Impact Ratio

August 2, 2018 / Media, News

An Investigation into Impact Ratio for Putter Club Design and Impact Location
Dr Paul D Hurrion.

2018 WORLD SCIENTIFIC CONGRESS OF GOLF
July 11-13, 2018   Abbotsford, BC Canada
Host: University of The Fraser Valley

Purpose                                                       

A putt hit with the perfect line but with the wrong speed might still miss the hole due to how the ball slows down and reacts with the terrain of the putting green. The following study investigated the significance of impact location for nine leading club designs (See ‘Putter Specifications’) including three blade style, three mallet style and three marketed as having a high moment of inertia (MOI). How does a different impact location on the putter face affectball speed and does the style of putter have any influence? Ball speed has a significant effect on putting results and should be considered an important factor when putting at any level (Pelz, 2000). Despite this, the ability to control ball speed can often be overlooked in coaching. Ball speed is one of the four reasons as to why a putt might miss (Cochran & Stobbs, 2005).

Figure 1: The effects of ± 50 percent errors in the initial trajectory (left) compared to the effects of only ± 10 percent errors in the putt speed (right). Dewhurst (The Science of the Perfect Swing, 2015, Oxford University Press). “Speed is more important than target line” (Dewhurst, 2015).

The ability to control the speed of the putter head with controlled face aim, along with green reading, are all a primary determinant of putting consistency (Karlsen et al.2008). However, little or no focus is aimed towards the effect of ball speed as a result of the design of the putter or even the club face material. The purpose of the study was to better understand the role of impact location and club design on the ability to control ball speed and ultimately control distance.

Methods

The Quintic Ball Roll system (Quintic 2016) uses a high speed camera (360 fps) to measure a variety of factors including clubhead speed, ball speed, face angle, face rotation and putter twist as a result of impact. Nine different putter designs were used for the study (three blade, three mallet and three high MOI design putters). Nine impact locations were analysed per putter (see Figure 2 below).

Figure 2: 9 Impact Locations

Locations 2, 5, and 8 were determined by the manufacturer’s markings indicating the centre alignment guide on the putter.  The toe and heel points are two centimetres either side of the midline. Points 4, 5 and 6 are in the middle of the face (top / bottom). The top and bottom rows were equally spaced out, depending on putter face depth or the insert depth (see Figure 3).

Figure 3: A visual representation of the impact location (top / middle / bottom)

Ten putts were recorded and analysed for each impact location reproduced by the putting robot (Figure 4). The clubhead was released from the same location for each putter on a straight back and straight through path. The protocol was conducted on an indoor artificial putting surface (Stimp 11). Clubhead and ball speed, face angle at impact and putter twist were recorded for the nine impact locations per putter design, using the Quintic Ball Roll system.

Figure 4: Average club head speed = 3.65mph ± 0.04 for each putt reproduced by the putting robot. The clubhead was released from the same location for each putter.

Results

The first part of the study was to investigate the impact ratio for a centre strike (impact location 5 – Centre, Centre) for all nine putters. The results can be seen in Table 1. Impact Ratio (Ball Speed / Clubhead Speed) ranged from 1.62 to 1.72.

Impact Location 5:The Impact Ratio (IR) is the ball speed divided by club speed. IR relates to the amount of energy transferred from the putter head to the golf ball during contact. The higher the impact ratio, the higher the energy transfer (the ‘hotter’ the putter face). The IR ranged from 1.62 to 1.72 for location 5 (impact centre / centre) for the nine putters. Thisvariation in ball speed, caused by a variation in IR, will cause the ball to travel different distances and therefore slow down at different rates, particularly relevant to the golfer on sloping putts.

A ball speed range of 0.47 mph was reported between the nine different putters for centre impact, despite the clubhead speed at impact having a range of 0.13 mph (3.59 to 3.72 mph. These differences are caused by the variance in material, head weight and design of the putter). The high MOI putters had on average a higher head weight of 365gms ±6. The blade style putters had the lowest head weight of 351gms ±2 (see ‘Putter Specifications’)

9 Impact Locations:  Centre, centre (Location 5) was always the highest IR for all nine putters. PING Vault Oslohad the highest IR of 1.72, with the lowest value being 1.46 (Low, Heel) for the TaylorMade Spider Red.

Table 2: PING Vault Oslo – Mallet   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.   % reduction in IR depending on Impact location (1-9).

Table 3 : TaylorMade Spider Red – MOI   Impact Ratio (IR) and % drop for the 9 Impact locations.
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

 

If both putters had an average clubhead impact speed of 3.65mph, this would equate to a 0.95mph difference in ball speed (3.65mph  x 1.72 (IR) = 6.28mph PING Vault Oslo : 3.65mph x 1.46 (IR) = 5.33mph Taylor Made Spider Red). How does this equate to ball roll out distance on the actual putting green?

Table 4 below highlights the initial ball speed in both feet per second and miles per hour for a flat (no wind or grain) putting green stimping at 8, 9, 10, 11 and 12 respectively. Rows 8 ft/sec (5.45 mph) and 9 ft/sec (6.14 mph) are highlighted in red, as they represent the closest ball speed readings for the Taylor Made Spider Red (5.33mph) and PING Vault Oslo (6.28 mph).

 

Table 4: Ball Speed (ft/sec) (mph) total roll out distance (feet) on a flat green, no grain or wind) for the respective Stimp readings. Data provided courtesy of Aim Point.

  • Stimp reading of 8, there is a difference in ball roll out distance (16.1 – 13.2) = 9ft
  • Stimp reading of 9, there is a difference in ball roll out distance (18.1 – 14.9) = 2ft
  • Stimp reading of 10, there is a difference in ball roll out distance (20.1 – 16.5) = 6ft
  • Stimp reading of 11, there is a difference in ball roll out distance (22.1 – 18.2) = 9ft
  • Stimp reading of 12, there is a difference in ball roll out distance (24.1 – 19.9) = 2ft

A 4.2ft difference in roll out ball distance (Stimp 12) of a putt travelling 24.1ft highlights the importance of IR (and putter specific designs) along with the impact location on the actual face. These differences in roll out distance will only increase as the putt is hit harder…

 

Discussion

There is a perceived notion that blade putters have the least amount of drop in ball speed with miss hits, but a greater horizontal dispersion. In contrast, high MOI putters are designed to reduce the horizontal dispersion, but as a consequence there is a lower ball speed from miss hits. The results from this study show that every putter is different. The MOI putters recorded the highest percentage drop in ball speedfor miss hits in location 4 and 6 (across the centre line, toe to heel). Evnroll ER2 – Blade had the lowest drop (2%) across the midline (impact location points 4, 5 and 6).

As a general observation, impact location points 2,5,8 (high / low) and 4,5,6 (across the face) have the least drop in energy transfer (impact ratio) across all nine putters. Low on the putter face (impact location points 7,8,9) have the largest drop, with low heel (impact location 9) having on average a drop of 10%.One particular blade putter (Bettinardi BB1F – Blade) had a 14% drop for impact location 9.  Evnroll ER7 – MOIhad the lowest drop (8%) between impact location 5 and 9 (Low Heel). 

 

Practical Application

Golfers need to be able to consistently control ball speed in order to achieve a consistent end distance. Impact ball speed is directly affected by the impact club head speed. However, head weight, face technology and impact location collectively all have an influence on the IR. Inconsistencies in impact location will cause an inconsistency in the impact ball speed. A consistent strike point is required for a consistent impact ratio regardless of head weight or face technology.

If you can’t hit it consistently out of the middle, how do you expect to start the ball on your intended line, with the correct pace”
Danny Willett   (Masters 2016 Champion) 

“Most three putts aren’t caused by bad green reading, but by bad judgement of speed”
Ben Crenshaw (Masters 1984, 1995 Champion)

During this study we saw a potential difference of 3.6ft ball roll out distance (16-20 ft putts on 10 stimp greens) with a clubhead speed of only 3.65mph, based solely on impact location and putter design.

A high IR will cause any variations in impact club head speed to be magnified, however, the speed the ball reacts from the putter face is often a personal preference and one the player often becomes accustomed to. If a new face insert is introduced, or even model style this may well result in a new IR. As a result this will affect the resultant ball speed and will require adjustment fromthe player on the putting green. Every putter is different and not every high MOI putter necessarily performs better than a blade putter on an off centre hit. This ultimately requires a player to measure any potential new putter and compare its characteristics to their current putter.

  • The IR is the ball speed divided by club speed.
  • IR relates to the amount of energy transferred from the putter head to the golf ball during contact.
  • Impact clubhead speed has the greatest effect on impact ball speed, but IR will also influence this.
  • Normally the consistency of the IR is more important than the average.
  • However, a high IR will cause greater variations in the impact ball speed.
  • IR is affected by the head weight, face technology (inserts, grooves, milling) and impact location.
  • Not every high MOI putter necessarily performs better than a blade for off centre hits.

An area for further research is that relating to clubhead twist and the effect this has not only of IR but also the horizontal start direction. During the study, it was noticeable that the different impact locations and models react differently in terms of IR, hence different ball speeds, but also increased variations in horizontal start direction. This is an area of further investigation, involving over head cameras to quantify the exact start direction. In addition to horizontal start direction, the influence on vertical ball launch caused by high and low strikes on the clubface is also an area of further investigation.

References

  • Cochran, A. J. & Stobbs, J. (2005). Search for the Perfect Swing. Chicago: Triumph Books.
  • Pelz, D. (2000). Dave Pelz’s Putting Bible: The Complete Guide to Mastering the Green. New York:
  • Karlsen, J., Smith, G, Nilsson, J (2008). The stroke has only a minor influence on direction consistency in golf putting among elite players. Journal of Sports Science, February 1st2008; 26(3): 243-250
  • Quintic (2016). Quintic Consultancy Limited, 160 Lichfield Road, Sutton Coldfield, B74 2TZ (UK) (quinticballroll.com)
  • Dewhurst, P. (2015). The Science of the Perfect Swing. Oxford: Oxford University Press.
  • Donaldson, J. (2013, March). Green Reading: Need for correct speed. Aimpoint Golf.(https://aimpointgolf.com/)

 

Putter Specifications:

Table (I) : Odyssey O Works #1 Wide – Blade   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: blade / Loft: 3° /  Lie: 70° / Hosel: S-neck / Offset: ¾ shaft / Toe hang: 47° / Head weight: 350g
Advertised features: Microhinge technology provides incredible gains in topspin and roll at impact regardless of the stroke. The stainless steel Microhinge plate is co-moulded into our Thermoplastic Elastomer Feel Layer, providing great feel and getting the ball into a better roll at impact. The new mallets with toe hang are all designed for players who like to feel the face of their putter rotate more in their stroke.

Table (II) : Bettinardi BB1F – Blade   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: “Anser 2” / Loft: 3° / Lie: 70° Hosel type: long plumbers neck / Offset: ½ shaft / Toe hang: Strong / Head weight: 350g
Advertised features: The BB1, our classic blade-style putter, has received unique cosmetic and performance upgrades for 2018 which includes a neck that has been moved slightly forward towards the sweet spot which promotes less toe hang. The traditional Honeycomb face has been replaced in favour of our aggressive fly mill milling technique, which produces a softer feel at impact. A new Stealth Black finish is complimented with an electric yellow paint scheme, reducing glare and improving aim optics.

Table (III) : Evnroll ER2– Blade   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: blade / Loft: 3° / Lie: 70° / Hosel type: Single bend / Offset: ½ shaft / Toe hang: Slight / Head weight: 355g
Advertised features: This precise face milling imparts progressively to provide more energy transfer on off-centre putts.This improves distance control to prevent you coming up short on off centre putts. This milling pattern also gears the ball back to the centre, so you hit the sweet spot of the putter for greater consistency.

Table (IV) : Odyssey O Works R Line – Mallet   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: mallet / Loft: 3° / Lie: 70°/ Hosel type: Long Hozel / Offset: ½ shaft / Toe hang: Face balanced / Head weight: 350g Advertised features: Our Microhinge Insert Technology provides incredible gains in topspin and roll at impact regardless of your stroke. The stainless steel Microhinge plate is co-moulded into our Thermoplastic Elastomer Feel Layer, providing great feel and the new geometry of the hinges and urethane together help to get the ball into a better roll at impact.

Table (V) : Taylor Made TP Berwick – Mallet   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: mallet / Loft: 3° / Lie: 70° / Hosel type: plumbers neck / Offset: ½ offset / Toe hang: face balanced / Head weight: 350g Advertised features: The Berwick putter is perfect for golfers who prefer a face-balanced, mallet style putter with a sleek profile. Created in a precise, rounded shape, this putter includes a single sightline on the back cavity. Complete with a double bend shaft and full shaft offset, this putter provides a straight back, straight through putter stroke. The putter has a new and improved pure insert roll for a better roll, and has adjustable sole weights to set the up the putter for your perfect playable swing weight. To help you stay on track and sink more puts the putter has two sightlines and has Tour validated putter grip to give you maximum feel and touch.

Table (VI) : PING Vault Oslo – Mallet   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: mallet / Loft: 3° / Lie: 70° / Hosel type: single bend / Offset: no offset / Toe hang: face balanced / Head weight: 365g Advertised features: a smaller mallet with geometric features to frame the ball at address, including a low level sightline. The Vault Oslo features a new True Roll (TR) face technology. This technology uses face grooves that are machined to varying depths to help speed up off-center hits and provide more consistency in your putts. A stainless steel bottom weighting boosts MOI and lowers CG to improve your putting performance.

Table (VII) : Evnroll ER7 – MOI   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: mallet / Loft: 3°/ Lie: 70° / Hosel type: single bend / Offset: ½ offset / Toe hang: Slight / Head weight: 370g
Advertised features: This precise face milling imparts progressively to provide more energy transfer on off-centre putts. This improves distance control to prevent you coming up short on off centre putts. This milling pattern also gears the ball back to the centre, so you hit the sweet spot of the putter for greater consistency.

Table (VIII) : TaylorMade Spider Red – MOI   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: mallet / Loft: 3° / Lie: 70° / Hosel type: long plumbers neck / Offset: ½ shaft / Toe hang: Moderate (38°) / Head weight: 355g Advertised features: High MOI for increased forgiveness and stability. Smooth crown, no sightline, and short slant neck hozel for Spider Tour Red and Spider Tour Black. Long sightline, double bend shaft and face balanced head for Spider Tour Platinum. Spider Tour Red has a Pure Roll™ Surlyn insert for softer sound and feel. Spider Tour Black has a Pure Roll™ 80/20 insert for firmer sound and feel. Vibration-dampening foam for consistent sound and feel.

Table (IX) : Ping Sigma G Wolverine T– MOI   Impact Ratio (IR) and % drop for the 9 Impact locations
0% = Centre, Centre impact location 5.  % reduction in IR depending on Impact location (1-9).

Head type: mallet / Loft: 3° / Lie: 70° / Hosel type: double bend / Offset: ½ shaft / Toe hang: face balanced / Head weight: 370g Advertised features: A high-energy Pebax elastomer insert behind the anodized 6061 aluminium face provides a soft feel without slowing ball speed, ensuring full-face forgiveness and consistent distance control. True Roll Face Technology supplements putting touch for improved consistency and fewer three-putts.