Hot Golf Forum Topics - Analyzing Ball Flight

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Topic: Little tip for analysing ball flight.

Posted By: doverall
Subject: Little tip for analysing ball flight.
Date Posted: 20 June 2006 at 9:20am

Some years ago on the golf channel i saw a programme where the guy presenting it said if you remember one thing from this programme remember this.

"The ball will start in the direction that your shoulders are pointing at impact and the ball will finish where your club face was pointing at impact"

Now this was the only thing i can remember from the programme, cant event remember who presented it.

It does seem to make sense to me, for instance if I want to hit a draw then I swing slightly more from the inside (so my shoulders would be slightly closed) and the club face would be slightly closed to this swing path creating a draw. if the club face was square to this path then i would hit a push.

Would like to know what you guys think of this little gem of information...

Replies:

Posted By: flyfishin
Date Posted: 20 June 2006 at 11:37am

I used to follow a general guide line of aligning the shoulders where I want the ball to start and align the clubface where I want it to end up. The difference is that these are address positions and not impact positions. With a ops your shoulders are very open to your line of flight at impact.

Posted By: Insight
Date Posted: 20 June 2006 at 6:25pm

I am sure he is referring to shaping shots and more how you align your shoulders at setup to influence the direction of the plane. It is entirely possible for your shoulders to be aligned one way at impact and your plane and face to be aligned other ways. not to say this would be efficient or "proper"... just possible.

Posted By: One Planer
Date Posted: 20 June 2006 at 6:40pm

Originally posted by doverall

Some years ago on the golf channel i saw a programme where the guy presenting it said if you remember one thing from this programme remember this.

"The ball will start in the direction that your shoulders are pointing at impact and the ball will finish where your club face was pointing at impact"

Now this was the only thing i can remember from the programme, cant event remember who presented it.

It does seem to make sense to me, for instance if I want to hit a draw then I swing slightly more from the inside (so my shoulders would be slightly closed) and the club face would be slightly closed to this swing path creating a draw. if the club face was square to this path then i would hit a push.

Would like to know what you guys think of this little gem of information...

I think it's dead wrong. The ball will always start in the direction the clubface is looking when the ball separates. The shoulders can be open, square, or closed, but the clubface angle at separation determines the initial direction of flight. Whether it curves in the air is influenced by the path of the club and the amount of clubhead rotation while the ball is compressed on the face.

Posted By: Chuck Quinton
Date Posted: 20 June 2006 at 6:52pm

You said all you needed to say in the first sentence: "on the golf channel"

This advice is wrong as a blanket statement, dead wrong, but for a two plane swing which he was likely talking about, it's a fair enough statement. For a one planer, not so much.

-------------
Current USGA Handicap +.2
http://www.oneplanegolfswing.com/forum/forum_posts.asp?TID=3130&PN=1 - See what's in my bag!
Scoring Avg. 72.92, GIR 65%, FIR 65.71%, Putts 30.38

Posted By: waltice
Date Posted: 20 June 2006 at 9:30pm

Just remember this about ball flight. The ball flight is affected by several variables 1) is the face angle and 2) swing path 3) the angle of the club and 4) the speed of the club. Of the 4 according to great John Jacobs the clubface at impact is the most important factor. In addition, keep this in mind: The angle of the clubface at impact will create the side spin and the swing path with determine where the ball will start off at. For example, a pull happens when your clubface is square to your swing path not your target line (the swing path will be moving from the outside to inside). I hope this helps a little bit. If you have any questions about this I will be more than happy to help. I have been studying a lot of Mr. Jacobs theory about ball flight I to me it is right on.

Chuck, if anything is off on this please correct me.

Remember fairways and greens!!!!!! (Phil should have listened to this on the 18th ahahah) That was a cheap shot but I couldn't resist

Posted By: One Planer
Date Posted: 20 June 2006 at 10:10pm

1. What does he mean by "angle of the club"? Is that like forward shaft lean?

2. Does he make a distinction between the clubface angle at impact vs. separation? If not, he has missed a crucial factor, clubface rotation during the compression phase.

Posted By: waltice
Date Posted: 20 June 2006 at 11:23pm

Angle of the club coming into impact meaning how steep/shallow.
And to answer your second question I believe he mentioned something about this. Let me go back through my notes on this one and I will get back to you.

Posted By: lpratt17
Date Posted: 20 June 2006 at 11:57pm

Originally posted by One Planer

I think it's dead wrong. The ball will always start in the direction the clubface is looking when the ball separates. The shoulders can be open, square, or closed, but the clubface angle at separation determines the initial direction of flight. Whether it curves in the air is influenced by the path of the club and the amount of clubhead rotation while the ball is compressed on the face.

For the first time ever, I have to disagree with OnePlaner.

As far as I understand, you have your influences reversed. The ball's initial direction is determined by the swing path - the club face at impact determines the side spin. An out to in swing path with an open face at impact will cause a pull slice. An out to in path with a closed face causes a pulled straight ball. Simplify (and slow down) the dynamics by putting. If you putt directly towards a target, but keep the face open; the ball will initially start out towards the target, but a slice spin will send it off course.

I don't quite understand how physics differs from a 1PS to a 2PS. Perhaps someone could enlighten me.

lp

Posted By: randini
Date Posted: 21 June 2006 at 12:26am

Initial direction is established by path. Face angle & rotation (or lack of) determines curvature. Curvature can be either verticle or horizontial........depends on face angle, face rotation (or lack of) & angle of attack.

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randini / 1 hdc

Posted By: acepepper
Date Posted: 21 June 2006 at 2:21am

Originally posted by doverall

"The ball will start in the direction that your shoulders are pointing at impact and the ball will finish where your club face was pointing at impact"

Surely, to make any sense at all, that should read, "The ball will start in the direction that your shoulders are pointing at ADDRESS and the ball will finish where your club face was pointing at impact"

Posted By: dave.
Date Posted: 21 June 2006 at 2:40am

Thye advice is pointless because he doesn't tell you what to do with it.He could have said "check you have a good posture and a good swing or the ball will go somewhere you don't want it to go",so pretty normal for the golf channel then.

Posted By: doverall
Date Posted: 21 June 2006 at 4:47am

Originally posted by acepepper

Surely, to make any sense at all, that should read, "The ball will start in the direction that your shoulders are pointing at ADDRESS and the ball will finish where your club face was pointing at impact"

Why do you say that, if as Chuck mentioned this tip is more based on a 2 plane swing then yoru swing path and shoulder should be approximately the same.

Originally posted by One Planer

I think it's dead wrong. The ball will always start in the direction the clubface is looking when the ball separates. The shoulders can be open, square, or closed, but the clubface angle at separation determines the initial direction of flight. Whether it curves in the air is influenced by the path of the club and the amount of clubhead rotation while the ball is compressed on the face.

One Planer, i dont agree with you either, remember my other post about "what causes a slice", you said you agreed with hank. A slice or a hook is caused by the direction the clubface points at impact in reltation to the swing path.
Therefore swing path dictates where the ball starts and clubface where the ball finishes.

Maybe the guy should have said:
"The ball will always start in the direction your swing path is on a impact and the ball will always finish where the clubface is point at impact in relation to the swingpath"

So if i were to hit a shot that starts towards the target but the moves to the right of the target this would indicate that my swing path was spot on but my clubface was open at impact therefore imparting left to right sidespin onto the ball

Posted By: One Planer
Date Posted: 21 June 2006 at 7:17am

Originally posted by randini

Initial direction is established by path. Face angle & rotation (or lack of) determines curvature. Curvature can be either verticle or horizontial........depends on face angle, face rotation (or lack of) & angle of attack.

Nope. That's a common misconception. Initial direction is a function of face angle at separation. The ball will always jump off the face and 90 degrees to where the face it looking at that instant.

Posted By: One Planer
Date Posted: 21 June 2006 at 7:40am

One Planer, i dont agree with you either, remember my other post about "what causes a slice", you said you agreed with hank. A slice or a hook is caused by the direction the clubface points at impact in reltation to the swing path.
Therefore swing path dictates where the ball starts and clubface where the ball finishes.

Maybe the guy should have said:
"The ball will always start in the direction your swing path is on a impact and the ball will always finish where the clubface is point at impact in relation to the swingpath"

So if i were to hit a shot that starts towards the target but the moves to the right of the target this would indicate that my swing path was spot on but my clubface was open at impact therefore imparting left to right sidespin onto the ball
[/QUOTE]

Here we go again. In the shot you've just described, the clubface was open at impact and square at separation, but there was insufficient clubface rotation during the compression phase to offset the slice spin resulting from the open face at impact. Hence, the ball started at the target because that's where the face was looking when it left. It moved to the right in the air because the toe of the clubhead didn't get around enough to cancel the slice spin caused by the open face at impact. This shot typically happens when you hold off the release.

Posted By: One Planer
Date Posted: 21 June 2006 at 9:07am

Originally posted by lpratt17

Originally posted by One Planer

I think it's dead wrong. The ball will always start in the direction the clubface is looking when the ball separates. The shoulders can be open, square, or closed, but the clubface angle at separation determines the initial direction of flight. Whether it curves in the air is influenced by the path of the club and the amount of clubhead rotation while the ball is compressed on the face.

For the first time ever, I have to disagree with OnePlaner.

As far as I understand, you have your influences reversed. The ball's initial direction is determined by the swing path - the club face at impact determines the side spin. An out to in swing path with an open face at impact will cause a pull slice. An out to in path with a closed face causes a pulled straight ball. Simplify (and slow down) the dynamics by putting. If you putt directly towards a target, but keep the face open; the ball will initially start out towards the target, but a slice spin will send it off course.

I don't quite understand how physics differs from a 1PS to a 2PS. Perhaps someone could enlighten me.

lp

It's a fallacy that swing path determines initial direction of flight. It assumes that the clubface is always square to the path. It ain't necessarily so. The clubface can be open, square, or closed to the path "at impact". In any case, where the face is looking "at separation" is where the ball will start, regardless of path.

In fact, it's wrong to think of "impact" and "separation" as occuring simultaneously. There is a phase when the ball is compressed on the clubface. Spin is imparted to the ball during this compression phase. Backspin is one thing that happens during compression. Backspin makes the ball go up in the air.

But sidespin is also imparted during compression. Curvature in flight results from the net effect of slice spin imparted by an open face and hook spin imparted by a rotating clubface.

Think of the ball as consisting of an inner hemisphere and an outer hemisphere.

Also, consider the fact that the golf swing is a "side swipe". That is, it is an inclined arc from the side of the ball.

Finally, consider the nature of the club itself. It is a two-levered tool. The clubhead is the second lever.

Because the swing is from the side and the clubhead extends outward from the shaft, the clubface will necessarily rotate during the swing. That is, the toe will revolve around the heel or the axis of the shaft.

During the compression phase in a typical golf swing, the clubhead comes from inside the target line and is open to the line at initial impact. Thus, the "inner hemisphere of the ball is where initial impact occurs. The clubface is slightly open to the line at that instant. The combination of the open face and inside path compresses the inner hemisphere of the ball and imparts slice spin.

However, the toe is rotating around the shaft axis while the ball is compressed on the clubface. The rotating toe compresses the outer hemisphere and thus imparts hook spin on the ball.

The net effect of slice spin and hook spin imparted during compression will determine how the ball curves in the air. If the net is zero, the ball will fly relatively straight in the direction the face it looking at separation. If the slice spin prevails over the hook spin, the ball will curve to the right. If the hook spin caused by clubface rotation prevails over the slice spin, the ball will curve to the left.

Now, that's what happens in a typical swing, but there are all sorts of combinations of swing paths, face angles, and degrees of clubface rotation. The club doesn't necessarily come from inside the line. It isn't necessarily open at initial impact. The toe doesn't necessarily rotate around the shaft axis if the swinger "holds it off"; or, indeed, if the swinger "flips it" or "comes over it", the outer hemisphere can be the point of initial impact.

The old "Ball Flight Laws" are wrong because they fail to consider the dynamics of impact, compression, clubface rotation, and separation.

Posted By: randini
Date Posted: 21 June 2006 at 9:52am

Wrong Wrong Wrong

I'm standing at home plate. My swing path is right down first base chalk line. My clubface at impact is spot on second base........and you are trying to tell me my initial ball path won't be down first base line? And then my curvature won't be towards second base? Wrong

If your physics are correct , it wouldn't matter where a golfer ever lined up. You are placing too much emphasis on "seperation". To say that impact & seperation angle over-rides a 100 mph swing path for initial direction is fallacy

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randini / 1 hdc

Posted By: One Planer
Date Posted: 21 June 2006 at 11:04am

Originally posted by randini

Wrong Wrong Wrong

I'm standing at home plate. My swing path is right down first base chalk line. My clubface at impact is spot on second base........and you are trying to tell me my initial ball path won't be down first base line? And then my curvature won't be towards second base? Wrong

If your physics are correct , it wouldn't matter where a golfer ever lined up. You are placing too much emphasis on "seperation". To say that impact & seperation angle over-rides a 100 mph swing path for initial direction is fallacy

Nope. Apart from the fact that you're mixing metaphores, if your clubface is looking at second base when the ball leaves, that's where the ball will start. No amount of shouting wrong will change that fact.

Think about it, Randini. The clubface can be open, square, or closed to the swing path at any point of the swing. Where it is looking when the ball separates is where the ball will start.

Actually, while I am placing emphasis on separation, I'm also placing emphasis on clubface rotation and path. It all works together to influence ball flight.

Furthermore, it doesn't especially matter where a golfer lines up so long as he/she has the right combination of alignment, path, face rotation, and timing to send the ball reasonably close to the intended target line. Snead aligned his shots to the right and pulled the ball toward the target. Trevino and Couples aiign to the left and push the ball toward the target. It all works if you can hit the same shot every time, which, again, is a matter of repeating all of the dynamics of impact consistently.

Edited to correct Snead (he aimed right, not left) and Trevino/Couples (they aligned left, not right). It was early in the AM when I wrote that.

Posted By: randini
Date Posted: 21 June 2006 at 11:20am

It's emphasis , I don't shout.

For every physics op. that states your version, I'll give you one stating my version, that the primary influence relative to the initial direction of flight is swing path.

My ball doesn't start towards second, it starts down the chalk-line & curves towards second. It certainly doesn't curve towards second because of swing-path. It doesn't start down first as a result of seperation angle.

I can be just as butt-headed as you

I'm done.........off to play

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randini / 1 hdc

Posted By: One Planer
Date Posted: 21 June 2006 at 11:34am

Originally posted by randini

I'm done.........off to play

That's a good thing. Have a great round, and watch out for that face angle at separation.

Posted By: GolfObsessed
Date Posted: 21 June 2006 at 1:16pm

interesting discussion. I always heard and understood it was Swing Path where the ball starts and clubface angle where the ball will curve to.

If I (feel like) I hit the inside 1/2 of the ball and let my hands turn over....it produces a ball that starts right and curves back to the left. Maybe that's just what I feel though.

Maybe I have this wrong, but I would swear I hear pros say all the time that at address they'll angle the club face where they want the ball to finish, and align their feet where they want the ball to start. ???

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Hcp: 6.4, Fairways: 79%, GIR: 59%,Putts: 36.67, Dist: 285+
"I'm..... kind of a big deal." - Will Ferrell as Ron Burgundy in "Anchorman".

Posted By: doverall
Date Posted: 21 June 2006 at 1:50pm

Originally posted by One Planer

It's a fallacy that swing path determines initial direction of flight. It assumes that the clubface is always square to the path. It ain't necessarily so. The clubface can be open, square, or closed to the path "at impact". In any case, where the face is looking "at separation" is where the ball will start, regardless of path.

In fact, it's wrong to think of "impact" and "separation" as occuring

Interesting oneplaner I think I understand where you are coming from now, correct me if i am wrong on my understandings.

Impact = The moment the club face first strikes the ball.

Compression = The ball compresses on the face of the club COR etc

Seperation - The moment the ball leaves the club face.

So to pick an analogy of a someone jumping onto a trampoline from a height:

Impact = momenet your feet hit the trampoline

Compression = the trampoline stretching down to take your force

Seperation = The moment your fett leave the trampoline

if I have everything correct I thinkg where people dont understand what you talking about is that most people consider impact to be what you call seperation.

Posted By: jonag
Date Posted: 21 June 2006 at 7:55pm

Hey-hey

It is a combination !

Try with a putter. The main reason for the putt direction is by far the face angle at impact, but if the path missalignment gets to big, the ball will leave the putter face not normal to the putter face.

The hit with a golfball on the clubface is mostly elastic, but also .. hm .. what do you call it .. like a piece of clay. A piece of clay would always be hit the direction the clubpath is going. A really hard metal ball would always go the direction the clubface is pointing. But the golfball hangs to the surface and is partly going the direction of the clubface and partly the path.

In my mind it makes sense that with small misalignments of the clubface, the ball mainly starts the direction of the swingpath and gets the sidespin according to the difference between the path and the clubface.

The more rotation you have on the clubface during the impact, the more friction you get between the golfball and the clubface. this gives more backspinn and more stable flight.

I do not think it is correct that the ball leaves at the angle the clubface had when the ball leaves it. The ball reacts to the clubface angle which is the mean value during the impact period.

The lower speed, the more the ball leaves in the clubface direction because the compression is smaller and the friction is lower giving a more metal ball effect.

And the higher speed, the more compression, the longer contact, the more friction, the more backspinn and the more the ball starts along the club path.

The same applies to the loft angle and the launch angle.   You never get 56 degrees launch angle even when you hit the SW flush !

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Jon Arne
golfaholic @ 10.7

Posted By: lpratt17
Date Posted: 21 June 2006 at 9:40pm

The rotation of the clubface through impact is minimal, so lets get that out of the equation now. We are talking about microseconds of contact between clubface and ball - you can't (or shouldn't) be rotating the clubface enough to impart spin through the impact zone.

OnePlaner - Are you telling us that a perfectly aligned (in to in) swing plane with an open face at impact will result in hook? Your logic says that this ball (for a right handed golfer) would start to the right and draw back down the center of the fairway. I can't see it. There is no doubt in my mind that this ball starts along the target line and slices to the right.

Posted By: One Planer
Date Posted: 21 June 2006 at 9:55pm

Originally posted by GolfObsessed

interesting discussion. I always heard and understood it was Swing Path where the ball starts and clubface angle where the ball will curve to.

If I (feel like) I hit the inside 1/2 of the ball and let my hands turn over....it produces a ball that starts right and curves back to the left.  Maybe that's just what I feel though.

Maybe I have this wrong, but I would swear I hear pros say all the time that at address they'll angle the club face where they want the ball to finish, and align their feet where they want the ball to start. ???

The ball that starts right and curves back to the left is the example I ofthen use to prove my point, but I add one other factor to it.   The divot points left. Strong players hit that shot often. It's the "draw". Starts right, curves left, divot points left. How is that shot possible if path sets the initial direction of flight?

Here's what happens when you hit that shot. The path is in-to-in. That's why the divot points left. The ball starts right because the face is slightly open at separation. It curves to the left because the toe rotates around the shaft axis and compresses the outer hemisphere more than enough to offset the slice spin from the open face at separation.

Again, path doesn't determine initial direction of flight. The clubface can be open, speare, or closed relative to the path at separation.   The ball always jumps off the face at 90 degrees to the face angle, regardless of path. Think about this one. The path is out-to-in with an open face at separation. Will the ball start left and slice back to the right, or will it start right and go farther right? It's the latter.

On your other point about the pros aligning the clubface where they want the ball to go and their bodies where they want the ball to start, they do that only when they want to hit a big hook or slice around a tree or some obstacle, not a draw or fade. They are pre-setting which hemisphere of the ball they want to compress the most. When they want to hit a draw, they add clubface rotation through impact. When they want to hit a fade, they hold off the clubface rotation through impact. They use the clubface to curve the ball with the bend of the fairway or in to left and right pin locations.

Posted By: Guests
Date Posted: 21 June 2006 at 10:04pm

wow.................hmmmm............Golf is really confusing.......and complicated. However, I've seen One Planer's posts, and he knows his stuff. No arguing here. But....................

Micah

Posted By: One Planer
Date Posted: 21 June 2006 at 10:05pm

Originally posted by doverall

Originally posted by One Planer

It's a fallacy that swing path determines initial direction of flight. It assumes that the clubface is always square to the path. It ain't necessarily so.    The clubface can be open, square, or closed to the path "at impact".   In any case, where the face is looking "at separation" is where the ball will start, regardless of path.

In fact, it's wrong to think of "impact" and "separation" as occuring

Interesting oneplaner I think I understand where you are coming from now, correct me if i am wrong on my understandings.

Impact = The moment the club face first strikes the ball.

Compression = The ball compresses on the face of the club COR etc

Seperation - The moment the ball leaves the club face.

So to pick an analogy of a someone jumping onto a trampoline from a height:

Impact = momenet your feet hit the trampoline

Compression = the trampoline stretching down to take your force

Seperation = The moment your fett leave the trampoline

if I have everything correct I thinkg where people dont understand what you talking about is that most people consider impact to be what you call seperation.

You're exactly right, Dover, except your trapoline comparison is just slightly off. There may be some compression of the clubface on newer drivers, but it is generally understood that the ball is what gets compressed, at least in terms of any effect on ball spin. You're also right in saying that many people think that impact and separation are so cluse together in terms of elapsed time that the compression phase isn't significant. They just haven't thought about the dynamics of the collision of a rotating clubface with an elastic spheroid.

Posted By: One Planer
Date Posted: 21 June 2006 at 10:41pm

Originally posted by lpratt17

The rotation of the clubface through impact is minimal, so lets get that out of the equation now. We are talking about microseconds of contact between clubface and ball - you can't (or shouldn't) be rotating the clubface enough to impart spin through the impact zone.
Really? Then how is it possible for the ball to leave the clubface with backspin and sidespin in one direction or another? Why does the ball go up? Why does it curve in the air?

OnePlaner - Are you telling us that a perfectly aligned (in to in) swing plane with an open face at impact will result in hook? Your logic says that this ball (for a right handed golfer) would start to the right and draw back down the center of the fairway. I can't see it. There is no doubt in my mind that this ball starts along the target line and slices to the right.

Lpratt, I'm telling you that the shot that starts to the right of the target line and draws back to the left from an in-to-in path is the result of an open face at separation and a rotating (closing) clubface during the compression phase.. It's not a hook, it's a draw. It's perfectly ok with me if you want to deny that there are any dynamics going on while the ball is compressed and the clubface is rotating. It's your choice.

Posted By: Skully
Date Posted: 21 June 2006 at 11:25pm

Originally posted by mpastula@att.ne

wow.................hmmmm............Golf is really confusing.......and complicated. However, I've seen One Planer's posts, and he knows his stuff. No arguing here. But....................

Micah

It's not any more complicated than you want to make it. Jack and Annika both open their stance for a fade and close it for a draw. I'm not arguing with 1plner either, but different approaches work for different people. Those 2 examples are also 2 of the best ball strikers to ever play the game so It's safe to say that they can keep their clubface pretty square to their lines through impact.

Posted By: jricci
Date Posted: 21 June 2006 at 11:57pm

I think these arguments from a physics point of view are too complex.

If the clubface is square to the path at impact the intial direction can only reflect the path of the club at impact. So inside out swing will produce an outside swing path and vice versa.

If the face is open at impact the initial ball flight will be impacted by the face angle in two ways.

The open face will cause the ball to start more to the outside

The open face will impart sidespin which will cause the ball to slice

The loft of the club imparts only topspin that reduces the impact of sidespin.
Hence more slices with drivers, pulls with wedges

Thus if the ball starts in, slices right the swing path was probably out to in, with an open face. If the face had not been open, the same swing would cause a straight pull.

Doesnt seem that complicated to me.

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jr

Posted By: randini
Date Posted: 22 June 2006 at 12:32am

This is getting silly. I did a little re-search tonight when I got in & for every person like 1P , there are 4 the other way. That doesn't really matter.

I spoke to a physics guy at FSU today & he says both sides have elements of truth. We all know that. His final was swing-path was primary relative to initial direction..........not final destination. He also stated the faster the swing-speed , more path influence. He mentioned that a golf ball can have only ONE type of spin at a time..............like you can't have back-spin & sidespin at the same time. HHHmmmmm. Interesting...........

also said it takes the average tour player 18-24 inches to rotate the clubface through the impact zone. I suppose that's the "foot on either side of the ball" we have heard about.

I think 1p is all wrong on this. If swingpath doesn't dictate initial line of flight what the hell difference does it make how we line up. Just make sure the face angle is right.............lol........ why set up open or closed? Wouldn't matter.......... & 1 your reference about the "divot pointing left" thing proves nothing ............ball is hit first and is long gone, then the divot.

I would love to see someone hit a ball that starts right of target & draws back with an open face at seperation.......lol

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randini / 1 hdc

Posted By: lpratt17
Date Posted: 22 June 2006 at 1:05am

Originally posted by One Planer

Really? Then how is it possible for the ball to leave the clubface with backspin and sidespin in one direction or another? Why does the ball go up? Why does it curve in the air?

Assuming the path is straight down the target line for the following example:

The ball spins in the direction that the face is pointing at impact - the end!

It has back spin, which curves it up, because the loft of the face is facing upward.

It has hook (or draw) spin if the face is closed at impact (thru separation) and slice (or fade) spin if the face is open at impact (thru separation).

I'm saying impact "thru separation" because the ball contacts the club face for 0.00045 seconds - I am pretty sure that you aren't changing the face angle too much in that amount of time. If your clubhead speed was 150 mph, your club would move 3 centimeter or just over an inch in .00045 seconds. I'm not denying that rotation is happening, I am telling you that the rotation has minimal effects on side spin. If it had more significant effects, as you contend, it would be difficult to remain even remotely consistent. It is nearly impossible to repeatedly manipulate the clubface at impact. That is what make the 1PS so nice - you don't consciously manipulate the club face throughout the downswing. It remains fairly square throughout the impact zone.

lpratt

Posted By: lpratt17
Date Posted: 22 June 2006 at 1:13am

Randini, you are the voice of reason. As I stated earlier in the post, OnePlaner is usually full of good information, but this is crazy talk - science doesn't lie. I can't even believe this is the same OnePlaner who gave me so many useful nuggets in the past.

I agree that swing speed is also a component in the equation. The slower the swing..i.e. a putt, the more club face determines initial direction; the faster the swing, the more swing path determines initial direction.

Posted By: dave.
Date Posted: 22 June 2006 at 3:33am

Hogan faded the ball off a closed stance and an in to out to in swing path.

The two things,face angle at impact and swing path are so interelated you can't really separate them.imho

Posted By: jonag
Date Posted: 22 June 2006 at 3:49am

The actual spin of the ball can be decomposed into pure backspinn and pure sidespinn. The axis of rotation on a ball that slices to the right is no longer horizontal, but is tilted clockwise seen from behind. It tries to climb a tilted trajectory, but since gravitation will never tilt its force to make the ball go where you aimed it, it will drop down right of your target. The same happens when hitting from a lie where the ball is below your feet.

The principal of superposition can be used so in calculations one could use dual spin of the ball.

Then aerodynamics makes it even harder to understand the ball flight and why the slice comes so late in the trajectory...

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Jon Arne
golfaholic @ 10.7

Posted By: doverall
Date Posted: 22 June 2006 at 4:04am

Originally posted by One Planer

Originally posted by lpratt17

The rotation of the clubface through impact is minimal, so lets get that out of the equation now. We are talking about microseconds of contact between clubface and ball - you can't (or shouldn't) be rotating the clubface enough to impart spin through the impact zone.
Really? Then how is it possible for the ball to leave the clubface with backspin and sidespin in one direction or another? Why does the ball go up? Why does it curve in the air?

OnePlaner - Are you telling us that a perfectly aligned (in to in) swing plane with an open face at impact will result in hook? Your logic says that this ball (for a right handed golfer) would start to the right and draw back down the center of the fairway. I can't see it. There is no doubt in my mind that this ball starts along the target line and slices to the right.

Lpratt, I'm telling you that the shot that starts to the right of the target line and draws back to the left from an in-to-in path is the result of an open face at separation and a rotating (closing) clubface during the compression phase.. It's not a hook, it's a draw. It's perfectly ok with me if you want to deny that there are any dynamics going on while the ball is compressed and the clubface is rotating. It's your choice.

I cant agree with this, how can the face be open at seperation but be rotating(closing) during compression. I thought the sequence was Impact->Compression->Seperation ???

Posted By: doverall
Date Posted: 22 June 2006 at 4:09am

Originally posted by dave.

Hogan faded the ball off a closed stance and an in to out to in swing path.

The two things,face angle at impact and swing path are so interelated you can't really separate them.imho

I think you will find that hogan had a closed stance but open shoulder, and your swing path most closely follow yoru should line. Therefore at impact his face is open to his swing path thereby creating the face, ball starts left because of swing path and fades because of face angle to the path at seperation.

Posted By: dave.
Date Posted: 22 June 2006 at 8:12am

Er,I think thats what I meant,but tbh,its now going over my head.

Posted By: One Planer
Date Posted: 22 June 2006 at 8:28am

Originally posted by randini

<snip>

I spoke to a physics guy at FSU today & he says both sides have elements of truth. We all know that. His final was swing-path was primary relative to initial direction..........not final destination. He also stated the faster the swing-speed , more path influence. He mentioned that a golf ball can have only ONE type of spin at a time..............like you can't have back-spin & sidespin at the same time. HHHmmmmm. Interesting...........
This discussion is fun. It always elicits the same incredulous responses.

1. The face doesn't rotate through impact.
2. Impact happens so fast it's impossibe to influence what happens.

Now we have the "testimony of an expert in the field".   He's a "physics guy" -- a real scientist -- so he can't possibly be wrong. Well, my physics guy says just the opposite of your physics guy. He's telling me than the ball leaves the face at 90 degrees to where the face is pointing and that will always be the initial direction of flight.
also said it takes the average tour player 18-24 inches to rotate the clubface through the impact zone. I suppose that's the "foot on either side of the ball" we have heard about.

But in a previous post you said something like, "The face doesn't rotate through impact. so let's get that out of the way right now." Are we to assume that the player starts rotating the face when it is 12 inches from the ball, stops rotating it at impact/compression, and then resumes rotating it for 12 inches after separation?   Of course not. Your "physics guy" is right in this instance. The clubface is constantly rotating relative to the target line from the beginning of the swing to the finish. It is geometrically inevitable. The golf swing is a "side-on" motion performed with a "two-levered tool". The toe travels farther and faster than the bottom of the shaft throughout the swing. That's a given. The other given is that the ball compresses at impact and rebounds off the face at separation. The flight of the ball is determined in that small fraction of a second when the ball is on the face of the club. It's simply illogical to assert that it happens too fast to have any consequence. It is the only thing of consequence. It is the moment of truth.

I think 1p is all wrong on this. If swingpath doesn't dictate initial line of flight what the hell difference does it make how we line up. Just make sure the face angle is right.............lol........ why set up open or closed? Wouldn't matter..........

Well, in fact it doesn't really matter. As I said previously, Snead aligned to the right and pulled the ball toward the target. Trevino aligns to the left and pushes the ball toward the target. If you get the face angle right durng the moment of truth, it doesn't matter at all......lol.....so long as you can do it repetitively.

& 1 your reference about the "divot pointing left" thing proves nothing ............ball is hit first and is long gone, then the divot.

But a proper divot starts very close to the front of the ball. If it points left of the target line, it indicates that the clubhead was on the target line at impact and no longer traveling in-to-out. But the clubface can be open, square, or closed to the line and the path at that instant. That will determine the initial direction of flight. How the ball is compressed while the clubface is rotating will detirmine the prevailing axis to spin and hence how the ball will curve in flight.

I would love to see someone hit a ball that starts right of target & draws back with an open face at seperation.......lol
Did you watch the US Open last week? That shot was hit thousands of times if you add in all the shots hit on the range......lol.

Posted By: One Planer
Date Posted: 22 June 2006 at 8:49am

Originally posted by lpratt17

<snip>

I'm saying impact "thru separation" because the ball contacts the club face for 0.00045 seconds - I am pretty sure that you aren't changing the face angle too much in that amount of time.

It doesn't take much. Impact is a pretty violent event from the balls point of view.

If your clubhead speed was 150 mph, your club would move 3 centimeter or just over an inch in .00045 seconds. I'm not denying that rotation is happening, I am telling you that the rotation has minimal effects on side spin.

Average swing speeds even among tour players aren't anywhere remotely near 150 mph, but it doesn't really matter. In fact, the higher the swing speed, the more the effect of the compression phase. More important is the speed of the toe relative to the speed at the bottom of the shaft. That differential is very significant in terms of how the ball is compressed. It adds leverage to the shot. Toe speed can be significantly higher than shaft speed for stronger players.

If it had more significant effects, as you contend, it would be difficult to remain even remotely consistent. It is nearly impossible to repeatedly manipulate the clubface at impact. That is what make the 1PS so nice - you don't consciously manipulate the club face throughout the downswing. It remains fairly square throughout the impact zone.

I'm not talking about "manipulating the clubface" at impact. I'm describing the dynamics of impact and why the ball does what it does when it leaves the clubface.

lpratt

Posted By: One Planer
Date Posted: 22 June 2006 at 9:01am

Originally posted by lpratt17

Randini, you are the voice of reason. As I stated earlier in the post, OnePlaner is usually full of good information, but this is crazy talk - science doesn't lie. I can't even believe this is the same OnePlaner who gave me so many useful nuggets in the past.

I agree that swing speed is also a component in the equation. The slower the swing..i.e. a putt, the more club face determines initial direction; the faster the swing, the more swing path determines initial direction.

I'm in a position rather like Galileo when he proposed that Copernicus' heliocentric theory of the universe was right.. I'm challenging the age-old ball flight rules. You and Randini are the Inquisition. Unlike Galileo, I will not relent.

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