## Thursday, September 1, 2011

### Trackman and Mis-Hits

A question was posed by John Erickson over at his forum (www.advancedballstriking.com/forum)

He asked how does Trackman measure shots that miss the sweetspot?

I believe this is the probably one of the best features of Trackman.

I think it does a few things:

1) Shows how ball flight can fool a golfer

2) Shows how a ball that feels like it was struck on the sweepspot may have missed the sweetspot

3) Can help a golfer correct those issues.

There are 2 excellent measurements that can help a golfer decipher if they missed the sweetspot, where they missed it and give an idea of how much they missed it. Those measurements are ‘smash factor’ and ‘spin axis.’

SMASH FACTOR

Smash Factor = Ball Speed / Clubhead Speed

If a golfer swings a 5-iron at 94 mph, a sweetspot strike will register a smash factor of about 1.41. That’s a ball speed of approximately 133 mph. Thus, if you take the same swing and register a 94 mph clubhead speed, but your smash factor is 1.33, your ballspeed went down (125 mph).

That’s a clear indicator if you mis-hit the shot because the clubhead speed was the same…but the ballspeed went down because you missed the sweetspot and could not generate that 133 mph ball speed.

SPIN AXIS

The golf ball spins on an axis. If the ball’s axis is spinning towards the left that produces a hook spin. If the axis is spinning towards the right that produces a slice spin.

Thus, if Trackman shows a spin axis of -3* that means that the axis is spinning leftward (hook spin) by 3*.

If it shows a spin axis of +7* that means it is spinning to rightward (slice spin) by 7*

Here’s a big reason why I think Trackman is so helpful. It is very easy to feel like you hit a shot on the sweetspot, but in reality miss the sweetspot by a few dimples. And those few dimples are more than enough to alter the spin axis and the shot.

Let’s say you hit a driver 250 yards long. The result is a ball that starts at the target, but then draws left and misses the fairway. However, when you look at the numbers, it shows a face of 0.0* and a path of -1* left of the target.

But, the spin axis is -5* (hook spin).

Well, how can that be?

If anything, the path and face relationship should’ve resulted in a slice spin.

But the ball had a hook spin. That’s because the golfer missed the sweetspot and hit more towards the toe of the club. The golfer may not have felt that. But according to Trackman, a ball hit 250 yards that misses the sweetspot by 1 dimple, will curve 10 yards off line.

1 dimple = 0.14 inches. You’re not going to feel 0.14 inches.

In fact, Trackman says a shot hit 250 yards that misses the sweetspot by ½ of an inch will curve off line by 35 yards. You might feel ½ of an inch. But, that’s only 3.5 dimples off the sweetspot.

So if you miss by 2 dimples, you may not feel that (particularly with titanium) and that could draw your ball 20 yards off line.

Important stuff to understand.

3JACK