By Carter Penley

In TBAR Part 5, we discussed that one of the major problems in the golf shaft industry is that the standard flex range is dynamically much larger and in many cases overlaps corresponding flexes. This is why some players who may need to build a backup club, or a replacement shaft for their club ends up finding out that the backup or or replacement shaft doesn’t feel or play the same as the first shaft model. This brings us to our 6th and final TBAR article- TBAR and the introduction to Zone Flex (‘Z’) characterization.

Descriptive Analysis:

‘FEEL’ is the design driver for all Penley designed golf shafts and is the prime attribute a player desires in his clubs.

‘FEEL’ is the comfort zone a player needs to be in to play his best game and Penley golf shafts specifically exhibits this most important attribute for players at all levels of play.

This article describes how the application of Penley’s TBAR method of golf shaft design with Zone Flex characterization accomplishes the ‘Feel’ attribute.

Zone Flex (‘Z’) is a defined flex zone within a specific golf shaft flex range.

Flex range and Zone flexes are determined by Penley’s TBAR (Tip to Butt Aspect Ratio) algorithm and are somewhat infinite vs. the long time excepted flex terminology.

To quantify Zone Flex Characterization Penley has selected eight specific zone flexes outside of a predetermined flex range denoted numerically as ‘1’ (Penley’s Std. Range ‘1’) of each defined flex range i.e. ‘L1’, ‘A1’, ‘R1’, ‘S1’ and ‘X1’ and so on as defined by the following four rules.

Rule # 1 – The 60% Rule

By analysis Penley determined that 60% of most golfers fall within flex range ‘1’ of the each and separate specific golf shaft flex ranges. ‘1’ is the center (1/3) of the full flex range (yellow dotted lines, 3-7). Penley tolerances are typically held to ~30%-40% of industry standards.

Rule #2:  The 20% Rule

By analysis Penley determined that 20% of most golfers fall within the following flex zone characterizations (‘Z1’ – ‘Z4’) which originate from within flex range ‘1’:

Zone ‘1’ flex characterization = Flex range ‘1’ at the butt,  to a stiffer tip section. (Z1)

Zone ‘2’ flex characterization = Flex range ‘1’ at the butt,  to a softer tip section. (Z2)

Zone ‘3’ flex characterization = flex range ‘1’ at the tip, to a stiffer butt section. (Z3)

Zone ‘4’ flex characterization = Flex range ‘1’ at the tip, to a softer butt section. (Z4)

Rule #3: The 15% Rule

By analysis Penley determined that 15% of most golfers fall within the following characterized flex zones ‘5’ and ‘6’ which extend outside of flex range ‘1’ at the tip and at the butt.

Zone ‘5’ flex characterization = ‘Z3’ stiffer butt section to ‘Z1’ stiffer tip section. (Z5)

Zone ‘6’ flex characterization = ‘Z4’ softer butt section to ‘Z2’ softer tip section. (Z6)

Rule #4: The 5% Rule

By analysis Penley determined that 5% of most golfers fall within the following characterized flex zones ‘7’ and ‘8’ to incorporate the most extreme zone flexes outside of flex range ‘1’ at the tip and at the butt.

Zone ‘7’ flex characterization = ‘Z4’ softer butt section to ‘Z1’ stiffer tip section. (Z7)

Zone ‘8’ flex characterization = ‘Z3’ stiffer butt section to ‘Z2’ softer tip section. (Z8)

Flex ranges developed through the TBAR algorithm yields generally a slightly higher flex range than the industry standard.

The new ET2  golf shaft design is primarily designed for the better player to include the Touring Pro to yield maximum control accuracy. This is achieved through design, materials and Penley’s TBAR matching, an internally developed algorithm to determine range ‘1’ and subsequent zone flex characterizations to perfect the optimum club.

Copyright © 2010,2016 Carter Penley. All Rights Reserved.

Part 5

By Carter Penley

The last ‘TBAR^tm” article (Part ‘4’) discussed the affects of the composite materials and geometric shapes on ‘TBAR^tm” measurement, with more emphasis on materials.

            Part’4′ ended with the discussion concerning lightweight shafts; specifically the effects of the measurement equipment in reference to failing the shafts internal wall structure at the tip and/or butt section. The task at this point was to ensure that all shafts could be flexed, measured and successfully achieved without damaging the shaft. The ability of the measuring equipment to measure all shaft flexes and weights would guarantee that a linear standardization could be established and maintained throughout the “TBAR^tm system. This would allow for all TBAR^tm data acquired being accurate and consistent.

            It was even more obvious to Penley that the limiting factor for “TBAR^tm” measuring equipment and the range of testing requirements was going to be the structural design and materials factor of the lighter weight shafts. The fact that a golf shaft may or does fail during testing is not always an indication that the golf shaft will always fail during play. Although, I will concede that if a shaft tends to fail at or below the DSO (Design Service Objectives) safety factor(s) more often than not during what engineering considers “non-destruct tests” then there would be an engineering requirement to further investigate the design and materials selection.

            Testing criteria is developed and put into place to “fail products” not “pass products” therefore, we must be very careful of how robust a test might be. If we become too critical of the requirements and safety factors, we will tend to either over design greatly exceeding the DSO which will not only increase cost, but discourage testing all together. The latter is the most common result, especially for small or less-knowledgeable golf shaft manufacturing companies.

            These design limits can be analyzed, tested and demonstrated with the proper equipment to destruct testing as required, specifically using the dynamic method of cyclic fatigue testing. Penley, to our knowledge is one of the few if any golf shaft manufacturing companies to have designed and placed into service their own cyclic fatigue testing equipment and has incorporated fatigue testing as part of their design and test analysis and to form DSO criteria. This test is performed primarily to determine a golf shafts tip sections durability and ultimate strength. The process requires that the shafts tip section is deflected to a predetermined load and if passes then the golf shaft is prepared and affixed in the cyclic test machine and then cycled at the maximum load (deflection) to ~10,000 cycles or failure which ever occurs first.

            Cyclic fatigue testing is critical to the design analysis because the results are a design driver for the engineer and if there is a failure it requires a full analysis from initial design solution to full cyclic fatigue testing again prior to release to the public. The old method of taking a newly designed golf shaft out to the driving range and hitting it a few times and if the golf shaft does not break it is deemed a successful design, are over! Because of concerns over liability and lawsuits, not to mention the wide range and diversity of player abilities requires that a quality golf shaft manufacturer be able to emulate all critical variables through design analysis and in the laboratory and field testing before you go to market with your product.

            So not only is the reliability of the standard golf shaft important but for the lightweight golf shaft it is most important to incorporate non-destruct testing, such as required for “TBAR^tm” analysis and machining processes.

            Therefore, the “TBAR^tm” measuring equipment must be designed to be user friendly and manufactured in such a way that a structural failure will not occur while being used by any skill level technician or employee.

            This brings us to the second design benefit of the TBAR^tm algorithm to define and implement “Zone Flex^tm characterization.

            As stated in the first article of this series “TBAR^tm vs. Kick (Bend) Point” it is stated that when you are working with a player and you build for him the perfect club and he asks you for a ‘back up club’. You purchase the same shaft, flex, kick point, weight and manufacturer and build him a club with the very same specifications, physical and mechanical properties and he takes it out to his next event and reports back to you that it does not feel or play the same at all ; as depicted in “TBAR^tm, Measurement and Method of, Part 3“

            The major problem is that the standard industry flex range is dynamically much larger and in reality in many cases overlaps corresponding flexes (‘S’ flex may overlap the ‘R’ flex and or the ‘X’ flex). Although a flex measured statically or dynamically appears to be a narrow range when in fact it is actually proportionally wider and more complicated when you compound the flex dynamic with the players attributes of swing speed, tempo, muscular and mental input.

            So now you are left with the realization of “what happened” and “why”, “what did I do wrong”, when in fact you may have had little or no control of the unfavorable outcome. The first club (the one the player preferred) that you built may have been with a shaft that was on the high side of the recommended flex range and the second shaft you received was vice-versa or cross-versa? Now do you tip it only or butt cut only or both or do you install off center? The fact is you have little or no idea of what to do and most likely your golf shaft supplier will be of little or no help either! But ‘PENLEY’ can and will help!

See “TBAR^tm with Zone Flex^tm Characterization” Part 6 of 6

Copyright © 2008, 2015 Carter Penley. All Rights Reserved
(all theories and analysis are still pertinent)

TBAR ^–

Part 4

By Carter Penley

Part 3 of TBAR’s series ‘Measurement and Method Of‘’ described the analysis and design solution process required to produce the empirical data to support the “TBAR hypothesis. The next phase was to correlate the composite materials and geometric profiles to test for a more accurate and defined “TBAR” envelope.

First Penley had to analyze the design criteria and implement the materials and geometric shapes that would yield the expected butt flex and tip flex relationship.

The next requirement was to develop shaft patterns and test how closely the tip flex and butt flex deflection numbers could be controlled. This process would also indicate how close the “TBAR ” flex tolerances could be held.

Once Penley generated by computer analysis of what we considered a successful base shaft pattern we would then apply this pattern to a series of computer generated geometric/shaft design combinations.

This in-house computer program was developed and written by Penley Sports to enable our engineering staff to instantly generate 90% of the shaft design and performance data by computer analysis, to include: moment of inertia, stiffness, torque curve, shaft weight, shaft balance point, shaft outer diameters, shaft wall thickness, and will generate an auto-cad drawing of all the composite patterns with wrap/overwrap, section gaps and dimensions for the complete fabrication of the prototype shaft; all before a single carbon fiber (graphite) pattern is generated.

To successfully complete this computer aided design analysis task the computer program must perform a series of calculations every tenth of an inch and will generate over 450,000 calculations for each shaft design depending on the shafts total length.

During this phase of the analysis we are able to develop flex and tolerance relationships of the shaft butt section.

This analysis process was confirmed by fabricating a number of shafts using Penley’s manufacturing processes and measuring butt flex at two specific manufacturing operations that we refer to as pre shaft data and machine-1 shaft data. After both sets of data are collected, a statistical analysis is applied and the arithmetic mean and standard deviations are calculated. The pre shaft and machine-1 data are compared, and if the tolerances and ratios stay within pre-defined boundaries, engineering will determine the design solution a success.

The same process is applied for the tip section except much more care during the manufacturing process must be exhibited.

The tip has a smaller diameter even though it has a much thicker wall thickness than the butt, it still has a lower M.O.I., EI and torque values and is much more susceptible to pattern and manufacturing process irregularities; specifically during manufacturing/fabrication and machining operations. Therefore, the engineer has a much more difficult task controlling the structural requirements of the tip section design.

The second engineering task concerning shaft patterns was to develop and test composite laminate stiffness patterns to evaluate the effects of shaft weight on the tip to butt flex ratio measurements.

This process required engineering to develop shaft patterns much like the first step, using different stiffness levels (‘E’ = modulus of elasticity) and fiber areal weight to test flexural resistance to deflection. A major design concern for light weight shafts was structural wall failure at the butt and or tip sections during field testing or play. Therefore cyclic testing exploits any possible catastrophic failure(s) that would present itself during cyclic fatigue testing (~10,000 cycles) in the test laboratory.

This step in the process was also to test how TBAR measurement/test equipment affected light weight shafts. Knowing that lighter weight shafts required the use of high modulus materials of lighter fiber areal weights we needed to develop structural damage data to test TBAR measurements at these lighter shaft weights to achieve comparative TBAR data to shafts of heavier weight.

See “TBAR DSO Incorporating Cyclic Fatigue Testing” Part 5 of 6 – Coming Soon!

Copyright © 2002, 2015 Carter Penley. All Rights Reserved
(all theories and analysis are still pertinent)

By Carter Penley

As discussed in TBAR Part 2 – “The Art of Golf Shaft Measurement“, kick point is not the best measurement to determine a golf shafts ability to contribute to a golf clubs launch angle. For one thing, how is kick point measured?  (See TBAR vs. Kickpoint Part 1).

At Penley, we recognized the need for a more precise and defined measurement for design purposes, and to allow a club maker or teaching professional to better fit their player with the proper golf shaft.

All flex measurements whether static or dynamic, are measured from the butt section of a golf shaft, with little or no attention being paid to the tip section. The results most of the time, can yield golf clubs of similar shaft flex, torque, head weight and swing weight, yet these golf clubs will have different feel, shot trajectory and/or dispersion; leaving you with the question, “what happened?” and “why”?

This problem became obvious back in 1999 during the first year of our PGA tour van operations. Although our tour representative and technician worked around the problem, I knew that if this was a problem for us, it was also a problem for the golf industry as a whole.

Having been in the composite golf shaft business for over twenty-five years and having experienced the above problem more than I had cared to count in my career,  I was fairly confident that we could measure and correct for this deficiency.

Obviously something is different and that something was a way to accurately measure the relationship between the butt section and the tip section of a golf shaft. You can have similar butt flex measurements but with different tip flex measurements, because they are not measured during the design and or manufacturing process,   they tend to be different in their relationship; and herein lies the problem.

It is this variable in tip section flex that contributes to launch angle, trajectory and feel (remember, kick point, ‘Article 1‘).
It is really the tip section flex in relationship to the butt section flex rather than some mythical bend/kick point.

To solve this problem, a series of data and measurements had to be generated to confirm our TBAR hypothesis, starting with the following:

1.   What method do we use to measure TBAR?
   
   Static measurement was the best fit using a digital flex board utilizing a fixed load cell and LED read out panel.

1. How accurate should our TBAR measurement be?
   Most digital load cells read out in Metric and US units. For our requirements Penley selected US because the data is in hundredths of a pound yielding the most accurate and greatest precision range.

1. How many measurement points would be required to develop the tip to butt aspect ratio?A series of measurement points were selected and tested. These test points were always in pairs. Penley knew long span  measurements were most accurate and generate more feel data. This reaffirmed Penley’s position that a golf shaft must be of a “one piece” design from tip to butt. A “one piece” golf shaft yields the best player feel, feed back, energy transfer and insures better distribution of stresses and mechanical loads throughout the golf shafts full length. (see “Long Drive Science” article by Carter Penley).

1. At which points along the length (‘X’ axis) of the golf shaft do we determine and administer the applied loads?
   The effective span length is determined by analyzing the deflection of the golf shaft during deflection testing and a series of golf swings. Using this analysis the appropriate span and the corresponding position of its two end points were determined and fixed.

1. Should these measurements be taken in the droop plane or in the swing plane along the ‘X’ axis?
   Penley defines only two planes for flex purposes: The droop plane and the swing plane (see ‘Shaft Spine” article by Carter Penley).
   The droop plane is located parallel to the club face at the 12 o’clock position looking at the butt end and possesses the dominate spine reading, the swing plane is located perpendicular to the golf club face at the 3 o’clock position looking at the butt end and possesses the less dominant spine of the shafts dominant quadrant.Those of you who read the “Shaft Spine” article know that here at Penley we have established through player testing and mechanical analysis, in my opinion, the swing plane contributes most to club control for the player.

1. By which method do we present the data so that it is easily understood by a majority of the club builders, OEM’s and teaching professionals?
   For engineering, design and calculation purposes a mathematical ratio expressed in proportional values/percentages is best; but for the everyday person a graphic is easiest to visualize and understanding of how to apply the information to help better fit a player with the best golf club for his level of play.

As we began to develop the measurements process and perfect the data, a tip to butt aspect ratio (TBAR) pattern/algorithm began to evolve. We are now able to test the TBAR   hypothesis in the laboratory and develop the process to include materials and geometric shape combinations and begin the full development and implementation of the TBAR system in the field of play.

See “TBAR Computer Design Program / Cad Laminate Schedule” Part of 4 of 6 – Coming Soon!

Copyright © 2002, 2015 Carter Penley. All Rights Reserved
(all theories and analysis are still pertinent)

By Carter Penley

Through the years there has been a quest by many to define a golf shafts performance or the ability to fit a player by some simple magic black or white number or method. Some like to know how fast a player swings their club, or prefer a torque number, or a flex, or a shaft weight, or clubs swing weight, or a club length, or a shaft color, or… The fact of the matter is that there are many variables that contribute to fitting a player, some of which are more important than others: It is all a sea of grey. While no single measurement can define the total “performance aspect” of a golf shaft, I do believe there is a way to simplify and reduce the number of measurement variables.

After close to thirty years of designing carbon fiber (graphite) tubes parallel and tapered tubes, specifically golf shafts, I have come upon some interesting correlations in golf shaft measurement that can yield a more accurate method to define the “performance aspects” of a golf shaft that technically affords the club maker or teaching professional the advantage to better fit a player at most any level of play.

Historically golf shafts have been measured and the data has been presented in four specific areas.

They are:

1. TORQUE
2. WEIGHT
3. FLEX
4. KICK POINT

For design and manufacturing purposes there are many more measurements required, but for current discussion I will focus on these four, which are most commonly published and used.

TORQUE

TORQUE stands alone and is one measurement most commonly debated throughout the golf industry, although used frequently when fitting. Yet it is probably among one of the most inaccurate golf shaft measurements because there is no standard in the industry by which to compare the data. Quite frankly, not many club makers can measure for specific torque in a particular manufactures product and therefore most club makers rely on the golf shaft manufacturer’s torque number, accurate or inaccurate as it may be. (See ‘Torque‘ article, 1997 by C. Penley)

WEIGHT

WEIGHT is another stand alone measurement and agreed to by most all is the most accurate measurement (one gram is one gram), although again there is not a standard. Weight is specified as ‘X grams +/- X’ grams, but some manufactures include paint some with out paint, sometimes weight at full length or at some unknown cut to club length, also some shaft lengths can very from model to model and manufacturer to manufacture.

This is because club manufacturers measure club length differently; some measure club length from the club heel, the center of the sole plate and if it is a bore-thru not to mention some club manufactures have a specific club length different from their competitors.

 FLEX

FLEX is a measurement that has somewhat of a standard due to the fact that this measurement is easy to determine statically (flexboard using a weight and a limit shaft), and does not require a costly piece of equipment. On the other hand a dynamic measurement as performed on a frequency machine and does promote somewhat of a standard because of the wide acceptance of the old Brunswick frequency charts by many club makers (not withstanding interlaminar opposing shear deformations). But even this form of dynamic measurement can be easily skewed due to the following:

1. At what position at the shaft butt do you clamp the shaft?
2. How much clamp pressure is used to clamp the shaft?
3. Do you use an actual club head and whose, blind bore or bore-thru?
4. Do you use a bob weight? Weight and hosel depth of bob weight?
5. Where is the bob weights center of mass in reference to the shaft tip?
6. Manufacturer and type of grip?

Again with no standard method, a comparable measurement is difficult to achieve.

Even with all the equipment, charts and graphs that are available to determine the flex range much of this data was developed as much as 20-70 years ago with steel shafts, and does not accurately reflect the standards required for today’s modern composite golf shaft.

 KICK (Bend) POINT

Last but not least. Most people have little or no idea of how this measurement is made much less its accuracy or its usefulness. This undoubtedly is the least understood measurement of all. I can tell you from experience that this measurement is probably the least useful for the fitting of a player. (See Part 1 ‘TBAR^tm vs. Kick (Bend) Point‘)

It is these last two measurements that I have a problem, specifically the latter.

Flex and kick point are measured and recorded as two separate measurements and I am of the opinion that these two measurements are closely related and should be combined to develop a new measurement. Standing alone they can be more of a hindrance than help when fitting a player. Combined they are a powerful fitting tool!

At Penley we have solved this problem and developed a new measuring system and related manufacturing design and process, called ‘Tip to Butt Aspect Ratio‘ (TBAR) algorithm that we believe will help the golf industry change the way it has measured and fit players for the past 30 or more years. We believe the relationship between the butt section and tip section of the golf shaft is and should be a single measurement and is most important to the fitting of a player with a club (Amateur, PGA or Long drive) that enhances and improves their overall skills.

Read more about TBAR with Measurement and Method Part 3 of 6 – Coming Soon!

Copyright © 2002, 2015 Carter Penley. All Rights Reserved
(all theories and analysis are still pertinent)

By Carter Penley

Over the years of designing composite golf shafts I have had the opportunity to analyze golf shaft failures ‘structural, physical, mechanical and design anomalies.

Of the above mentioned failures design anomalies are the most difficult to dissect and analyze unlike structural and or mechanical failures which usually exhibit telltale clues; anomalies do not. Not only is there not an obvious, visual or a logical path to a remedy but there is also a compounding factor of the anomaly affect and that factor is the player.

I became most aware of this problem through feedback from our tour van based on feedback specifically from the touring professionals. Tour players would often request a backup club, say a driver, our tour van would build them a backup driver only to discover that it did not (according to the player) match the playability of their primary driver. Most tour players have the ability to make muscular and mental adjustments to correct for the difference. Many players do not like to nor can many at the less than professional levels of play make the required adjustments.

So I initiated a study to define why and how these anomalies manifest themselves. To initiate this study as a designer I had to step away from the mechanical, structural and geometrical analysis side of golf shaft design and become more practical and analytical. This method of study soon centered on the primary mechanical measurements we tend to rely on and have become the basic design drivers most as we have come to accept for golf shaft performance factors.

As a primary manufacturer of composite golf shafts I spend a great deal of time on design analysis, product development and testing. In my observations I have recognized in my opinion a basic flaw in the standard criteria of golf shafts, essentially in the method in which ‘flex’ and the much misunderstood term ‘kick point’ is measured and their relationship.

The result I call TBAR which is a way to measure and tune the relationship between the golf shafts butt flex and tip flex, which I believe has more impact on the performance of a golf shaft and or club. This process in my opinion also allows for better fitting of a player by club builders and teaching professionals.

I have written a thesis consisting of six articles and will publish them in five following issues of the ‘Penley Newsletter’.

See “TBAR vs Kick (Bend) Point” Part 1

Copyright © 2015 Carter Penley. All Rights Reserved

By Carter Penley

The term “kick point”, originally referred to as bend point, has been a popular term for many years by many shaft manufactures and yet the most misunderstood and least useful term applied to the performance criteria of a golf shaft.

I once heard it summed up in this manner:

• 50% of the players think they know what it is!
• 50% of the players don’t know what it is!
• 100% of the players don’t know why or how the measurement is made?
• 101% of the players have little or no idea at what position or point these measurements are on a golf shaft!

Originally “bend point” (kick point) was considered a simple black and white measurement; something a club maker could use as a way of differentiating how ‘soft’ or how ‘stiff’ the tip section of a golf shaft is.

In reality this is not the best indication or measurement of the golf shafts tip section stiffness.

By using this measurement as indicated by the golf shaft manufacture and as it is printed on the shaft, a club maker would determine how to fit his customer. A high bend point equates to a lower ball trajectory and a low bend point a higher ball trajectory.

To a point the above statement is true; but not because high bend (kick) point and low bend (kick) point as measured on a golf shaft actually yields the above result. The fact of the matter is that the golf shaft manufacturers have accepted and adopted this theory. Therefore bend point now became the term ‘kick’ point and manufacturers now determine ‘kick point’ by hitting the golf clubs and observing the ball trajectory and have labeled the golf shafts accordingly.
If the ball appears to go higher then the golf shaft is labeled ‘low’ kick point and if the ball appears to go lower the golf shaft is labeled ‘high’ kick point and ‘mid’ kick point is somewhere in between. When in reality, I have measured shafts for bend (kick) point position and discovered in some cases that a Senior (‘A’ flex) shaft could have a higher kick point than a high modulus (‘X’ flex). How is that possible, you say? Well let me explain how this measurement is made and what influences bend (kick) point and where on the golf shaft these kick points are located.

Originally the kick point measurement was determined by compressing a golf shaft from tip to butt using over center clamps and a tooling ball fitted to accept the small (tip) ID and the big end (butt) ID of the golf shaft being measured. The over center clamp is closed and the golf shaft is compressed to a length of approximately ¼’’ to ½’’ less than its uncompressed free length. The golf shaft would then bow (up) and the highest point between the two centers on its ‘X’ axis measured with a DRO (Digital Read Out) unit is the bend (kick) point position of that golf shaft (usually measured in inches from the tip end of a golf shaft). You notice that I said that golf shaft, because you could test golf shafts of the same flex from ten different manufacturers you would most likely find ten different bend (kick) points measurements for reasons I will describe next.

The kick point in a golf shaft is controlled primarily by two criteria and they are geometric shape and materials selection, usually in that order. A golf shaft designed with a long parallel tip section such as a senior (‘A’ flex) or a ladies (‘L’) but not limited to these, would tend to have a low bend point. On the other hand a golf shaft designed using very stiff (high modulus) material in the tip section, like boron, could also cause a golf shaft to exhibit a low bend point, because the tip area is so stiff that the golf shaft has no opportunity to bend except at the termination of the boron or high modulus material pattern(s). Because of this fact it is sometimes possible for a senior (‘A’ flex) shaft to have a higher bend point than a high modulus (X flex) shaft but have a higher ball trajectory than a high modulus (X flex) golf shaft.

There is another misconception by many players as to just where these bend (kick) points are located on a golf shaft? The general thinking is that a low kick point is down near the club head, and a high kick point is up near or just below the grip area and a mid point is in the middle of the club, give or take. When in actuality most all kick point measurements of ‘high, mid and low’ are all within approximately a 5’’-7’’ range of each other, at about 18’’ to 25’’ from the tip of the golf shaft and when you swing a golf club it very seldom, if at all physically bends at any one of these kick points. In a carbon fiber tapered tube (golf shaft) the controlling factors are referred to as stress risers in the laminate modulus (stiffness) analysis.

To further illustrate this point concerning kick point as it relates to ball trajectory, would be to fix (clamp) the tip end of a Senior (‘A’ flex) and a high modulus (‘X’ flex) and then apply an equal load to the butt end of the Senior (‘A’ flex) golf shaft with a high bend point and a high modulus (‘X’ flex) with a lower bend point and you would observe that the Senior (‘A’ flex) golf shaft will deflect much more than the high modulus (‘X’ flex) which it should, even though it has a higher kick point. So what are we measuring? In reality, it is actually a golf shafts tip section stiffness in reference to its butt section stiffness rather than kick point. So, why is this measurement made and how useful is it?

Therefore what does influence ball trajectory and how does PENLEY design to and more accurately measure a golf shafts ability to launch at a higher or lower ball trajectory? The answer is the “TBAR “(Tip to Butt Aspect Ratio) algorithm.

See “TBAR- The Art of Golf Shaft Measurement” Part 2

Copyright © 2002, 2015 Carter Penley. All Rights Reserved
(all theories and analysis are still pertinent)

Over the past several years, there have been many discussions and theories on how to develop golf equipment that makes those long Par 5’s more user friendly for the average player. Advances in material, processes and club geometry have fuelled the latest technologies in golf equipment. The importance of the shaft, Penley’s area of expertise, cannot be overlooked. The shaft plays a fundamental part in golf club design because it functions as the interface (a veritable suspension system and drive train) between the player and his or her striking surface-the club head.

Think of it this way: what good is it to have a 5 liter Ferrari with the top of the line tires, linked with a poorly designed transmission or suspension system? The power of the engine and responsiveness of the tires cannot be maximized because of their weak suspension link. The correlation is the same in golf clubs. Through the shaft, the player feels and controls the shot. The full power of a player’ swing and the design virtues of a quality club head cannot be maximized unless linked with a quality shaft. That is the reason Penley has spent years developing high performance shafts. This focus has paid off-Penley is the prominent shaft in long drive championships and a leader on the PGA tour. As a leader in the golf shaft industry, Penley continues to develop state of the art, cutting-edge products delivering the highest performance and consistency on the course.

There are three fundamental parameters that characterize the performance of a golf shaft. The first, and probably most important, is the feel of the shaft. Put simply, does the club feel comfortable during the swing from address through follow through? Technically speaking, Penley has determined the best combinations and distributions of shaft weight, stiffness, torque, and dampening that yield an incredibly responsive and comfortable feeling piece. The second fundamental parameter of shaft performance is control. Does the shot go where it was intended to go? That is, for a driver, did it stay in the fairway; and for iron, did the distance and dispersion put it where desired on the green?

Through computer-aided analysis and state of the art manufacturing techniques, Penley creates the most concentric shafts on the market. This translates into unparalleled accuracy and consistency from club to club, shot to shot. The final factor of shaft performance is distance. This can be quantified by determining how much of the club’s energy during impact is transferred to the ball. Designing shafts that maximize these three-performance parameters-feel, control, and distance-requires some extremely complex and creative engineering solutions.

Fortunately, Penley is solving many of these engineering and design challenges through high-tech analytical, high-speed computer programs (one such program requires 900,000 calculations per individual shaft design) developed and written in house. One program is Energy Transfer Accelerance (ETA), which, pertains to the distance portion of shaft design. In this program, we address the much asked question, “how much energy can or does a player transfer to the ball?”

Early in 1997, Penley sports determined that the next level of shaft design had to incorporate energy transfer. But since there was little or no data about this topic, we had to develop the data ourselves. The scope of this ETA research and development project was to derive a theory about energy transfer efficiency, prove and apply the theory, then generate data about shaft efficiency through a test phase using a mechanical hitting device. If successful, we would go to the field for human testing (staff personnel and our full time PGA Tour Van.)

ETA focuses on the efficiency of the club to ball energy transfer. A hypothesis was developed stating: For longer drives and less human effort, the maximum amount of energy transfer must take effect between the club and the ball. Assumptions were made that maximum energy transfer will occur if the club head is square and at its maximum velocity just prior to ball impact (1-3 milliseconds.) Shafts, therefore, can be designed to unload into the squared position (while generating maximum club head velocity) according to a player’s swing speed and tempo.

With the hypothesis and assumptions formulated, the engineering staff was able to construct a mathematical model of how energy is transferred from the club to the ball. The theory was successfully tested, so the engineering staff created a parametric computer model of the ETA derivation. A mechanical hitting device and high-speed cameras were then used to demonstrate and apply the practicality of the ETA computer program. Some sample results follow:

Player #1 (Class ‘A’ Player)
• Club Head Velocity: 101 mph
• Ball Velocity (at launch): 149 mph
• Back Spin: 4800 rpm
• Side Spin: 646 rpm
• Effective Mass of Club: 231 g
Energy transferred is 74.443 Ft-Lb.
Percentage of energy transferred from the club to the ball is 21.44%

Player #2 (Staff Player-Long Drive Specialist)
• Club Head Velocity: 140 mph
• Ball Velocity (at launch): 210 mph
• Back Spin: 4200 rpm
• Side Spin: 598 rpm
• Effective Mass of Club: 220 g

Energy transferred is 148.620 Ft-Lb.
Percentage of energy transferred from the club to the ball is 23.42%

This type of testing and analysis explains not only the energy transfer efficiency of a particular shaft, but offers insight into where the energy losses occur. Through the use of high-speed cameras, deformations of the ball, shaft, and head at impact can be detected and analyzed. The amount of energy loss due to heat, ball spin, and elastic waves within the ball, head, shaft, and grip can then be determined. This data is used to understand how and through which method a shaft absorbs and dissipates energy. Future designs incorporate this information to maximize energy transfer while minimizing energy losses in the shaft.

The ETA program also allows Penley’s research and development staff to:

• Demonstrate to prospective customers which combination of shaft and club head will transfer
the highest percentage of energy to the ball with the most effective spin rates.
• Develop and apply data that can be used to create improved materials and processes.
• Develop and apply data that can be used to reduce fatigue rates of shafts.
• Develop and apply data that can be used to reduce interlaminar shear loads in shafts.
• Develop and apply data that can be used to enhance micro mechanics for maximum shaft load
transfer.
• Develop and apply data that produces a more consistent performing shaft or set of shafts.

As shown, the ETA program is an extremely powerful analytical tool. It clearly defines the “distance performance” of a shaft while giving insight into many other mechanical properties of a shaft.
This, however, is only the tip of the iceberg when looking at the hi-tech design and analysis techniques used by the Penley Sports engineering staff.

Other static and dynamic swing analysis programs that process immense amounts of data include a Spine Reduction System (SRS) and Lamination Theory Analysis (LTA) package. The SRS ensures a concentric, symmetric shaft. This minimizes or effectively eliminates any dominant spine while maximizing the consistency and control factor of the shaft. The LTA package allows shafts to quickly be designed with the desired torque, stiffness, dampening, and mass distributions. This program facilitates the design of shafts or sets of shafts that have a specified “feel”. The Penley Sports engineering staff wrote all of these programs in house, then combined them to create a design and analysis package that maximizes the fundamental variables of shaft performance-feel, control, and distance. Needless to say, this design approach has been extremely successful.

Penley creates the highest quality, best performing, most consistent shafts in the industry. Using Penley shafts, golfers can increase their confidence and overall performance on the course. The top competitors on PGA tour and in long drive championships prove this point. All golfers can benefit from the power of Penley.

Contributions by Pete Wagner, Staff Engineer

There are varying opinions as to where the spine should be located in a finished club. Based on tests I had conducted years ago, I defined two planes in a golf shaft:  the droop plane and the swing plane. The droop plane is parallel with the clubface and the swing plane is perpendicular to the clubface. For our purposes, the spine of a golf shaft is the stiffest plane of the shaft.

Finding the stiffest plane can be performed by several different methods. One method is by using the Lockie board. When a shaft is placed on the board and bent, a state of equilibrium exists when the weaker plane is the bend plane. The stiffest plane (spine) is on the sides of the shaft and perpendicular to the bend plane. Equilibrium exists because the stronger plane is not in a state of compression and tension simultaneously (as it is when it is bent). Performing the same test on a long flat ruler is the easiest way to visualize this. A shaft with a very dominant spine resembles the ruler. The weaker plane bends easily and the “spine” of the ruler is on the sides since it is more difficult to bend.

Another method is using the Autoflex Machine. The Autoflex machine performs the same basic test as the Lockie board, but bends the shaft up instead of down. The Autoflex then marks the inside of the curved shaft (the weak plane).

The H.O.A.M. (Harmonic Oscillation Analysis Modeling) machine finds the spine in a much different and more precise manner than either the Lockie board or the Autoflex machine. It has a strain gauge that measures the force required to bend the shaft. The H.O.A.M. machine analyzes the force readings, finds the stiffest part of the shaft and prompts the user to mark that as the dominant spine. If the long flat ruler were placed in the H.O.A.M. machine, it would treat the unbendable side as the spine.

There are varying opinions as to where the spine should be located in a finished club. During the days of  Penley Sports, we conducted a series of field tests with the spine located in either the droop plane or the swing plane. And this is what we discovered in our extensive testing:

Someone driving the ball about 350 yards with the spine located in the droop plane gained only a yard or two when the spine was located in the swing plane. Based on drive distance alone, there is no significant reason to position the spine in the swing plane. Additionally, the players could feel and react to the club more easily when the spine was located in the droop plane, placing the weakest plane in the swing plane. It was much harder to control the club if the droop plane was the weaker plane.
Our second position is that by having the spine in the droop plane, the shaft has a more positive and consistent reaction at impact than when the weak plane is in the droop plane.

Based on the testing (with more coming shortly) the club performs and feels better with the spine located in the droop plane. Since Penley shafts are checked on the Autoflex machine which marks the weaker plane, graphics are placed on the shaft with Penley located 90° from the Autoflex mark (on the spine). Once again, visualizing the ruler, Penley shafts would be printed on the unbendable side, and the flexible plane of the ruler would be in the swing plane.

Over the past few years interest in Long Drive Competition has grown and along with that growth so has the popularity of the graphite shafted club; the weapon of choice for all serious Long Drive Competitors.

This fact should not be a surprise to anyone when you consider the versatile design of carbon fiber materials. And no one understood this better than Joe Bianchi, who for the past several years was looking for (to quote Joe) “The best graphite shaft in the industry”. So far Joe had tried them all except for the Penley Power Shaft.

That was the basis of our first meeting, to determine not if we could develop a shaft, but which of our current designs would best fit Joe’s requirements. I recommended two shafts that I thought would be most suited for the task at hand. Joe played them both and selected one that was subsequently tested at different lengths, heads and head weights to fine tune for the best combination possible.

These were the results. Joe out drove 55 competitors to become the #1 qualifier for The “Chrysler” Long drive, San Diego sectional, and then went on to out drive the 26 competitors at the State sectional qualifier to capture the “Chrysler” Long Drive 11th district (California State) competition. This is an impressive feat when you consider we used a shaft from our standard line and Joe Bianchi is not the hulking mass most professional long drivers are. (Joe is approximately 5’11” and 185Ibs.)

I was quite confident that one or more shafts in our Penley Power Shaft line would work because of one basic theory, FEEL. This is not measured in robotics, pure number crunching or following the lemmings, by just designing another tapered plastic tube!

Quite simply I look at things differently than many other designers or manufactures; for instance, set aside the usual design theories and ask;

· If one horsepower is one horsepower (and mathematically it pencils out) then why is one horse faster than another?

· If two race car engines are assembled to the exact same specifications, then why will one engine develop more horsepower than the other?

· If you assemble two golf clubs, using shafts of different manufactures, to the same specifications (length, swing weight, over-all-weight & grips) and by the same clubmaker, why will one club yield more distance or better dispersion or both?

Obviously there are many factors to consider, but one word in my opinion can best sum it all up and that word is efficiency!!!!! More specifically ETA (energy transfer accelerance). Ultimately, a golf shaft must be very efficient from tip to butt to give the best ETA performance:

1. The shaft must have the highest quality carbon fiber not too stiff) to withstand maximum compressive loads and still exhibit enough yield to be able to recover quickly enough to generate the highest head speeds possible.

2. Preferably, the shaft must have the highest quality epoxy matrix to bond the fibers and transfer the highest percentage of flexural loads possible.

3. Preferably, the shaft should be one complete piece no matter the length from tip to butt.

4. The shaft must effectively transfer back to the player a positive feel throughout the entire swing and thru impact.

5. The club head must recover within milliseconds prior to impact.

6. The shaft must perform with a very high degree of consistency for distance and dispersion.

7. The shaft must not be super sensitive to head weight variations.

8. The shaft must be of such a design as to deliver the above qualities at a wide range of swing speeds.

The shaft Joe is currently using performs very well from approximately 70 mph to 145 mph.

Needless to say, these designs incorporate the highest grade of fibers available and the blending of as many as three to five different grades of fiber and epoxy matrixes along with unique fiber patterns, mandrel designs, and manufacturing processes, and several years of continuous testing and along with a high degree of R&D activity all of which are proprietary to Penley Power Shaft.

Joe Bianchi’s longest drive to date with a Penley shaft is 478 yards with 455 yards of carry (Joe also had the longest district qualifying drive last year 392 yards recorded by the LOA) Surveyors report and signed witness reports on file at Penley.