A Publication of Tom Wishon Golf Technology   •   September 2004

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September 2004 TWGT eTECHreport

Summer's really almost over now. Driest wishes for those of you down in the South/Southeast section of the States...

• The kudos are piling up in the TWGT Testimonials section.
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How Weight Adjustments Affect Ball Flight

It’s not a secret that one of the trends in clubhead design that has gained momentum this year, and will undoubtedly increase in consumer demand through 2005, are drivers created to allow weight movement around the head as a means of correcting golfer ball flight problems. What this means is that clubmakers will be asked questions by golfers about how such weighting modifications actually change the ball’s flight. Because TWGT knows it’s important for clubmakers to be there with the right answers, the following information will help you explain to your customers how moving weight around a clubhead brings about this change.

 

Draw Bias Weighting

The term “bias” has been used in conjunction with weight distribution to connote the ability to move weight around a clubhead to create more of a tendency, or a bias, to a specific direction of ball flight. Hence “draw bias” weighting is when more mass is placed on the heel side of the clubhead to reduce a slice/fade, and in turn enhance the golfer’s ability to draw the ball more than with a clubhead designed with “neutral weighting.”

Putting more mass in the heel side of the clubhead reduces the tendency to fade the ball in two ways:

1. By reducing the Moment of Inertia (MOI) of the head about the shaft axis or hosel. There are two important MOI’s in the clubhead. First, the MOI about the axis of the Center of Gravity (CG) of the head, and second, the MOI about the axis of the hosel bore, i.e. the shaft centerline. MOI about the CG of the head has to do with allowing the head to be “more forgiving” from an off-center hit. MOI about the shaft has to do with the golfer’s ability to rotate the entire head back to square during the downswing, before impact with the ball. Thus by adding more weight to the heel area of the clubhead, the MOI of the head is reduced, which makes it easier for the golfer to rotate the head from open to square or possibly even more closed, before the clubhead makes impact with the ball. For a person who slices the ball, adding weight to the heel allows them to deliver the club face less open and thus help reduce the amount of slice or fade on the ball. (see fig. 1)
2. By changing the “gear effect” of the head in response to impact with the ball. As you know, the “gear effect” describes the way the ball is able to pick up more “hooking” sidespin when impact occurs toward the toe side of the CG position of the head. If the golfer makes contact on the toe side of the CG position in the head, the head will respond by immediately beginning to rotate clockwise around its CG (clockwise for a RH head, and counter clockwise for a LH head, but the effect is the same). In this split second of head rotation while the ball is on the face, the head rotation will cause the ball to slide and roll toward the hosel. That movement of the ball across the face causes the ball to pick up more of a tilting of the axis of backspin rotation in a hooking direction. Thus by moving greater mass toward the heel of the head, the CG is usually moved in that direction as well which causes the golfer to be able to hit the ball in the center of the face and still receive this “gear effect” of slightly more hooking sidespin to reduce their amount of fade or slice. (see fig. 2)

 

 

Fade Bias Weighting

This is the opposite of draw bias weighting in that the weight is placed more toward the toe side of the clubhead. Thus, the explanation for how this encourages less tendency to draw the ball and more chance to enhance a fade action of the ball flight is exactly opposite to the explanations for how Draw Bias weighting works. The additional weight out toward the toe end of the clubhead increases the MOI of the clubhead about the axis of the shaft. This in turn causes the face to be delivered to impact a little more open, or less closed to thus create the change in ball flight for less draw or more fade movement of the ball. (see fig. 3) In addition, the “gear effect” of the “fade biased” clubhead is reversed from that of the draw bias weighting position so that a center face impact will result in more tendency for the head to rotate counter-clockwise (counter-clockwise for a RH head, clockwise for a LH head, but again, the results are the same to allow for more tendency toward a fade sidespin). (see fig. 4)

 

High Launch Weighting

With weight moved toward the rear of the clubhead, the center of gravity will be moved farther back in the head away from the shaft centerline. This more rear-located CG position will cause the shaft to flex forward more, and from that, increase the actual loft on the clubhead at the moment of impact with the ball. (see fig. 5) Thus with the actual loft on the head at impact increased by the forward bending of the shaft, the ball takes off on a higher launch angle and achieves a higher trajectory in flight. The reason the more rear-located CG position causes the shaft to flex forward more before impact is because under the force of the wrist-cock release, the CG tries to get in direct line with the center of the shaft at the grip end of the club. Using the weight of the head, this action of physics causes the head to move more forward and thus flex the shaft forward. Thus because the higher flight results from the action of the clubhead’s CG on the flex profile of the shaft, rear weighting in a head can and will be affected by the actual overall flex of the shaft. If the golfer uses the same shaft in the rear-weighted head as was used in a normal-weighted head, if the two heads have the same loft, the one with the more rear-located CG will increase the launch angle by approximately 1.2° for each 5mm more the CG has been moved back from the shaft.

 

Low Launch Weighting

Again, the explanation of how moving more weight toward the face and closer to the shaft to lower the flight of the shot is the opposite of the explanation for how rear weighting increases shot trajectory. By moving weight more toward the face, the CG of the head moves closer to the shaft. (see fig. 5) This in turn reduces the amount of forward bending of the shaft prior to impact with the ball, which means the actual loft of the clubhead is going to be less at impact than when the clubhead is much more rear-weighted. And likewise, if the golfer uses the same shaft in the front-weighted head as was used in a normal-weighted head, if the two heads have the same loft, the one with the more front-located CG will decrease the launch angle by approximately 1.2° for each 5mm the CG has been moved closer to the shaft.

One of the most important things for clubmakers to understand and explain to their golfers is the fact that any driver head weight location change has to be compared to the weight distribution, loft and shaft of the golfer’s existing driver head before any estimation for how much the weight movement will affect the golfer’s ball flight can be predicted. In addition, all design specifications that affect shot direction and height also have to be considered on the old versus the new driver head.

Just simply giving a golfer a driver head in which the weight can be moved around the head will not necessarily guarantee each golfer will actually see a change in their ball flight direction or height. For example, let’s say the golfer’s current 11° loft driver has a more rear-located CG to begin with. If the golfer comes in and wants a new driver with movable weight to the rear of the head to further increase his trajectory, if that new driver had a loft of 10° and is much smaller in face-to-back size such that the movement of the weight in the new head can’t get the CG back any farther than where it was in the golfer’s current head, no increase in trajectory would occur. And the golfer might think that he has been “hoodwinked.”

The same scenario could exist with regard to face angle on the golfer’s current driver head compared to the face angle on the new weight adjustment head, for situations concerning the draw or fade bias design of the weight changeable head design. Let’s say the golfer’s current head has a face angle of 2° closed, but the face angle design of the weight adjustment head is 0 square. In that case, moving a moderate amount of weight toward the heel and expecting more fade reduction than what the golfer gets on his current head with 2° more closed face angle is just not going to happen.

So please, as the industry moves in the direction of altering woodhead weight distribution for game improvement head design, do keep in mind that you have to look at the entire matter of design specifications versus ball flight change for the golfer’s former head design before you recommend one of the new weight movement models.

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The Most Sure Fixes for Distance Improvement

It is possible to make a list of 21 different golf club, head, shaft and grip fitting specifications that define all of the possible performance differences between any two golf clubs. A major theme of my 1997 book, The Practical Fitting Program, was to identify these fitting specifications and then to place a priority on which would have a significant effect on real ball flight changes as well as which would not. The concept I was stressing in prioritizing the fitting specifications in this manner was to inform clubmakers which fitting factors to focus upon when trying to build new custom clubs that would truly make a difference for each golfer.

The great thing about continuing to work in club design and fitting research is that I have the opportunity to learn more all the time about what makes golf clubs work, and well, not work too! Over the 7 years since I wrote The Practical Fitting Program, much has changed with respect to the priorities of what fitting changes can make the most dramatic change in ball flight. In addition we have determined more about the level of change that we can expect from certain fitting specification recommendations. While it is important for clubmakers not to ignore all of the fitting specifications which do not have as visible of an influence on game improvement, I wanted to offer the following fitting information as a means for you to be able to enable your customers to get the most “bang for their buck” when they come to see you for custom clubs.

As I did in the book, I will identify the most important fitting specification areas of game improvement because this is predominantly how you have to think about fitting changes for your golfers. The fitting recommendations then are listed in order of importance for each game improvement desired.

To Increase Distance for the Driver...

1. LOFT

While I first began to recognize in 1996 the beginning signs of advising more loft for slower swing speed golfers as a means to increasing distance, at that time I had only caught sight of the part of this iceberg that lay above the surface. Since 2002, we have been able to dig a lot deeper into this area of real distance gain to more fully understand how to determine what loft for which golfer will result in how much distance gain.

• It is critical to be able to determine the golfer’s angle of attack from their swing before being able to know what driver loft can maximize distance for the golfer. The angle of attack from the swing plus the loft of the driver head plus the golfer’s swing speed determines their launch angle for the shot. The angle of attack describes whether the driver arrives at the ball on a downward path, a path level to the ground, or whether the club is hitting the ball on the upswing. (See table 1 below for examples of golfer swing speed compared to different angles of attack in the swing to note how different the optimum loft angle to maximize distance can be. Hence you must have an idea of the golfer’s angle of attack to be able to know what loft will maximize distance for each different golfer.)
  • Click here for more information on measuring the Angle of Attack

The Effect of Swing Angle of Attack on Optimum Driver Loft for Maximum Carry Distance (Table 1)

Driver Swing Speed	Angle of Attack	Best Driver Loft	Carry Distance
miles per hour	degrees	degrees	yards
55 mph	downward -4°	26	96
	level 0°	21	101
	upward +4°	19	107
65 mph	downward -4°	23	131
	level 0°	20	137
	upward +4°	18	142
75 mph	downward -4°	21	165
	level 0°	17	169
	upward +4°	15	173
85 mph	downward -4°	18	194
	level 0°	15	198
	upward +4°	13	201
95 mph	downward -4°	16	220
	level 0°	13	222
	upward +4°	10	225
105 mph	downward -4°	13	242
	level 0°	11	245
	upward +4°	9	247
115 mph	downward -4°	11	263
	level 0°	10	266
	upward +4°	7	267

2. LENGTH

The length of the club is critical to the golfer’s ability to hit the ball on-center the highest percentage of the time. Any fitting recommendations aimed at increasing distance for the golfer have to follow a pre-requisite of hitting the ball on center. Thus any change in shaft length intended to increase swing speed has no chance of successfully increasing distance unless the length is matched to the golfer’s ability to swing the club under complete control.

With the vast majority of golfers using 45” drivers and correspondingly longer fairway wood lengths as well, the potential for switching golfers to lengths that are much more compatible with their athletic ability is great.

3. SHAFT WEIGHT

The weight of the shaft affects the total weight of the golf club more than any other component. The effect of a lighter total weight on the potential for greater swing speed has been known for some time among clubmakers. This factor of fitting for more distance has not changed in its importance – it is a fact that significantly lighter total weight clubs can be swung faster. However, two very important points have to be noted by clubmakers when trying to help golfers gain more distance.

• Many golfers already use very light graphite shafts in their driver and often, fairway woods as well. Thus, unless the clubmaker were to find a suitable flex shaft for the golfer that weighs at least 20-25 grams less than their current shaft weight, no more distance potential from shaft weight could be offered to the golfer. This is the main reason that shaft weight sits in the third position for priority in increasing distance for the golfer.
  At the same time, there are a lot of golfers who still play steel shafts in the fairway woods and particularly in the irons. In these two areas the chance to shed a significant amount of total weight by switching the golfer from steel to light graphite, gaining distance in the process, is virtually untapped in fitting. However, this chance for more distance may likely be hampered by the increased cost of switching from steel to graphite in multiple clubs.
• Determining the best swingweight or MOI of the club for the golfer is absolutely critical for allowing the chose shaft weight to deliver more distance. This is because the wrong swing balance of the golf club will cause the golfer to hit the ball off-center a higher percentage of the time, which means a loss of distance. Thus every effort has to be made when choosing a different shaft weight to nail down the right swingweight/MOI for the club for each individual golfer.

4. MOMENT OF INERTIA MATCHING OF CLUBS

In 1997, no one was working to create a method of truly MOI matching clubs to the strength, tempo, rhythm and athletic ability of the golfer. Thus all recommendations made to golfers for establishing the right swing balance of the club were in the area of swingweight. Now that MOI matching of clubs is a reality, early feedback is showing that if the right MOI is found for the golfer, an increase in distance can result both by allowing the golfer to hit the ball more on-center, as well as to squeeze out an increase in swing speed from the MOI being far better matched to the golfer’s swing than a suitable swingweight.

Visit http://wishongolf.com/moi/ for more info.

 

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Tips for the Dreaded Pitch Shot

By David March

Do you have trouble with short pitch shots from inside 100 yards?

1. Look at ball position. Many times players struggle because the ball is not played in the proper position in the stance. If the ball is played too far forward then the club will not contact the ball consistently. Sometimes hitting behind the ball, sometimes hitting the middle of the ball and on that rare occasion, exactly where you want it to go. So for more consistency the ball should be played in the middle of the stance so that the shorter club will catch the ball as the club is bottoming out in the swing.
2. If you are having problems with distance control, take a look at how you are trying to control it. Most players try to control distance by how hard they hit the ball vs. how long of a swing they take and what lofted club they are using.

First let’s take a look at the swing. The best way to control the length of a shot is by the length of the swing. Imagine that you’re swinging in a clock and that however far you swing going back, you’ll mirror going through. So if you swing your hands back to the 9 o’clock position then you will want to follow through with the hands to the 3 o’clock position.

That would be for a mid-length pitch shot. To hit a shorter length pitch just shorten the backswing, and for a longer pitch, lengthen it.

A good mental picture for making crisp contact comes from Victor East who had his students hit balls from a few yards behind a low-hanging tree branch. He instructed them to try to hit the ball under the branch, which prevented the students from trying to scoop the ball into the air, and allowed the club’s loft to easily pop the ball over the target.

Next, you can also control distance and height by changing which club you use:

1. If you want a lower flight that will run out, use a club like a 6- or 7-iron, and in some cases, like this year’s British Open, a hybrid can be used.
2. If you want a higher and softer shot that will stop quickly use a 56° or 60° wedge. But again on these more lofted clubs remember to let the loft of the club do the work and try not to help the ball into the air.

Hopefully, keeping these pointers in mind will help you become more consistent with those yardages that are less than a full swing away from the hole.

David March is a member of the TWGT Sales and Technical Staff and a former member of the PGA of America. An accomplished teacher of the swing with years of experience, David was a member of the teaching staff of the Harvey Penick Golf Academy in Austin, Texas.

 

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You Might be Missing the Boat on Driver Fitting

Most clubmakers are aware that most golfers are using drivers with too little loft to maximize their potential for distance. In an industry where distance sells, it is truly a golden opportunity to know that most golfers still have 10 more yards of distance inside them, waiting only for the correct driver loft recommendation to allow these extra yards to play out.

But driver loft fitting is much more than a matter of simply handing every golfer with a swing speed under 90mph a driver with a loft of 12°, 13° or 14°. To find the precise loft for any golfer that will maximize their distance potential requires the clubmaker to know the relationship between the golfer’s swing speed AND the angle of attack the golfer has with their golf swing.

Take a look at the chart created to go along with this month’s eTECHreport article on Sure Fixes for Distance. (Table 1)

The chart shows the optimum driver loft for different swing speeds and for a range of different golfer angles of attack. It is a fact that the angle of attack is supremely important to know for each golfer swing speed to be able to predict the correct loft that will maximize each golfers distance potential off the tee. The only way you can determine the golfer’s angle of attack is with some means of being able to accurately measure the golfer’s launch angle using a driver of known loft.

While some clubmakers have taken the big step to invest in a launch monitor, the majority will not be able to afford the thousands of dollars necessary to buy an electronic launch monitor. That is why TWGT decided to develop its Launch Angle Gauge as a perfectly accurate and very inexpensive means to allow all clubmakers to be able to measure this super critical launch parameter of launch angle. Used in conjunction with the TWGT Trajectory and Ball Flight software program, the fitting recommendations for driver loft made from using these two very affordable items are as accurate as any far more expensive means of fitting. In truth, no launch monitor will tell you what driver loft is best for any golfer. They are great for obtaining information, but none are developed with the capability to predict ball flight from any combination of launch parameters.

Thus if you own a launch monitor and you are not yet using the TWGT Trajectory and Ball Flight software to translate the data you obtain into real fitting recommendations, then you are simply performing your work by trial and error.

The Trajectory and Ball Flight software sells for just $69.50. The Launch Angle Gauge mat sells for only $59.50. Together this $129.00 investment will make you the best clubfitter in your area. Please take the time to check out this tutorial on our web site [http://wishongolf.com/trajectory/] showing you just how simple the Trajectory software is to use. If you don’t take advantage of this incredible shot prediction technology to guide your driver fitting, you are just guessing and you will miss the boat when it comes to recommending the best loft to achieve the most distance for your golfers.
Click here for more information on measuring the Angle of Attack

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TWGT 949G/Ti Driver Moves to the Head of the Graphite + Titanium Class

I am glad to say we have achieved an “In-Stock” position with our popular new 949G/Ti graphite and titanium driver so our production has caught up with the demand. As a result, now I don’t feel “guilty” about pointing out the specific design features of the 949 to show you the performance of this design, and worrying that we would have to backorder your request!

Over the past month I really have been working hard with our foundry to “fine-tune” the production tooling and manufacturing procedures so that completing the 949G/Ti drivers on a timelier basis became a reality. We’ve changed the installation and finishing process for the tungsten rear weights and all graphite sections of the head to ensure a smoother flow of the 949 through the production process. The result is no “bottlenecks” and superb quality and performance on all of the 949G/Ti driver heads.

The main design feature of the 949G/Ti is its more rear-located Center of Gravity (CG) compared to all of our current TWGT titanium driver designs and to the OEM graphite and titanium drivers we have been able to measure and analyze. Early this year, I had the chance to perform an analysis of a number of the industry’s graphite and titanium drivers in a project Golf Digest magazine had asked for my assistance. They wanted to compare the graphite + titanium drivers to the all-titanium drivers from a number of companies. Thus I had the chance to measure all specifications and be involved in robot hit testing to determine the differences. Table 2 below illustrates some of the design differences between these OEM drivers and TWGT drivers, focusing on the Center of Gravity and Vertical Roll for each of the heads I was asked to measure:

Center of Gravity Differences in All-Titanium and Graphite+Titanium Drivers (Table 2)

Model	Construction	Face Height	Face to Back Breadth	Vertical Face Roll	Rear CG	Vertical CG
Callaway Great Big Bertha II	All-Titanium	53mm	93mm	9"	33.5mm	33mm
Callaway Fusion	Graphite+Titanium	52mm	95.5mm	10"	38.8mm	33.5mm
Mizuno Blue Rage	All-Titanium	51mm	95mm	12"	35mm	33.5mm
Mizuno MP001	Graphite+Titanium	51mm	99.5mm	12"	34mm	33mm
Yonex V-Mass 400	All-Titanium	57mm	100mm	10"	34mm	35.5mm
Yonex Cyberstar Power Brid 400	Graphite+Titanium	57mm	98.5mm	12"	31mm	33mm
TWGT 915CFE 360cc	All-Titanium	51mm	102mm	15"	34mm	33.5mm
TWGT 915CFE 420cc	All-Titanium	54mm	105mm	15"	35mm	34.5mm
TWGT 919CCG 380cc	All-Titanium	56mm	103mm	13"	37.5mm	33mm
TWGT 515GRT 395cc	All-Titanium	56mm	102mm	15"/0" GRT	33mm	35mm
TWGT 515GRT 360cc	All-Titanium	54mm	100mm	20"/0" GRT	32mm	36mm
TWGT 949G/Ti 390cc	Graphite+Titanium	53mm	99mm	16"/0" GRT	41.5mm	33mm
Callaway, Great Big Bertha and Fusion are registered trademarks of Callaway Golf Company; Mizuno, Blue Rage and MP001 are registered trademarks of Mizuno Corporation; Yonex, V-Mass, Cyberstar and Power Brid are registered trademarks of Yonex Golf Company.

My goal in the design of each of my driver models is to create shape, design and performance differences so that each TWGT model can stand on its own with its individual performance characteristics. That is why you see the face-to-back CG location of the TWGT models each offer a little different position to correspond to different golfer types.

My goal in creating the new 949G/Ti was to use the graphite + titanium construction to move the CG farther back in the head than with any other TWGT driver. In comparison to the other graphite + titanium drivers I was asked to measure, I am pleased that we have been able to achieve that, as seen by comparing the Rear CG measurements of all the heads in the table below. If the higher trajectory required to maximize the golfer’s carry distance can result from the Rear CG’s effect on the forward bending of the shaft, then the loft can be reduced to slightly increase ball speed off the face.

Thus the 949G/Ti is designed for golfers who need a higher trajectory that would normally require increasing to as much as 12° of loft, but who do not wish to risk losing ball speed from actually moving to a 12° loft driver with a more normal Rear CG location of 34-35mm.

In addition, the Graduated Roll Technology (GRT) face design of the 949G/Ti becomes an added benefit to ensure a much more consistent launch angle over drivers made with as much roll curvature as 9” to 12”. When a driver of >50mm face height is made with 9”-12”, the loft on the bottom and top of the face will be between 2.5° to 3.5° different than it is in the center of the face. Thus low face hits fly very low and high face hits much higher, both of which can rob the golfer of distance. The game improvement performance of the GRT 0 Roll face is proven – feedback we have received from clubmakers this year has indicated their golfers who use the GRT face design on a TWGT 515 or 949 driver do experience a much more consistent launch angle with less distance loss when the golfer makes a swing error.

At TWGT we are proud of our clubhead design skills. Our commitment is to make not just the best performing designs in the component clubmaking industry, but to challenge the entire golf equipment industry with our original head designs.

Kudos for the 949G/Ti:

“The 949 is a real winner! With [Hand Selected] 11° loft and the rearward c.g. it is definitely longer than my previous 14° driver, with about the same trajectory.”

– Bill Day

“This is the first driver head I’ve purchased from you and it is without a doubt, the best head I’ve ever hit.

“It is 15 - 20 yards longer than any driver head I’ve assembled.”

– Grady Larson

"I Was a 6 handicap when I got my 915CFE driver and within 8 mos. I dropped down to a 3 hdc. Yesterday I received a 949G/Ti driver head and put on the same shaft that my my 915 was on. I hesitated to try it out today, as I felt it would be almost impossible to replace the head that had been so forgiving and easy to hit, surely the best driver head I had used in my 44yrs. as a golfer.

"Well I am happy to report that I was not disappointed with its performance.

• (A) It is as easy to hit.
• (B) It is very solid.
• (C) It has a higher trajectory.
• (D) It is much longer.
• (E) It's in the bag to stay.

"The feel is very solid unlike the hollow pinging sound of the all-metal woods, this has a much more pleasant sound somewhat along the lines of the old Persimmon woods.

"You have a winner here, and I wish you much success with it, and also with your complete line of superior products."

– Regards, Bob Barrette, Professional Clubmaker (Ret.)

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