What’s a Flightscope?
It’s a radar unit designed to track the complete flight of a golf ball from the point of initial impact to where it finally lands on the ground. But this radar is not the kind your local police officer uses to give you a speeding ticket. Its far more sophisticated. Its a three-dimensional Doppler radar system designed to track the golf ball as it moves forward, sideways, up and down. Using microwave technology, it sends out 120,000 impulse waves per second in a “phased array” to track the golf ball’s x-y-z coordinates and spin rates as it flies through the air.
Flightscope is a subsidiary of EDH Systems of South Africa. EDH is a global defense manufacturer that sells missile tracking devices. Transitioning their product line to golf was a natural. How hard can it be to track a golf ball over 300 yards when your primary product line tracks a launched missile over 30 miles!
I purchased my Flightscope Kudu two years ago and was interested in using it for clubfitting purposes. It’s neat to have but expensive. I shelled out $8000 which required ongoing justification for its use. I was an early adopter and watched the product progress both in its sophistication and in the ways that clubfitters and teaching professionals now use the product. At first, I just wanted accurate spin rates and launch angles so I could use it to fit drivers. I wasn’t paying much attention to the many other variables it tracked including angle of attack, face angle at impact, swing path and the angle of descent when the ball hits the ground.
Flightscope is not the only 3-D radar doppler ball tracking system out there. The other competitor is Trackman, created by Frederick Tuxten who came out of EDH years ago. The Trackman product launch was very successful and yet cost more than $30,000. Why so much more? It was touted as superior. But how much better? Worth the $22,000 delta versus Flightscope? That’s a big difference and it led more than a few pro’s and clubfitters to do some pretty serious due diligence evaluating differences between the two products.
Over the winter I re-read the book The Physics of Golf by Theodore Jorgensen who originally established a phrase called the D-plane. Brian Manzella, an avid Trackman user, spoke a few weeks later at the Illinois PGA Teaching Summit on how he was using D-Plane concepts in his teaching. Intrigued, I did further research and came across a pro from New York state named John Graham. You can watch his excellent (albeit lengthy) discussion on the d-plane here. John was one of the pros who did early comparative work on Trackman versus Flightscope and he came away from his analysis highly concerned about Flightscope’s accuracy measuring initial clubstrike angles, in particular the vertical “angle of attack.”
The D-plane explains how the face angle at impact and the horizontal swing plane interact to produce the golf ball’s spin axis, which is a key variable defining the shot shape of the golf ball’s flight through the air. Add ball velocity to the mix and now you know how far that shot shape travelled. One “aha” to come out of this work is that a normal iron swing with a downward angle of attack will likely produce drawspin. Want to hit it perfectly straight? You can’t do it with a face angle of 0* and a shot that takes a divot. Why? Because if the clubhead hits the ball prior to the low point of its arc (which is inherent in taking a divot), the horizontal swing plane will be in-to-out. This in-to-out action produces drawspin even with a square face angle. In this case, the ball comes off the face with a spin axis tilted to the left and this produces the draw. This revelation is of immense importance to both teachers and players. It means we will have to create a little “cut” action in our downswing plane, or leave the face angle a tad open at impact to produce a spin axis that is level to the ground and will fly straight.
Now back to my Flightscope. Once I developed a better understanding of the D-plane, a light was suddenly turned on in a very dark room for me. I became much better at evaluating the internal consistency across a complete set of launch statistics. And guess what? There were indeed consistency problems. Some were unique to my hitting conditions indoors and the specific unit I had. But John Graham was right. I was getting positive angle of attack figures hitting down on the ball with a six-iron. That’s just impossible. I alerted Flightscope management to my issues and they were highly responsive. They offered to send me a revamped Prime unit, which was nice since it is completely portable with an internal battery and bluetooth features. Yeah! No more wires! The hardware internal to the Prime is identical to the newer X2, and the v6.0.3 software used by both is identical.
Graham tested the X2 at the 2011 PGA Show and was impressed with the improvement in angle of attack numbers. I have been too. Below is a table of data I obtained from one of my first fittings after taking possession of the Flightscope Prime unit. This is a driver fitting with a 5-handicap client who has a 108-109 mph clubhead speed. A player of this caliber should have a positive angle of attack for a driver. This checks. With the exception of the last shot, they were consistently positive in the +1.5-2.5 degree range.
What’s cool is the relationship between the angle of attack and the difference between the horizontal swing plane and club path statistics. A clubhead that has not yet reached its lowpoint will have a clubpath that is more in-to-out than the horizontal swing plane. So it will be more right relative to the horizontal swing plane. The clubpath can only be moving left relative to the horizontal swing plane after the clubhead has reached its lowpoint. The same is true for the angle of attack. It will be positive at impact only if the clubhead has reached its lowpoint prior to impact, and negative if it has not.
Below is a screenshot from Flightscope that illustrates this. The club path runs along the curved red line and points 7.6* left at impact. The horizontal swing plane points 10.3* left. So the club path is less left (more right) relative to the horizontal swing plane. It does not show on this diagram, but the swing produced an 8.7* downward angle of attack, consistent with a down and out club path. Also notice the 8.2* rightward face angle (relative to the club path). This set of stats arises when the golfer is aimed left relative to the direction the Flightscope unit was pointed. It shows a descending leftward swing where the golfer managed to deliver the face almost square to the horizontal swing plane (7.6* left club path minus a 8.2* right face angle = 0.6* open). This is why I’m not too eager to spend $4000 on the optional camera based pointing system. You still have to get clients to hit to the target when they are being tested. Good luck!!
Take a look at the graph below. The data was taken from two golfers, one hitting a driver and the other hitting a six-iron. Both were 5-handicaps with great swings and late releases. The graph plots the Angle of Attack versus a statistic I made up and dubbed the “Clubhead Difference.” This is the difference between the horizontal swing plane and the clubpath at impact. When the difference is negative, the club path is moving down and out relative to the horizontal swing plane and is consistent with a negative Angle of Attack. When the difference is positive, the club path is moving upward and left of the horizontal swing plane and is consistent with a positive Angle of Attack. See the near linear relationship between the two! This tells me that the newly updated version of Flightscope is finally producing accurate clubstrike numbers! The one datapoint that is off is likely due to my iron-hitter taking a shot from outside the 20-inch recommended circle.