CT Values

[wmclarenf1]

I'm not even sure its called CT values.

A lot of JDM clubs are offering CT/CG value info these days.  I don;t know what to make of it and what a reference point is.

Anyone know how to interpret these numbers inton lay terms like low/high CG, low/high spin etc?

Nob, you seem to understand these values well.  A tutorial in this would be much appreciated.

Thanks.

[db2]

I don't see a CT value listed in your attachment but I have seen it on tour-issued heads.  It's the COR measurement.

[wmclarenf1]

Yeah.. You're right.  Shows you how much I know about these values.

[95124hacker]

CT = characteristic time

It’s a measurement of the period (inverse of frequency) of a pendulum mass striking a clubface.
239 (+18 tolerance) microseconds is the limit. Anything over is non conforming.

The USGA test method is described here:
https://www.usga.org/content/dam/usga/pdf/Equipment/TPX3004-procedure-for-measuring-the-flexibility-of-a-golf-clubhead.pdf

[db2]

Values over 239 are nonconforming?  Most of the values I've seen on EBay and GWRX BST are in the 240s.

[95124hacker]

Values over 239 are nonconforming?  Most of the values I've seen on EBay and GWRX BST are in the 240s.

Paragraph B.2.1 states the limit is 239+18 (=257)

[nobwas]

Yea  I can provide detailed explanation based on an article from a Japanese magazine.  Stay tuned. 
But for starters CG distance is the distance from CG location to axis of rotation (I.e. “ shaft” axis )
The longer it is ,  the bigger the potential energy transfer at impact (possible distance advantage)
But longer CG distance means the head needs to rotate more for square impact.
Heads with shorter CG distance will be easier to rotate back to square but the potential energy transfer may not be as big and thus distance may be shorter.
Modern drivers generally have longer CG distance in pursuit of greater distance potential so they have been harder to square at impact. Most amateurs tend to leave the face open at impact. 

Today CG distance values range from 30mm to about 45mm
Grandista RS001 was 40mm  but the new RSD is 35mm
I believe recent Ping G models are around 45mm along with other popular USDM drivers.

[wmclarenf1]

Yea  I can provide detailed explanation based on an article from a Japanese magazine.  Stay tuned. 
But for starters CG distance is the distance from CG location to axis of rotation (I.e. “ shaft” axis )
The longer it is ,  the bigger the potential energy transfer at impact (possible distance advantage)
But longer CG distance means the head needs to rotate more for square impact.
Heads with shorter CG distance will be easier to rotate back to square but the potential energy transfer may not be as big and thus distance may be shorter.
Modern drivers generally have longer CG distance in pursuit of greater distance potential so they have been harder to square at impact. Most amateurs tend to leave the face open at impact. 

Today CG distance values range from 30mm to about 45mm
Grandista RS001 was 40mm  but the new RSD is 35mm
I believe recent Ping G models are around 45mm along with other popular USDM drivers.

Thanks Nob.  So what do change depth and height indicate?  I think they affect launch and spin?

[wmclarenf1]

Found a good article that explains cor and Ct in a simple easy to comprehend manner.

http://www.golfalot.com/equipment-news/guide-to-coefficient-of-restitution-cor-chracteristic-time-ct-2803.aspx

[nobwas]

CG depth indicates how far away the cg is from the face towards the back/tail end of the head. 
Deeper the CG ,  easier to launch and provides higher MOI  but also causes higher spin.
Ping G series had very deep CG so it was easy to launch and high MOi.

CG height dictates the spin the most.   Lower CG height will produce lower spin.
Carbon Crown heads aim at low CG by using light weight crown.

conversely for clubs that you want more spin,  like a wedge,  you want more weight higher on the club head. 

CG height is generally the height of the cg location from the bottom of the face.
CG height 2 is the cg location to the top of the face
Heads that have proportionately larger CG height 2 is said to have lower spin potential.

When you hit the ball above the CG ,  you produce lower spin and when you hit the ball below the CG it results in higher spin.   

Different combinations of CG parameters will result in different flight characteristics.   

There is a balance to maintain some level of forgiveness and playability against spin and distance performance.   the Head designers struggle to find that golden combination. 

[wmclarenf1]

CG depth indicates how far away the cg is from the face towards the back/tail end of the head. 
Deeper the CG ,  easier to launch and provides higher MOI  but also causes higher spin.
Ping G series had very deep CG so it was easy to launch and high MOi.

CG height dictates the spin the most.   Lower CG height will produce lower spin.
Carbon Crown heads aim at low CG by using light weight crown.

conversely for clubs that you want more spin,  like a wedge,  you want more weight higher on the club head. 

CG height is generally the height of the cg location from the bottom of the face.
CG height 2 is the cg location to the top of the face
Heads that have proportionately larger CG height 2 is said to have lower spin potential.

When you hit the ball above the CG ,  you produce lower spin and when you hit the ball below the CG it results in higher spin.   

Different combinations of CG parameters will result in different flight characteristics.   

There is a balance to maintain some level of forgiveness and playability against spin and distance performance.   the Head designers struggle to find that golden combination.

Uber thanks Nob.  Very clear.  Have you got the ranges for cg  height and depth?

[ian-500]

Great info nob 👍

[95124hacker]

Here’s some CG data for USDM drivers:

https://mygolfspy.com/mygolfspy-cg-driver-locations/

[nobwas]

Range for CG depth is somewhere similar to CG distance.    If you remember Grandista,  uses a 1:1 ratio of CG distance vs CG depth.  Which is believed to provide optimal stability.

As for CG height,   This varies quite a bit.
You need to look at CG height 2 divided by the total face height which will give you a percentage of low spin impact zone.   Most heads stand around 35% to about 50%   
Cobra King LTD pro I believe had a whopping 51.9% where the low spin impact zone (upper face ) was larger than the high spin zone.

While the trend at one point was to produce lowest spin as possible,  recent JDMs have actually been moderately higher spin compared to USDM going for more stability vs ultimate occasional distance. 

Based on these CG specs alone, USDM drivers generally have the potential to produce lower spin super long distance shots once in a while whereas JDM drivers can produce moderate spin but more consistent distance.  For me, that seems to be true most of the time but not always. 
I mean the head is only part of the solution, right... then you got hundreds of shaft options that affect the shot characteristics...  You could have a shaft that can counteract the head design or maximize the
desired effects.   But the biggest variable and the most inconsistent one at that is , by far , the player themselves.   Swing path, AoA, SS,  Face Angle are all part of the equation.

[ian-500]

My XR16sz has a cg sooooo far forward(I have the heavy weight at the front). I assume that means it's low spinning...?