How did you discover that attack angle was such an important club delivery data parameter?

For the last couple of years, the golf industry has been saying ‘High Launch and Low Spin’ when it comes to driver optimization.

More or less, all the equipment manufacturers have recommended a launch angle of around 11 degrees and a spin rate of 2700 rpm for a ball speed of 150 mph. But this simply doesn’t work! When we observed the TrackMan™ data from the Tour players during competition, we saw huge variations in both launch angle (5-16 degreees) and spin rate (1600-3500 rpm), with only very few players having the “11 deg/2700 rpm” type of data. Since we could not believe that the Tour players would be so poorly fitted, this motivated us to dig deeper.

Optimizing driving distance is a question of high ball speed, high launch angle and low spin rate. But you can, in general, not increase your launch angle without also increasing the spin rate. So the fundamental question was: What determines what spin rate/launch angle combination can be obtained? It turns out that for a well hit shot, attack angle is the primary parameter dictating what combinations of launch angle /spin rate are obtainable for a given player.

What is so important about this parameter compared to other club and ball data parameters?

Attack angle is the primary parameter telling you why you obtain certain combinations of launch angle and spin rate – it is even more important than the club head speed! Also, the attack angle is related almost solely to your golf swing and not equipment related, which means it is something you, as a golfer, can change – it is pure technique!

Why is attack angle so significant in Driver fitting?

Attack angle, together with club head speed, are the individual swing parameters which dictate the dynamic loft (loft of club at impact) your driver should accomplish. If you have a 90 mph club head speed with an attack angle of -5 degrees (hitting down on the ball), your optimal launch angle/spin rate is around 10 degrees and 3100 rpm.This would typically require a relatively high lofted driver (around 13-15 deg) to achieve this. On the other hand, if your attack angle is +5 degrees (hitting up on the ball) with the same 90 mph club head speed, your optimal launch angle/spin rate is around 16 degrees and 2200 rpm, but this would require a relatively low

lofted driver (around 9-10 deg) to achieve this. Significantly, this last combination will carry the ball almost 30 yards further than the -5 degrees negative attack angle numbers.

To what degree can attack angle stand alone as a parameter to secure optimal ball launch, i.e. the perfect shot?

The attack angle is a characteristic of your swing which can be difficult to change. A high positive attack angle with your driver gives you the potential to achieve long carry and total distance limited only by your club head speed. But, in order to take advantage of this potential, you still need to hit the ball in the center of the face, align your club path and face angle towards the target, and finally use the proper club head design, loft, and shaft in combination with the ball you play.

If attack angle is so important, why haven’t we heard more about it in the golfing community?

I think there are two main reasons: 1) It may be due to a lack of knowledge among the broader golfing segment on the impact attack angle has on trajectory, and 2) Efficient, accurate, and easy-to-use equipment that can actually measure the attack angle has not been available. This is where TrackMan™ provides great utility and value!

All things equal, how can the average golfer improve his/her attack angle?

While this is a question for golf coaches to answer, I can provide some general suggestions such as moving the ball forward in the stance – and probably teeing it a bit higher. This will typically require you to swing a bit more inside-out than you are used to, in order to compensate for the inwards moving direction of the club head after passing the bottom of the swing arc. But, contact your teaching professional… in many cases it will be necessary to make some dramatic swing changes to improve the attack angle without ruining something else. Then make sure after you increased your attack angle to visit your club fitter and get fitted for a new driver, you will almost certainly need a lower loft!

How much do tour pros focus on maintenance/improvement of their attack angle?

It varies… Some really dig into it and spend a lot of time on changing things in their swing – this is typical for players with low club speed and negative attack angle – they really need the extra 20-30 yards this can give them. Others are happy with their swing and don’t want to make swing changes to jeopardize their accuracy. Yet, the tour pros are only beginning to learn about this new important measurement parameter now, so things are rapidly changing. Again, the availability of TrackMan™ has changed the scope for many tour pros. Attack angle measurements have previously been recorded only in high tech lab environments indoors. Now, for the first time, attack angle measurements are available to the tour pros in the environment where they normally practice – outdoor with  TrackMan™ Pro, indoor with TrackMan™ Launch - without having to do much more than swing their driver.

What is the most positive attack angle from tour pros you have witnessed in your work with TrackMan™ and who obtained it?

The most positive attack angle I have seen from a pro in a tournament is Cristie Kerr's. During Wendy's 3-Tour Challenge in December, on the play-off hole versus Fred Funk, Cristie had a positive attack angle of amazing +8.1 deg. Cristie's average attack angle is slightly above +5 deg! Testing drivers, Mark Brooks has achieved an attack angle of +9.6 degrees which is a very impressive number.

Actually, there are some very interesting observations of the LPGA players. In general, their attack angle is on average around 3 degrees more positive than the PGA TOUR players. But LPGA players also have much more reason to maximize their potential due to their average 20 mph lower club head speed.

Among tour pros, both Michael Campbell and Charles Howell III have very negative attack angles, I have seen both players having -7.5 degrees in attack angle! Apparently, they are deliberately hitting their drives with very flat trajectory and not focusing on carry distance.

Is it so that all the better players have a positive attack angle with their driver?

No, this is not the case for many of the US PGA players. Players like Tiger Woods, Phil Mickelson, Sergio Garcia and Charles Howell III are all players who often swing with significant, negative attack angles. However, common for this group of players is their very high club and ball speeds, so they fly the ball pretty far despite their negative attack angle – they do not really have a distance problem! However, if they increased their attack angle they could hit the ball 30-40 yards further. But apparently they have deliberately chosen not to do this.

Have you found any discoveries during your investigations of attack angle?

Yes! It turns out that if you hit down or up on the ball with the same club, the spin rate will be more or less identical if you impact the ball on the same spot on the face. This is in contradiction to the myth saying that hitting down on the ball increases the spin rate.

Are you saying that hitting down on the ball has no impact on the spin rate?  That sounds very surprising…

Yes, actually you do not change the spin rate by hitting more down or up on the ball with the same club, assuming that the ball is impacted on the same spot on the face. Simplified slightly, the correlations are: Attack angle changes the launch angle, with club loft, including shaft flex, changing the spin rate.

When you hit more up on the ball, the launch angle will be higher but the spin rate will be virtually the same. The spin rate is dictated primarily by the spin loft and impact position on the club face. The spin loft is the difference between the dynamic loft and the attack angle. The spin loft is virtually constant for a given club. Of course, also the ball and club characteristics play an important role in the generation of spin.

Having said all this, it is still a good idea to hit down on the ball with irons and wedges. A negative attack angle makes it easier to get proper contact to the ball which insures a predictable spin rate for your approach shots.

What other club delivery data discoveries are left to make?