Definitive Club Face Angle & Swing Path on Ball Flight Thread

[iacas]

The Two Schools of Thought
The PGA has long held the belief that the swing path (SP) is the primary determinant of the starting line (SL) of the ball, and the clubface angle (CFA) roughly determines where the ball will finish.

New information suggests that the CFA is the primary determinant of the SL.

The purpose of this thread is to debate - with civility - these two possibilities.

The Facts
Two facts are not up for debate here.

The first is that nothing is 100%. Regardless of which school of thought you support, neither the CFA nor the SP are a 100% determinant. Furthermore, varying conditions (swing speed, quality of contact, loft, relative differences between CFA and SP) introduce further ambiguity so that even something that's, for example, a 70% determinant isn't 70% under every set of circumstances.

The second fact is that the ball spins based on the CFA and the SP. If the CFA is closed relative to the SP, the ball has draw sidespin. If it's open, fade sidespin. If CFA is square to SP, the ball has relatively little to no sidespin and will not curve laterally. This assumes the ball is struck on the center of the clubface, and leads to a rule for this discussion: mis-hit shots and the gear effect are not up for discussion here.

Why This Matters
Those looking to diagnose swing problems or to fix their swings on the range or golf course need an understanding of how their club is meeting the ball. It's commonly said that "the ball doesn't lie," so understanding what the ball is telling you is important to not only making an on-course correction, but also to improving your ball striking and your golf swing in the long term.

Abbreviations
CFA - clubface angle (relative to what you should specify)
SL - starting line of the ball after it's hit and until spin begins to take over.
SP - swing path of the club (relative to the target line)
TL - target line (straight line from the ball to the target)

Some Ground Rules:
1) Use reputation (+ or -) appropriately. "I agree" or "I disagree" doesn't qualify.
2) Please limit or suspend the use of hand-drawn graphics and no attachments.
3) Please cite sources where possible (and if not already cited).
4) Please don't say "this is how it is" and little else. That doesn't help anyone.

[iacas]

When I first took up the game, I thought "the ball can't possibly come off at anything but a right angle to the clubface."

That'd work for an elastic collision, of course, but that's not what golf (or even pool balls) are about. The ball is compressed against the golf club and is "carried" to some degree or another by the clubface along the SP.

The more compression, the more carrying. The most compression happens with higher swing speeds (duh) and lower loft (more lateral force from the swing speed transferred into compression rather than rolling). Also, a softer ball will be more affected, too: we all know range balls tend to roll up the face of a sand wedge more than a Pro V1.

This led me to adopt a sort of "split" understanding of ball flight and the primary determinant. For a driver, I took the primary determinant to be SP; for a pitching wedge (or a putter!), the CFA. Everything else existed in a four-axis (clubhead speed, quality of contact, CFA, SP) "grey area" in between these two extremes.

This understanding meshed not only with the PGA manual, which I knew was written quite some time ago, but also with things said by top players (Tiger Woods, Annika Sorenstam, etc.) and top teachers (Butch, Hank, Leadbetter, etc.). It meshed with what club designers and fitters told me. It meshed with the data I saw from various driver fitting launch monitors and what the people who used them told me.

Think about the number of times you've heard this, for example: "To curve the ball, I line my feet up where I want the ball to start, point the clubface at the target, and swing along my foot line." That's pure PGA method (with SP determining SL).

I've never really committed to putting down any percentages - nor have I ever asked anyone to give any - because I know it's a tough thing to determine. Again, it's a four-axis problem (and that's just in my mind - I'm sure "quality of contact" in my system is probably four or five different things in and of itself), so nobody could say anything like "with the driver, the SP is about 60% of the SL for a guy swinging 110 MPH and hitting the center of the clubface." Even in a statement like that, the loft, CFA, SP, the type of ball used, the temperature... all of it could affect the SL.

With this understanding - and again, for incredibly low-lofted clubs swung at higher speeds and with good contact (i.e. no rough, which would limit quality of contact, discouraging compression and encouraging sliding) - I came to tweak my swing to be a bit more reliable and consistent. No earth-shattering improvements, but enough that I felt that the understanding helped me.

Anyway, now we have the Trackman guy's article which says that the SL is virtually never determined by the SP and is vastly weighted towards the CFA. Frankly, I wish we had more - all I've seen is a short interview with the guy spread across two PDFs. Is there more here? I'd like to read it if so. At any rate, from what I've gathered, his understanding doesn't reverse what I'd previously held to believe, but it shifts the balance point quite a bit.

Anyway, now it's your turn...

[RC]

Erik has stated quite well that this is at least a four parameter (or axes) problem. But for those with a bit of mathematical inclination, as Erik has suggested, it is not a simple, linear four term relationship. It more like a 4x4 tensor, so that each of the terms has coupling factors between them. This is what he meant when he said you could not say one term was 60 percent of the effect. If CFA, SL, clubhead speed (CS), and impact term (IT, or quality/duration/inelasticity, etc., of impact) are the items along the diagonal, there are at least 16 coupled numbers in the whole matrix. And that does not count that (IT) is likely to be a complex, multivariant additional tensor by itself. One could say with a lot of confidence that CS and IT are strongly coupled. Also, as has been noted, the club loft is buried in the (IT) matrix.

Any change in one of the diagonal terms will change the coupling values off the diagonal. I don't know how you could generalize much better than what has been said... namely that low speed putting strokes might be skewed one way and high speed long irons skewed another way. I am not knowledgeable enough to even suggest how you would state a definitive but succinct or short answer to the question. My inclination is to agree with the old standard (the PGA) explanation of what is going on. I have always said the golf swing is more complex than the quantum mechanical solution for the two body problem.

I don't know how long a high speed swing with a tour type ball stays in contact with a club, but I always thought another factor might come into play -- the rate at which the CFA is changing during contact -- and this could be utter bunk, just something I think I feel. I would like to know more about the trackman article.

[SpacklersEdge]

Erik has stated quite well that this is at least a four parameter (or axes) problem. But for those with a bit of mathematical inclination, as Erik has suggested, it is not a simple, linear four term relationship. It more like a 4x4 tensor, so that each of the terms has coupling factors between them. This is what he meant when he said you could not say one term was 60 percent of the effect. If CFA, SL, clubhead speed (CS), and impact term (IT, or quality/duration/inelasticity, etc., of impact) are the items along the diagonal, there are at least 16 coupled numbers in the whole matrix. And that does not count that (IT) is likely to be a complex, multivariant additional tensor by itself. One could say with a lot of confidence that CS and IT are strongly coupled. Also, as has been noted, the club loft is buried in the (IT) matrix.

Your last thought is an interesting one. The fact the the CFA DOES change during the time in which the ball is in contact with the clubface, could itself increase or decrease that time, which in theory could increase/decrease the effect of the CFA. I would also be interested in this article, is there a link?

[Chief Broom]

I've been told I have an outside-in swing path by a PGA pro (apprentice). I know that typically speaking my ball follows my intended target line and then curves to the right of that target line. This ball flight is fairly graceful and consistant. Meaning the ball follows a gradually increasing arc to the right. The swing thought that seems to help me the most is an aggressive following of the club head down the intended target line. In my mind this seems to promote me better closing the club face at impact, so that it isn't open. Whether or not this is the case I really can't say. My main problem is consistancy with this because I never know how dramatic that arc to the right will be: anywhere from 10yds (good) to 100 yds (bad). My better driving rounds happen when I find some consistancy with how far that fade will be and then aiming my drives accordingly. Various things I've tried to introduce more consistancy in my swing include changing my aligment at set up (something I pretty much always do with the driver - aim left), changing my grip strength, changing my back swing (taking it back to the inside or outside - even to the point of a Charles Barkley-esque swinging way outside and then looping back around), changing shoulder alignment, and probably a few other things as well. What happens is that occassionally I'll stumble on something that works and begin striping the ball down a predictable flight path. But no matter what the "fix" only lasts a week or so and suddenly I'll find that either the slice returns or some new and equally unpredictable flight path results (read: hook). Then I try to tone down the change to regain balance, yet I never regain that initial positive change. Eventually I find myself going back to my "natural" swing because it is more predictable off the tee. The last set of lessons I took were beneficial but ultimately did nothing to change the nature of my full swing (primarily the driver). In fact durring that course of lessons the instructor would add on swing thoughts to the point where he acknowledged that it was all too much to contemplate durring the golf swing. And that too brought me back to my "natural" swing. I do it without thinking and it does offer me some consistancy to rely upon. I honestly believe my problem is a combination of SP and CFA, and no doubt that's tricky to fix.

It does seem that with the amount of resources put into golf by equipment makers and all of the various orgainizations that cater to the sport the golf swing could be approached a bit more scientifically. I suppose much of that has all been done but ultimately it still comes down to each one of us executing the swing. It's funny but I'd swear I had an easier time hitting a baseball where I wanted in high school than I do a stationary golf ball, but that's a deceptive analogy. In baseball you have multiple chances to hit the ball and a good base runner can turn a poor hit into a base hit, but in golf you only have one chance. One strike, one ball and you're out.

[wedge player]

i feel that the swing path indicates starting line at a very high percentage,at least 90%.the way i think about it is,lets take a bedinner that has a major out to in swing path with an open face.the ball takes off left of target line due to swing path and has a huge curve to the right where the clubface was roughly pointed.no wind,decent contact the above always seem to be true.i will keep believing in the old belief as it has worked for me and i have based my swing on this.

[laxbballgolf]

Here are the Trackman articles. (Scroll down to the "Secret of the Straight Shot" articles in each one)

http://trackman.dk/getmedia/55e8af48...wsJan2009.aspx

http://trackman.dk/getmedia/2f6c5cdc...Jul2009_1.aspx

[laxbballgolf]

i feel that the swing path indicates starting line at a very high percentage,at least 90%.the way i think about it is,lets take a bedinner that has a major out to in swing path with an open face.the ball takes off left of target line due to swing path and has a huge curve to the right where the clubface was roughly pointed.no wind,decent contact the above always seem to be true.i will keep believing in the old belief as it has worked for me and i have based my swing on this.

The other possible scenario would be that the slicer points his CFA left of the target at impact, but his SP is so extremely out to in that it is still out to in relative to the left pointing CFA. Ball takes off left of target line and slices to the right.

This scenario would explain why really bad slicers still struggle to eliminate the slice even when they hold the CFA closed or use a game-improvement driver with a closed CFA. Closing the CFA reduces the severity of the problem, but it doesn't eliminate it, because it is a problem fundamentally with the slicer's SP rather than his CFA. I'm not convinced one way or the other, but what I described is the other side of the debate.

[bunkerputt]

Here are the Trackman articles. (Scroll down to the "Secret of the Straight Shot" articles in each one)

I read both parts of the article. Quite interesting. I can see how there is some debate going, particularly in light of Tuxen's comment that "All scientific golfers know this". I'd like to see some actual data and methodology rather than have to take some guys word for it just because he's a "scientist", thought I don't have any real reason for not believing him. Another really interesting piece of information... he seems to indicate that it's necessary to have a slightly out to in path for shorter clubs and in to out for longer clubs to get the ball started on the correct line. This reminded me of the picture in Hogan's book of the progressively open setup for clubs shorter than a 5-iron and the progressively closed setup for anything longer than a 5-iron. Combined with something I read that the hips tend to align to the feet and the path tends to follow the hips, it seems like Hogan might have been onto something.

[ninetwothree]

I think the easiest way short of studying trackman or reading through the moronic asskissing on Manzella's site is to think about your ball flight.

There is a target line, and swing path, and a clubface angle. If you can get the clubface angle to point in between the path and the target line, you'll have your desired curve that should not over curve and cross the targetline.
This really goes against the oldschool ideas that path gave us initial direction and face gave us curvature. As well as the idea that you hit the back of the golf ball. if you are looking to curve it with a draw, it requires an open clubface hitting the inside quadrant of the ball.

Great thread. There should be more REAL info throughout this site.

[Phil McGleno]

As well as the idea that you hit the back of the golf ball.

You still hit the back of the darn ball. It's not like you hit it 45 degrees off the inside back quadrant - that'd be a clubface 45 degrees open, and that's ridiculous. You hit the back of the ball within an area of about +/- 5° on virtually every normal shot. Period.

If your clubface is square to the target line you can come over the top or from the inside by 45° and you're still gonna hit the back of the golf ball. This is probably off topic though. It's only really about clubface angle with a tiny bit of path thrown in and has nothing to do with ball flight. Not in the sense that this thread's intended to discuss.

[Ringer]

2 years later and the debate still hasn't been put to rest.

He is right that there are more factors than just path and face. In fact, center of gravity should be the #1 cause for path IMO, but it's just easier to point to the face alignment. This is why off center hits (toed and heeled) have different results. The club has a center of gravity which is called the sweet spot.

When we strike the ball in the center of the clubs gravity then the clubface will not deflect. When we strike the ball on the toe of the club, then the club deflects so that the clubface opens slightly. When we strike the ball on the heel of the club then the club deflects so that the clubface closes slightly.

Now, it's easy to say "The clubface was closed and so the ball will go left." But the actual reason for the ball going left could easily be said that the clubs center of gravity struck the outside half of the golf ball. The opposite would be said for a ball struck on the inner half and causing the ball to go right. This is, of course, for a right handed player.

As for spin, the amount of compression will determin how FAST the ball spins as well as the waywardness of the clubs center of gravity from the ball's center of gravity.

Afterall, if you put a basketball on the ground, then try to kick the outside half of it there will be some side spin. Obviously there is no "clubface" on your foot. So instead it's more accurate to say the center of gravity of your foot struck the outside half of the ball causing it to spin to the left as well as travel to the left.


This may seem all so minor and inconsiquential... but in fact I find it causes many people to make incorrect diagnosis and changes in their golf swing.


For many who slice, they have progressively started to aim more and more to the left. They think they are compensating for what they know to be a slice that will come. However, they don't change the clubface. Instead they still aim it in the direction of the target. The result is a BIGGER slice than they anticipated and it still ends up in danger.

Instead the correct action would be to aim more to the RIGHT.

Ever heard of the idea to aim AT the danger? Well that's why the advice is sometimes right.

[Zeph]

That does seem like the most reasonable explanation so far. That the clubface is the primary determant of which angle the ball is launched at. The swingplane is used to get the ball spinning in the preferred direction, away from trouble. A lot of variables will determine the exact angles, including loft of the club, but you can create spin with any club, of course.

Like Iacas said, the more loft, the more the ball will start on the angle of the clubface. That doesn't mean you can't curve with short irons, but it will curve less. It is also a matter of how it comes down on those shots. You may want the ball to roll in a certain direction, so you curve it from either side toward where you want it to come down. I remember Tiger saying he loves to shape his shots into the green with the shorter irons. You often see the ball rolling sideways after it land on the green, which is a result of a shaped shot, though it will not shape as much as a longer iron, you'll still impart a lot of spin. On a clean square stroke with a straight ball flight, you'll create backspin which can cause it to spin back. If you come across the ball and create sidespin, you can spin it sideways instead.

By using high tech equipment I assume you could see this quite easily by doing some testing. Have a machine which monitor clubface angle, swing path, ball spin and launch angle.

[Divot Tool]

Your last thought is an interesting one. The fact the the CFA DOES change during the time in which the ball is in contact with the clubface, could itself increase or decrease that time, which in theory could increase/decrease the effect of the CFA. I would also be interested in this article, is there a link?

Very interesting point. Take a closer look. . . Here's an older clip of Ernie Els captured with Swing Vision @ 7000 frames/second. Given the duration of time in which the ball stays on the clubface, the question remains is the CFA opening/closing in relation to the starting line even a variable in this question? Is it negligible? Just picking your brains. . . If the science articulated in the 2 pdfs which Iacas provided is sound-of which I am not arguing against/for-how does one break down the the ball flight? A good buddy of mine will often hit a big in-to-out push hook (block/hook). He gets the club inside way too early on the backswing and is stuck coming down, but flips his hands to save the shot. I'd love to hear an explanation . . . or simply see the equation which summarizes ball flight.

[iacas]

Given the duration of time in which the ball stays on the clubface, the question remains is the CFA opening/closing in relation to the starting line even a variable in this question? Is it negligible?

Despite what Johnny Miller says, I think it's negligible. There's absolutely no way in which you can control how the club rotates in that amount of time.

The more you compress the ball, the more time you have, but it's still always very short. But pool balls don't compress much either, so the people who say the club's path matters for starting direction are simply keying on the fact that the ball "sticks" to the clubface and is "carried" in that direction a little, influencing the starting line. And even those who say CFA is the primary determinant can't argue with that. The closest they can get is to say swing path only matters, say, 15% or so.

If the science articulated in the 2 pdfs which Iacas provided is sound-of which I am not arguing against/for-how does one break down the the ball flight?

I started this thread partly because those two PDFs are severely lacking in scientific evidence. First off, there's no way it's always 85% or whatever number that article stated, and second, how did they determine 85%? They never really say.

I've also deleted a few pictures of Manzella's D-Plane in this discussion. If you want to include it, fine, but include some discussion as well. Posting just a picture does nothing to add to the conversation.

A good buddy of mine will often hit a big in-to-out push hook (block/hook). He gets the club inside way too early on the backswing and is stuck coming down, but flips his hands to save the shot. I'd love to hear an explanation . . . or simply see the equation which summarizes ball flight.

His blocks come from a clubface square to his inside-to-out swing path. His hooks come when his clubface is slightly closed relative to that. That part's easy and everyone will agree.

If his ball starts 10 degrees right and draws 15 degrees, then the question is which if these is more correct: a) his clubface was 10 degrees right and his swing path 25 degrees inside-to-out (15 relative to the clubface). b) his clubface was pointing five degrees left of the target and his swing path was 10 degrees inside-to-out (15 relative to the clubface).

[trumps4]

I don't have much to add in the way of research but in my experience, it seems that when I hit a slice, the ball starts on line and works to the right. It may be that it just seems that way but I never experience a "pull-slice" with the ball starting left and then working across the target line. When I look at the clubface, it almost always indicates that I hit the ball with the toe of the club.
I will add that I think I am making an over-the-top move when this happens. I say this because I get the sensation of my finish being low and around my body rather than out toward the target (shaking hands with the target is the way I think of it. the slice swing would be more like slapping at the target).
I guess what I am getting at is that it all depends on the quality of the strike. I think that if you hit the ball squarely in the middle of the clubface with an out to in path and a CFA square to the target line (open to the swing path), the ball should start mostly left (with the swing path) of the line and work to the right (clubface relative to swing path) during flight. However, if you DON'T make perfect-center contact, all bets are off. In my case, a out to in path leads to toe-contact which I think is why my slice starts on line and slices.

[MiniMoe]

Does thinking about all of this really help anyone achieve better control of the ball? The golf swing is a very complex sequence of events for the purpose of flinging a golf ball toward an intended target. However, the simpler you make it, the better you will do. It is very much a reactionary sport. You look at a target, then you hit it there. if you are thinking about how to do it, it's almost impossible to do it with any consistancy.

Let me try to break all that complicated talk into a simple formula..... The ball goes where the hands go. Do you think that if you flip the hands at impact the ball will go right? If it does, you have issues with the grip. heheh

Keep the game simple. It's more fun that way.

[iacas]

Does thinking about all of this really help anyone achieve better control of the ball?

Yup. Now let's stick to the topic, please. If you want to talk about something else, please start a different thread.