James Marshall (Hogan1953)
New member
Does the golfer actually physically "compress" the ball more the lower the spin loft or is it a turn of speech?
What tilts the spin axis?
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Brian Manzella
Administrator
Let's assume everything else is equal:
CofGs line up.
Path/Face.
Then the answer is ABSOLUTELY yes!
What other factors are you considering that would change it?
Brian Manzella
Administrator
Other than non-lined up CoGs it is on the D-Plane.
How d'ya know, bro?
Michael Finney
New
With respect to the top of the D plane - it is a vector - no magnitude......simply a pointer in space. The "angle of attack" portion of spin loft is really a part of the bottom path vector (which has a magnitude - namely velocity).
In essence, the top of the D plane is a really long line in space (gathered at max deformation about halfway through the interval)....the bottom of the D plane is a tiny line 1/4" long or so - which represents the 3D movement of the COG of the head and 5 inches of shaft flying through the air...
see...that's simple
In essence, the top of the D plane is a really long line in space (gathered at max deformation about halfway through the interval)....the bottom of the D plane is a tiny line 1/4" long or so - which represents the 3D movement of the COG of the head and 5 inches of shaft flying through the air...
see...that's simple
Brian Manzella
Administrator
I really don't know what the big deal is....The D-Plane is shown as a plane with two vectors....Spin Loft is simply not just the loft built into the club, or the loft delivered to the ball, or the virtual Dynamic or Effective loft at mid-impact interval, it is THE LOFT THAT MAKES THE BALL SPIN, the loft that is the DIFFERENCE between the TOP of the D-PLANE, i.e. "Dynamic Loft" PLUS the divergence between that "Dynamic Loft" and where that dynamic loft is being swung through the ball, i.e, the Angle of Attack.
Now when the PATH is 0° and the FACE is 0° everything is easy, or when the PATH and the FACE are both pointed in the same place horizontally, for example 2° inside-out PATH and 2° open face.
But....!
When the PATH and the FACE diverge you have a different REAL "Spin Loft."
Imagine three buildings standing right next to each other.
If you are on the 5th floor and your buddy is in the basement—in the same building—ya'll are "X" distance apart.
But....!
If you are on the 5th floor in the building on the far left, and your buddy is in the basement on the far right, YOU GUYS ARE FURTHER APART THEN WHEN YOU WERE IN THE SAME BUILDING.
Therefore, more Effective Spin Loft.
Now when the PATH is 0° and the FACE is 0° everything is easy, or when the PATH and the FACE are both pointed in the same place horizontally, for example 2° inside-out PATH and 2° open face.
But....!
When the PATH and the FACE diverge you have a different REAL "Spin Loft."
Imagine three buildings standing right next to each other.
If you are on the 5th floor and your buddy is in the basement—in the same building—ya'll are "X" distance apart.
But....!
If you are on the 5th floor in the building on the far left, and your buddy is in the basement on the far right, YOU GUYS ARE FURTHER APART THEN WHEN YOU WERE IN THE SAME BUILDING.
Therefore, more Effective Spin Loft.
drewyallop
New
H
Probably not relevant to your main point Michael but you are mistaken on the definition of a vector. A vector has both direction and magnitude. Velocity is a vector. The magnitude of the velocity vector is speed and is proportional to the length of the vector. The direction is the direction in which the velocity vector is pointed.
Probably not relevant to your main point Michael but you are mistaken on the definition of a vector. A vector has both direction and magnitude. Velocity is a vector. The magnitude of the velocity vector is speed and is proportional to the length of the vector. The direction is the direction in which the velocity vector is pointed.
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Yeah this is starting to confuse me. I thought I had it all figured out but now I'm just getting confused.
Would it not be simpler to say (and I'd like to know if I'm wrong about any of this), when the ball is at maximum deformation the specific line in space that the clubface is aimed makes for the top line of the D plane. Then the path that the COG of the clubhead travels from impact to maximum deformation makes up the bottom line of the D plane.
This doesn't account for any gear effect or off centered hits which adds more factors to the equation.
Would it not be simpler to say (and I'd like to know if I'm wrong about any of this), when the ball is at maximum deformation the specific line in space that the clubface is aimed makes for the top line of the D plane. Then the path that the COG of the clubhead travels from impact to maximum deformation makes up the bottom line of the D plane.
This doesn't account for any gear effect or off centered hits which adds more factors to the equation.
Michael Finney
New
you are correct - i misspoke with regard to the word "vector"- as ringer says...the top line is just that - a line in space that is pointing somewhere....at max deformation.....the top line would be a ray - thanks dbl
Michael Finney
New
this is fun - the top line (now known as RAY) IS FACTORING IN GEAR EFFECT - 360* of gear effect.....and the bottom line (now known as VECTOR) IS FACTORING IN GEAR EFFECT because the ball just got hit and the club's COG is changing its course....but remember, the two lines are only receiving gear effect adjustments for half the interval - about 220 microseconds worth.....what a country
Michael Finney
New
clubface normal will now be known as RAY and the club's COG 3D orbit will be known as VECTOR.....
"So, Mrs. Haverkamp, we need to fix RAY to improve your VECTOR..."
The s & t'ers will say that when we fix VECTOR, RAY will come along for the ride
"So, Mrs. Haverkamp, we need to fix RAY to improve your VECTOR..."
The s & t'ers will say that when we fix VECTOR, RAY will come along for the ride
I would beg to differ regarding ray vs line.
Ray suggests that there is a starting point, but there doesn't necessarily need to be. Either line or ray works just fine. The clubhead could be merely a coordinate along the line, or it could be the starting point of the ray. Neither is wrong.
My personal preference is that since we are working with planes, they should be viewed as infinite. The D Plane doesn't start at the clubface because planes don't have starting points. They have coordinates. At least, that's what I remember from my days in geometry.
Ray suggests that there is a starting point, but there doesn't necessarily need to be. Either line or ray works just fine. The clubhead could be merely a coordinate along the line, or it could be the starting point of the ray. Neither is wrong.
My personal preference is that since we are working with planes, they should be viewed as infinite. The D Plane doesn't start at the clubface because planes don't have starting points. They have coordinates. At least, that's what I remember from my days in geometry.
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Your confusion contains some valid points.
First, we have some simplification Spin loft = DL - AoA
It may work well for irons, but not for driver where gear vertical and horizontal effect comes into play with a rearward Center of Gravity.
Second, we often hear how Attack Angle has no impact on spin rate. If that's the case why not just drop the AoA from the equation?
Third, the mathematical relationship between spin loft and actual spin has never been clearly defined. The data rarely has spin loft ever approaching club loft for higher lofted clubs.
Fourth, the use of the word 'SPIN' in the phrase 'SPIN LOFT' may be not be the best choice of word. It's all about launching it vertically on a certain trajectory. Horizontally we know how face to path affects horizontal launch angle, and the curve of the shot. TrackMan says Dynamic loft (or delivered loft) is more important than Attack Angle in determining vertical launch angle. If you hit down on the ball, you're changing it's trajectory lower. Keep it simple for launch feedback. If you want to get into the details of SPIN, it should have real meaning in how it directly affects spin, or risk confusion with the underlying message.
Fifth - I could continue with a few more points but it would risk derailing the train off the tracks.
Am I off base ? Do you agree? Let me know your thoughts.
Brian Manzella
Administrator
Here we go again.....
Well, only on TrackMan, but my definition is more accurate and may one day be TrackMan's as well.
GEAR EFEFCT IS FACTORED IN TO THE D-PLANE!!!!.....it happens during the first half of the impact interval.
Did you read my long post on the last page?
SPIN LOFT!!!
If it doesn't change, spin won't.
Why would it ever, necessarily?
Again, did you read my post on the last page??????
Yes, you are off base.
But, I'll smarten you up. No charge.
Well, only on TrackMan, but my definition is more accurate and may one day be TrackMan's as well.
GEAR EFEFCT IS FACTORED IN TO THE D-PLANE!!!!.....it happens during the first half of the impact interval.
Did you read my long post on the last page?
SPIN LOFT!!!
If it doesn't change, spin won't.
Why would it ever, necessarily?
Again, did you read my post on the last page??????
Yes, you are off base.
But, I'll smarten you up. No charge.
Thanks Brian. I'm not so convinced and have read your posts.
Please explain why would the actual measured spin axis be different than from what is prescribed by the D-plane? Is it a flaw in the measurement or the simplification of D-Plane (eg never intended to explain off center hits)?
We all are trying to learn something here and look forward to the discussion.
Based on the video I've seen regarding off centered hits, I don't see how this is the case.
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