is with an oiled counter top, and the one on the right is cleaned and dry counter top. For both tests, I cleaned the ball with soap and water and let dry. I also cleaned the disk and then didn't touch the edge that contacted the ball so I didn't introduce any skin oil. I marked a spot where I would start to push the disk so I started from the same distance each time. I did my absolute best to make identical pushes of the disk and I was pretty happy with how well I controlled that, it is however a variable I would need to control to get a more accurate result.

 

Anyways, what I show is what I expected to see this time. I saw lower launch higher spin with the oiled surface, and higher launch lower spin with the dry surface. I am guessing my other tests with the soap were not very representative of what I was trying to test. The viscosity of the soap could have hindered spin (you can see the soap stretch out to stay attached to the ball for a frame or two in the videos).

 

I hope to do some better tests just to try and capture a difference in ball flight given only surface friction changes. I hope to do enough controlled tests to show a consistent behavior if there is one. These couple of tests I did were just quick and dirty to tell me if there is even potentially anything to it. It seems there may very well be, but I can understand any skepticism.

 

Edit: Just to state my case better for this idea of a surface friction causing at least part of the issue that is seen when hitting off mats. When the ball is struck, motion is induced into the ball and it travels at an upward angle. Immediately however upon being struck, there has to also be an initial rotational motion induced in the ball. My thought is that the friction of a grass lie is significantly less than the friction of a mat lie. What I think happens is, the mat prevents some of the intital rotation of the golf ball and it tends to then pop upwards more and with lessened spin than a ball struck off a lower friction lie.

 

That's funny I would have thought that the mat, especially an old hard one, provided less resistance than grass, assuming we are not trying to take a divot out of the mat. Take a look at these short shots producing different ball flights. http://www.aroundhawaii.com/fitness/how-to-hit-the-low-spinning-wedge-shot/ The floater (2nd high speed video looks like using the bounce type shot) has some grass between the face and ball while the spinner is pretty clean. The water content of the grass reduces spin if it gets between the face and the ball. You don't get that on mats.

 

A reasonable strike sends the ball on an upward angle on the plane of the path and the normal (the d-plane). It's usually closer to the normal than the path. I would think that the upward motion would significantly reduce any friction forces between the mat and the ball. The idea of hitting down on the ball and forcing the ball down is not real. It's a behavior modification tool that instructors use to get students to produce a solid strike on the ball from a descending blow. The face angle of the club ensures that the ball moves up.

 

Yeah I am not comparing this at all to how a flyer lie works, I mentioned it a while back as a way to look at the behavior of a ball off a mat vs grass. A nice fairway or tee box lie is all I care about regarding this little thought experiment. I am not considering grass getting between the ball and the club nor mat material getting between ball and club. I am merely suggesting that right when the ball is struck, the ball both starts on an upward angle and it starts to spin, both at the same time. If there is low friction between the surface and the ball, I hypothesis that it will come out lower and with more spin than when their is higher friction.

 

A way to kind of visualize this is to take a basketball, put it on a grippy surface, hold the ball still with one hand and slowly try to slide your hand underneath the ball. The ball doesn't want to start to rotate or go forward, it wants to pop up. If you take the same ball and place it on a piece of paper on your same surface and then slowly try to slide your hand underneath it, the ball will want to go forward and rotate. I think this same mechanism occurs in that tiny amount of time that the club impacts the ball.

 

Another little tidbit that might add a little credibility to my idea (or just make more questions), comes from a video I saw. It is a Titleist video and they show many slow motion shots with a driver being swung by a robot. They show several shots of it hitting a ball off a typical wood tee and one where it is struck off of a rubber tee. You can clearly see the ball get grabbed by the rubber tee and spin noticeably less than any of the shots off a wooden tee. You can even see the tee edge deform as the ball is struck. The edge stays in contact with the ball for a significant amount of time and "seems" to reduce backspin. This I feel might be a more extreme example of what also occurs during a shot off a mat. The wooden tee in this case would be more representative of a shot of grass, and the rubber tee, a shot off of a mat.

 

Edit: Do you think you can fix that link? I copied and pasted it and it worked but a working link would be even better I'd think.

The link works for me, click and go.

Got a link on the Titleist video?

[cxx]

I don't agree with the friction with the surface being a big factor. The maximum rotational force is at the moment of impact which would be proportional to the weight of the ball times the ball's radius. The force on the ball from the club is forward and up. The question is how much rotation can be imparted during the very brief time between initial contact and the gravitational force on the ball being overcome. I think very little.

 

One could do an experiment on the rubber tee / driver effect. Might be an easy one to reproduce. Get one of those consistent strikers on youtube to hit 100 shots alternating between wood and rubber tees.

[clevited]

I don't agree with the friction with the surface being a big factor. The maximum rotational force is at the moment of impact which would be proportional to the weight of the ball times the ball's radius. The force on the ball from the club is forward and up. The question is how much rotation can be imparted during the very brief time between initial contact and the gravitational force on the ball being overcome. I think very little.

 

One could do an experiment on the rubber tee / driver effect. Might be an easy one to reproduce. Get one of those consistent strikers on youtube to hit 100 shots alternating between wood and rubber tees.

 

I know what I am suggesting is controversial and seemingly unlikely but I haven't seen very many good alternatives. I just can't accept that all low spin shots off a mat are from user error. I would love to take the human element away and test various mat surfaces and a grass surface and take video in slow motion. I have a pendulum style chipping rig all designed up I just haven't got around to making it yet. I need to put more thought into how to best do the tests so that it isn't just a waste of my time getting inconclusive data.

 

For some reason link doesn't show for me, no biggy. Great web page btw, I am still reading through it, so thanks for that.

[clevited]

Here is the video. Rubber tee is at 3:19. It looks like they have dew on everything in that shot, so it is only a suggestion as to what might happen but for all I know it could be completely from the dew that it looks to spin less. Could be a different ball too for all I know. You can see the tee grab, but of course it is also surrounding the ball more to begin with. Interesting at the very least I thought.

 

Edit: If you look carefully at the rubber tee video and any of the wooden tee vids, and go frame by frame, the initial rotation of the golf ball seems significantly less when the ball was struck off of the wooden tee but I will admit, it is hard to see for sure. Focus on the rubber tee grabbing the ball, that is what I theorize happens off the ground.

 

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Edit:2 I added this video of shots off of turf. The ball to me, seems to definitely maintain contact with the turf for a frame or two after impact, which to me makes my hypothesis seem plausible. Notice this has several shots where the club just skims the surface of the mat and gets all ball. There is a shot or two that are fatter than ideal too mixed in there.

 

http://www.youtube.com/watch?v=6dG9hb3_blo

[cxx]

Cool video. I watched it a several times. I saw 1 shot off a rubber tee but that ball had water on it. All the others were regular tees. It's also hard to know what kind of experiment they were doing and what setup was used. I can't judge where the impact point on the face is or the clubhead speed.

 

If you check out more of Kelvin's high speed videos you see quite a bit of unexpected stuff, especially on off center hits.

[Stuart_G]

Thanks for sharing the video. What I'd give to play around with that camera and set-up :-)

 

The driver 'grabs' the tee because the compression causes elongation of the ball in the vertical axis - so the bottom of the ball is actually pushing down on the tee a little bit prior to the ball starting to move forward - at the same time that the loft is pushing up on the ball. The wooden tee looks like it resists that downward pressure a bit less than the rubber tee. BUT realize that this compression and elongation is parallel to the face - so the effect will be biggest for the driver and a lot less as the loft increases and the upward motion increases, the club head speed decreases, and the amount of deformation also decreases. At what point the two opposite (up vs down) effects zero out is impossible to say just from those video's - but I wouldn't expect it to increase any friction with the turf/mat for the majority of the irons.

[clevited]

Yeah those videos I find fascinating and I would absolutely love to have one of those cameras as well. Oh the stuff I would do with it!

 

I just find this subject interesting and I have never been completely satisfied with any of the guesses that are out there. It should be easy to test if a person has the tools that say titleist has. Most of us just don't. I would like them to take high speed video of a robot swinging various irons off of mats and off of grass and see if there is or is not a difference in launch height and spin given identical contact and minimal turf interaction with the club prior to impact. It would not tell us the mechanism for sure if there is a difference, but at least it would show whether there is still an issue when the human element is taken away. The best I will ever be able to do is my chipping rig.

[clevited]

A couple other videos to add in here for discussion.

 

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[Frankensteins Monster]

[clevited]

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I have seen that video. Unfortunately, I have seen too many other "tests" with a very good golfer that show the opposite is true. I would be inclined to throw their experiment into the mix if they didn't also have something they were trying to sell, their services. I would also want the golf mat if there test was indeed unbiased and accurate.