## Friday, November 6, 2009

We talked about what effects curvature of the ball flight from a swing perspective in the previous post.

It should also be noted that wind certainly effects the curvature of the ball as well as off-center hits. Being off by one-dimple from the sweetspot can dramatically cause the ball to curve. However, it's reduced a bit with woods because woods have 'gear effect' which is the 'bulge' on the clubface designed to make the ball fly straighter when they are mis-hit. I've hit hickory shafted clubs before and one of the things that will amaze you is how difficult it is to control the ball because there is no gear effect.

But what also effects the flight of the ball is the angle of attack. That is something that really has never been discussed before until D-Plane and Trackman started coming about.

The angle of attack plays a big part in determining 'true path.'

Basically what D-Plane and Trackman state is that:

1. The spin axis imparted on the ball plays a factor in ball flight.
2. The spin axis is different for woods and irons.
3. For woods, in order to 'zero out' the 'true path', the golfer needs to match the degree of angle of attack with the degree of horizontal swing plane.

Let's go into this now.

All this means is that if I'm hitting a driver and my angle of attack is -4*, then in order to hit that driver straight (provide the AoA is at 0.0* to the target), I need to zero out my true path. In order to zero out that true path, my horizontal swing plane would have to be -4* (to the left or outside-to-in). Basically, my PLANE line for the driver would have to go -4* (to the left). If my Angle of Attack with the driver is +3*, then to hit it straight and zero out the path, by horizontal swing plane would have to be +3 (to the right or inside-to-out).

4. For irons, in order to 'zero out' the 'true path', the golfer needs to have a horizontal swing plane that is 1/2 of the angle of attack.

So, if a golfer hits a 9-iron with -5* angle of attack, then in order to 'zero out' their true path, they would need to have a horizontal swing plane of -2.5.

Here's a Trackman diagram explaining such.

The diagram shows an iron being struck with an angle of attack (AoA) of -5*. In the top path, the golfer has a swung the traditional way of 'inside-square-inside.' This has produced a 'horizontal plane' of 0.0* to the target. But because the AoA is -5*, in order to hit the ball dead straight, the golfer needs to have a horizontal swing plane of -2.5*

Here's the big thing to note, 'true path' (or 'Club Path' on Trackman) is a formula taking into account angle of attack and horizontal swing plane. Here's another big thing to note, you certainly do not have to have a zeroed out true path in order to play good golf or even phenomenal golf. However, if you want to hit it dead straight, much like Moe Norman did, you do have to zero out the path.

As Brian Manzella noted over at his forum, many golfers play their best golf playing a certain way. I know I certainly play my best golf hitting a small draw. So if I were to zero out my path that would be a bit problematic for me if I wanted to still hit a draw. Instead, I would want to have a (+) true path in order to hit an accurate draw. That being said, it should be noted that I consider Moe Norman the greatest ballstriker ever because he could hit it dead straight on command like nobody else could and could do it with power.

3JACK