Friday, December 4, 2009

Trackman Translations - Part I

In the past I've been asked to do some Trackman translations in regards to what all of the numbers mean. I have been putting them off, but with the help of people like Kevin Shields, John Graham and some others who wish to not be named, here's what I've come up with.

First, we'll take a look at some sample Trackman Data of a shot hit with an iron (IIRC, a 6-iron):
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
Clubhead speed and ball speed are pretty self explanatory. They are the two biggest factors that correlate to distance. Usually, clubhead correlates to ball speed, meaning usually the higher the clubhead speed the higher the ball speed. The times when you have higher clubhead speed but a lower ball speed usually means that you mis-hit the ball. However this is usually determined by 'smash factor.'

Smash Factor

Smash Factor is the result of Ball Speed / Clubhead Speed. In the case above, 127.1 mph / 87.3 = 1.46 smash factor.

The higher the smash factor the more 'pure' the golf ball was struck (in most cases). The longer the club, the more *potential* there is for a high smash factor. Due to golf club technology regulations, the max smash factor is about 1.53 and that's with a driver.

The PGA Tour average smash factor with a driver is about 1.48. With a 5-iron it's about 1.44. In the example above of 1.46, the golfer struck this shot very well. A golfer can hit a driver right in the middle of the sweetspot and have a low smash factor if they have a steep angle of attack with a driver as steep angle of attacks with the driver reduces ball speed.

Attack Angle (aka Angle of Attack)

Attack Angle is the angle at which the clubhead is coming towards the ball at impact. This is measured in relation of the clubhead to the ground.

The PGA Tour averages are approximated, but with a PW it's a little steeper than than -5*. With a 7-iron it's about -4*. With a 3-iron it's about -3*. And with a driver it's about -1*. So as you can see, the longer the club the more shallow the attack angle should be.

With irons, you should always strive for a downward angle of attack so you can consistently compress the golf ball properly. Now, one *can* have a very slightly upward angle of attack with an iron, but they probably will not compress the ball consistently.

With a driver, an upward angle of attack optimizes distance. There *can* be a tradeoff in accuracy with an upward AoA (angle of attack) with a driver, but there are ways to get around that. Almost the entire LPGA Tour has an upward AoA with the driver so they can optimize their distance with the relatively lower clubhead and ball speed.

AoA also is a major factor in the height of a shot. Contrary to popular golf instruction theory, the steeper the AoA, the more likely the ball will go lower. The shallower the AoA, the more likely the ball will go higher. Here the golfer has an AoA of -3.4* with what we believe is a 6-iron. That's right around the Tour average and that is excellent. AoA is very important IMO because the reason why I believe many golfers 'flip' thru the ball is that they simply do not hit 'down' enough with their irons.

Vertical Swing Plane

Vertical Swing Plane is more or less the 'inclined' plane the golfer swings on in the downswing. Here's a pic from Jeff Mann's site showing 3 of the more popular swing planes golfers use.

Again, for Trackman the Vertical Swing Plane is what plane the golfer uses on the downswing. In this case, Aaron Baddeley uses the elbow plane. In the Trackman Data above, the higher the number, the steeper the swing plane uses. The lower the number, the flatter the swing plane used.

Take a look at the pic below:

In this case, Mr. Nicklaus' downswing was down the steeper 'turned shoulder plane' while Mr. Nelson's downswing was on the flatter 'elbow plane.' Therefore, if they were to be on Trackman, Mr. Nicklaus would have a higher number in the vertical swing plane.

There is no correct swing plane number that one can use, the key is to consistently use about the same number. The PGA Tour average with a driver is about 48*. That's because *most* PGA Tour pros use the elbow plane on the downswing. In the Trackman data above the main question is whether or not the golfer can consistenty produce a vertical swing plane of 63*.


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