Maltby Ping VCOG? What’s going on here?

[NRJyzr]

18 minutes ago, gtrade said:

 

Does it just tell how hot the middle is in GI irons? i230 has similar vcog than i525 and no similar drop-off visible.

 

If you make 1:1 comparison between players irons with different vcog's and horisontal axis MOI's, I'm not sure anyone can tell if differencies are due to vcog or not.

 

Nothing that I've seen. 

 

It might be hard to parse the individual sources' influences on results.  The way to do it would be isolating each variable, which is a "good luck with that" moment.  LOL

 

[NRJyzr]

9 minutes ago, ThinkingPlus said:

MOI is always a secondary effect relative to CG. In the real world the club head motion can line up the CGs, but they will never be coincident because the club-ball interaction happens at their respective surfaces. Also, to get height and spin, you want the clubhead CG driven below the ball CG. The only players who don't want or need that are high swing speed, high spin players. For them, the higher clubhead CG helps prevent ultra-high ballooning shots.

 

This has always made me think...

 

The clubhead that got me to switch to blades was the MP14, famous for its quite low CG.  When I did that testing, I hadn't reached my speed peak; that happened 6-10 years later.  I'd always wondered how MP14s would have worked for me if I had just grabbed a set, anywhere in that higher speed window.

 

Given that I had serious trajectory and speed issues with the MS-11s that I *did* eventually acquire, I have a hint.  But it's only speculation.

 

Random thought.  😁

 

[is1ander]

39 minutes ago, gtrade said:

 

Does it just tell how hot the middle is in GI irons? i230 has similar vcog than i525 and no similar drop-off visible.

 

If you make 1:1 comparison between players irons with different vcog's and horisontal axis MOI's, I'm not sure anyone can tell if differencies are due to vcog or not.

 

i230 has slightly higher MOI which is probably not important for low center misses but lower VCOG. I'm thinking i230 is safely in the threshold of playable VCOG while i525 is not so much. I've heard of many golfers who love i230, even Ian from TXG gamed a set for a bit. Can't say I've heard anywhere similar positive vibes about i525. Also seems that Ping brought out i530 a little earlier than the average Ping update which is longer than industry standard.

[ThinkingPlus]

2 minutes ago, NRJyzr said:

 

This has always made me think...

 

The clubhead that got me to switch to blades was the MP14, famous for its quite low CG.  When I did that testing, I hadn't reached my speed peak; that happened 6-10 years later.  I'd always wondered how MP14s would have worked for me if I had just grabbed a set, anywhere in that higher speed window.

 

Given that I had serious trajectory and speed issues with the MS-11s that I *did* eventually acquire, I have a hint.  But it's only speculation.

 

Random thought.  😁

 

I don't know when speed starts causing ballooning issues because it has never happened to me. Lots of anecdotal info from speed monsters and most pros. They tend to gravitate towards the higher CG irons.

 

High CG can also benefit players with very high AOA especially off the tee. They can get a more efficient strike. As long as they play lush, soft turf it's a good bandaid.

[ChaosTheory]

@NRJyzr

The i230 and Blueprint T are much tighter than the 525.  From what I've seen over the last year of CC reviews, all of the hot irons have a large vertical spread. 

[gtrade]

32 minutes ago, ThinkingPlus said:

MOI is always a secondary effect relative to CG. In the real world the club head motion can line up the CGs, but they will never be coincident because the club-ball interaction happens at their respective surfaces. Also, to get height and spin, you want the clubhead CG driven below the ball CG. The only players who don't want or need that are high swing speed, high spin players. For them, the higher clubhead CG helps prevent ultra-high ballooning shots.

 

What do you mean with club cg driven below the ball cg? Even with 0.7" club vcog the ball cg is lower than the club cg when compared to normal impact force (in joostin's pic).

 

Hovland is a picker of the ball, plays on the hardest fairways but also plays one of the highest cg clubs. Something is missing, maybe it's the combination of shaft lean, cor and horisontal axis moi, like joostin wrote.

[ThinkingPlus]

5 minutes ago, gtrade said:

 

What do you mean with club cg driven below the ball cg? Even with 0.7" club vcog the ball cg is lower than the club cg when compared to normal impact force (in joostin's pic).

 

Hovland is a picker of the ball, plays on the hardest fairways but also plays one of the highest cg clubs. Something is missing, maybe it's the combination of shaft lean, cor and horisontal axis moi, like joostin wrote.

The ball CG is 0.84". Clubs first engage the turf, especially on firm, tight fairways, right under the ball typically. If the clubhead CG is higher than the ball, then it is difficult to get the clubhead CG below the ball CG. So you get less spin and less height. Low CG clubhead can be driven below the ball CG getting higher launch and more spin which is beneficial for slower swingers.

 

Hovland has speed and spin to burn. He could have thin strikes and wouldn't notice. Shaft lean does help and with Hovland's speed because he can lean the shaft alot and still get sufficient height and spin. Since he is a little OTT, I am surprised he is a picker. Seems like he would have a steeper AOA.

[is1ander]

14 minutes ago, ThinkingPlus said:

The ball CG is 0.84". Clubs first engage the turf, especially on firm, tight fairways, right under the ball typically. If the clubhead CG is higher than the ball, then it is difficult to get the clubhead CG below the ball CG. So you get less spin and less height. Low CG clubhead can be driven below the ball CG getting higher launch and more spin which is beneficial for slower swingers.

 

Hovland has speed and spin to burn. He could have thin strikes and wouldn't notice. Shaft lean does help and with Hovland's speed because he can lean the shaft alot and still get sufficient height and spin. Since he is a little OTT, I am surprised he is a picker. Seems like he would have a steeper AOA.

 

I always thought for tight lies, you want less loft and to get the ball first so that you don't bounce off the turf and thin it. I rarely try to get under the ball for a tight lie. But my short game ability is pretty average.

 

[ThinkingPlus]

3 minutes ago, is1ander said:

 

I always thought for tight lies, you want less loft and to get the ball first so that you don't bounce off the turf and thin it. I rarely try to get under the ball for a tight lie. But my short game ability is pretty average.

 

Talking about full shots. No matter the turf, on full shots you want ball first contact and you want the club CG to be driven below the ball CG. On firm turf with a high CG iron there is very little, if any, margin to do that. So most players end up hitting shots thin. If you have enough speed, it won't matter much. If you don't, you hit low shots that lose alot of distance.

[gtrade]

46 minutes ago, ThinkingPlus said:

The ball CG is 0.84". Clubs first engage the turf, especially on firm, tight fairways, right under the ball typically. If the clubhead CG is higher than the ball, then it is difficult to get the clubhead CG below the ball CG. So you get less spin and less height. Low CG clubhead can be driven below the ball CG getting higher launch and more spin which is beneficial for slower swingers.

 

Ok I'm not sure I get your point. The forces at impact were previously explained quite thoroughly with physics, and it seems the direction of normal impact force should be taken into account when discussing vcog's. I'm not sure if you saw that post? Based on that, the club cg is always higher than the ball cg at impact.

 

However, the basic logic is still there about the low cg, higher launch, lower spin etc., but the difference between 0.89" and 0.7" vcog's may not be that significant when taking other factors into account.

[NRJyzr]

31 minutes ago, gtrade said:

but the difference between 0.89" and 0.7" vcog's may not be that significant when taking other factors into account.

 

That CG difference is *quite* significant in iron design.  Even half that is significant  

 

Edited January 11 by NRJyzr

[ThinkingPlus]

9 hours ago, gtrade said:

 

Ok I'm not sure I get your point. The forces at impact were previously explained quite thoroughly with physics, and it seems the direction of normal impact force should be taken into account when discussing vcog's. I'm not sure if you saw that post? Based on that, the club cg is always higher than the ball cg at impact.

 

However, the basic logic is still there about the low cg, higher launch, lower spin etc., but the difference between 0.89" and 0.7" vcog's may not be that significant when taking other factors into account.

The physics is incomplete and @joostin mentions it. The CG location's impact on the club-interaction isn't included. I don't know how to do that, but we all know it matters. Everyone has hit the ball "thin" and noticed a low ball flight that doesn't usually travel as far as a well struck shot. Everyone has also hit a shot high on the face and noticed a significant drop off in distance as well.

 

Moving the CG of a clubhead from low to high will also change where on the face we get a "thin" shot and where we get a "high on the face" shot. So vertical CG location matters.

 

Can high vertical MOI help mitigate the effect of a high vertical CG? The answer is yes. Can a flexing face mitigate the effect of a high vertical CG? Probably true too. How much do these design features help? No way to really know. We don't have the data or a sophisticated enough description of the physics to make that determination.  This is not a slight to joostin. He did a very good job describing the basic torques and moments, but partially elastic collisions are not easy to model.

[is1ander]

1 hour ago, ThinkingPlus said:

The physics is incomplete and @joostin mentions it. The CG location's impact on the club-interaction isn't included. I don't know how to do that, but we all know it matters. Everyone has hit the ball "thin" and noticed a low ball flight that doesn't usually travel as far as a well struck shot. Everyone has also hit a shot high on the face and noticed a significant drop off in distance as well.

 

Moving the CG of a clubhead from low to high will also change where on the face we get a "thin" shot and where we get a "high on the face" shot. So vertical CG location matters.

 

Can high vertical MOI help mitigate the effect of a high vertical CG? The answer is yes. Can a flexing face mitigate the effect of a high vertical CG? Probably true too. How much do these design features help? No way to really know. We don't have the data or a sophisticated enough description of the physics to make that determination.  This is not a slight to joostin. He did a very good job describing the basic torques and moments, but partially elastic collisions are not easy to model.

 

I have a bucket list set of Miura KM700. They were specifically designed by Papa Miura to shift the CG low and out to the toe, which for a blade is just to the middle instead of a heel bias. They are not nearly as forgiving as ZX7 but I can attest that thin shots are extremely forgiving. Also what we've learned recently from Qi35's push for CG projection is that lower CG will decrease spin for impacts above the CG which should mitigate distance loss on irons as well.

 

 

 

 

 

[Cwebb]

12 hours ago, is1ander said:

 

I have a bucket list set of Miura KM700. They were specifically designed by Papa Miura to shift the CG low and out to the toe, which for a blade is just to the middle instead of a heel bias. They are not nearly as forgiving as ZX7 but I can attest that thin shots are extremely forgiving. Also what we've learned recently from Qi35's push for CG projection is that lower CG will decrease spin for impacts above the CG which should mitigate distance loss on irons as well.

 

 

 

 

 

 

Non extreme iron/wedge designs do not have gear effect, so when the COG is driven further below the center of the ball with clean contact, it will tend to produce more spin not less.

 

Drivers, fairways, and hybrids have gear effect, in descending order.

 

One of the better tests you can do, if you have the chance, is to compare two iron designs...one with a measured and verified low COG vs another that has a high COG.  Both built to the same same specs.

[NRJyzr]

16 minutes ago, Cwebb said:

 

Non extreme iron/wedge designs do not have gear effect, so when the COG is driven further below the center of the ball with clean contact, it will tend to produce more spin not less.

 

Drivers, fairways, and hybrids have gear effect, in descending order.

 

One of the better tests you can do, if you have the chance, is to compare two iron designs...one with a measured and verified low COG vs another that has a high COG.  Both built to the same same specs.

 

Vertical gear effect actually does exist in irons. 

 

Just a dumb accountant here, so I shan't be citing theory being it.  A fair number of folks in the business mention it from time to time, have seen it many times over the years in the golf nerd world.  The most recent mention I've seen was from Howard here on WRX a few months ago...

 

[Cwebb]

39 minutes ago, NRJyzr said:

 

Vertical gear effect actually does exist in irons. 

 

Just a dumb accountant here, so I shan't be citing theory being it.  A fair number of folks in the business mention it from time to time, have seen it many times over the years in the golf nerd world.  The most recent mention I've seen was from Howard here on WRX a few months ago...

 

 

All I can say at this point, is do some testing.  Get one of the Maltby iron designs with a very low AVCOG and see what it does

[is1ander]

55 minutes ago, Cwebb said:

 

Non extreme iron/wedge designs do not have gear effect, so when the COG is driven further below the center of the ball with clean contact, it will tend to produce more spin not less.

 

Drivers, fairways, and hybrids have gear effect, in descending order.

 

One of the better tests you can do, if you have the chance, is to compare two iron designs...one with a measured and verified low COG vs another that has a high COG.  Both built to the same same specs.

 

The way TaylorMade explains CG projection, it doesn't have anything to do with gear effect. Simply having ball impact above the CG projection will result in decreased spin. When I first started golfing, before the low spin revolution of SLDR, I learned that the perfect driver impact spot is high center. That will decrease spin without any consideration for gear effect. I don't think there's any need for testing. The closer to CG the ball impact, the more ball speed is retained. For the same thin shot, an iron with CG lower will mean closer to the thin impact and more ball speed is retained.

 

I have a Maltby TS3 6i and 5i which have an extremely low CG. They work. Ball goes high without ballooning. The most curious benefit is that distance retention in the cold and wind is out of this world. I played in 50 degree weather with 15 mph winds. I was expecting 15 to 20 yd distance loss but only got a 5 yd loss.

[is1ander]

10 minutes ago, Cwebb said:

 

All I can say at this point, is do some testing.  Get one of the Maltby iron designs with a very low AVCOG and see what it does

 

Here are other 5 irons I've tried in the past three years: T150, MP 243, Vega VSC, Vega Mizar Plus, OG ZX5, ZX7 MKII, PXG 0311 Gen 3, 2019 T100, 2021 T100, 2023 T200, Ping S59. The only 5 iron that's close would be 712 AP1 from way back in the day. I should have kept those instead of getting 714 AP1. And guess what, 712 AP1 had a lower CG. SMH.

[Cwebb]

1 hour ago, is1ander said:

 

Here are other 5 irons I've tried in the past three years: T150, MP 243, Vega VSC, Vega Mizar Plus, OG ZX5, ZX7 MKII, PXG 0311 Gen 3, 2019 T100, 2021 T100, 2023 T200, Ping S59. The only 5 iron that's close would be 712 AP1 from way back in the day. I should have kept those instead of getting 714 AP1. And guess what, 712 AP1 had a lower CG. SMH.

 

The lower AVCOG irons fit a lot of players well, because a lower sweet-spot makes them easier to hit from normal to tighter lies.  Not surprised you had good success with the 712 AP1 and Maltby TS3.

 

 

 

Edited January 12 by Cwebb

[J.Bex]

@gtrade @ThinkingPlus

Good discussion.  Ok let's do a little more of the basic physics that I can do from my phone.  It helps to look at extremes so we'll do that, but let me first try to show the Maltby statement that's always repeated here (that you know I disagree with) in diagram form:

 

 

That means this below from my understanding, looking at the dashed light blue arrow.  It's the same total force as the solid arrow at point of impact, just moved to the clubhead's CG.  In this case we're hitting ball and firm ground at the same time with a -2° AOA.  If the ball is on a tee or fluffy grass then it's ball first contact:

 

 

That's fine, right?  Probably a good strike even if it's a little thin.  Club CG (blue dot) is still "driven below" ball CG (black dot).  There's a torque generated (red arrow) around the head CG, but nothing really to worry about.  We know wear marks are usually lower on an iron face.

 

If you have a steeper AOA like -7°, it will just make that light blue arrow angle down more.  The green and yellow arrows will be a little shorter, and the royal blue arrow will be a little longer (more friction with the ball).  If the point of impact is the same, the red torque arrow will look the same, but it will have a lower value because the normal force is lower.

 

If you have more shaft lean, delofting, the point of impact will be a little higher up the face.  It's less of a glancing blow, so the green and yellow arrows will be a little longer (more projectile force), and the royal blue arrow will be a little shorter.

 

Going back to the diagram, however, the dashed light blue arrow does not play a direct role in the impact collision for launch.  You have to take that force at point of impact, and then the CG will play a direct role with what's happening with torque and twisting.  It's actually that simple, without needing to take any elastic deformation of the head or ball into account.

 

Crazy light club example (loooow MOI)

 

Now let's imagine the clubhead was extremely light, made of Aerogel, which is almost weightless.  A 266 gram 7 iron head in steel will weigh less than 0.7 grams in Aerogel 😆.  Also assume it won't shatter at impact.  Heck, even just imagine the head is a shell of plastic or titanium - super light.  That red torque?  Better believe that'll twist that clubhead a lot more noticeably!  Why?  Because the head's MOI (horizontal axis) will be so much lower than a real iron's MOI.  Same CG location on the Aerogel vs the steel head, but you can't decouple CG from MOI (horizontal axis in this case) because that's what controls how much the head will twist.  Torque = MOI * angular acceleration.  For the same Torque, the head with the lower MOI has a higher angular acceleration.

 

If the CG was crazy high, like a 12"?  Yup, more torque, more twisting.  If the CG was super low?  Better, less twisting.  Inline with the yellow arrow?  Ideal, no torque, no twisting. 

 

Crazy heavy club example (really fn high MOI)

 

Imagine the clubhead were a train 😆 - a locomotive with a 7 iron loft at the front.  You can tee/hold the ball at any height.  You can come to the ball at any angle, but we'll assume around the -2° AOA again with my awesome phone sketch.

 

Here we're hitting the ball with the train's CG way below the ball's CG.  Let's look at the same force arrows, including where the "head" CG is "driving".

 

Next we'll hit the ball with the train CG driving way above the ball's CG. 

 

It doesn’t matter where on the train's face you make impact.  That ball will have the same launch in both cases.  Why?  Because the "head" train is not twisting at all at impact, because it has crazy high MOI.

 

The impact is still creating a torque.  The torque is governed by the same equations as a cluhead that I showed before:

 

T = I * α = F * d

Torque = MOI (horizontal axis through the head CG) * angular acceleration 

= Normal force (yellow arrow) * its distance from the head CG.

 

Again, we can't decouple the head's CG position from its MOI.  Crazy high MOI = little twist.  Crazy low MOI (Aerogel head) = a lot of twist.  You can make the same train out of Aerogel.  It's gonna be really light, but you can apply the same ball launch as the heavy train, create the same torque from impact, same CG location, and that Aerogel train is the only one that'll have any noticeable twist.

 

Calculating torque and angular acceleration 

 

Let's calculate torque in the regular clubhead's diagram.  Let's say the ball launches at 110 mph.  It got that fast in the impact time of .5 milliseconds.  We already knew from before that the distance of the normal force was 0.747" away from the head CG.  Also from CAD the MOI horiz. is 557 g-cm² (3.1 oz-in² vs the MOI vertical axis of 11.9 oz-in², so you would see 11.9 in MPF numbers).

 

Now the train can launch the ball at the same speed and angle.  Let's say the yellow arrow normal force is 6 feet away from the train's CG.  I'll give the train a crazy high MOI of 10 trillion g-cm² lol.

 

From Excel:

 

The iron shot is creating 63 foot-pounds of instantaneous torque, from an instantaneous force of 1,017 lb.  You don't want to get hit point blank, as you know!  Look at the angular acceleration.  You don't have to visualize that because no one can visualize radians per second squared, but just look how big the number is compared to that of the train.

 

The train sees a whole lot more torque from impact because the ball's normal force (which is the same as the iron's) is much farther away from the train's CG.  However the train doesn't even budge (see angular acceleration again), because it has a crazy high MOI.  There's no need to even mention "driving the train's CG at or below the ball's CG", because it doesn't matter here.

 

Driving the clubhead's CG at or below the ball's CG with an iron?  Maybe it's a good way of thinking for some, but the point with the examples is that the amount of twisting is all about impact forces, torque, and MOI.  Obviously with golf clubs we're talking much smaller differences in MOI from club to club, but the same physics applies for all.  Can we calculate these things to compare clubs with data available?  Nope.  Literally only the CAD model I have is what's calculatable for comparative purposes, unless other engineers come out of the woodworks.

 

So.......

 

Correlation does not imply causation.  The .84" high (or below) CG number of a clubhead vs the .84" high CG of a ball, for all the variables we have with creating those force vectors, delivery conditions, ground conditions, when .84" (+/-) head CG doesn't even take loft or basic normal forces and torque into account... well you know how I feel about that 😆.  This is really all about how much we can reduce twisting.  But again, I agree that "low" CG is generally "better" for most, for the lessening of the torques and twisting shown above, or probability of that, not for the statement highlighted at the beginning.

 

We also have clubheads with low or high VCOGs paired with different RCOGs for rearward or forward CGs that would affect dynamic loft differently.  Shafts, feel, poor or better fits, visuals... too many variables 

 

TLDR

Just think of the extremes like an almost weightless super low MOI clubhead vs a super heavy super high MOI one, and you can see why we can't decouple CG position and MOI in impact physics.  Again we are missing the right MOI we need to analyze these things from club to club, let alone we don't know CGs other than a single cluhead of each model.  We also can't know what's really happening with the COR from club and ball deformation along with spin without meausuring or computer simulation.  Too little knowns.  Lot's of anecdotes and thoughts from Ping and non-Ping users though of all different swing speeds and life choices!

Edited January 14 by joostin

[bellairemi]

I think I have relayed this previously (including partially in this thread) but I compared Ping i210s (very high COG) versus Maltby TE Forged and later tried the i230s.  All the irons were set up the same - length, loft and lie with the same shaft.  I hit the 210s and 230s on average higher than the TE Forged which seems counterintuitve.  But what became evident was that my ballspeed was better maintained on misses and that helped launch.

 

Fast forward to a lot of rounds with the i230s.  They did not feel good to me when I first hit them but over time they became better.  What did not get better was my swing - I increased shaft lean and started to struggle.  I hit balls on a Trackman regularly and it was clear my delivery changed.  Why?  I am sure, for me at least, that I was trying to get to the feel sweetspot which is the COG.

 

I have subsequently gone back to a lower COG iron and my delivery (slowly) has moved back to its historical norm.  A fitter I know who has been fitting for 20+ years does not, in his experience, think my story is unique.  He has seen this from players who hit a lot of balls.  Once he knows the class of iron a customer wants, he tests at the vertical COG extremes first and sees if there is a strong "feel" reaction.  If there is, he stays with low or high COG irons depending on what the feel says.

[is1ander]

2 hours ago, joostin said:

@gtrade @ThinkingPlus

Good discussion.  Ok let's do a little more of the basic physics that I can do from my phone.  It helps to look at extremes so we'll do that, but let me first try to show the Maltby statement that's always repeated here (that you know I disagree with) in diagram form:

 

 

That means this below from my understanding, looking at the dashed light blue arrow.  It's the same total force as the solid arrow at point of impact, just moved to the clubhead's CG.  In this case we're hitting ball and firm ground at the same time with a -2° AOA.  If the ball is on a tee or fluffy grass then it's ball first contact:

 

 

That's fine, right?  Probably a good strike even if it's a little thin.  Club CG (blue dot) is still "driven below" ball CG (black dot).  There's a torque generated (red arrow) around the head CG, but nothing really to worry about.  We know wear marks are usually lower on an iron face.

 

If you have a steeper AOA like -7°, it will just make that light blue arrow angle down more.  The green and yellow arrows will be a little shorter, and the royal blue arrow will be a little longer (more friction with the ball).  If the point of impact is the same, the red torque arrow will look the same, but it will have a lower value because the normal force is lower.

 

If you have more shaft lean, delofting, the point of impact will be a little higher up the face.  It's less of a glancing blow, so the green and yellow arrows will be a little longer (more projectile force), and the royal blue arrow will be a little shorter.

 

Going back to the diagram, however, the dashed light blue arrow does not play a direct role in the impact collision for launch.  You have to take that force at point of impact, and then the CG will play a direct role with what's happening with torque and twisting.  It's actually that simple, without needing to take any elastic deformation of the head or ball into account.

 

Crazy light club example (loooow MOI)

 

Now let's imagine the clubhead was extremely light, made of Aerogel, which is almost weightless.  A 266 gram 7 iron head in steel will weigh less than 0.7 grams in Aerogel 😆.  Also assume it won't shatter at impact.  Heck, even just imagine the head is a shell of plastic or titanium - super light.  That red torque?  Better believe that'll twist that clubhead a lot more noticeably!  Why?  Because the head's MOI (horizontal axis) will be so much lower than a real iron's MOI.  Same CG location on the Aerogel vs the steel head, but you can't decouple CG from MOI (horizontal axis in this case) because that's what controls how much the head will twist.  Torque = MOI * angular acceleration.  For the same Torque, the head with the lower MOI has a higher angular acceleration.

 

If the CG was crazy high, like a 12"?  Yup, more torque, more twisting.  If the CG was super low?  Better, less twisting.  Inline with the yellow arrow?  Ideal, no torque, no twisting. 

 

Crazy heavy club example (really fn high MOI)

 

Imagine the clubhead were a train 😆 - a locomotive with a 7 iron loft at the front.  You can tee/hold the ball at any height.  You can come to the ball at any angle, but we'll assume around the -2° AOA again with my awesome phone sketch.

 

Here we're hitting the ball with the train's CG way below the ball's CG.  Let's look at the same force arrows, including where the "head" CG is "driving".

 

Next we'll hit the ball with the train CG driving way above the ball's CG. 

 

It doesn’t matter where on the train's face you make impact.  That ball will have the same launch in both cases.  Why?  Because the "head" train is not twisting at all at impact, because it has crazy high MOI.

 

The impact is still creating a torque.  The torque is governed by the same equations as a cluhead that I showed before:

 

T = I * α = F * d

Torque = MOI (horizontal axis through the head CG) * angular acceleration 

= Normal force (yellow arrow) * its distance from the head CG.

 

Again, we can't decouple the head's CG position from its MOI.  Crazy high MOI = little twist.  Crazy low MOI (Aerogel head) = a lot of twist.  You can make the same train out of Aerogel.  It's gonna be really light, but you can apply the same ball launch as the heavy train, create the same torque from impact, same CG location, and that Aerogel train is the only one that'll have any noticeable twist.

 

Calculating torque and angular acceleration 

 

Let's calculate torque in the regular clubhead's diagram.  Let's say the ball launches at 110 mph.  It got that fast in the impact time of .5 milliseconds.  We already knew from before that the distance of the normal force was 0.747" away from the head CG.  Also from CAD the MOI horiz. is 557 g-cm² (3.1 oz-in² vs the MOI vertical axis of 11.9 oz-in², so you would see 11.9 in MPF numbers).

 

Now the train can launch the ball at the same speed and angle.  Let's say the yellow arrow normal force is 5 feet away from the train's CG.  I'll give the train a crazy high MOI of 10 trillion g-cm² lol.

 

From Excel:

 

The iron shot is creating 63 foot-pounds of instantaneous torque, from an instantaneous force of 1,017 lb.  You don't want to get hit point blank, as you know!  Look at the angular acceleration.  You don't have to visualize that because no one can visualize radians per second, but just look how big the number is compared to that of the train.

 

The train sees a whole lot more torque from impact because the ball's normal force (which is the same as the iron's) is much farther away from the train's CG.  However the train doesn't even budge (see angular acceleration again), because it has a crazy high MOI.  There's no need to even mention "driving the train's CG at or below the ball's CG", because it doesn't matter here.

 

Driving the clubhead's CG at or below the ball's CG with an iron?  Maybe it's a good way of thinking for some, but the point with the examples is that the amount of twisting is all about impact forces, torque, and MOI.  Obviously with golf clubs we're talking much smaller differences in MOI from club to club, but the same physics applies for all.  Can we calculate these things to compare clubs with data available?  Nope.  Literally only the CAD model I have is what's calculatable for comparative purposes, unless other engineers come out of the woodworks.

 

So.......

 

Correlation does not imply causation.  The .84" high (or below) CG number of a clubhead vs the .84" high CG of a ball, for all the variables we have with creating those force vectors, delivery conditions, ground conditions, when .84" (+/-) head CG doesn't even take loft or basic normal forces and torque into account... well you know how I feel about that 😆.  This is really all about how much we can reduce twisting.  But again, I agree that "low" CG is generally "better" for most, for the lessening of the torques and twisting shown above, or probability of that, not for the statement highlighted at the beginning.

 

We also have clubheads with low or high VCOGs paired with different RCOGs for rearward or forward CGs that would affect dynamic loft differently.  Shafts, feel, poor or better fits, visuals... too many variables 

 

TLDR

Just think of the extremes like an almost weightless super low MOI clubhead vs a super heavy super high MOI one, and you can see why we can't decouple CG position and MOI in impact physics.  Again we are missing the right MOI we need to analyze these things from club to club, let alone we don't know CGs other than a single cluhead of each model.  We also can't know what's really happening with the COR from club and ball deformation along with spin without meausuring or computer simulation.  Too little knowns.  Lot's of anecdotes and thoughts from Ping and non-Ping users though of all different swing speeds and life choices!

 

Wow, thanks for the info. This might explain why Srixon irons are extremely playable-- they have those higher MOI healthy toplines. Haha. Korean market Mizuno JPX S30 appears to have a very low CG as well as a healthy topline. This could be a special club.

https://corpkr.mizuno.com/golf/club/iron/24_jpxs30fgd

[J.Bex]

Looking at more Cool Clubs testing per @NRJyzr, as the Ping i525 wasn't good with carry dispersion from middle to low strikes, and has a high CG.

 

Here's a table using MPF actual VCOGs (6 irons) and the Cool Clubs carry distances (7 irons) of middle center strikes vs low center strikes, all with 80 mph swing speeds.  It's sorted by VCOG from high to low, to see of there's a correlation with carry drop-off %.

 

 

In this list the two "best" in terms of least carry drop-off were Titleist T100 and Ping i230.  Two very different VCOGs, minus all the stuff I posted earlier.  Worst was i525 by far.

 

After the first 2, correlation with CG height alone wasn't there.  Maybe the most we can make from this is that the more GI or distance-oriented clubs are, the more likely they will have a bigger carry drop-off %.  That can indicate that there's a bigger ball speed and COR drop-off with springy faces vs more bladey irons.  Nothing really new there.  The "tech" like power slots, VFT, etc, maybe moreso expanding hot areas, but just can't wake up the more deadened leading edge or borders enough.  P790 did well in this regard, maybe due to the combination of low CG and the slot, which IMO makes a lot of sense for allowing flex on the leading edge (and is present on some of my own clubs).

 

2 hours ago, is1ander said:

 

Wow, thanks for the info. This might explain why Srixon irons are extremely playable-- they have those higher MOI healthy toplines. Haha. Korean market Mizuno JPX S30 appears to have a very low CG as well as a healthy topline. This could be a special club.

https://corpkr.mizuno.com/golf/club/iron/24_jpxs30fgd

Interesting that they show what looks to be both the vertical and horizontal axis MOIs I keep talking about.  First that I've seen!  They're in the ballpark of the CAD model I showed.

 

 

Edited January 13 by joostin

[Cwebb]

6 hours ago, is1ander said:

 

The way TaylorMade explains CG projection, it doesn't have anything to do with gear effect. Simply having ball impact above the CG projection will result in decreased spin. When I first started golfing, before the low spin revolution of SLDR, I learned that the perfect driver impact spot is high center. That will decrease spin without any consideration for gear effect. I don't think there's any need for testing. The closer to CG the ball impact, the more ball speed is retained. For the same thin shot, an iron with CG lower will mean closer to the thin impact and more ball speed is retained.

 

I have a Maltby TS3 6i and 5i which have an extremely low CG. They work. Ball goes high without ballooning. The most curious benefit is that distance retention in the cold and wind is out of this world. I played in 50 degree weather with 15 mph winds. I was expecting 15 to 20 yd distance loss but only got a 5 yd loss.

 

Taylormade is now claiming that the reason for lower spin above the COG on a driver, is not a result of gear effect?

 

That is quite a claim.

 

[is1ander]

1 hour ago, Cwebb said:

 

Taylormade is now claiming that the reason for lower spin above the COG on a driver, is not a result of gear effect?

 

That is quite a claim.

 

 

Yup. TM is pushing CG projection and closure rate for Qi35. I love the low spin goodness of my Ping 10K which by consensus is much lower spin than Qi10 Max. Why? Seems like CG.

Edited January 13 by is1ander

[Cwebb]

6 minutes ago, is1ander said:

 

Yup. TM is pushing CG projection and closure rate for Qi35. I love the low spin goodness of my Ping 10K which by consensus is much lower spin than Qi10 Max 10K. Why? Seems like CG.

 

Why are you convinced that it's not because of gear effect?

[is1ander]

14 minutes ago, Cwebb said:

 

Why are you convinced that it's not because of gear effect?

Center shot vs center shot, Ping 10K is much lower spin.

[PedronNiall]

7 hours ago, joostin said:

@gtrade @ThinkingPlus

Good discussion.  Ok let's do a little more of the basic physics that I can do from my phone.  It helps to look at extremes so we'll do that, but let me first try to show the Maltby statement that's always repeated here (that you know I disagree with) in diagram form:

 

 

That means this below from my understanding, looking at the dashed light blue arrow.  It's the same total force as the solid arrow at point of impact, just moved to the clubhead's CG.  In this case we're hitting ball and firm ground at the same time with a -2° AOA.  If the ball is on a tee or fluffy grass then it's ball first contact:

 

 

That's fine, right?  Probably a good strike even if it's a little thin.  Club CG (blue dot) is still "driven below" ball CG (black dot).  There's a torque generated (red arrow) around the head CG, but nothing really to worry about.  We know wear marks are usually lower on an iron face.

 

If you have a steeper AOA like -7°, it will just make that light blue arrow angle down more.  The green and yellow arrows will be a little shorter, and the royal blue arrow will be a little longer (more friction with the ball).  If the point of impact is the same, the red torque arrow will look the same, but it will have a lower value because the normal force is lower.

 

If you have more shaft lean, delofting, the point of impact will be a little higher up the face.  It's less of a glancing blow, so the green and yellow arrows will be a little longer (more projectile force), and the royal blue arrow will be a little shorter.

 

Going back to the diagram, however, the dashed light blue arrow does not play a direct role in the impact collision for launch.  You have to take that force at point of impact, and then the CG will play a direct role with what's happening with torque and twisting.  It's actually that simple, without needing to take any elastic deformation of the head or ball into account.

 

Crazy light club example (loooow MOI)

 

Now let's imagine the clubhead was extremely light, made of Aerogel, which is almost weightless.  A 266 gram 7 iron head in steel will weigh less than 0.7 grams in Aerogel 😆.  Also assume it won't shatter at impact.  Heck, even just imagine the head is a shell of plastic or titanium - super light.  That red torque?  Better believe that'll twist that clubhead a lot more noticeably!  Why?  Because the head's MOI (horizontal axis) will be so much lower than a real iron's MOI.  Same CG location on the Aerogel vs the steel head, but you can't decouple CG from MOI (horizontal axis in this case) because that's what controls how much the head will twist.  Torque = MOI * angular acceleration.  For the same Torque, the head with the lower MOI has a higher angular acceleration.

 

If the CG was crazy high, like a 12"?  Yup, more torque, more twisting.  If the CG was super low?  Better, less twisting.  Inline with the yellow arrow?  Ideal, no torque, no twisting. 

 

Crazy heavy club example (really fn high MOI)

 

Imagine the clubhead were a train 😆 - a locomotive with a 7 iron loft at the front.  You can tee/hold the ball at any height.  You can come to the ball at any angle, but we'll assume around the -2° AOA again with my awesome phone sketch.

 

Here we're hitting the ball with the train's CG way below the ball's CG.  Let's look at the same force arrows, including where the "head" CG is "driving".

 

Next we'll hit the ball with the train CG driving way above the ball's CG. 

 

It doesn’t matter where on the train's face you make impact.  That ball will have the same launch in both cases.  Why?  Because the "head" train is not twisting at all at impact, because it has crazy high MOI.

 

The impact is still creating a torque.  The torque is governed by the same equations as a cluhead that I showed before:

 

T = I * α = F * d

Torque = MOI (horizontal axis through the head CG) * angular acceleration 

= Normal force (yellow arrow) * its distance from the head CG.

 

Again, we can't decouple the head's CG position from its MOI.  Crazy high MOI = little twist.  Crazy low MOI (Aerogel head) = a lot of twist.  You can make the same train out of Aerogel.  It's gonna be really light, but you can apply the same ball launch as the heavy train, create the same torque from impact, same CG location, and that Aerogel train is the only one that'll have any noticeable twist.

 

Calculating torque and angular acceleration 

 

Let's calculate torque in the regular clubhead's diagram.  Let's say the ball launches at 110 mph.  It got that fast in the impact time of .5 milliseconds.  We already knew from before that the distance of the normal force was 0.747" away from the head CG.  Also from CAD the MOI horiz. is 557 g-cm² (3.1 oz-in² vs the MOI vertical axis of 11.9 oz-in², so you would see 11.9 in MPF numbers).

 

Now the train can launch the ball at the same speed and angle.  Let's say the yellow arrow normal force is 5 feet away from the train's CG.  I'll give the train a crazy high MOI of 10 trillion g-cm² lol.

 

From Excel:

 

The iron shot is creating 63 foot-pounds of instantaneous torque, from an instantaneous force of 1,017 lb.  You don't want to get hit point blank, as you know!  Look at the angular acceleration.  You don't have to visualize that because no one can visualize radians per second, but just look how big the number is compared to that of the train.

 

The train sees a whole lot more torque from impact because the ball's normal force (which is the same as the iron's) is much farther away from the train's CG.  However the train doesn't even budge (see angular acceleration again), because it has a crazy high MOI.  There's no need to even mention "driving the train's CG at or below the ball's CG", because it doesn't matter here.

 

Driving the clubhead's CG at or below the ball's CG with an iron?  Maybe it's a good way of thinking for some, but the point with the examples is that the amount of twisting is all about impact forces, torque, and MOI.  Obviously with golf clubs we're talking much smaller differences in MOI from club to club, but the same physics applies for all.  Can we calculate these things to compare clubs with data available?  Nope.  Literally only the CAD model I have is what's calculatable for comparative purposes, unless other engineers come out of the woodworks.

 

So.......

 

Correlation does not imply causation.  The .84" high (or below) CG number of a clubhead vs the .84" high CG of a ball, for all the variables we have with creating those force vectors, delivery conditions, ground conditions, when .84" (+/-) head CG doesn't even take loft or basic normal forces and torque into account... well you know how I feel about that 😆.  This is really all about how much we can reduce twisting.  But again, I agree that "low" CG is generally "better" for most, for the lessening of the torques and twisting shown above, or probability of that, not for the statement highlighted at the beginning.

 

We also have clubheads with low or high VCOGs paired with different RCOGs for rearward or forward CGs that would affect dynamic loft differently.  Shafts, feel, poor or better fits, visuals... too many variables 

 

TLDR

Just think of the extremes like an almost weightless super low MOI clubhead vs a super heavy super high MOI one, and you can see why we can't decouple CG position and MOI in impact physics.  Again we are missing the right MOI we need to analyze these things from club to club, let alone we don't know CGs other than a single cluhead of each model.  We also can't know what's really happening with the COR from club and ball deformation along with spin without meausuring or computer simulation.  Too little knowns.  Lot's of anecdotes and thoughts from Ping and non-Ping users though of all different swing speeds and life choices!

 

So this is the benefit of lower CG game improvement clubs for players who tend to catch it fat?  On a fat hit, the slight offset that's usually also present I could see allowing for a little longer for the face angle to "improve" towards one more favorable for generating optimal spin to keep the ball aloft as well, beyond the main benefit of having longer to square the face, but the pictured CG would seem to place the initial impact on a fat shot in a location that minimizes torque on a strike with a club that's already seen at least some deflection and loss of speed from digging well before the ball. 

 

Feel free to correct me if I'm misunderstanding. 

[gtrade]

12 hours ago, joostin said:

Going back to the diagram, however, the dashed light blue arrow does not play a direct role in the impact collision for launch.  You have to take that force at point of impact, and then the CG will play a direct role with what's happening with torque and twisting.  It's actually that simple, without needing to take any elastic deformation of the head or ball into account.

 

Thanks for the clarification. This was what I thought as well. So the vcog itself doesn't tell everything without taking horisontal axis MOI into account.

 

8 hours ago, joostin said:

In this list the two "best" in terms of least carry drop-off were Titleist T100 and Ping i230.  Two very different VCOGs, minus all the stuff I posted earlier.  Worst was i525 by far.

 

 

This supports the above statement as well. No causality on low vcog and the performance on thin shosts -> cannot make a statement that higher vcog is automatically worse than low vcog for thin misses. Of course, low vcog would be better if all other factors remain the same, ceteris paribus.

 

8 hours ago, joostin said:

Interesting that they show what looks to be both the vertical and horizontal axis MOIs I keep talking about.  First that I've seen!  They're in the ballpark of the CAD model I showed.

 

 

 

Are you able to do any calculation based on the above, that how much above MOI differencies can compensate the vcog? Would be helpful to know if MOI can "over compensate" the higher vcog, propably not. My assumption is that it cannot compensate even 0.1", which would still make lower cg preferred option for thin misses.

 

About the spin, should the spin not be impacted by the vcog itself, but rather due to possible gear impact, which is then dependant on the horisontal axis MOI? So, if the horisontal axis MOI would over compensate the higher vcog, it means the higher vcog club would actually spin less than the low cg one with lower horisontal axis MOI.

 

The whole other topic is on feel and how that will impact player's delivery. If the higher vcog will cause too much shaft lean etc., that's ofc bad.

 

I think Marty told in some video that Blueprint S has a bit lower vcog than e.g. i230, because on tour irons are mostly hit either from the fairway or the tee box, and those lies prefer lower vcog for feel at least, if not performance as well. It was quite opposite for amateurs; a lot more shots from rough and fluffy lies, and thus higher vcog and higher horisontal axis MOI would make sense. But it's not just preferred on tour. Interesting to see if that changes with i240.

 

[J.Bex]

19 hours ago, PedronNiall said:

 

So this is the benefit of lower CG game improvement clubs for players who tend to catch it fat?  On a fat hit, the slight offset that's usually also present I could see allowing for a little longer for the face angle to "improve" towards one more favorable for generating optimal spin to keep the ball aloft as well, beyond the main benefit of having longer to square the face, but the pictured CG would seem to place the initial impact on a fat shot in a location that minimizes torque on a strike with a club that's already seen at least some deflection and loss of speed from digging well before the ball. 

 

Feel free to correct me if I'm misunderstanding. 

Maybe, just depends what you're hitting fat on lol.  Dense dirt slowing the club a lot it's probably not gonna do anything to save the shot.  Loose grass, sand, a squishy mat, where you keep better speed, you might hit a good fat shot, maybe striking on friendlier part of the face like you're saying.

 

As far as the offset purposes that's definitely another topic that's been debated.  The most supported view it seems isn't about extra time but rather just the dynamics it creates where the CG becomes more aligned with the shaft/grip as you release and pull on the club, so you get more dynamic loft and some face closure from the shaft bending.