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

[bladehunter]

In a proper hit iron shot, the ball is long gone from the face of the club before the clubhead hits the ground. Could the difference be the golfer behaving different such as not afraid to hit down on grass but afraid to hit down on mats?

Can you prove that either mathematically or with high speed video?

 

I agree with you thinking. I knew that's what this topic was getting at too.

 

I find it hilarious that it's said this is the case. Take a high vertical cog iron and show me how to get a strike with the cog in the proper place and not have the bottom of the arc be under the ball. Cannot be done. Not from a tight lie like hard pan or a mat. This myth is perpetuated because it is true on fairways that perch the ball up and tees up lies otherwise. Problem is the local muni doesn't have these fairways. Hit one off the cartpath flush and let me know.truth is it's lie dependent. And a mat isn't going to let you catch ball and then hit turf 4-5 inches in front of the ball. Not and get it anything but 2 grooves low.or break a wrist.

 

OK I'll bite. The ball has a diameter of 1.68. Half is .84. An AP2 actual vertical center of gravity is .803. Even a sweeping pick stroke would hit above the AVCOG. For the titleist blade .826. Can still hit above that and not touch the mat.

 

Edit

Most mats will hold the ball proud. Grass, not so much.

 

I said high V cog. The i500 is .940. .... that’s what I’ve been comparing to an MB (681) for months now. It’s amazing the difference.

 

The two examples you give are mathematically possible. But even then. You have to have such a descending blow that you’re going to bottom out into them mat ( or cart path ) you have to adjust aoa for this. Your brain will do it involuntarily.

[bladehunter]

Look. I’m not arguing all or nothing. I’m just saying it’s very lie , aoa and overal short dependent. But. I’ve been preached to 100 times by the “ no the ball is long gone before any turf interaction “ crowd. Just not true except on a small sample of perfect scenario shots.

[cxx]

In a proper hit iron shot, the ball is long gone from the face of the club before the clubhead hits the ground. Could the difference be the golfer behaving different such as not afraid to hit down on grass but afraid to hit down on mats?

Can you prove that either mathematically or with high speed video?

 

I agree with you thinking. I knew that's what this topic was getting at too.

 

I find it hilarious that it's said this is the case. Take a high vertical cog iron and show me how to get a strike with the cog in the proper place and not have the bottom of the arc be under the ball. Cannot be done. Not from a tight lie like hard pan or a mat. This myth is perpetuated because it is true on fairways that perch the ball up and tees up lies otherwise. Problem is the local muni doesn't have these fairways. Hit one off the cartpath flush and let me know.truth is it's lie dependent. And a mat isn't going to let you catch ball and then hit turf 4-5 inches in front of the ball. Not and get it anything but 2 grooves low.or break a wrist.

 

OK I'll bite. The ball has a diameter of 1.68. Half is .84. An AP2 actual vertical center of gravity is .803. Even a sweeping pick stroke would hit above the AVCOG. For the titleist blade .826. Can still hit above that and not touch the mat.

 

Edit

Most mats will hold the ball proud. Grass, not so much.

 

I said high V cog. The i500 is .940. .... that's what I've been comparing to an MB (681) for months now. It's amazing the difference.

 

The two examples you give are mathematically possible. But even then. You have to have such a descending blow that you're going to bottom out into them mat ( or cart path ) you have to adjust aoa for this. Your brain will do it involuntarily.

 

.940 sounds like a glutton for punishment.

 

It's not hard for a picker of the ball to hit off hardpan.

[cxx]

Look. I'm not arguing all or nothing. I'm just saying it's very lie , aoa and overal short dependent. But. I've been preached to 100 times by the " no the ball is long gone before any turf interaction " crowd. Just not true except on a small sample of perfect scenario shots.

 

No problem with that. All but the most steep get into the grass before the ball. Hopefully just the blades. That's why special effort is required when it's really soggy. We've had way too much soggy turf lately.

[chonkoa]

I knew I was going to learn something new today. Thanks for all that have contributed to this discussion.

[ThinkingPlus]

.940 sounds like a glutton for punishment.

 

It's not hard for a picker of the ball to hit off hardpan.

Cally CF16s are 0.864. Most folks rave about their forgiveness and they are - horizontally. Not so much in the vertical axis.

 

If you sweep you have the best chance of replicating apex off hard pan, however, generally the shots will come out lower because good ball strikers naturally lean the shaft more off the firm stuff (somewhat club dependent). For example if you don't lay that 14° bounce sand wedge on its face off hard pan, you will be living in scull city.

[Stuart_G]

The Fiberbuilts create a mostly permeable grasslike layer above a firm rubber mat if I remember correctly. The resistance to motion feels very similar to what you get with real grass. The club will slow slightly, but won't vary in path until it gets to the firm rubber part. If the permeable grasslike layer is more than 1 - 1.5 cm, the ball is gone before the club impacts the firmer rubber layer.

 

In the context of the mats - it will be determined by the length and density of the fibers. In the case of Fiberbuilt, they are relatively long (1.75" for 'fairway' turf) and not as dense as many others allowing the club to move more freely through it w/o resistance. A lower quality turf mat can have fibers ~3/8" in length but can still be dense enough to impact the motion of the head before the ball is gone. Medium grade will tend to be 1"-1.25". But even they can be pretty grabby - whether it's soon enough to effect the ball flight I can't say as I haven't done that much testing yet.

[ThinkingPlus]

Look. I'm not arguing all or nothing. I'm just saying it's very lie , aoa and overal short dependent. But. I've been preached to 100 times by the " no the ball is long gone before any turf interaction " crowd. Just not true except on a small sample of perfect scenario shots.

 

No problem with that. All but the most steep get into the grass before the ball. Hopefully just the blades. That's why special effort is required when it's really soggy. We've had way too much soggy turf lately.

It is irritating (not you, but others) getting constantly lectured on how the pros "divot" starts N inches in front of the ball, blah, blah, blah when you can see video of one of the top ballstrikers on tour clipping a good bit of grass prior to the ball. This begs the question of whether our metric is appropriate or consistently defined. I would claim a "divot" is a poor metric because it's definition depends intrinsically on the turf/lie. Dependent metrics are generally worthless. I don't have an appropriate independent metric as a substitute either, but lots of teachers out in the world have been giving lessons for years and they should have come to some kind of consensus by now. Rant over. :blush:

[ThinkingPlus]

The Fiberbuilts create a mostly permeable grasslike layer above a firm rubber mat if I remember correctly. The resistance to motion feels very similar to what you get with real grass. The club will slow slightly, but won't vary in path until it gets to the firm rubber part. If the permeable grasslike layer is more than 1 - 1.5 cm, the ball is gone before the club impacts the firmer rubber layer.

 

In the context of the mats - it will be determined by the length and density of the fibers. In the case of Fiberbuilt, they are relatively long (1.75" for 'fairway' turf) and not as dense as many others allowing the club to move more freely through it w/o resistance. A lower quality turf mat can have fibers ~3/8" in length but can still be dense enough to impact the motion of the head before the ball is gone. Medium grade will tend to be 1"-1.25". But even they can be pretty grabby - whether it's soon enough to effect the ball flight I can't say as I haven't done that much testing yet.

Agree. Same thing applies to real turf. Much more complicated than folks realize.

[cxx]

.940 sounds like a glutton for punishment.

 

It's not hard for a picker of the ball to hit off hardpan.

Cally CF16s are 0.864. Most folks rave about their forgiveness and they are - horizontally. Not so much in the vertical axis.

 

If you sweep you have the best chance of replicating apex off hard pan, however, generally the shots will come out lower because good ball strikers naturally lean the shaft more off the firm stuff (somewhat club dependent). For example if you don't lay that 14° bounce sand wedge on its face off hard pan, you will be living in scull city.

 

My favorite shots are from tight surrounds that extend back from the green, probably because I do come in shallow and it's a natural shot for me. I don't have anything with 14 degrees of bounce. My sandwedge has 10 degrees and some extra heel relief. My 60 has 7. I prefer a cutting edge rather than bouncing. Lots of ways to play the game.

[Stuart_G]

I didn't really think of an old hard driving range mat as the test bed. I could believe that those would bounce the club.

 

Yet that's what most people end up hitting on. Very few commercial places are going to have very high end hitting mats.

 

But - the TM article only mentioned drivng range mats, they didn't go into any more details about the mats they used when they collected the data.

 

 

Regarding the friction idea, I always wanted to make a test rig where i swing a pendulum at a ball sitting on a lie board and then the same thing with a ball sitting on sandpaper being careful to make impact the same each time. I would capture what ends up being a chip with my skytrak and see what happens with these extremes.

 

My thoughts were that a grippier surface would not allow the ball to gear up the face quite as quickly and instead, slide up a couple grooves first. Essentially it would slide up face more than off grass and less spin would be imparted. I don't see how those physics can't work. I do however think lots of things can be the culprit at any give time but if we were to use a repeatable swing like that of a robot, and a high speed camera, what would we see? Would grass and mat behave the same or would there be an obvious mechanism creating higher launch and lower spin every time?

 

That will be tough to get accurate enough duplication. You'd really need to take a lot of samples and hope the results showed some type of statistical difference between the two. In fact, if you just want to explore the theory dont' stop at just sand-paper - take it too a bigger extreme - superglue the ball to the ground.

 

Although I still don't see it being a factor, that's different than what you talked about before with the emphasis on compression. The Friction between the ball and the ground doesn't have anything to do with how much the ball compresses. Keep in mind, the initial force imparted on the ball by the club is upward, away from the surface.

[cxx]

I didn't really think of an old hard driving range mat as the test bed. I could believe that those would bounce the club.

 

Yet that's what most people end up hitting on. Very few commercial places are going to have very high end hitting mats.

 

But - the TM article only mentioned drivng range mats, they didn't go into any more details about the mats they used when they collected the data.

 

 

Regarding the friction idea, I always wanted to make a test rig where i swing a pendulum at a ball sitting on a lie board and then the same thing with a ball sitting on sandpaper being careful to make impact the same each time. I would capture what ends up being a chip with my skytrak and see what happens with these extremes.

 

My thoughts were that a grippier surface would not allow the ball to gear up the face quite as quickly and instead, slide up a couple grooves first. Essentially it would slide up face more than off grass and less spin would be imparted. I don't see how those physics can't work. I do however think lots of things can be the culprit at any give time but if we were to use a repeatable swing like that of a robot, and a high speed camera, what would we see? Would grass and mat behave the same or would there be an obvious mechanism creating higher launch and lower spin every time?

 

That will be tough to get accurate enough duplication. You'd really need to take a lot of samples and hope the results showed some type of statistical difference between the two. In fact, if you just want to explore the theory dont' stop at just sand-paper - take it too a bigger extreme - superglue the ball to the ground.

 

Although I still don't see it being a factor, that's different than what you talked about before with the emphasis on compression. The Friction between the ball and the ground doesn't have anything to do with how much the ball compresses. Keep in mind, the initial force imparted on the ball by the club is upward, away from the surface.

 

Yes, hitting down on the ball is an unfortunate expression. While the clubhead might be descending the hit forces the ball up, not down.

[clevited]

Just some cool footage regarding this subject.

http://youtu.be/6dG9hb3_blo

 

 

[ThinkingPlus]

.940 sounds like a glutton for punishment.

 

It's not hard for a picker of the ball to hit off hardpan.

Cally CF16s are 0.864. Most folks rave about their forgiveness and they are - horizontally. Not so much in the vertical axis.

 

If you sweep you have the best chance of replicating apex off hard pan, however, generally the shots will come out lower because good ball strikers naturally lean the shaft more off the firm stuff (somewhat club dependent). For example if you don't lay that 14° bounce sand wedge on its face off hard pan, you will be living in scull city.

 

My favorite shots are from tight surrounds that extend back from the green, probably because I do come in shallow and it's a natural shot for me. I don't have anything with 14 degrees of bounce. My sandwedge has 10 degrees and some extra heel relief. My 60 has 7. I prefer a cutting edge rather than bouncing. Lots of ways to play the game.

7° and 8° for me unless playing in swampy conditions. S. TX hardpan cured me of bouncy wedges.

[Cwebb]

 

I said high V cog. The i500 is .940. .... that's what I've been comparing to an MB (681) for months now. It's amazing the difference.

 

The two examples you give are mathematically possible. But even then. You have to have such a descending blow that you're going to bottom out into them mat ( or cart path ) you have to adjust aoa for this. Your brain will do it involuntarily.

 

.940 sounds like a glutton for punishment.

 

It's not hard for a picker of the ball to hit off hardpan.

 

It's a real issue with many iron designs. If we look at the actual measurements, we find that many irons have COG's (sweet-spots) higher than the center of a ball (.840").

 

Doesn't make a whole lot of sense for someone who is looking for "game improvement" help in irons, to be playing one that has a sweet-spot that is more difficult to "find" in the vertical aspect of contact

[cxx]

I said high V cog. The i500 is .940. .... that's what I've been comparing to an MB (681) for months now. It's amazing the difference.

 

The two examples you give are mathematically possible. But even then. You have to have such a descending blow that you're going to bottom out into them mat ( or cart path ) you have to adjust aoa for this. Your brain will do it involuntarily.

 

.940 sounds like a glutton for punishment.

 

It's not hard for a picker of the ball to hit off hardpan.

 

It's a real issue with many iron designs. If we look at the actual measurements, we find that many irons have COG's (sweet-spots) higher than the center of a ball (.840").

 

Doesn't make a whole lot of sense for someone who is looking for "game improvement" help in irons, to be playing one that has a sweet-spot that is more difficult to "find" in the vertical aspect of contact

 

I think Maltby puts an awful lot of weight on the C dimension, which increases with the distance from heel to toe. I don't think that counteracts a high vertical COG.

[Cwebb]

I said high V cog. The i500 is .940. .... that's what I've been comparing to an MB (681) for months now. It's amazing the difference.

 

The two examples you give are mathematically possible. But even then. You have to have such a descending blow that you're going to bottom out into them mat ( or cart path ) you have to adjust aoa for this. Your brain will do it involuntarily.

 

.940 sounds like a glutton for punishment.

 

It's not hard for a picker of the ball to hit off hardpan.

 

It's a real issue with many iron designs. If we look at the actual measurements, we find that many irons have COG's (sweet-spots) higher than the center of a ball (.840").

 

Doesn't make a whole lot of sense for someone who is looking for "game improvement" help in irons, to be playing one that has a sweet-spot that is more difficult to "find" in the vertical aspect of contact

 

I think Maltby puts an awful lot of weight on the C dimension, which increases with the distance from heel to toe. I don't think that counteracts a high vertical COG.

 

It certainly doesn't. They are separate categories. Take two small blades of the same size and face length, but one with a low COG and the other with a really high COG....and they will perform different. The one with the lower sweet-spot will be easier to hit for most players, especially from tighter lies

[DavePelz4]

In a proper hit iron shot, the ball is long gone from the face of the club before the clubhead hits the ground. Could the difference be the golfer behaving different such as not afraid to hit down on grass but afraid to hit down on mats?

Can you prove that either mathematically or with high speed video?

 

Isn't the theory hit the little ball before the big ball?

[Cwebb]

In a proper hit iron shot, the ball is long gone from the face of the club before the clubhead hits the ground. Could the difference be the golfer behaving different such as not afraid to hit down on grass but afraid to hit down on mats?

Can you prove that either mathematically or with high speed video?

 

Isn't the theory hit the little ball before the big ball?

 

Of course, but what happens in reality when the sole starts touching the turf or ground at the same time as the face touches the ball....or a fraction before?

[ThinkingPlus]

In a proper hit iron shot, the ball is long gone from the face of the club before the clubhead hits the ground. Could the difference be the golfer behaving different such as not afraid to hit down on grass but afraid to hit down on mats?

Can you prove that either mathematically or with high speed video?

 

Isn't the theory hit the little ball before the big ball?

Sure, but that is imprecise. A bladed wedge meets that criteria.

[DavePelz4]

In a proper hit iron shot, the ball is long gone from the face of the club before the clubhead hits the ground. Could the difference be the golfer behaving different such as not afraid to hit down on grass but afraid to hit down on mats?

Can you prove that either mathematically or with high speed video?

 

Isn't the theory hit the little ball before the big ball?

 

Of course, but what happens in reality when the sole starts touching the turf or ground at the same time as the face touches the ball....or a fraction before?

 

The fraction before would be a normal shot for me.

[Cwebb]

In a proper hit iron shot, the ball is long gone from the face of the club before the clubhead hits the ground. Could the difference be the golfer behaving different such as not afraid to hit down on grass but afraid to hit down on mats?

Can you prove that either mathematically or with high speed video?

 

Isn't the theory hit the little ball before the big ball?

 

Of course, but what happens in reality when the sole starts touching the turf or ground at the same time as the face touches the ball....or a fraction before?

 

The fraction before would be a normal shot for me.

 

So if you were to hit off mats, your impact conditions would be some sort of a "drop kick" and would result in a different flight and spin rate than what you'd experience from real turf

[DavePelz4]

So if you were to hit off mats, your impact conditions would be some sort of a "drop kick" and would result in a different flight and spin rate than what you'd experience from real turf

 

First apologies...I was making fun of myself which clearly didn't come through. My swing is very upright and hitting off mats is very comparable to hitting off normal turf. It's rare that I "bounce into" a shot as suggested but it happens.

[clevited]

You guys be the judge of these. I controlled all the variables I could, I wish I could have made a good way to hit with exact same speed each time but I did my best.

 

This was an attempt to show my friction difference thought and why I think it could be one mechanism causing the problem.

 

 

[clevited]

Second set of tests

 

[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.

[malamig]

flier lies! also easier to hit draws for some reason.

[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?

[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.

[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.

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.