AOA to LAUNCH ANGLE - SPIN SAVED or LOST - LOFT COMPENSATION NEEDED

[nkurz]

I'm excited that you think there might be something here.  I often worry I come across as deranged.   If it's OK, I'm going to respond only to your later posts.  If I failed to answer something previous and it's still relevant, please redirect me.  

 

Thinking about it in terms of a stroboscopic photo seems helpful.  I'll offer a slightly clearer one from Cochran and Stobbs "The Search for the Perfect Swing": 

 

 

This nicely illustrates the "double pendulum" model: the shoulders swing the hands, and the hands swing the club. Near the top of the backswing the angle of the club to the arms is almost constant (wrists cocked) and the club and hands move at about the same speed.  But by the time the shaft is parallel, the hands slow and the angular acceleration of the club becomes dominant.  

 

By the time of impact, the head (due to the increases angular speed of the shaft) is moving much faster than the hands.  The usual estimate is that for a 100 mph swing, the hands are moving at about 20 mph forward and slightly upward.  Here's a video that tries to make that more explicit.  It's interesting, but you don't need to watch it for our discussion.  The preview scene tells most of the story for our purposes: 

 

 

There are thus two ways that a positive Angle of Attack can be created: the hands can be moving upward, or the shaft can be past vertical at impact.  Or both!  Almost always, the hands will be moving slightly upward through impact.  But relative to the speed of the head, they are moving very slowly.  As Stuart points out, it's only their upward motion that affects AOA---the forward motion just "lengthens" the flatter section at the bottom of the swing.  

 

Since we looking at the change in AOA (and not just the absolute AOA) what really matters is whether the  direction of the hands changes significantly based on the forward and back distance of the impact position.    I'm asserting that it doesn't, or at least doesn't change much when the ball is positioned somewhere between the golfers feet.  

 

When I say that I expect a 1:1 correspondence between a change in AOA and change in Dynamic Loft, what I really mean is that I'm assuming that for a given golfer with a given club almost all the change in AOA corresponds to a change in shaft lean at impact, and that Dynamic Loft changes almost directly with shaft lean. 

 

I'm not sure whether it's going to possible to confirm or deny this from looking at historical swings:  different golfers do have different natural hand paths at impact.  For it to work the way I'm proposing, I think one does need to vary the ball position with the same swing, or at least have a record of the ball position chosen.   I'm not trying to claim that all means changing of AOA will produce an equal change in Dynamic Loft, only that there exists at least one way where this can be done by most golfers if they were to so desire.  

 

 

Thanks for continuing to engage!

[hwturner17]

I have tried to comprehend what Howard wrote but my brain is too small and too frail. Can someone who has a good hold of this topic look at these numbers and tell me if my loft is correct? This was 8 degrees in a Ping 430 LST

[Stuart_G]

38 minutes ago, nkurz said:

Since we looking at the change in AOA (and not just the absolute AOA) what really matters is whether the  direction of the hands changes significantly based on the forward and back distance of the impact position.    I'm asserting that it doesn't, or at least doesn't change much when the ball is positioned somewhere between the golfers feet. 

 

That's not an uncommon occurrence - particularly when am's are told a higher AoA is better and try to increase it on their own without the benefit of proper instruction.

 

But it's far from the only possible way.  The (in many top instructors opinion) better way to increase AoA does involve leveraging the upward motion of the hands at impact either from a change in ball position - but more likely a change in the amount of secondary tilt.  But in this case without any significant change in shaft lean or dynamic loft.  So ball is still forward in the stance but hands keep a similar position relative to the ball position.    That is the more common method used among high level players (like the ones I believe Howard was predominately working with).
 

And of course like any spectrum - there is a wide range between those two extremes that are also possible.

 

So the assertion can be true - but is not always going to be true.   There are just too many possibilities to be able to simplify it down to any single assertion.

Edited March 22, 2023 by Stuart_G

[nkurz]

22 minutes ago, Stuart_G said:

The (in many top instructors opinion) better way to increase AoA does involve leveraging the upward motion of the hands at impact either from a change in ball position - but more likely a change in the amount of secondary tilt.  But in this case without any significant change in shaft lean or dynamic loft.  

 

I agree.  I'm not trying to say that hitting the ball on the upswing is the best way for anyone to improve their scoring at Golf (which I presume is the instructors goal) although I guess I do think it's necessary if the goal is to compete successfully in Long Drive.  Far back in the thread I offered the example of putting Iron Byron on a ramp and asking how this would change the dynamic loft.  In that artificial case, I think Launch Angle has to increase one for one with the ramp.  I had presumed that this would be analogous to a golfer leaning away from the target, but I'm not sure of this.  Do you have reason to believe that upper body lean wouldn't affect shaft lean?  

 

22 minutes ago, Stuart_G said:

So the assertion can be true - but is not always going to be true.   There are just too many possibilities to be able to simplify it down to any single assertion.

 

That's correct too.  I've probably stated it wrong at times, but my belief is not that "all sheep in Scotland are black".  I'm making the much narrower claim that "at least one side of one sheep in Scotland black".  I'm not trying to say that all changes in AOA must always be accompanied by a corresponding change in Launch Angle.   I'm saying that it's frequently possible for a golfer who wishes to optimize their driving distance to increase their Launch Angle by several degrees without significantly increasing their spin, and that one way of accomplishing this is to play the ball higher and farther forward.   I'm not claiming that this is a good idea for most golfers, that there are no downsides, or that there is no other way to accomplish this, only that it is an option that can at least theoretically produce the desired result. 

[Stuart_G]

1 hour ago, nkurz said:

Do you have reason to believe that upper body lean wouldn't affect shaft lean?  

 

(Not an instructor so take this with a grain of salt).

What happens to the shaft lean will depends on what other corresponding changes are made - more commonly with the release timing.   Delaying it a bit is what I believe is generally required to keep the shaft from getting too much forward lean and too much dynamic loft being added.

 

 

1 hour ago, nkurz said:

I'm saying that it's frequently possible for a golfer who wishes to optimize their driving distance to increase their Launch Angle by several degrees without significantly increasing their spin, and that one way of accomplishing this is to play the ball higher and farther forward.

 

Possible - but not guaranteed.   Just based on observations and other's experiences here - increasing AoA in a way that also increases dynamic loft  can increase the launch angle but also adds to the spin.  That generally doesn't help much with distance because of the added spin.   And that's assuming that face impact location doesn't deteriorate - which it commonly does when people try to go too far with the concept and end up catching it low on the face - which adds even more spin.

 

What has a much better chance of helping distance is if one can increase the AoA with no or minimal change to the shaft lean or dynamic loft.  That's were the most theoretical improvement can typically be seen.

 

1 hour ago, nkurz said:

  I'm not claiming that this is a good idea for most golfers, that there are no downsides, or that there is no other way to accomplish this, only that it is an option that can at least theoretically produce the desired result. 

 

No worries.  Understood.

[nkurz]

2 hours ago, hwturner17 said:

I have tried to comprehend what Howard wrote but my brain is too small and too frail. Can someone who has a good hold of this topic look at these numbers and tell me if my loft is correct? This was 8 degrees in a Ping 430 LST

 

Might not be the best thread for it, but since no one else has answered, I'll try: it's a great poke but really hard to say whether your current loft is optimal without knowing exactly where that particular impact was on the clubface.    Use something like "foot spray" on the face and check the mark.  Your current loft is probably pretty close to optimal, though.  The problem with going to a lower loft is that you'll have a lower launch angle.  The problem with going to a higher loft is that you'll have more spin.  Where you are is probably a decent tradeoff.  https://trajectory.flightscope.com is a good tool for playing around with what changes would look like.    It gives a shorter distance than you got (are you at altitude?), but probably the relative changes will be the same.  

 

Theory would say that you could get a few more yards of distance if you could launch the ball even higher with even less spin.   Practicality would say that what you have is pretty good, and if you can do it repeatedly you probably should stick with it.  Your smash factor is a little low, and your launch angle is rather high for your AOA, so I'd suspect you caught that above the COG.   This is great if you can do it consistently, since that's one of the best ways to get a high launch and low spin.   Teeing it higher farther forward might be something else to try if you want more distance, but I'm the only one in this thread who thinks this, and the others are more expert than I am.   

 

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[Howard_Jones]

4 hours ago, hwturner17 said:

I have tried to comprehend what Howard wrote but my brain is too small and too frail. Can someone who has a good hold of this topic look at these numbers and tell me if my loft is correct? This was 8 degrees in a Ping 430 LST

 

 

 

Lets start with PTR/ smash factor, it tells that your impact is heel side of center with 1.46as smash.

Try to move impact to the area of the center and max to 3/8" toe side vs center. Potentially, your smash factor improves from 1.46 to 1.51 - 1.52, and that means ball speed goes up from 175.2 to 181-183 mph.

Launch angle.
- its good for max carry from that ball speed, but not with that much spin.
(A good mix of carry and total is with a descent of 40* .
143.5 rpm changes descent with 1.0*, so to get to 40* we must cut of 143.5 x 2.2 = 316 rpm of spin...NO problem)

Its vertical gear effects who is the "spin monster", and for each 1/8" we move impact UP, spin will drop with 240 rpm average, and launch will go up with 0.35*. So, you only need to move impact 2/8" higher to cut of close to 500 rpm. (at your club speed, most likely 500 rpm at 2/8" - 500 rpm down = 3.5 down on descent = boosted roll out.

But moving impact 2/8" higher will bring launch 0.7* higher....

At your club speed, ball compression is higher than it is from 100, (20% higher), and that lowers the RATIO from Dynamic loft to launch angle vs those numbers ive got at hand, but expect about 0.8-0.82 difference for launch for each 1.0+ you change loft....

(The suggested movement of impact 2/8" UP, moves launch higher close to what 1.0* loft delivers, so to keep LA as now when moving impact, you need lower 1.0* loft for that reason.)

APPLE TO APPLE of the datas you got, vs potential from Flightscope
(Same swing and club, just move impact as i suggest)
- Another 16 yards can be found on carry (290.9 vs 306.6)
- Another 18 yards can be found vs total ( 315 vs 333.2)
(Flightscope and Trackman dont return the same values, but the difference should be what we see here)

Edited March 22, 2023 by Howard_Jones