## Friday, December 4, 2009

### Trackman Translations - Part III

Click on the links to find PART I and PART II of the Trackman Translations. Here again is the sample Trackman data:

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

DYNAMIC LOFT

'Static Loft' is the loft of the club at address. This usually consists of the given loft of a club (say a 10* driver) and any loft added or subtracted by either closing or opening the clubface at address.

Trackman doesn't measure 'static loft.' But it does measure dynamic loft which is the loft of the club at impact. Typically the formula looks something like this.
Dynamic Loft = Static Loft + Attack Angle + adjusted for the
impact of the bended shaft (typical +2° for a driver)
As I stated in Part II, there really is no 'turning a 7-iron into a 5-iron loft' with the golf swing. The actual dynamic loft is quite a bit lower, regardless if the golfer has a flat or bent left wrist at impact.

In the sample we are dealing with, the golfer is hitting a 6-iron which has about 32* of loft. The golfer had a -3.4* attack angle which is about the Tour average and likely had some forward shaft lean.

The result? It took that 6-iron loft and turned it into a 11.3* loft at impact.

SPIN AXIS

Spin axis is the amount and direction of the side spin. A negative number means the axis is spinning to the left (hook spin) and a positive number means the axis is spinning to the right (slice spin).

The rule of thumb the ball will swerve 0.7 % off line per 1° spin axis.

In this case, the golfer has a spin axis of -17.9°. That's a hook spin on the ball. The ball also carried 165.4 yards.

So the formula is:

-17.9 x 0.7% = -0.1253

-0.1253 x 165.4 = -20.7 yards to the left

Of course that's not a definitive number because you have to account for things like margin of error and the wind.

Spin axis is usually caused by face angle, horizontal swing plane and attack angle. But also caused by the 'centerness' of the strike. If you catch it off the toe, you're likely to impart hook spin and if you catch it off the heel, you're likely to impart slice spin.

SPIN RATE

This is the backspin imparted on a ball right after impact. There's a misconception (and I had it as well) that one can create overspin on the ball with a hook. That's actually untrue, as the ball will have backspin regardless if they hit a roundhouse hook or not. The hook will have less backspin and that's why it tends to roll much more than a straight shot or a fade.

Furthermore:

More Clubhead Speed = usually higher spin rate

More Static Loft = higher spin rate

Steeper AoA = higher spin rate

Higher Spin Rate = higher ball flight

Higher Spin Rate = less roll

Normally spin rate is looked at with the driver as golfer's want to reduce the spin rate, preferably under 3,000 RPM's with the driver. The Tour average spin rate with a driver is 2,650 rpms.

Most Tour pros try and achieve this by hitting a lesser lofted driver with a shaft with a higher kick point (which launches the ball lower), then have a more upward angle of attack.

PGA Tour pro Kevin Streelman is a perfect example of this.

According to Trackman's July 2009 Newsletter, Streelman started off with the following when he first started working with Trackman:

10.5* Cleveland Driver
1.43 smash factor
-5.6 AoA
2,887 Spin Rate
267 yards carry

Streelman noticed that his AoA was way too steep with the driver and started to shallow the AoA with his swing.

Streelman then shallowed out his AoA from -5.6* to -1.0* and had to change his driver from a 10.5* loft to an 8.5* loft. He also got a stiffer and slightly shorter clubshaft to adapt to his shallower AoA. His stats a year later looked like this.

1.49 smash factor
2,399 Spin Rate
290 yards carry

So Streelman was able to increase his carry by 23 yards and reduce his spin rate by 478 rpm's by gradually shallowing out his AoA and thus being fitted for a driver that better matched the change in his AoA.

In the sample Trackman data above, the spin is at 6,194 rpm's which is about the average spin rate for a Tour pro with a 6-iron. If the spin rate was abnormally higher than that, I would probably check the golf ball being used, the shafts being used, the static loft of the iron, and the attack angle.

VERTICAL LAUNCH ANGLE

Vertical Launch angle is the initial launch of the ball right after impact in relation to the ground. I don't have tour averages with an iron, but with a driver the golfer wants a vertical launch angle in the 10-14* range. A golfer with too low or too high of a vertical launch angle may need to change the loft of the driver and/or the attack angle and their face angle. Trackman advises that golfers hit up with the driver if they can. So if the golfer hits up with the driver and has a vertical launch angle higher than 14*, then they need to get a lower lofted driver and/or a higher kick point shaft.

With that, in this example we see a vertical launch angle of only 7.2* with a 6-iron. Note though, the clubface was closed by -3.6* which help launch the ball lower than normal.

LANDING ANGLE

This is the angle of descent the ball lands at. The higher the number, the more vertical the angle the ball lands. The Tour average with a 5-iron is about 53*. Landing Angle is usually more important with the driver where the Tour average is 39* and usually golfers should look for a landing angle of 35-45*. Too high of a landing angle with the driver usually means the golfer needs a better fitted driver. Too low of a landing angle can mean the same thing or they could have an attack angle issue as well. This golfer didn't provide any landing angle data in his Trackman report.

Here's a video of how Ping fits their golfers with their drivers using Trackman.

HORIZONTAL ANGLE

Horizontal angle is the direction the ball initially takes right after impact. A negative number means left of the target, a positive number means right of the target. In the sample below the horizontal angle is -0.9* which means the ball started out initially 0.9* left of the target.

MAXIMUM HEIGHT

Maximum Height is the maximum height the ball reaches during flight. The tour average with a driver is 34 yards, with a 5-iron is 32 yards. Here the maximum height is only 15.5 yards which is a very low shot. But again, note that the golfer had a clubface that was closed by 3.9*. That along with the -3.4* AoA helps contribute to the very low ball trajectory.

3JACK

#### 1 comment:

dsizemore said...

I know this is an older post, but hopefully it's still monitored for comments.

Can you explain in further detail how the formula for dynamic loft results in 11.3? Taking the formula you supplied 32° + -3.4° = 28.6. So, what am I missing that get's that 28.6 down to 11.3 dynamic loft? The only way I can get it to 11.3 is to first figure out spin loft and then use: dynmaic loft = spin loft + attack angle which I assume isn't correct.