Wedges: Friction and Trajectory

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The other day during a Three Day Golf School I hit four demonstration pitch shots for my students. My intent was to repeat the same shot in each attempt, with the only difference being how I manipulated the amount of friction between the club face and the ball.

The amount of loft I was able to deliver for each of the four shots was between 44.3º and 45.3º - the best I've been able to do! The interesting part is that the launch angles ranged from 30.4º tall the way up to 40.0º. How does that happen?

The Four Shots

The Four Shots

The reasons why the launch angles are different is something that too few golfers (and coaches) understand and while I've written on this before it's a mission of mine to get the good word out. My intent was to carry each shot 50 yards and they are all played in the same fashion, with the same club except for shot 4.

Shot 1 - clean, dry club face and a clean, dry range ball. Spin rate - 6246 rpm. Launch is a respectable 32.1º

Shot 2 - clean, wet club face and a clean, wet range ball. Spin rate - 2782 rpm. Launch is a whopping 40º

Shot 3 - clean, dry club face and a clean, dry premium ball. Spin rate 6923 rpm. Launch is the lowest at 30.4º

Shot 4 - clean, dry grooveless club face and a clean, dry range ball. Spin rate is 5837 rpm. Launch is decent at 33.6º

I must mention that in order to 'manage' the friction between the club face and the ball each of these shots is played off a tee so as to eliminate grass and outside matter from interfering.

While the loft is maintained the launch, spin rate and peak height can be greatly influenced by the amount of friction generated between the club face and the ball. The moral of the story here is that the best pitchers in the world hit low launching, high spinning shots when the conditions allow. There is more at play than simply the loft at impact determining the launch angle. As you can tell friction plays a massive role too. It is my hope that in understanding this you will be less likely to try and 'fix' something that isn't broken. Hope this helps and thanks for reading!

Luke Donald

Luke Donald

 

 

Knowledge to Help You Spin Your Wedges

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When it comes to wedge shots, spin has always been somewhat mystical. Why will one shot check like crazy while most shots seem to want to scamper well beyond the pin?

This is a little experiment I do in all my Three Day Golf Schools to illustrate a few of the important factors that influence spin rates...

This video clearly illustrates the role of water, grass, a premium golf ball and a clean clubface - the big factors that influence friction between face and ball and ultimately, spin.

As a golfer you are fully responsible for how the sole of the club interacts with the ground while you are only partially responsible for how the face interacts with the golf ball. Understanding factors that serve to decrease friction will only help you from trying to fix a motion that isn't broken.

While it is important to realize that we don't need maximum spin in order to pitch well, we do need ENOUGH spin. To generate more RPM's use a professional grade wedge, replace it as often as needed, keep the face clean and dry and use a premium golf ball. Of course hitting from a tight, dry fairway would be nice too, but we cannot always control that one...

For more on wedge spin and improved wedge play see:

The Wedge Project

Spinning the Wedges - Friction

 

 

Spinning the Wedges - Smash Factor

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Smash factor is a measurement of the ball speed relative to the club speed. I have learned that with wedges, when smash factor is 1.0 spin rates have the potential to be maximized. This video discusses the value in having the ball and the clubhead travel at the same speed and gives you a few ideas on how to make that happen...

Things to remember:

  • Avoid too much shaft lean and feel the hands and the shaft lining up at impact
  • This should give you a sense of using the bounce or sole of the club more through impact
  • Don't be afraid to allow the lead wrist to unhinge/extend as soon as possible through impact

Keep in mind that while very high spin rates are sexy, your final objective should be control. Better control and predictability means better results. Don't allow a quest for more spin erode your ability to get the ball close to the hole!

Thanks for watching and check in soon for my next in the Spinning the Wedges series on Spin Loft.

Wedge Project Color.jpg

To Mill or Not to Mill?

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My three test subjects...

I must be honest and write that I did this test in the hopes of proving a few people wrong. Instead, I have proven myself wrong. With my research for the Wedge Project I put my "stake in the ground" on what I believed regarding milling on the clubface. All the tests I performed using TrackMan and various wedges always showed that a wedge without a milled face generated less spin (albeit slightly) than wedges with the fine "corduroy" look of milling between the grooves.

I looked up a person I believe to be very knowledgeable when it comes to equipment, Tom Wishon. I read all that he had to say on the matter of grooves and surface roughness and his findings aligned with the results I was seeing in my tests.

Based on what I had available to me I had done my homework and had placed my "stake in the sand" in favor of milling on the clubface. It just made sense to me. Until this....

David Neville and the crew from Vokey Wedges have been kind enough to let me have access to a few test wedges. They sent me six wedges of which I chose to use three for this test.

No grooves and no milling

No grooves and milling

All three wedges have the same grip, shaft (DG S200), length, grind (M) and a stated loft of 56 degrees. I did not check their weight, actual loft, lie angle or bounce measurements. I hit 60 shots off a mat (to eliminate ground interference) with the no groove, no milling club and 60 shots off a mat with the no groove, milled club. I then eliminated the 15 lowest spinning shots to leave the remaining 45 highest spinning shots with each club. I used slightly used ProV1X balls and attempted to carry each shot 50 yards. I wiped or cleaned the clubface between every 3rd or 4th shot. Here are the results:

Titleist SM4 TVD M 56 degree Chrome Fly Cut without Grooves or Milling

Titleist SM5 56.10 M 56 degree Raw Surface without Grooves/Milling Only

As you can see the club that had surface milling or roughness actually generated less spin - 6009 RPM to 6229 RPM. While the difference between the two is negligible and most golfers would have a hard time telling the difference between the ball flight of one versus the other (myself included), the result is significant to me in that I firmly believed the outcome would be reversed.

Keep in mind this is a test involving one golfer hitting a limited number of shots to one distance. The results might be a slightly different with multiple golfers at different distances, but I don't believe different enough to sway the outcome of this test.

I recently posted this quote by Martin Palmer on Twitter: "The secret to mastery in any field is to forever be a student." Today my "stake in the sand" moved - I was a student and I learned something. I think it is vital as a coach, or even as a golfer, to place your "stake in the sand" and firmly believe in a method, approach or theory. Stand by it and argue in its favor. That is, until you uncover sound evidence or reasoning against your viewpoint - then you pick up your stake, admit you were wrong and adjust your approach.

As a point of interest I wanted to see how a standard clubface might interact with the ball. I hit 25 shots (keeping the best 20) with the Titleist SM4 TVD M grind that has 17 standard grooves and a milled face. Here are those results:

Titleist SM4 TVD M 56 degree Black Oxide 17 Grooves with Surface Milling

As you can see this clubface with both grooves and surface roughness generated the highest spin rates of all three clubs. This leads me to believe that grooves play a larger, more important role on cleanly struck shots than I originally thought.

As I continue to learn and work towards providing my students with what I believe to be the best current information and knowledge available I know that I will continue to be wrong. The blessing is that each time I am wrong I will learn, adjust and be less wrong than I was before.

The Driver and Accuracy (Part 2)

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We all want to hit the ball straight and far of the tee don't we? In more technical terms our goals with the driver are to achieve the highest ball speed possible (distance), along with the desired flight pattern (accuracy). We want cake and we want to eat it too!  Here's a run down on what club manufacturers have been working on to help us keep the ball in the fairway...

The primary factors directed towards accuracy are bulge and gear effect, center of gravity placement, adjustable heads or weights, a preset face angle and the clubhead design.

  • The most interesting element built into each driver that serves to increase accuracy is the one two punch of bulge and horizontal gear effect.  The face of every driver (all clubs requiring a headcover for that matter) has roll and bulge while irons do not.  Bulge is the curvature of the face from its heel to its toe, while roll is the curvature of the face from the crown to the sole.  Bulge starts the ball farther to the right on toe shots and farther to the left on heel shots and is a correction for the clubhead’s center of gravity (CoG) that causes hooking or slicing (gear effect) on off center shots. In other words, manufacturers have built bulge into the face to counter the negative results of gear effect.  Here is an explanation (BTW Irons do display gear effect just far less than drivers):

Here's a definition of gear effect from Dave Tutelman (who has an excellent site for the scientist golfers out there):

Gear effect causes a ball to  have sidespin which is the result of an off-center hit with a club whose center of gravity is well back from the clubface.

Without an off center hit and a CoG that is well behind the face gear effect cannot happen.  In the picture above, we have a toe impact with an iron and a driver.  The center of gravity (CoG) is indicated by the black and white circle.  The collision between the clubface and the ball on the toe creates a torque that causes the club to twist - the club twists around the clubs' CoG which is indicated by the red arrow.

The CoG on the iron is virtually on the face and this type of strike causes the face to rotate open.  This invariably causes the ball to fly weakly to the right as there is no gear effect on the spin imparted on the ball.

The driver is very different.  With the CoG being further back from the face a toe impact causes the entire face to rotate around the CoG.  As the ball compresses and grips on the face the red arrow causes the ball to actually rotate to the left (blue arrow) - the ball and the face actually work like two gears!  Thus the term gear effect.  And the reason why a toe hit with a driver tends to hook and a a heel hit tends to fade.  Bulge helps out by launching a toe hit to the right of the target - a good thing if the ball has draw spin.

  • The design and shape of the clubhead is something that we have seen much tinkering with in recent years.  From the triangular Titleist 907 D1 (how could you forget that!) to the onslaught of ugly square heads - these designs all strive to do one thing - re-position the CoG to stabilize the head during off center hits.  The longer (from face to back) the clubhead is, the further back the center of gravity is from the face which also increases gear effect.  If you can deal with the aesthetics of these scientifically upgraded clubs by all means have at it.
  • Another modern trend that has been proven to straighten wayward tee balls is the advent of adjustable weights or screws on the clubhead.  Originally introduced by TaylorMade in their R7 line, tests have shown that the higher the swing speed the more a golfer is able to curve a ball by changing the weights in the clubhead.  A golfer with a swing speed of 115mph (PGATour average is 112mph) will experience 35 yards of curve while a golfer with an average type speed of 85 mph will only experience 6 yards of corrective curve.
  • Along similar lines are the adjustable heads where the shaft rotates in order to adjust the loft or lie. While changing the loft will not do much to improve your accuracy, altering the lie angle can help you make subtle changes.  Moving the shaft to a more upright position will promote a draw, while flattening will promote a fade.
  • There is also the preset face angle. For those golfers out there who struggle with slicing this has been a tremendous help.  If you feel like you could benefit from this just look for on offset driver or one that says draw somewhere on the head.

There are also rumors that there are certain shafts (Nunchuk) that make the ball go straighter, but I have not read anything or seen any convincing evidence to support this.

Thanks for reading and I hope that now you have a better understanding of what your driver can do for you....

Understanding Swing Plane and Club Path

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There are important differences that occur at impact when a golfer hits either down or up on the ball (attack angle).  I have always espoused that golfers hit down on all clubs, the driver included, but my research with Trackman has convinced me otherwise.  The ball should be struck with a subtle downward blow with all shots off the ground (irons, hybrids and fairways), but the driver should ideally be hit with an upward strike for optimal trajectory and spin patterns.  I will attempt to explain the differences in the direction the clubhead travels (relative to the target line) as it moves both down, and up, into the ball.

Firstly, it is important to understand the difference between swing plane (also referred to as swing direction) and club path, because too many golfers believe they are one and the same.  Let's view swing plane as the hula hoop in the pictures below - it is the angle upon which the arc of the swing travels.  Club path is the direction the clubhead is travelling in, relative to the target line, at the moment of impact.

Hitting down on the Ball:

 

PGA Tour golfers hit down on a 7 iron with an average attack angle of slightly more than 4 degrees.  You should be able to tell to what degree you hit down on the ball simply by analyzing your divots - too much dirt being moved and you're more than likely 8 degrees down, no divots would mean a flat or neutral attack angle.

When a golfer hits down on the ball with a neutral swing plane (straight at the target) notice how the pencil (used to illustrate club path) points right of the target. The table's edge indicates the target line.

Hitting down...

Down with a neutral plane...

This means that with a straight plane/swing direction, when the clubhead travels down, it is also travelling from in to out relative to the target line.

Left swing plane for neutral path...

In order to neutralize the club path, the swing plane must actually be rotated to the left.  Thus, with a descending attack angle, in order to create a straight club path, the swing plane must be rotated to the left of the target line (for right handers).

Hitting up on the Ball:

 

Better drivers of the ball tend to hit up on the ball - anywhere from 1-5 degrees up.  This reduces the amount of spin on the ball and increases the launch angle - thus increasing both carry and roll distance.

When a golfer hits up on the ball with a neutral swing plane (straight at the target) notice how the pencil (club path) points left of the target. 

In this example, with a straight plane/swing direction, when the clubhead travels upward, it is also travelling from out to in relative to the target line. 

This out to in path can be neutralized by rotating the swing plane/direction to the right (for right handers).  Notice how the pencil (club path) is now straight.

So if somebody ever asks you if the swing with the driver and the irons is the same, just smile and say, "No, not really!"

Any thoughts?  Questions....

Playing Golf in the Wind

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One of the biggest mistakes golfers make when playing in the wind is to make full swings. It almost seems as if they try to overpower the wind - that cannot happen! This is a perfect example: A golfer faces a 120 yard shot that is into the wind; they calculate the shot to be playing approximately 130 yards; they pull their 130 yard club and make a full swing; the ball comes down 25 yards short of the pin. The reason this happens is that the harder you strike the ball the more it spins and spin creates turbulence, which leads to lift, which leads to height, which leads to soemthing far less than the expected distance.

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