Question about driver loft and spin (for the gear junkies really)....

[Lord Helmet]

So Im watching some videos killing time.  Talking about driver.  I have a 9* head that I turn to 10.5.  In the vids I was watching, cant recall the specifics, it was stated that reducing loft takes off spin (thus increasing loft adds spin).  Simple google search said neighborhood of 400revs per degree.  I dont think Ive ever heard of this or if I have, I totally forgot about it.  Why does this happen? here is what i found:

 

Per ° loft, the spin of the driver changes by about 400-500 rpm. The more loft, the higher the spin. You should consider this aspect before you change driver loft. The spin contributes significantly to the overall length.

 

[Howard_Jones]

57 minutes ago, Lord Helmet said:

So Im watching some videos killing time.  Talking about driver.  I have a 9* head that I turn to 10.5.  In the vids I was watching, cant recall the specifics, it was stated that reducing loft takes off spin (thus increasing loft adds spin).  Simple google search said neighborhood of 400revs per degree.  I dont think Ive ever heard of this or if I have, I totally forgot about it.  Why does this happen? here is what i found:

 

Per ° loft, the spin of the driver changes by about 400-500 rpm. The more loft, the higher the spin. You should consider this aspect before you change driver loft. The spin contributes significantly to the overall length.

 

That's far off from reality
Trackmans algorithm is based on THIS formula

1 degree change of loft at 80 mph club speed = 208 rpm
If club speed is 10% higher (88), spin is 10 % higher = 229 rpm
if club speed is 20% higher (96) spin is 20% higher = 250 rpm
Up at 120 mph, CS is now +50% so spin level is plus 104 or 312 as sum.

The problem with the driver is IMPACT location and vertical gear effects.
We need a ROBOT to get impact tight enough to isolate this numbers, so what we will see is only trends and averages vs NEW impact location after changing.

Moving impact 1/8" lower on the face, will add 240 rpm....raising impact 1/8" will cut off 240 rpm
Thats why it is so hard to judge this with a human player.

 

Edited Thursday at 08:02 PM by Howard_Jones

[dsmil]

Other than what's mentioned above, there is also a difference between making a loft adjustment via the adapter vs. going from an actual 9 degree to 10.5 degree clubhead.  All else equal, changing to an actual 10.5 degree head will increase spin.  "Adding loft" with the adapter just closes the face.  Some people will then simply hit the ball more left with no change to launch/spin.  Some people will adapt to the closed face and simply add launch/spin.  Many of us will be somewhere in the middle.

[Stuart_G]

14 hours ago, Lord Helmet said:

it was stated that reducing loft takes off spin (thus increasing loft adds spin). 

 

 I dont think Ive ever heard of this or if I have, I totally forgot about it.  Why does this happen? here is what i found:

 

I'm pretty sure you have heard of it, you just didn't recognize it in a different context.  

 

It's the same reason why shorter irons spin more than the longer irons.    e.g. PW spins more than a 7i.  Doesn't really matter if the change in loft is  1* or 10* or 15*  - the reason is the same, it's just the magnitude of the change that's different.

 

The simple answer is that the more the face is tilted back (the more the loft increases), the lower the impact is on the ball.  The impact moves more "under" the ball.   And the the lower impact means more below the c.g. of the ball - relative to the direction of travel of the head.   And the more the impact location is offset from the c.g., the more of the impact force goes into rotating the ball.

 

It's the same with any impact with a ball in other sports - soccer, tennis, ping pong, etc...

 

Gear effect is different in that it's all about the where the impact is on the head relative to the c.g. of the head and how the resulting rotation force on the head adds or subtracts to the basic spin of the ball caused by the dynamic or spin loft.

 

Edited Friday at 09:19 AM by Stuart_G