Andrew Rice Golf

Posts Tagged ‘attack angle’

Few golfers are aware of what really happens when a clubhead collides with a golf ball at high speed, not to mention how much an off-center collision can effect the flight of the ball. My hope is that this article and the accompanying video footage will give each of you a much better understanding of the importance of solid contact.

I would encourage you to watch the following PGATour.com video a few times…

As you can see a strike away from the center of gravity of the clubhead will lead to twisting of the clubhead. While most of the twisting occurs after impact, a portion of it does occur during the impact interval. It is this twisting during impact that leads to gear effect which can greatly alter the flight of a shot.

An off-center collision will twist the clubface in any direction.

A hit high on the face will tilt the face upward and reduce the amount of spin on the ball, while a low strike point will deloft the face and increase spin rate. A strike towards the toe will open the clubface and increase draw or reduce fade and a strike towards the heel will close the face and increase fade or reduce draw. Interestingly, the clubface will tilt vertically (top/bottom) almost as much as it will horizontally (toe/heel).

There are seven shots in the video and if each of them had a neutral club face and club path during impact, the results of each shot due to gear effect would have been as follows:

Shot 1 – A strike above the “equator” of the clubface and slightly towards the toe. Ideal if you would like to hit high launching, low spinning, draws that go a long way.

Shot 2 – A High Toe Side Strike

Shot 2 – A more pronounced high, toe side strike. This strike point is too far from aligning with the center of gravity of the clubhead to be beneficial. This flight due to gear effect would have been fairly high launching, low spinning and would not have faded as much as it might have appeared.

Shot 3 – Another extreme high, toe side strike along with a heavy descending blow – not good. High and right, but a fairly straight flight.

Shot 4 – A Low Heel Side Strike

Shot 4 – A severely off-center hit where the collision is with a very low portion of the face and in the heel. Believe it or not this ball gets airborne and will almost always be an unimpressive high spinning,  low fade with very little distance.

Shot 5 – Charley Hoffman: I have seen numerous clips of high speed driver footage like this and I don’t think I have ever seen one where I cannot detect any twisting at all. A slight downward attack angle. Appears to be very close to a perfect center of gravity strike – a truly rare event! Very straight.

Shot 6 – Matt Kuchar: A neutral attack angle along with a high, toe side strike. High launch, lower spin and a slight draw – boom!

Shot 7 – Luke Donald: About as solid as Charley Hoffman’s shot, but the interesting thing about this clip is the attack angle – quite severely down. Solid and straight, but not optimal for maximum distance.

It is interesting to note that today’s larger clubheads will resist twisting due to having a higher moment of inertia. MOI is a measure of a body’s resistance to angular acceleration or twisting. MOI really comes into play when the ball and the clubface meet someplace other than the sweet spot. The MOI of a club is higher for heel/toe mishits than it is for high/low mishits and therefore tends to be more forgiving on heel/toe mishits. However, golfers tend to mishit a shot further towards the heel/toe than they do high/low so the clubheads’ resistance to twisting tends to even out.

Please know that physics is not selective and any golfer, pro or amateur, can hit any shot solidly or severely off-center. Also – no golfer can “stabilize” the clubface during or after impact due to an off-center strike.

This article shows you which part of the clubface is best.

I love this video footage and from here on out it will be required viewing for all my long term and golf school students. Would love to hear your thoughts….

What causes a golfball to fly the way it does?

There is so much complex information out there regarding the Ball Flight Laws – a ten second Google search yields enough confusion to get my head spinning for a month.  The “old” or “new” ball flight laws, Dr. Wiren, TrackMan…..who or what should you believe?

Albert Einstein

In light of Dr. Einstein‘s insightful quote I am going to give this touchy topic my best shot and try to keep it as simple as possible.  Please don’t check out!  This is important information for any golfer to comprehend, so bear with me and you’ll gain a far better understanding of why your golf ball reacts the way it does.

There are only four factors that influence ball flight when clean (not necessarily solid) contact is made between a golfball and a clubface.

They are:

Club Speed

The faster the clubhead travels the further and higher the ball will travel – generally with more spin. Compare a chip (slow speed) with a pitching wedge vs. a full swing (faster speed) with a pitching wedge…simple enough.

Clubface Orientation

Orientation is a fancy term that refers to where the clubface is angled.  Keep in mind that the face angles both left or right or up or down – left or right being an open or closed face and the up/down variable (although hopefully never down) referring to the loft imparted at impact (dynamic loft).  The face angle largely determines where the ball launches – left or right of the target and at what angle relative to the ground.  A good general point to remember is clubface (for the most part) = launch.

Clubhead Direction

Once again the direction the clubhead travels relative to the target line at impact – left or right (clubpath) and up or down (attack angle) – plays a role in determining ball flight.  A lesser role than the clubface, but a role nonetheless.  A good general point to remember is clubpath (for the most part) = curve.

Centerdness of Contact

This is a big one and something the vast majority of teachers and golfers tend to underestimate.  Most golfers strike the ball on the sweet spot far less frequently than they think .  I often see golfers that swing for a draw, yet strike for a fade – in other words they have a clubpath that is in to out, yet hit the ball slightly out the heel which leads to a fade.  An off center point of contact on the face leads to gear effect, which overrides or reduces the effect the face orientation and clubhead direction have on ball flight.  This factor plays a bigger role than most realize – watch out for it.  And the best way to do that – a  spray of Dr. Scholl’s foot powder.

Impact Point

Read an earlier article on centerdness of contact and a great article on the TrackMan blog illustrating the importance of center contact.

Here are a few simple factors to understand and remember:

• The ball launches primarily in the direction of the face – varying degrees of up and either left or right.
• Given a centered hit, clubpath leads to curve.  With the curve being away from the clubpath.
• Hitting down does not increase spin, and conversely, hitting up does not necessarily reduce spin.
• Heel hits encourage fades or reduce hooks and toe hits encourage draws or reduce slices.
• The more you hit down on the ball, the more you will swing in to out and the more you hit up on the ball the more you will swing out to in.

Now that you’re finished reading shoot back up to the top and read again.  This is vital information to assist with your understanding of of how your golf club “communicates” to your golf ball.

If you’d like to try out your new understanding of the Ball Flight Laws in southwest Florida check out this Fort Myers Golf Guide for a great course to play.

Thanks for reading and feel free to fire away with any questions you may have…..

Flighscope vs TrackMan

My good friends Tim and Simon Cooke from GolfPrep on Hilton Head Island recently brought their new Flightscope X2 out to Berkeley Hall. Our objective was to learn more about the numbers that TrackMan and Flightscope are putting out and we wanted to get a sense of how well one machine performed relative to the other.

I have pondered the best way in which to convey my findings and have finally committed to just simply jotting down my thoughts. My intent is certainly not to create controversy or confrontation – these are simply my own honest impressions from the day. Please also keep in mind that I am a TrackMan owner and supporter and no matter how I attempt to remove my bias I doubt whether I am able to remove all of it…

• Prior to the test I had been having trouble with my TM unit giving unusual spin numbers every 30-40 shots, something it had never done before. As a result I had contacted TM support and was informed that I more than likely had a bad USB cable. I was also informed that the classic indicator of a bad cable would be a “double” or “half” spin. Sure enough during the test TM gave out three spin numbers from the 60 shots we hit that were right around double what the FS reported. I have since replaced the cable and have yet to see a spin rate that seems odd.
• As you peruse the following thoughts keep in mind that good players , which all three of the test subjects were,  are very good at controlling the direction the clubhead travels (angle of attack and club path) from shot to shot. The direction may not be ideal, but better players are consistent with clubhead direction. That means that dramatic changes in either of those categories, along with sizable changes from shot to shot in club speed, were going to draw my attention and raise a red flag.
• Since running the tests I have spoken to many “in the biz” people about radar interference. It was mentioned that the machines, when set up side by side as we had them, will occasionally give corrupted data due to the influence of the outside radar. I have not run enough tests to ascertain if this is or is not the case, but during the testing the FS seemed to give a few numbers that were incorrect and this could be due to the TM being directly alongside the unit. The TM did not do anything different to what it normally does as it seemed to be unaffected by the additional radar.
• If a shot off turf has a decent size divot TM will only provide ball data and no club data, whereas FS reported both ball and club data for just about every shot hit off the ground. On the occasions that FS reported club data and TM did not the numbers did not look correct – meaning the attack angle and/or club path seemed to be too far from what the subject would normally generate. We hit numerous 50 yard pitch shots and TM did not offer any club data while FS reported for most of these shots. The problem was that the club path was said to be almost 15 degrees from in to out along with a spin rate of 14,000 rpm – just not happening! I actually preferred that TM did not provide club data as I would rather have no information than have to explain away improper information. That being said I would love a radar that provided correct club data on all shots.
• With both units unplugged and PC’s powered down the TM (2:05) was aligned and ready to roll in about half the time of the FS (4:16). I was told that with an iPad the FS can be aligned and operational in far less time.
• We noticed that both machines reported different Swing Plane numbers when they were moved (flipped positions) relative to the same golfer. I have tested this before and the changes in data are due to the hardware in the TM II. Each machine appeared to provide better data when the golfer is hitting shots aligned with the center of the unit – something that was not possible when running two machines.
• We tested the ability of each unit to report gear effect, by logging the point of contact on certain drives and then comparing each units Face to Path and Spin Axis numbers. The TM reported gear effect as I would have anticipated and most of the time FS reported along similar lines. However the first shot we examined, a big heel hit, was actually reported by FS as being a slight toe side hit. TM reported a Face to Path of -9.3 and a Spin Axis of -5.4 while FS reported a Face to Path of -2.2 and a Spin Axis of -11.0
• I was amazed at how closely aligned the Spin Rate numbers were for each machine. Unless there were dramatic differences the spin rates were almost always within 100 rpm’s.
• There seemed to be quite a few instances during the testing where the attack angles were not even in the same ball park. I had nothing to help me determine which machine was correct, other than the aforementioned fact that better players tend to be very consistent, and all too often it was FS reporting wide ranges of variation from the player.

Keep in mind that my intent is merely to report what I observed and not to offend anybody or any entity.  I could tell that Tim and Simon were a little concerned with the results and they went home and performed additional tests. I am happy to report that the FS performed much better without the influence of additional radar and when shots are hit from the center of the unit. Tim’s follow up comment to me was:

I believe that side by side testing, although seeming to be a good idea, does not work.  Clearly there was some radar interference at work as the inconsistent numbers were not reproduced in stand alone tests.  Maybe the only way you can really compare the units is with extreme high speed cameras with the units working independently of one another.

I would have to agree with Tim’s sentiments and I have started to make plans to have each unit test the same golfer on the same day, but without the potential interference of outside radar.

You know I’ll report back on that one….

Steve Stricker

For years golfers have asked me how to hit low, spinning wedge shots and I’ve never been able to give them a confident response.  After the research I’ve put in over the past few weeks I can give them a certain answer – and perhaps even explain a few other interesting shots we encounter on the course.

In polling better golfers regarding what really good pitch shots look like, the response has almost unanimously been that they tend to be lower with more spin.  Edoardo Molinari, the European Ryder Cup golfer and former US Amateur champion was kind enough to help with the research for this article and he stated,

I’ve watched Tiger, Mickelson and Ernie hit hundreds of 50 yds shots, I’ve played with them and they all seem to deloft the club without taking much divot.

Which I agree with by the way – the best pitchers always seem to have a knack for nipping the ball off the turf without much divot and then firing the ball in there low and spinning.  The problem with this shot has always been how to hit it low, yet make it spin at the same time….

If you hit down on the ball you’ll be able to hit it lower, but hitting down more only lowers height and does not, as is commonly believed, make the ball spin more.  So that option is out.  If we take a more lofted club to spin it more then we may get a little extra spin (although that’s not a given), but now the shot will fly too high.

Here is where we need to get a little technical and talk about the forces and angles the club is imparting on the ball at impact.  TrackMan uses a term spin loft and it refers to the vertical difference between where the clubhead is travelling at impact (attack angle) and where the clubface is angled at impact (dynamic loft). My research shows that good wedge players have a narrower spin loft (dynamic loft minus attack angle). Let’s get a better understanding of these important factors:

Attack Angle (angle that indicates if the clubhead is travelling up or down, relative to the ground at impact)

In studying hundreds of 50 yard pitch shots on TrackMan over the last few weeks I have found that good pitchers tend to not take very large divots.  Yes, they always contact the ground, but the club ‘bruises’ the turf more so than cuts it.  This would indicate that the attack angle is shallow – it is down but not hugely so.  Now hold on for the following part, because this should not change the way you think about a club striking a ball: my research shows that the attack angle should be shallow enough so that the sole of the club (bounce) actually makes contact with the grass/ground before the ball.  And this occurs even on ideal hits…..

Dynamic Loft (the angle of the face/loft at impact)

Really good pitchers have the ability to deloft the club without hitting down more.  This means that the hands are in front of the ball at impact and the loft on the clubface is often more than 10 degrees less than the static loft. For example in much of the testing a 54 degree wedge would apply 41-44 degrees of dynamic loft to the ball.

Spin Loft (dynamic loft – attack angle)

This is a very important factor as it contributes to, but does not solely determine, how much spin and loft each shot will have.  If you hit a pitch shot with 42 degrees of dynamic loft and you have an attack angle of -3 degrees (the minus indicates a downward hit) your spin loft would be 45 degrees.  Common wisdom indicates that a broader spin loft (eg. 50 degrees) would create more spin and height, yet my research indicates that when it comes to chipping and pitching a slightly narrower spin loft (without much downward hit), coupled with clean contact between ball and face increases the golfers ability to hit low spinning wedges. An easy way to narrow your spin loft with pitch shots is to take a lesser lofted club.  My students have had tremendous results by using the lob wedge less and getting a little more accustomed to hitting a variety of  shots with the pitching wedge.

Friction Launch (the amount of grip between face and ball and how that effects launch conditions)

This type of strike on the ball leads to a scenario where the friction between the face and the ball is far higher than normal.  This increased friction leads to a lower launch and trajectory with a substantially higher spin rate.  This grip between the ball and face is what I call ‘friction launch’ and just like the term spin loft it addresses the friction and launch of any shot.

As golfers we’ve all hit that pitch shot that comes off the face very low and the moment you strike the ball you know it’s going to grab as soon as it hits the green. Your playing partners are yelling bite and as soon as the ball gets near the hole it comes to a screeching halt!  You have just experienced high friction launch.

Please check back in a few days for the follow up post The Science Behind Superb Wedges: Part II where I’ll discuss friction launch in detail and show the results of much of the research I’ve done.

To get a much better look at the data be sure to read Part II HERE

The TrackMan Screen

With so many questions after my two most recent posts I thought it would be enlightening to show you what we see when using TrackMan.  This particular driver was hit by Rick Hartmann – my boss and the Head Professional at Atlantic Golf Club.  Rick played on the European Tour for ten years and is a fantastic driver of the ball.  This is a good drive, but not anything unusual for Rick (it was into a very slight headwind).  These particular numbers are very close to optimal and should be something we should all be working towards regardless of what our club speed might be.  Of course that is if you happen to like high, long draws…

If you want to be efficient with your driver here is an explanation of what I look for:

• The Attack Angle (0.9 degrees up) is positive – a good sign for maximum efficiency as an upward hit is better than a downward hit (if you want to hit it as far as possible).
• Notice how (because the Swing Plane is very close to 45 degrees) that the Attack Angle + Club Path = Swing Direction.  Not unusual really, this is a helpful indicator in understanding what factors effect  the club path.
• The Spin Loft is close to 11 degrees – a solid number that seems to work for most golfers.  Spin Loft = Dynamic Loft - Attack Angle. Think of spin loft as a measure of ‘ball compression‘.
• In order to hit good draws the face must be open relative to the target at impact and here you see how the Face Angle is open (2.7 degrees) with the Club Path being further to the right (3.5 degrees). Couple that with a centered hit and you’ve got lovely push draws.
• A centered hit is vital and that’s why I like to keep Face to Path alongside Spin Axis.  If the hit is in the heel the face angle would be closed ( a negative number) and the spin axis would be tilted to the right (positive) and vice versa for a toe hit.  Here you see how with the face slightly closed to the path, you should get a baby draw, and that’s exactly what we got – all from a centered hit.
• Club Speed and Ball Speed are fairly self explanatory, but if you divide the club speed into the ball speed you will get 1.48 which equals the Smash Factor.  Smash factor is merely a measure of how efficiently you translated club speed into ball speed and is not purely a measure of how well you struck the ball. The maximum smash factor for a driver 1.53. (I have seen 1.54 twice!)
• The Height of the shot, which is measured from flat and not necessarily the ground, is right where I’d like to see it for this particular club speed.  PGATour average swing speed is 112mph and they hit all their clubs 90 feet in the air. At around 108mph I think 88 feet high works very nicely.
• Launch Angle and Launch Direction are largely influenced by the club face and I like both here.  I look for draws to launch to the right of the target (positive) and the launch angle to be somewhere between 10 and 16 degrees depending on the players club speed.
• The Spin Rate for this shot is a touch high, but I would attribute that to a shaft that is softer than what the golfer should be using.  I’d like to see the spin rate at this club speed be somewhere between 2000 and 2200.
• Side Total indicates that this ball is straight down the center and finished less than 4 feet right of the intended target line – just another ho-hum 280 yard drive down the pipe.

Somewhat advanced I know, but after the response to my last few posts I know there are thousands of golfers out there who are looking for a better understanding of what really happens at impact and what they should be working towards for maximum efficiency.  If you can duplicate these numbers you won’t need me for much…at least not for the driver.