New Ball Flight Laws (since 2009) 针对初学者的很好理论指导<资深球友 needs Reloaded for Revolutions!>


Ball Flight Laws

The Secret of the `Straight Shot´ I
The horizontal launch angle is determined by only two parameters,the club path and the face angle. As a rule of thumb, the horizontallaunch angle is 15% determined by the club path and 85%determined by the face angle.
-by Trackman (


For decades, golf instructors have been teaching the ball flight laws incorrectly. Many blame the PGA Teaching Manual, and have said that it has contained some incorrect or incomplete information pertaining to a golf ball's flight. Many pros - from Butch Harmon to Nick Faldo - sum up the ball flight laws as follows: "The golf ball starts on the direction of the swing path and curves back to where the clubface was aimed at impact."

Put another way, many instructors and famous golfers have stated that the swing path is the primary, over-riding determinant in the golf ball's initial starting direction. This information is wrong. This information is slowly coming to be understood as wrong in recent years, yet many golfers - famous or otherwise - and instructors - famous or otherwise - still believe it.

Mike Bennett and Andy Plummer discuss the ball flight laws on Charlie Rose on December 23, 2009.

The (Non-)Debate
The debate over the nature of a golf ball's initial direction of flight is, unfortunately for generations of golfers, a relatively recent one in golf. Only within the past few years have instruments which can measure the moment of impact in precise detail been developed, and those instruments have just recently started to see data that contradicts the decades-old (incorrect) information about what governs a golf ball's launch and flight.

When I first started playing golf, I never considered the possibility that the ball could come off the clubface in any direction other than nearly perpendicular. It seemed like common sense. Though I realized a golf ball-golf club collision was not elastic, I didn't think that a ball could be "carried" very much in the .000045 seconds the ball is compressed on the face - not enough to determine where the ball went, anyway.

Eventually I changed my mind. I'm sad to say that this change was not based on science but rather the fact that awesome instructors and world-renowned players all seemed to say the same thing. "I aim my feet where I want to start the ball and I aim my clubface where I want the ball to go, then swing along the line of my feet" they'd say. During this phase I even went so far as to point out that pool balls, collisions between which are almost as elastic as we see in real life, can be "thrown" off-line due to friction between colliding balls.

It turns out I should have trusted what I felt was common sense in the beginning: that the clubface has a much larger effect on the ball's initial path than any amount of "carrying" on the clubface by the swing path. Even though it's in another plane (vertical rather than horizontal), consider which direction a ball travels when you properly strike it with a descending blow: upward, because the loft of the clubface is pointing that way.

The Science
Though [ame=""]The Physics of Golf[/ame] shared the information years ago (the second edition is dated 1999). The information is available elsewhere too (like [ame=""]here[/ame] and [ame=""]here[/ame] - thanks to [ame=""]John Graham[/ame] at Richie3Jack's for those links). All of those works are fairly scientific, and though widely read and understood among the scientific component of the golf industry, the average golfer (and golf instructor) remained unaware.

One year ago marked a turning point in the battle of current, correct information versus "the way we've always told people to do it." In January, 2009 Trackman - makers of a popular launch monitor - publicly released information in their newsletter which shared the information in an accessible, easy to understand format. Again, while the scientific community - and a few instructors and golfers - knew this already, the Trackman newsletter was significant simply because of the easy digestibility.

From the January newsletter's article "The Secret of the Straight Shot" here (emphasis added):
The horizontal launch angle is determined by only two parameters, the club path and the face angle. As a rule of thumb, the horizontal launch angle is 15% determined by the club path and 85% determined by the face angle. For example, assume a club path of +6.7 degrees (6.7 degrees inside-out for a right-handed player) and a face angle of -1 degree (1 degree closed for a right-handed player). This would result in a horizontal launch angle of 0 degrees (ball starting at the target line).

In other words, you are saying that the face angle is by far the most dominating factor for the initial direction of the ball. Is this not in direct contradiction with the "Ball Flight Laws"?

Yes it is. According to the "old" ball flight laws, the initial direction of the ball (HLA) is 100% dictated by the club path. All the scientific people in the golf industry know that this is wrong, yet still a lot of PGA professionals use the incorrect 'old' ball flight laws in teaching. And many PGA organizations around the world do not teach their apprentice and member professionals according to the 'true' ball flight laws.

Fredrik Tuxen, Trackman January 2009 Newsletter
The science gets a bit headier beyond that - the downward angle of attack and its effect on the "true swing path" is considered - but the key piece is fairly clear: 85% of the ball's initial direction is determined by the clubface angle and only 15% of the ball flight is determined by the path.

These numbers vary little. You might think long drivers, who compress the bejeezus out of the golf ball, flip the ratio, but they don't even get out of the 80s, reaching roughly an 80/20 ratio at best. In fact, the ratio is much more easily pushed in the other direction: a putter, swung at a relatively slow swing speed, can generate ratios approaching nearly 100% clubface oriented.

So How'd They Do It?
During a recent telecast at the Sony Open, Nick Faldo - a six-time major winner and one of the best golfers in the history of the game - shared this advice, captured in the screen shot you see here:

Nick Faldo in the process of giving advice that's clearly based on the old - and very much wrong - ball flight laws.

So how on earth did Nick Faldo shape the ball - and break par let alone win six majors - if he had the wrong information? The power of his subconscious mind. Science tells us that if Nick Faldo set up with his clubface at the tree in the picture above and his shoulders aimed just to the right at the escape route, he would either:
  1. return his clubface to the same angle as it was at address and swing along his shoulder line.
  2. subconsciously return the clubface open to (right of) where it was at address and swing even more inside-out than his shoulder alignment.
Shot #1 is what Nick said you should do. If Nick followed his own advice and performed #1, he'd hit the ball right into the tree. If Nick was on a golf course with no trees, the ball would start just right of the target and hook well left of it.

If Nick subconsciously manipulated both the clubface angle and the swing path to produce #2, he'd start the ball to the right of the tree and hook it back towards the target - the shot he wants to play.

What are you going to believe - science or Nick Faldo's feel? Even Nick Faldo's subconscious mind didn't trust his feel, favoring the reality of science (or the instincts of having been a great golfer for a long time) instead!

Ball Flight Laws and Their Effects on Teaching
Consider a student who's hitting a straight-fade or a straight-slice. A straight-fade starts straight at the target and then, for a right-handed golfer, peels off to the right.

If this golfer visits an instructor who believes the old ball flight laws, he's going to have the student trying to square up the clubface. After all, the instructor believes that the ball starts on the swing path, and then reacts based on the face. So the instructor will believe that the student's swing path is fine and that his clubface is open.

This instructor will spend a lot of time trying to get the student to "square up the club at impact" when he's already doing so! Best case scenario? The student starts hitting pulls. Hey, at least they won't slice…

The reality is that this student needs to work on his swing path. His clubface is already awfully close to square at impact - the ball is starting at the target. It's purely his outside-in swing path that's causing the fades or slices.

During the Bob Hope Classic, Michael Breed used what appeared to be the old ball flight laws in helping actor Michael Peña. Peña was hitting a pull-fade - not a bad shot if you can hit it repeatedly because the fade works back to the target - and Breed gave him the advice to swing more from the inside (which is fine if you want to hit a draw) and to release the clubface (oof).

True Ball Flight Laws
One thing is not up for debate and never has been: a ball curves based on the clubface angle at impact relative to the swing path. A closed clubface relative to the swing path always draws/hooks and an open clubface relative to the swing path always fades/slices:

With arrows representing the swing path, the balls in these images will fade/slice, travel straight, or draw/hook from top to bottom.

You can combine these three basic clubface positions with the three basic swing paths:

The combination of the two triplets result in a combination of nine possible ball flights:

This diagram demonstrates every possible shape a well-struck golf ball (we're not talking about tops and shanks here, people!) can have. The true ball flight laws tell us that a pull (B) is a combination of an over-the-top (outside-in) move with a closed clubface that matches the amount of outside-in swing path.

The true ball flight laws tell us that a push-draw (G) is a result of an open clubface with a swing path that's more inside-out than the clubface is open. For example, if the clubface is 3° open at impact but the swing path is 6° inside-out, the ball will start right (open clubface relative to the target) and curve left (closed clubface relative to the swing path).

How would the old ball flight laws tell us to hit a push-draw (G)? They'd tell us to swing in-to-out while keeping the clubface square to the target. Basically, they'd tell us to hit shot D. Ouch.

In the chart above you'll notice that the straight shots - B, E, and H - are italicized. These shots are each hit with a clubface square to the swing path and are the only shots on which the "old" and "true" ball flight laws agree.

I've also marked in bold the "good" shots: a pull-fade, a straight shot, and a push-draw. The straight shot is good for obvious reasons, but as you can see the pull-fade (C) and the push-draw (G) work because, though they start away from the target, they curve towards the target.

(Side note: That's not to say the other shots aren't good. Lee Trevino and Jack Nicklaus both played a push-fade. On my graph, that's shot (I), the farthest right. How could they win majors or even break par hitting that shot? Take the whole graph above and rotate it counter-clockwise (to the left). Imagine Lee Trevino: he aims his feet and swings his club 20° left, pushes the ball 10° right, and lets his fade take the ball the remaining 10° back to the target. That's how shot (I) can win a major - when you play for it.)

Where Do we Go from Here?
If you're like most golfers, having toiled under the old, incorrect ball flight laws, you may feel energized reading this. Perhaps you've been battling a persistent slice by trying to "release the club." It's a common suggestion, but if your ball starts at the target before slicing, you should have gathered that you need to work on your swing path, not your clubface angle at impact. That's even more important if the ball starts left before slicing two fairways over.

Armed with the proper knowledge, you're going to be amazed at how often you hear advice based on the old, incorrect ball flight laws, and from whom you hear it. Magazines, television, respected teachers, and accomplished players will all dish out advice that's potentially damaging to your golf game because it's based on the "old" laws.

The ball flight doesn't lie. Now that you know how to read it, you can spend your time working on the right things.


Consider the ball flight control method a golfer should use to bypass an obstruction (eg. tree alongside the fairway).

Ball flight predicament

Consider the predicament of the golfer in image 1. His ball has landed at point X - just off the right side of the fairway, about 180 yards from the green, which is surrounded on the left-and-right by two bunkers. There is a large tree (colored in dark green) about 40 yards in front of him obstructing his view of the center of the green and the hole, which is in the middle of the green. The tree is too high for him to consider the optional choice of hitting a straight shot over the top of the tree. There is a lake (colored in blue) on the right side of the rough and alongside the right side of the right bunker.

What can the golfer do to get the ball to land on the green near the hole? Image 2 shows that he has two ball flight options - he can either try to hit a pull-slice shot (yellow curved arrow) or he can try to hit a push-draw shot (orange curved arrow). The major problem associated with trying to hit a push-draw shot is that it is a very risky endeavour, because of the presence of the lake on the right side - he could easily land in the lake if he doesn't successfully draw the ball enough. So, his best option is to try and hit a pull-slice shot. At the worst, if he doesn't curve the ball back enough towards the center, it will either land in the bunker to the left of the green or in the left rough.

How should he execute this pull-slice shot?

Image 3 shows the approach recommended by the "old" ball flight laws. The clubface (short black line) should be aimed towards the center of the green (orange arrow) and his clubhead path should be directed left of the tree (yellow arrow). Theoretically, according to the tenets of the "old" ball flight laws, the ball should start along the direction of the clubhead path, and skirt the tree, before slicing to the right (secondary to the presence of slice spin due to the fact that the clubface is open to his clubhead path). However, that "imagined" ball flight will not happen in "reality" if he adopts that particular choice of clubface orientation and clubhead path. Image 4 shows what will happen in "reality". The ball will start off just to the left of the clubface orientation (85% in the direction of the clubface orientation relative to the clubhead path) and curve to the right (red dotted arrow) into the tree.

The correct approach should follow the tenets of the "new" ball flight laws - see image 5. The clubface (short black line) should be angled to the left of the tree (orange arrow). The clubhead path should be directed even further left (yellow arrow). If the swing is executed correctly, then the ball will start off 85% in the direction of the clubface orientation and curve to the right (due to the fact that the clubface is open to the clubhead path). The ball should then follow the red dotted arrow path to the center of the green.

The golfer needs to ensure that the degree of divergence between the clubhead path angle and the clubface orientation angle is appropriate - so that the ball acquires the "correct" amount of slice spin in order that it can curve rightwards towards the center of the green. If the ball is 40 yards from the tree, rather than 80 yards from the tree, then the golfer will need to curve the ball more to the right. To acquire a greater amount of slice spin, he needs to increase the magnitude of the divergent angle between the clubhead path and the clubface orientation - while keeping the clubface pointing just to the left of the tree. In other words, he will have to swing his club more leftwards if he wants to produce a greater degree of slice spin. It is only through repeated practice that a golfer can learn how to vary the magnitude of the divergent angle between the clubface orientation and the clubhead path to produce a certain finite amount of slice spin that is optimal for this particular ball flight predicament.



The Secret of the `Straight Shot´ II

[ame=""]James Leitz Understanding D plane - YouTube[/ame]

Here is an ancient proverb which says: “May you live in interesting times.” In golf instruction these are THE most interesting times. Like any other discipline we have come of age thanks to technology; things like radar and 3D capture systems have taken much of the guesswork out and replaced it with immutable laws of physics. We started out in the “dark ages” of golf instruction using only our eyes. We, the instructors, would watch the flight of the golf ball and infer from it what the golf club might have done to cause a shot. We helped some people but there was still something missing. Then came the video era and we got at least a better look at what the body was doing in the swing, but a certain ambiguity still surrounded impact. Now we have come pretty much full circle to the enlightenment era of Doppler Radar. This article deals with some of the new findings and how the data debunks certain long held myths.

If you are a fan of this or any of the other popular golf forums, you most certainly have heard of something called the D Plane. The D Plane was popularized by Theodore Jorgenson in his seminal work “The Physics of Golf” back in 1999. He used the term D Plane because it “described” the collision of the golf club and golf ball. His findings were somewhat controversial because he took issue with prevailing ball flight and impact theories; namely the initial direction of the golf ball and the role of the clubface, path and angle of attack at impact. So let’s look into the D Plane and explain it in practical terms that you can understand and use to help your game.

D Plane definition: The wedge shaped plane between two three-dimensional directions — 1) The club head direction, which is a combination of the path AND the angle of attack; and 2) The club face orientation, which is a combination of dynamic loft and face angle.

Interpretation: The golf club swings up, down, reaches the very bottom of its arc, and travels back up. Because we all swing on an inclined plane (somewhere between 45 and 65 degrees) when the club is traveling down it is NOT swinging at our target (assuming we are aimed parallel left of our target line). It is in fact swinging to the right of the target. And when the club is swinging up, it is actually swinging to the left of the target (stand up and try it.) The only point in the entire arc of the swing where the golf club is swinging at our aim point is at the very bottom of the swing arc, what we call low point. This might be a better way to understand it: If the golf club was swung on an entirely vertical plane (90 degrees) then ALL points in the swing, up and down, would be swinging at the target. This is physically impossible on an incline. So with that in mind, we learn something critical about the “true path: of the swing. It is not simply directional. It is a combination of the up and down in conjunction with the left and right. This is why video can NEVER show the true path. Video is a 2-dimensional representation of a 3-dimensional motion! The knowledge of this, thanks to Trackman, Flightscope, etc., has all but revolutionized teaching. Here’s why…

Technically you cannot hit a straight shot with an in to in path aimed at the target. The more DOWN you swing the more you need to aim or swing left. The more UP you swing (driver) the more you need to swing or aim right. It’s that simple. Because remember: If you hit the golf ball BEFORE you reach low point, which of course you should on any shot on the ground, at impact your path is in-to-out. This will give you a clubface that is closed RELATIVE to the path, and curve the golf ball to the left (for a right handed player.) And if you hit a golf shot AFTER low point you are swinging to the left. This gives you a face that is open RELATIVE to the path. It is not the position of the clubface relative to the target but RELATIVE TO THE PATH that gives the shot its shape. This explains quite categorically how a square face draw/hook or a square face fade/slice can be hit. Very often you can look at high speed video, see the face DEAD SQUARE to the target, and watch the ball curve. Maddening!

Finally all of the information above is based on hitting the golf ball on the center of the face (Which is rare by the way). Toe hits, heel hits, high or low on the face contact, twist the golf club. Here’s where the beauty of modern golf clubs comes into play. We have what is known as horizontal gear effect, which actually helps straighten the flight of the golf ball, when hit off center. When the toe of the golf club strikes the ball, the clubface opens, and when the heel of the club strikes the ball, the face actually closes. But … here is the where the integrated help I referred to comes into play: The toe hits have hook spin and the heel hits have fade spin. So … on a toe hit the flight actually starts to the right (open face) and curving a little back to the left. And on a heel hit, we get flight beginning to the left (closed face) and curving back to the right. So here we actually observe open face hooks and closed face slices! A real true draw is hit with a slightly OPEN face with a path from the inside. And a true fade is hit with a slightly closed face and a path well outside that face. Horizontal gear effect is more built more into woods than irons, but irons have it as well. And you think this is isn’t a crazy game!

It’s difficult to understand in words but there are plenty of D Plane videos on the net, and if you like I’ll do one here on the GOLFWRX forum as well.