Monday, July 5, 2010

Why We Got The Old Ball Flight Laws Wrong

A blog follower e-mailed me, essentially asking the question 'why do you think they got the old ball flight laws wrong?' You can see a demonstration of the old ball flight laws in the diagram above.

I think that is an excellent question. For starters though, I would suggest checking out Jeff Mann's excellent review paper on the ball flight laws that can be found HERE.

If we remember, the old ball flight laws state that the initial direction is due to where the clubhead path is going and the curvature of the ball flight is due to where the face is in relation to the path. However, many pros were even more incorrect by stating that the curvature was dependent upon where the face was pointing in relation to the target at impact.

In fact, there are many pros that still live by these old, incorrect ball flight laws.

Eventually Homer Kelley came along and said that the face was responsible for the initial direction, but didn't get much into the path and its effect. Then physics professor Dr. Theodore Jorgenson wrote 'The Physics of Golf' and came up with what he called the 'D-Plane' which explains that the face is responsible for about 85% of the initial direction (the other 15% being the path) and that the ball curves depending on where the path is going in relation to the face.

NOW, it appears that considering certain factors like clubhead speed the face is about 70-87% responsible for the intial direction and path in relation to the face is responsible for the curvature (presuming the ball is in good condition, no wind and the ball is struck on the sweetspot).

One question that was asked was did the old equipment have any influence on getting the ball flight laws wrong?

I say NO.

Why? Because it appears that the faster the clubhead speed and ball speed and the higher the smash factor, the more responsible the face is for the initial direction. Since today we are using titanium instead of metal or persimmon and the old ball was a very soft, low ball speed ball...I think that the initial direction was more dependent on the face back then than it is now. Still though, I would say that most golfers TODAY wind up having their initial ball flight being about 85% towards the face.

I think a big reason for the incorrect ball flight laws is that the instruction industry has changed vastly over the years. Back even in the 80's, there were not a lot of swing gurus who made a living just doing golf instruction. I think of Ted Fort who teaches out of Marietta Golf Center driving range just outside of Atlanta. He makes his living with the occupation of 'Golf Instructor.' Back in the day, those guys practically did not exist. You had some guys that worked at resorts like Jim Flick or Bob Toski, but most of the rest of them were working in the pro shop and using instruction as a way to supplement their income.

Eventually Jimmy Ballard came along and started to show that Tour players could have some success and improvement going to one instructor and I think David Leadbetter saw that and saw the opportunity to expand that living. While I'm not a fan of Leadbetter's instruction, he did show the ability to market himself and opened up a whole industry of jobs for people. And he did it way before Butch Harmon and Hank Haney. In fact, if not for Leadbetter, we probably wouldn't see a Harmon or a Haney today or a Manzella or a Fort or a David Orr, etc.

The problem is that most of the instructors before the Leadbetter era were just golf pros. It was not until the boom of instruction that we saw more experts from different walks of life come in and figure these things out. It's like anything in life, once the world sees that there is money to be made, they flock to it like bees flock to honey.

This eventually led to the Jorgenson's, Dr. Aaron Zick's (physics professor at Stanford) and Dr. Robert Grober (physics prof. at Yale) to get into the game. Going from a Bob Toski to a Dr. Jorgenson explaining the physics of golf is a gigantic leap in expertise...probably like going from a Dr. Jorgenson to a Bob Toski having to hit a golf ball (for those who don't know, Toski was a phenomenal golfer in his playing days).

So, the money that was being made in instruction caused more experts in physics to come over into the game and they were a better authority on figuring out how the ball flies rather than a pro golfer who uses the pedestrian research of hitting a ball and observing it.

The other big part has to do with the diagram above. If you look at the 'PULL' and the 'PUSH' parts of the diagram, they got those right....but for all of the wrong reasons.

The D-Plane (correct ball flight laws) state that a straight push is caused when the face is open and the path matches the face. The face causes the ball to go initially to the right and the path, since it matches the face, will cause the ball to go straight.

Thus, I think a big reason why they got the ball flight laws wrong was that they were technically correct on the straight shot at the target, the straight push and the straight pull. You get those technically correct, but for all of the wrong leads to inaccurate conclusions.

The other reason why I think they got them wrong is that initial direction can often be tough to tell.

For instance, when I was on Trackman last Saturday I had a few shots where my path would be about -1* (left), but my face would get closed by about -4.5* (I was sweating profusely in the Florida heat and the grips started to slip until I changed gloves).

Because the face was closed, the ball would go low. Because it went low, seeing the initial direction was hard to really distinguish. Furthermore, it started to curve very quickly in it's ball flight. So again, the initial direction was hard to distinguish.

To me, it looked like the ball started at the target and hooked low and left. But on Trackman it showed how the ball actually started out low and LEFT and then just hooked even more. And like I said, it showed on Trackman that the path was pretty much square to the target.

I thought the ball went straight at the target initially and then hooked left. According to the ball flight laws, that would say that the path was square and the face was closed. Which is what actually happened with the CLUB at impact. But what actually happened to the BALL (which started left and hooked even more) is a different story.

The problem I see now is that many instructors and golfers have the ball flight laws memorized, but do not actually understand them so they can use them for their advantage.

We've seen it with the Haney Project where instructors seem to worry about the path with every golfer first and foremost. The problem with this is that if you take a golfer who has a wide open face at impact (we'll say +5*) and a path that is well over the top (we'll say -7*) and then you square up the path so it's reading 0.0*....the golfer still has a +5* open face. And from what we know about the ball flight laws, he's still going to hit a push slice. In fact the old swing may have been better becasue that 15% responsibility for initial direction caused by the path can at least start the ball somewhat to the left.

Thus my final point being, don't just memorize the ball flight laws...truly UNDERSTAND them so you can use them to your advantage.



Philippe Bonfanti said...

I used to believe that correcting the face was the first stage when working with a slicer. Through practice, I now know that when you change a slicer's path and make it significantly in/out this usually has an effect on their face angle also. A player who slices usually has an open clubface because of their out/in path and the realisation that a closed clubface to their path with their swing equals left and going left. Path and face are closely linked. In your example of making the golfer go from -7 to 0, that simply isn't enough of a correction, the coach needs to be able to make his student swing from in/out if the student wants to draw the ball., this is where many coaches may fail.

Anonymous said...


I think you miss the point that the biggest reason for face/path % responsibility is simply the angle of the face/path discrepancy. Small face/path angle you are closer to 85%. Large face/path angle and you move to the 65% face responsibility.

Rob McGinnis said...


I am really working on understanding this and I am not sure I yet understand your example at the end of the post.

You mention a +5 clubface and a square path leading to a push/slice

But if the face is +5 and the path is square to the target (0.0) wouldn't you get a push/draw as the square path is closed in relationship to the face?

and if I am misunderstanding what the "square" reading relates too (target line or face) It doesn't really help me.

If path is square to face and face is +5, wouldn't I get a straight push?

I've read Nicklaus and Trevino played the push fade. Do you have a feel for what numbers they might have had for driving that flight on the professional level?


Anonymous said...

In that diagram, if the club face angle is relative to the club path and not the target line, I don't see why it's wrong. Seems spot on to me.

The slice description: "The club face angle aims right of in to in club path angle", even seems to indicate that.

Aiming right of an in to in club path, would be close to square to target line.

Rich H. said...

Wow, lots of responses. It would be easier if the names were not anonymous.

Anyway, from what we've been told that the face is 70%-87% responsible. Sure, they could be wrong on that equation in the end. Trackman surely justifies it and I'll just take the MIT guys and the other physicists word for *now*. Although I always have the right to change my mind.

As far as my example of +5 face angle and 0* path. The is actually out-to-in with relation to the face...not inside-to-out. The FACE is the 'base point.'

The diagram is very wrong. The push hook and pull slice is wayyy off. Push hook has the face going out to the right of the target and the path going more to the right of where the face is pointing.

Rich H. said...

Phillip - I do agree that a better path can help square up the face. But I think if you can get the face square up first, then the transition to working on the path becomes easier for most students.

Rob McGinnis said...


Almost got this I think.

But let me see if I can clarufy my thought-- If the path is square to the face angle and face angle is +5, why arent we getting a straight push and not a slice?


Rob McGinnis said...

I think I figured it out. 0.0 is "left" (for a right hander) of the +5 face angle. Any path to the left will result in a slice/fade. For it to be the push draw I was looking for the path will need to get "right" of that +5 face.

this helps clarify something I was struggling with.

Rich H. said...

Now you got it.

Good job.

You should now be able to understand what happens on each shot.

Eventually you'll learn how attack angle effects things.

Anonymous said...


We're not connecting....

The face/path contribution percent VARIES mainly due to the face/path angle.

It's NOT like one camp says 85%, and another camp says 75%, so let's go test on a Trackman to see who's correct.

It's like what's the spin RPM off an 8-iron? It VARIES due to the face/path angle.

So does the face/path initial direction contribution percentage.

From all the message boards, I get the feeling that a lot of folks think it's one fixed number, and since there seems to be some "arguement" or disagreement over what that number is, some folks may interpret that the whole D-plane thing is foo-foo because of this "minor" issue. Just wanted to try to clear my point up.

I appreciate what you bring to the table regarding swing theory, etc.

Anonymous said...

Can someone give me a new piece of instruction and tell a simple way how to fade and draw the ball, if Justin's advice was based on incorrect theory. Although it works for him as it did work for Jack N. and millions of their followers as well. :-p

Rich H. said...

Jack wasn't hitting many draws or hooks out there. But, if it works for them..fine. HOWEVER, what is happening at IMPACT (y'know..that thing that everybody says that is all that matters) is a completely different story from what they are saying. If their face and path did what they were saying, they would 'over-fade' or 'over-draw' the ball because the face angle is going at the target.

And I'll say this again. D-Plane is really at its best when you have a string of errant shots and notice a trend (say your bad shot is a snap hook). Everybody wants to use it for working the ball, but using it for your normal swing is where it's at its most useful.

And if you want to hit a draw and do it with ease...move the ball position slightly back and the handle slightly forward and take your normal swing. You'll increase your attack angle and move your path slightly out to the right and the hand forward will also get the face slightly to the right as well.


james said...

Interesting.. I never thought that the difference between the effect of path vs. face would be so drastic. Like you said, I thought path determines starting point, face determines end result. To hit draws and fades, I just control my follow through. Any time I'm off line, I blame my path, but I guess the effect of the path is really negligible compared to my timing of the clubface at impact.

For those trying to get a consistent trajectory, I think just gripping the club while its off the ground has a big effect. A lot of people set the club down so it can wiggle around a bit (especially with the driver), then set their hands. Experiment with holding the right hand up, taking the left hand grip with the club square, then adding the right