reducing spin on drives

[iacas]

Originally Posted by broomhandle

I understand just fine. It's translating my understanding to Trackman's terms AND your terms that is a struggle.

I'm using the same terms as Trackman.

Originally Posted by broomhandle

Trackman says - SL = DL - AOA   - agrees with you

Yes.

Originally Posted by broomhandle

Trackman's seems to be DL = Static Loft +- shaft lean + AOA

Nope.

First off, dynamic loft is calculated by Trackman. It's not measured. But regardless of that, dynamic loft is simply this: the amount of loft, relative to vertical, at the moment of maximum compression of the golf ball.

AoA is not a factor in dynamic loft. This clubface has the same dynamic loft whether the AoA is +8° or -4° or 0° or whatever:

The simplest way of considering dynamic loft is simply static loft +/- shaft lean. It's not entirely accurate because the shaft kicks and does other things to change the actual loft, but it's close. It's also not accurate with metalwoods because of roll (more loft at the top, less at the bottom).

But in all cases, AoA is not a factor in dynamic loft except to say that if you have the shaft leaning forward, you'll TEND to hit down, and if it's leaning back, you'll TEND to hit up... but that changes the actual dynamic loft of the club, it doesn't change the Dynamic Loft because of the AoA.

Originally Posted by broomhandle

assume a neutral shaft for simplicity and spin loft = static loft

Spin loft does not equal static loft.

If we freeze dynamic loft at 10 degrees, a driver with AoA of -5° will have a spin loft of 15° and a LOT more spin than the same dynamic loft delivered with an AoA of +5° (spin loft = 5°).

Assuming that ball against the driver face was at maximum compression: you could calculate or even measure if the picture was good enough quality the dynamic loft. But you have no idea if the club is traveling up or down slightly.

Originally Posted by broomhandle

10* driver 5* down:

dl = 10-5 = 5

sl = 5--5 = 10

10* drive 5* up:

dl = 10 + 5 = 15

sl = 15 - 5 = 10

The bold ones are wrong... Trackman says what they say (and they're correct) because you tend to see charts like this.

AoA	Dynamic Loft	Spin Loft	Result
-5°	5°	10°	Low launch
0°	10°	10°	Medium launch
5°	15°	10°	High launch

In other words, to hit down on the driver the shaft will often be leaning forward, and vice versa to hit up on the driver.

The amount of spin often remains the same.

I'll bring it all home for you now...

The driver fitting chart is still a driver fitting chart because you cannot get your maximum distance given an AoA of -5 with the same spin loft as someone hitting up 5°. SO they recommend that you increase the spin loft (typically by changing the shaft to change the dynamic loft, but only after you change the clubhead to have more loft, as that's MUCH easier and has a bigger effect) in order to increase the spin loft.

"High launch, low spin" is the mantra for the longest drives, but if someone's going to hit down, they're going to need "high enough launch with lots of spin (relatively speaking)."

For example, the 90 MPH guy. He can carry the ball 214 when AoA is +5°. If you had that guy with 13.4° spin loft and an AoA of -5°, that means his dynamic loft is 8.4°. He'll have 2630 RPM backspin and his ball will launch at about 6°. Low launch, low spin is not going to have that guy carrying the ball very far at all. So he needs a higher launch and a higher spin to get it to carry 191 given the constraint that his AoA is -5°.

[Golfingdad]

Originally Posted by iacas

First off, dynamic loft is calculated by Trackman. It's not measured. But regardless of that, dynamic loft is simply this: the amount of loft, relative to vertical, at the moment of maximum compression of the golf ball.

AoA is not a factor in dynamic loft. This clubface has the same dynamic loft whether the AoA is +8° or -4° or 0° or whatever:

The simplest way of considering dynamic loft is simply static loft +/- shaft lean. It's not entirely accurate because the shaft kicks and does other things to change the actual loft, but it's close. It's also not accurate with metalwoods because of roll (more loft at the top, less at the bottom).

But in all cases, AoA is not a factor in dynamic loft except to say that if you have the shaft leaning forward, you'll TEND to hit down, and if it's leaning back, you'll TEND to hit up... but that changes the actual dynamic loft of the club, it doesn't change the Dynamic Loft because of the AoA.

OK, now you guys are getting into area of the things I mentioned kicking around in my head, so I'll jump in.

How does dynamic loft relate to launch angle?

From what I'm reading above, it sounds like they must be equal.  (If launch angle is just degrees above the horizontal that the ball leaves the clubface, and dynamic loft is degrees behind the vertical of said clubface at impact, and the ball leaves the clubface in the direction it is pointing, then DL would equal LA)

Which means that launch angle would be static loft - shaft lean.  But with any decent amount of shaft lean and a typical driver (say, 10 degrees) then you'd be talking about 5-7 degrees launch?  When I believe 10 or so is optimum, correct?

So, what am I missing?

[broomhandle]

Quote:

Originally Posted by Golfingdad

OK, now you guys are getting into area of the things I mentioned kicking around in my head, so I'll jump in.

How does dynamic loft relate to launch angle?

From what I'm reading above, it sounds like they must be equal.  (If launch angle is just degrees above the horizontal that the ball leaves the clubface, and dynamic loft is degrees behind the vertical of said clubface at impact, and the ball leaves the clubface in the direction it is pointing, then DL would equal LA)

Which means that launch angle would be static loft - shaft lean.  But with any decent amount of shaft lean and a typical driver (say, 10 degrees) then you'd be talking about 5-7 degrees launch?  When I believe 10 or so is optimum, correct?

So, what am I missing?

Quote:

a) The initial launch angle of the ball always falls between
the dynamic loft and attack angle at impact.
b) TrackMan data has shown for drivers, that dynamic loft
normally accounts for about 85% of the launch angle, while
attack angle accounts for the remaining 15%. For irons, the
ratio is around 75% dynamic loft and 25% attack angle.
For example, a 10° launch angle would result from a iron
shot where the attack angle is -5 degrees and the Dynamic
Loft is +15 degrees (15 * 75% plus -5 * 25% equals 10).

[Golfingdad]

Originally Posted by broomhandle

a) The initial launch angle of the ball always falls between

the dynamic loft and attack angle at impact.

b) TrackMan data has shown for drivers, that dynamic loft

normally accounts for about 85% of the launch angle, while

attack angle accounts for the remaining 15%. For irons, the

ratio is around 75% dynamic loft and 25% attack angle.

For example, a 10° launch angle would result from a iron

shot where the attack angle is -5 degrees and the Dynamic

Loft is +15 degrees (15 * 75% plus -5 * 25% equals 10).

OK, that makes sense.  Thanks.

[broomhandle]

Quote:

1. Spin loft does not equal static loft.

2. If we freeze dynamic loft at 10 degrees, a driver with AoA of -5° will have a spin loft of 15° and a LOT more spin than the same dynamic loft delivered with an AoA of +5° (spin loft = 5°).

3. The bold ones are wrong...

1. It does when the shaft is neutral by my definition.

2. But you can't. Dynamic loft and AOA are tied together in one equation. There are other variables but when those stay equal every degree of change of AOA changes DL a degree.

3. Not if the shaft is neutral by my definition.

Ok, DL is simply actual loft at impact.

Assume: 0 shaft flex and 0 clubface roll to simplify for now.

Assume: 10 degree driver

DL = club loft  + shaft lean       ~ that arbitrarily makes hands leading club negative shaft lean

Shaft lean is determined almost entirely by left arm angle and angle between the clubshaft and left arm(call it lag or flip)

SL = LAA + lag/flip

So with a vertical left arm and 0 lag/flip

SL = 0 + 0

DL = Club loft = 10

With left arm 5 degrees short of vertical and 0 lag/flip

SL = -5+0

Dl = CL - 5 = 5

With left arm 5 degrees short of vertical and 5 lag

SL = -5-5

DL = CL - 10 = 0

With left arm 5 degrees past vertical and 0 lag/flip

SL = +5+0

DL = CL+ 5 = 15

With left arm 5 degrees pat vertical and 5 degrees flip

SL = 5+5

DL = CL+10= 20

******************************************************************************************************************************

Now for the connection with AoA

Exact AoA is complex but certainly dominated by left arm angle.I think that left arm angle is a workable approximation.

Low point is basically at left arm vertical and low point is by definition AoA = 0

It really should be shoulder-to-clubhead angle but I doubt if that makes 1 degree of difference in AoA. I'll do the trig sometime.

AoA = Left Arm Angle

Dynamic Loft = Club Loft + Shaft Lean

Shaft Lean = Left Arm Angle + lag/flip

so:

Dynamic Loft = club loft + Left Arm Angle + lag/flip

Dynamic Loft = club loft + AoA + lag/flip

Spin Loft  SL = DL - AoA

so

spin loft = club loft + AoA + lag/flip - AoA

spin loft = club loft - lag/flip

neutral shaft = lag/flip = 0

So for a neutral shaft spin loft = club loft

summary of possibilities:

Left Arm Angle	lag/flip	Shaft Lean(LAA+lag/flip)	Dynamic Loft(CL+SL)	AoA(LAA)		Spin Loft(DL-AoA)
-5	0	-5	5	-5		10
-5	-5	-10	0	-5		5
-5	+5	0	10	-5		15
0	0	0	10	0		10
0	-5	-5	5	0		5
0	+5	5	15	0		15
+5	0	5	15	+5		10
+5	-5	0	10	+5		5
+5	+5	10	20	+5		15

I think if you flip on a downward or level swing you have bigger problems than loft calculations.

so the only time you could realistically increase spin loft above club loft would actually be on the ascending blow.

[Golfingdad]

Originally Posted by broomhandle

But you can't. Dynamic loft and AOA are tied together in one equation. There are other variables but when those stay equal every degree of change of AOA changes DL a degree.

I got lost with most of what you were saying in that last post, but this part I can address.  Erik explained pretty clearly that AA is not a function of Dynamic Loft.

If I slide the club along the ground (AA=0) with the shaft vertical, the dynamic loft will be equal to the static loft.  If I were to drop the club straight down to the ground with the shaft vertical (AA=90) it would still have a dynamic loft = to static loft.  Obviously that is an absurd example because the ball couldn't get to the clubface, but the point still stands, dynamic loft and attack angle aren't related.  (Other than considering that, like Erik already mentioned, steeper attack angles are usually a by-product of a lot of forward shaft lean and vice versa)

The relationship between dynamic loft and attack angle only comes together to help determine spin.

[broomhandle]

Originally Posted by Golfingdad  Erik explained pretty clearly that AA is not a function of Dynamic Loft.

dynamic loft and attack angle aren't related.

They are related if we're talking about them in the context of a practical golf swing.

In any useful golf swing if you swing down you inherently remove loft. You may do other things to get some back.

In any useful golf swing if you swing up you inherently add loft. You may do other things to give some back.

For 1 degree differences you can net out at 0.

Swinging down at 10 degrees ain't hard. Show me any workable way to get all 10 degrees back.

[broomhandle]

Imagine swinging a 20 degree chipper with a perfect one lever pendulum putting stroke.

The shaft is perfectly vertical at low point/0 AoA.

The dynamic loft at low point/0 AoA is 20 degrees.

To get -5* AoA the ONLY possibility is to hit the ball 5 degrees before the single lever reaches low point.

That MUST produce an effect of 5 degrees of 'shaft lean' and dynamic loft of 20-5 = 15.

Spin loft = 15 - -5 = 20

For every degree around the circular arc the AoA changes 1 degree AND the dynamic loft changes 1 degree.

The spin loft is always and only 20 degrees.

These relationships stay true in a full swing. There are only other variables ADDED.

[iacas]

Originally Posted by Golfingdad

How does dynamic loft relate to launch angle?

Did you get this answered satisfactorily?

Originally Posted by Golfingdad

From what I'm reading above, it sounds like they must be equal.

Nope. Clubhead speed and AoA (and centered-ness of contact, but we tend to assume sweet spot contact in these kinds of threads) factor in. The faster the clubhead speed the more the ball will come off closer to the face angle, but even at 90 MPH I think it's north of 80% face angle.

Originally Posted by broomhandle

1. It does when the shaft is neutral by my definition.

2. But you can't. Dynamic loft and AOA are tied together in one equation. There are other variables but when those stay equal every degree of change of AOA changes DL a degree.

3. Not if the shaft is neutral by my definition.

Don't take this personally. They're just facts...

1. Spin loft does not equal the static loft. Not unless the stars align perfectly - no shaft deflection OR lean and 0° AoA.

2. They aren't tied together. No. You're wrong and using a bad formula. AoA has no effect on dynamic loft. It's independent. Spin loft is defined as the angle between the normal to the dynamic loft and the club's AoA. (See the postscript as we're limiting this to 2D.) You can deliver 10° of dynamic loft with the same clubhead with all sorts of AoAs and thus a range of spin lofts.

3. Your definition doesn't match reality, then.

You can try to simplify things down to a chart as you've done, but the shaft kicks, the clubhead leads, and small bits of angle matter. The shaft kicks, the player is in the process of jumping, the left shoulder is moving upwards, etc.

This is particularly evident of the photo here. By simple measurements, Tiger Woods drives this ball into the ground. He's de-lofted his 3W so much that it would have negative loft using the simple math you're attempting to use. Yet the ball takes off on the angle shown in orange AND his AoA is about -3°.

Similarly, predict Grant's AoA? Or just tell me if it's positive, negative, or neutral. And is his dynamic loft higher or lower than his club's static loft?

Originally Posted by broomhandle

In any useful golf swing if you swing up you inherently add loft. You may do other things to give some back.

Swinging down at 10 degrees ain't hard. Show me any workable way to get all 10 degrees back.

PGA Tour averages barely get to half of -10° and that's with a pitching wedge: http://thesandtrap.com/t/32498/trackman-data-pga-tour-vs-lpga .

Rory: hitting down or hitting up?

Robert: hitting down or hitting up?

Or maybe they're both 0°?

You can't know. Rory might be jerking his left shoulder up like crazy. Robert might be keeping his left shoulder low and might brush the mat after hitting the ball. You can't know - and any angles you get here don't tell you.

Originally Posted by broomhandle

Imagine swinging a 20 degree chipper with a perfect one lever pendulum putting stroke.

The shaft is perfectly vertical at low point/0 AoA.

The dynamic loft at low point/0 AoA is 20 degrees.

A chipper doesn't have much shaft deflection, and the stroke is not a full swing. So you've removed from the equation several pieces which can affect AoA and dynamic loft, including: shaft kick/bend, toe droop, the body going into extension/flexion, etc.

I can lag a clubhead well behind my hands, have a lot of forward shaft lean, and get a positive AoA if the center of that circle is being pulled upward.

I can also flip a clubhead past my hands and still get a negative AoA if the center of that circle is still being driven downward.

Originally Posted by broomhandle

To get -5* AoA the ONLY possibility is to hit the ball 5 degrees before the single lever reaches low point.

That MUST produce an effect of 5 degrees of 'shaft lean' and dynamic loft of 20-5 = 15.

Spin loft = 15 - -5 = 20

You're looking at a single lever system. The golf swing is not a single lever. Even if we ignore the entire rest of the body (the legs, the spine), it's a dual lever - your wrists and your shoulder are the two levers.

Originally Posted by broomhandle

For every degree around the circular arc the AoA changes 1 degree AND the dynamic loft changes 1 degree.

The spin loft is always and only 20 degrees.

These relationships stay true in a full swing. There are only other variables ADDED.

If only that were true. Unfortunately, they do not.

Heck, I don't even have to get that far into it. The driver club shaft, at impact, is not straight. That alone throws off the math.

NOW, to answer the original question. If you want to reduce spin on drives, reduce the spin loft.

P.S. We haven't even touched on the fact that spin loft is a 3D measurement. This assumes a path "square" to the clubface angle. We'll keep things simple for now - but it's basic trig if anyone wants to get into it on their own.

[chris3putt]

Originally Posted by Beachcomber

I don't know?  But I'd like to meet him.  He looks like he can swing the golf club?

Just FYI, Grant Waite is a New Zealand born golfer, who played on the PGA tour for 12 years, his highlight being a win at the 1993 Kemper Open. He also shot a 60 during the 1996 Phoenix Open.

Always admired for his swing and long game, lack of sucess with the flat stick eventually lead him to switch to coaching, and I believe he is now based out of Ocala in Florida.

Being a fellow Kiwi, I just had to throw this in!!

[Sacman]

I have seen multiple people say hitting the ball higher on the club face would help reduce the spin on my drives. I got out to the range after work friday and made a conscious effort to hit it higher on the face. I felt like this caused me to make an even steeper downward strike. I need to see my numbers on a simulator but I think that my numbers have gone up. I am still hitting the high center of the club face so the strike is still good.

[iacas]

Originally Posted by Sacman

I have seen multiple people say hitting the ball higher on the club face would help reduce the spin on my drives. I got out to the range after work friday and made a conscious effort to hit it higher on the face. I felt like this caused me to make an even steeper downward strike. I need to see my numbers on a simulator but I think that my numbers have gone up. I am still hitting the high center of the club face so the strike is still good.

Hitting higher on the face - with everything else the same - will reduce spin, yes. Will increase launch angle too.

But if your angle of attack becomes more negative, then you're right, you may not decrease spin at all and may even increase it slightly.

[mvmac]

Originally Posted by Sacman

I have seen multiple people say hitting the ball higher on the club face would help reduce the spin on my drives. I got out to the range after work friday and made a conscious effort to hit it higher on the face. I felt like this caused me to make an even steeper downward strike. I need to see my numbers on a simulator but I think that my numbers have gone up. I am still hitting the high center of the club face so the strike is still good.

Quote:

Originally Posted by iacas

Hitting higher on the face - with everything else the same - will reduce spin, yes. Will increase launch angle too.

But if your angle of attack becomes more negative, then you're right, you may not decrease spin at all and may even increase it slightly.

Just tee it higher.  Make sure that you are not actually hitting down with the driver, ideally want to have a positive angle of attack.  And like Erik said, yes hitting it higher on the face, with everything equal will lower spin and launch it higher, that's vertical gear effect Opposite is true when you hit it low on the face.

[Sacman]

Curious to know how shoulder tilt at set up would help with striking the ball on the up swing?

[mvmac]

Originally Posted by Sacman

Curious to know how shoulder tilt at set up would help with striking the ball on the up swing?

I like to see more right tilt at address, due to the hips being pushed a few inches forward (towards the target) and the ball being off your left toe, generally

http://thesandtrap.com/t/44307/hitting-up-or-down-with-the-driver-in-an-inline-pattern

[Beachcomber]

Originally Posted by chris3putt

Just FYI, Grant Waite is a New Zealand born golfer, who played on the PGA tour for 12 years, his highlight being a win at the 1993 Kemper Open. He also shot a 60 during the 1996 Phoenix Open.

Always admired for his swing and long game, lack of sucess with the flat stick eventually lead him to switch to coaching, and I believe he is now based out of Ocala in Florida.

Being a fellow Kiwi, I just had to throw this in!!

Cheers mate!

[Sacman]

Went to the local shop with a launch monitor today to try and get a feel for how my ball striking has improved since I started this post. Hit some 6 irons and drivers.

Driver titleist D3 B-3 setting- 280 carry on a majority of my shots and was more of a pull but straight otherwise (improvement from 258 carry)

6 iron Mizuno MP-53- 190 carry on a majority of my shots and was more of a push but like my driver it was straight (improvement from 170 carry)

I would say that I have made some progress with my distance due to a little shoulder tilt with driver and driving my right shoulder through with my irons. I'm excited about my progress.

[jgreen85]

The chart references a "tour type ball." any material changes attributable to a non-urethane ball?