Unlocking Distance: Launch Conditions and Angle of Attack

By Chris Broadie

We’ve long known that higher launch and lower spin is a powerful combination for generating consistently long and straight tee shots. A key factor in optimizing launch conditions, one often overlooked, is angle of attack. Improved diagnostics and trajectory modeling shed new light on the importance of angle of attack in maximizing driving performance. 

In the graph above, with a 167-mph ball speed, carry distance is optimized with a 17° launch angle and a spin rate between 2,000 and 2,500 rpm. Players with slower ball speeds may need a little more spin to keep the ball in the air to maximize carry. The net effect stays the same, though: very high launch and relatively low spin optimize distance.
 

In 2018, the highest average launch angle on the PGA Tour belonged to Sam Saunders at 14.7°. If a 17° launch angle maximizes distance, why does no one on the PGA Tour launch their driver that high? The answer is angle of attack. 
 

To explain why, we first need to understand ball-flight laws. Ball-flight laws determine, for a given angle of attack and loft presented at impact, how high the ball will launch. If launch angle was determined entirely by the club face, then the ball would launch with exactly the presented loft at impact (100% toward the face). If launch angle was determined entirely by the path of the club, then the ball would launch along the angle of attack (0% face). As a sanity check, we know that a negative angle of attack does not launch the ball into the ground, so launch angle should be primarily determined by the loft at impact (>50% face). In fact, according to research conducted at the PING Proving Grounds, on a driver the ball will launch 85% toward the face. 
 

According to Trackman, PGA Tour golfers have an average angle of attack (AoA) of -1.5° on a driver. For a -1.5° AoA and desired launch of 17°, the delivered loft at impact needs to be 20.25° in order to satisfy our 85% ball-flight laws. (Explanation: The presented loft is 21.75° greater than the AoA, the ball launches 85% of the way toward the face (21.75° * 85% = 18.5°), which results in a 17° launch (-1.5° + 18.5° = 17°). 

However, this simply isn’t practical for a PGA Tour golfer. Hitting a ball at a “glancing” angle of 21.75° (20.25° delivered loft minus -1.5° AoA) reduces ball speed and would likely result in 4,500 rpm of spin. Therefore, the recommendation would be to try less loft, as this can result in a lower launch angle, less spin and greater ball speed. This now becomes an optimization problem to find the perfect loft. Through impact modeling and ball-flight simulation, we can evaluate all the potential lofts and pick whichever loft maximizes distance.

In our simulation, the launch conditions range from 171.3 mph ball speed, 3.8° launch angle, and 980 rpm spin at the lowest loft, 168.1 mph ball speed, 10.4° launch angle, 2,760 rpm spin at the optimal loft, and 157.2 mph ball speed, 20.5° launch angle, 5,450 rpm spin at the highest loft. Interestingly, the projected optimal launch angle of 10.4° and back spin of 2,760 rpm closely matches the actual PGA Tour averages of 10.9° launch angle and 2,686 rpm spin rate. The best golfers in the world, naturally, have gravitated toward the launch conditions that optimize performance for their given attack angle. 

Unlike simple launch angle vs. spin charts, which would recommend more than 17° launch, this optimization provides data-driven analytics so a player can maximize performance. Based on the metrics gathered through player testing at the PING Proving Grounds, we can now project an optimization range based on angle of attack, an industry first, and ball speeds.

The general principal – that slower-ball-speed players need higher launch and higher spin while players with faster ball speeds require lower launch and lower spin – isn’t always correct. In the optimal launch and spin chart, in general, slower ball speeds and increased attack angles result in higher recommended launch angles. However, ball speed does not have much influence on the recommended spin rate; angle of attack is the primary source of change in the recommended spin rate.

Even though each angle of attack and ball-speed combination has a unique optimal launch and spin, this does not mean that each combination is equally good. Increasing ball speed has the obvious effect of helping the ball go farther. Similarly, increasing angle of attack also can help increase distance. 

For instance, given a constant 160 mph ball speed, a -5° angle of attack optimally generates a 8.2° launch angle, 2,994 rpm spin rate and a 264-yard carry.  With a +5° angle of attack we optimally get a 15.1° launch angle, 2,179 rpm spin rate and a 281-yard carry. Increasing angle of attack, for the same ball speed, can improve carry distance by 17 yards!

While swinging up on the ball can consistently increase carry distance for many golfers, you can find an optimal launch condition without changing angle of attack. Let’s say two players with the same swing speed but different angles of attack arrive at a PING Fitting Experience. Each player should walk away with different optimal launch and spin conditions, and different driver specifications, to enhance their individual driving performance.

As we advance our biomechanical understanding of why golfers move the way they do, we might find that certain movement patterns predispose themselves to different club deliveries, which may explain why PING Pro Lee Westwood has been very successful with a negative angle of attack, while other golfers have found success with a positive angle of attack. Instead of trying to force all golfers into a positive angle of attack with high launch and lower spin, we should customize our fitting methods to identify each player’s optimal launch and spin – and keep unlocking distance.

References:
Andrew Rice on the TrackMan Blog (2017): What is Attack Angle?