This is an update of a story that originally appeared in 2006
One opinion often accepted as conventional wisdom is that modern golf balls used on the PGA Tour give an unfair distance advantage to players with very high swing speeds. The thinking is that golfers with very fast swing speeds (for example, 115-plus mph) have gained a disproportionate amount of distance because modern golf balls only get "activated" when they're compressed at very high swing speeds. Another belief is that ball aerodynamics also result in disproportionately greater distance increases for those with very fast swing speeds.
Let's look at the physics, laboratory test results, and the actual PGA Tour driving distance results to see what the facts really are.
What the Science Says:
In short, there is no extra distance "bonus" for high swing speeds. This is true for balls used on the PGA Tour, and all others as well. In fact, distance does not even increase in a straight line (see Figure 1): there are diminishing returns at higher swing speeds – just the opposite of the popular misconception. To be sure, hitting the ball faster means it goes farther; it's just that you don't get quite as much bang for the buck at the highest speeds.
Figure 1
Why is that? Examining this, let’s dispel the myth that balls only compress at Tiger Woods’ swing speeds. In a second figure, let's pretend we see a golf ball (used extensively on the PGA Tour as of this writing) hit at 89 mph, and at 120 mph in the next figure. To be sure, the ball struck at 120 mph does compress more, but the difference is not nearly as dramatic as folk wisdom would suggest.
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| 89 mph |
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| 120 mph |
Figure 2
Moreover, when a ball compresses more, it actually becomes less efficient. To show this, the USGA tested the “coefficient of restitution” or COR (which measures how efficiently impact energy gets turned into ball speed) at speeds from 90 mph (typical for a male amateur golfer) to well over 120 mph (the fastest PGA Tour player swing speed averages less than 125).
The result is that the COR for golf balls goes down as clubhead speed goes up (see Figure 3). Tests have proven repeatedly that the energy “boost" at Tour-level speeds is a myth: balls are actually less effective at translating energy into distance at higher swing speeds.
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Figure 3
After the ball leaves the clubface, the combination of speed and trajectory angle, along with two aerodynamic forces – "lift" (which keeps the ball in the air) and "drag" (which slows the ball down) determine how far the ball will go.
The USGA has tested the aerodynamic properties of several thousand golf balls, including all models currently used on the PGA Tour, and balls with speeds of more than 195 mph. As scientists predict, both of these aerodynamic forces on the golf ball rise significantly with ball speed. Positive lift force, which makes the ball fly, increases with ball speed, though there is a limit to how much is helpful; too much makes the ball balloon. Unfortunately, drag force also increases dramatically with ball speed; drag is the enemy of ball distance, especially for golfers with fast swings.
All together, this explains the diminishing returns with additional club speed seen in Figure 3.
What the Stats Say:
So, here's a question: regardless of what the science says should happen, what actually has happened on the PGA Tour?
Let's consider a couple of snapshots in time: In 2000, the most common ball used on Tour was a high-spinning wound ball based on technology that was decades old. By 2005 Tour players had entirely replaced the wound ball with the advanced multipiece "solid" balls used today. So, how did this change affect Tour players with varying swing speeds?
To answer the question, let's look at the 100 players who were on the Tour in both 2000 and 2005 (before and after the changeover to modern balls) whose average driving distance was recorded in both 2000 and 2005 (courtesy: PGA Tour website). For these players, the average distance increase was 11.6 yards. Now, if it was true that these new, high-tech balls were benefiting longer hitters the most, we would obviously expect to see that they had the biggest distance increase. However, as the chart clearly shows, this just wasn't true.
In Figure 4, we see how players ranked in distance in 2000 (in groups of 10, so the 10 shortest players are at the left, the 10 longest at the right): the heights of the bars show how much they increased their distance. In fact, the longest players (in 2000) did not gain the most distance over that five-year period.
Note that since 2005, the average drive distance on the PGA Tour has remained steady. In fact, in 2010 it was slightly less (287.3 yards) than in 2005 (288.4 yards). Summing it up: the physics, the experiments and the actual distances from the PGA Tour agree: the balls used on Tour today do not give a distance "boost" to players with higher swing speeds.
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Figure 4