## Friday, December 4, 2009

### Trackman Translations - Part II

Just so we don't lose track, here are the sample Trackman numbers again.
1. Clubhead speed = 87.3
2. Ball speed = 127.1
3. Attack angle = -3.4
4. Club Path = 5.7
5. Vert swing plane = 63.1
6. Horiz swing plane = 3.9
7. Dyn Loft = 11.3
8. Face angle = -3.6
9. Smash factor = 1.46
10. Vert. angle = 7.2
11. Horiz angle = -0.9
12. Spin rate = 6194
13. Spin axis = -17.9
14. Max Height = 15.5
15. Carry = 165.4
And Part I of the translations can be found HERE.

HORIZONTAL SWING PLANE

Horizontal Swing Plane is often termed as 'clubhead path.' In typical golf terminology, clubhead path is usually described as 'inside-to-out' or 'outside-to-in' or 'square.' In Trackman terms horizontal swing plane is assigned a number. A positive number means the golfer is swinging 'inside-to-out.' A negative number means the golfer is swinging 'outside-to-in.' In the data above, the golfer has a Horizontal Swing Plane which means that they swung the club a bit 'inside-to-out.' This *normally* will produce a hook spin on the golf ball (conversely a negative number *can* impart a slice spin on the ball). Here's a diagram of what 'inside-to-out', 'square' and 'outside-to-in' looks like.

FACE ANGLE

Simply, the angle of the clubface at impact. Positive number means it's 'open' to the target, negative number means it's 'closed' to the target.

In the data above, the golfer has a -3.6* Clubface Angle. This golfer is right handed, so they have the clubface pointing 3.6* left of the target.

One thing that is greatly misconstrued by golfers is confusing the effect of a flat left wrist and forward shaft lean on the golf ball. There's a misconception that the pro golfers hit the ball further because the shaft lean at impact 'causes them to hit a 7-iron with a 5-iron degree loft.' That's actually very untrue. When a golfer has a FLW at impact and some forward shaft lean they are just helping optimize their clubhead speed and their ball speed. Their loft of the club at impact will actually be less than it was at address, regardless if they flip or not. So the club is de-lofted most of the time, regardless if the left wrist is flat or bent at impact.

I hear some very good golfers say that the way they rid themselves of the flip was to prevent the clubface from opening at impact. This can work for many golfers and makes sense. OTOH, many flippers (like my former self) would have a perverted sense of closing the clubface by flattening the right wrist at impact.

CLUB PATH (aka TRUE PATH OR DYNAMIC PATH)

Club Path is very different from Horizontal Swing Plane. Club Path is the clubhead path measured at impact. Club Path is a number determined by Horizontal Swing Plane, Angle of Attack and Vertical Swing Plane. That's why it's often called 'true path' or 'dynamic path' because there are other factors that determine this number.

Generally, in order to hit the ball straight, a golfer who has a downward (negative) attack angle needs to also have a negative horizontal swing plane. Often times, here's the formula to 'hit it straight.'

WITH IRONS

Horizontal Swing Plane = 1/2 of Attack Angle

WITH DRIVER

Horizontal Swing Plane = Attack Angle.

Below is a diagram from Trackman's latest newsletter showing what a golfer would have to do to hit it straight with an iron with a -5* angle of attack.

Now, this doesn't mean that the top part of the diagram cannot hit the ball well, but to hit it dead straight with no curvature, they must have a horizontal swing plane of about -2.5*.

In the data above, the attack angle is -3.4*. In order to hit the ball straight with no curvature and establish a 'true path' of 0*, here's the 'math.'

0* 'true path' = -3.4* AoA + -1.7* HSP

Instead, here's what happened in the Trackman Data above:

-3.4* AoA + 3.9* HSP

We know from the Trackman diagram that this will create a 'true path' that is very out to the right. So the final formula for the data above is.

-3.4* AoA + 3.9* HSP = 5.9* 'true path'

NEW BALL FLIGHT LAWS

What we know from Trackman and physicists who have studied golf is that:

Initial Ball Flight Direction = 85% due to Face Angle + 15% 'True Path'

Curvature of Ball Flight = 100% due to 'true path' in relation to the clubface angle.

The 'old ball flight' laws would state to the effect that you couldn't hit a draw with an open clubface. But the correct ball flight laws state the opposite. In fact, one can can a clubface that is open by 2* and still draw the ball if they can manage to get a true path that is more than 2*.

So, when looking at Trackman and trying to figure out how to hit the ball more accurately, three factors to look at are:

Attack Angle, Horizontal Swing Plane, Face Angle, True Path.

In this case we've got the following:

-3.4* Attack Angle
+3.9 HSP

With this we know that the 'true path' will be a pretty high positive number.

-3.6* Face Angle
+5.9 'True Path'

The 'true path' is very 'inside-to-out' to begin with. With the face angle pointing closed, this will mean that the true path is extremely inside-to-out in relation to the face angle. Remember:

Initial Ball Flight Direction = 85% due to Face Angle + 15% 'True Path'

Curvature of Ball Flight = 100% due to 'true path' in relation to the clubface angle.

So, with the face angle pointing very much left and the path very much inside-to-out, we should see a big pull hook or snap hook.

Looking at this the golfer needs to improve their clubface angle and the horizontal swing plane. Their clubface angle is too closed and they swing too much inside-to-out.

IMO, the golfer in the data above should work on the clubface angle first since I believe this game is about who can control the clubface angle the best. If the golfer could get the face angle closer to 0*, they could start missing their shots less drastically to the left. If they could get the face angle at say +2*, they would probably hit a big hook that can still find the target.

The closed clubface may be due to something as simple as the grip or aiming incorrectly at address or releasing the #3 Power Accumulator too soon. A good way to check this is with the video camera.

From the DTL view, you want the clubface at the same angle as the left forearm at the top of the golf swing. Here's a pic of Moe Norman back in 1955 executing a square clubface perfectly at the top of the swing.

Golfers who have a clubface that is closed at the top of the swing have the face pointing more towards the sky. An open face at the top has the toe of the club pointing more straight down.

You can also check this from the Face On view to a degree. Take a look at Ben Hogan in this pic.

Mr. Hogan had a square clubface as you can see the grooves of his iron clearly here. With closed clubfaces, the clubface is not visible at the top of the swing from the face on view.

More importantly, checking the club at P6 is even a better indicator of what the face angle will be at impact.

Here the clubface is square as the toe is pointing straight up at the sky. If the face was closed, it would be facing more towards the ground. If it was open, the face would be facing more towards the sky.

3JACK

Kevin said...

Wonderful job with Track Man and the ball flight Laws. VERY well done!

Kevin

John Graham said...

Rich,

I would reword how you say your final formula. Club path=(Aoa and vsp adjustment)+/- the hsp.

John Graham said...

Sorry, that should say,club path= hsp +/- (aoa and vsp adjustment)

Rich H. said...

Thanks John. I was trying to keep it sort of simple and that's why I wrote 'about 1/2 of the attack angle.'

Bryan Baz said...

"I believe this game is about who can control the clubface angle the best."

Great quote, I tend strongly to agree with you on this.

What would be your best guess as to the optimal impact parameters might be for minimizing clubface rotation relative to target line? This is taking into account clubface rotation during the impact interval.

I am thinking a high VSP with a positive club path and a positive face to path, with a negative face angle (to target). Also I am thinking an impact slightly toe side of the club's COG.

Constraints are that the shot must end up at or near target line and must be struck fairly solidly.

I'd be really curious to hear your feedback. Pleast let me know if you have any thoughts or questions.

Bryan Baz said...

sorry, i meant negative club path (out to in relative to target line)