Ball Flight Science for All
BY Todd Kos
There is much focused writing and conversation about gaining the maximum distance via a high launch angle and a low spin rate and the use and accuracy of Launch Monitors and how they help our games.
In this article, we have invited one of the world’s leading ball flight ballistics men to introduce us to some of the information that Launch Monitors collect and then how to use that information with the knowledge that it is good data in comparison to real world testing.
The game of golf offers a wide array of products, techniques, and equipment to make a difference. The typical experience often starts with a product demo – if it feels good, buy it and put it in play. There’s always something to change or improve in our golf bag or in our swing to pursue the goal of a better golf game.
This article takes a closer look at feel, launch conditions, and how the gap can be bridged together with an understanding of ball flight science.
Measures Of A Better Game
Feel in golf is very hard to measure. It is subjective and different from person to person. How it sounds (clicky, squishy, or plain loud) may be part of the feel a player wants out of their clubs. To make matters complicated, a golf club consisting of a head, shaft, and grip has to feel right when you swing it.
Endless combinations of club head, shaft, grip, ball and weight are available. How do you know which one is right for you or where to start? Most will often settle for what’s available, how it looks, first impressions, and adapt on the course for any shortcomings that may arise. If it is not working out over a period of time, the search continues for something better.
Let’s say you’re testing two clubs. They both launch the ball exactly the same way. The decision of which club is better becomes a no-brainer. The decision is based on the one that feels best.
To Err Is Human
Launching the ball the same way every time is something a robot can do. A golfer will have some variation from shot to shot. What do we do now?
We can take a performance-oriented approach and find out which club allows the ball to be launched consistently. The expected results from consistent launch conditions are similar ball flights and distance.
A launch monitor is a tool designed to gather information on how the ball is being launched. The basic measurements in defining a ball’s flight are ball speed, launch angle, and spin. Today’s article will focus on these three measurements and a follow-up report will look at more advanced measurements.
Launch monitor systems are designed to gather data indoors or outdoors or both. Outdoor systems offer the benefit of providing actual ball flight and feel feedback, which can be valuable in confirming the better result rather than the better feel.
Ball Flight Standards
There are ball flight standards that help validate the theoretical to the real world as a starting place. The United States Golf Association tests golf balls under controlled launch conditions in an indoor test range. The USGA Standard Launch Conditions are shown in Fig 1.
The average carry results over 18 consecutive controlled environment indoor tests over a 5-week period is 237.1 metres (or 259.3 yards). The average total distance result is 258.9 metres (or 283.2 yards). (source: “Golf Ball Performance Evaluation Using High-Volume Indoor Aerodynamic Testing” by Steven J. Quintavalla, ITEA Journal, December 2001/January 2002, pp. 21-25.)
The USGA Standard Launch Conditions were entered into a ball flight trajectory program called OptimalFlight, as shown in Fig 2. OptimalFlight expects carry to be 238.9 metres which is reasonably in agreement with USGA real world results by 1.8 metres.
OptimalFlight has a conservative estimate of bounce and roll results for well-conditioned short fairway turf. These results may be more appropriate for Australia’s summery conditions and how it can create more generous roll than many courses in the United States.
The real world USGA total distance (or carry + roll) results happen to be a bit shorter than OptimalFlight’s estimate. Earlier, we observed how the carry results are near identical. This means the difference can be clearly attributed to the results on the ground. OptimalFlight’s roll results are therefore scaled to 87% to match the USGA total distance results as illustrated in the bar chart in Fig 3.
Basic Ball Flight Parametres and Examples
For the purpose of this article we will take a closer look at three basic ball flight parametres (Ball Speed, Launch Angle and Ball Spin) by varying each one a little and keeping all other parametres the same. The graphs will clearly show the results of the changes and from these club fitters are now armed with top level information on how to improve your equipment, swing, or both.
Ball Speed is measured by how fast the ball leaves the clubface. It may seem obvious to all that the faster the ball can come off the clubface the more potential distance can be found. Fig 4 illustrates how an 8 mph (or 5%) ball increase speed translates into the biggest change in carry: 15.6 metres.
The impact on landing angle (which can affect roll out on the fairway) is slightly steeper or 2.4 degrees. It is important here to mention that we are focusing on ball speed as opposed to club head speed. An off centre hit often translates into a poor result with a lower ball speed than a centre hit.
Launch angle is the initial angle of the ball’s flight when launched into the air. Much has been written in the last few seasons about creating the maximum distance for a given ball speed. Changing your launch angle is another way to accomplish this goal. In the example shown in Fig 5 it is shown how a 2° increase in launch angle translates into a 6.1 metre increase in carry for the single ball speed reading. The impact on landing angle is a bit more steeper or 3.7 degrees.
More launch angle can indeed be the friend of a slower swinger and less for the faster swinger to prevent ballooning. The emphasis here is on launch angle instead a club’s loft because launch angle is a product of how your swing and club impacts the ball (ex: Teeing it high and hitting it on the upswing has a different launch angle than teeing it low and hitting down on the ball).
Spin is measured as the amount of spin the ball has when it leaves the clubface. Fig 6 illustrates the effect of a 500 rpm increase in spin (Flight C). It translates into a modest 2.4 metre increase in carry. The impact of spin on landing angle is a bit more steeper or 4.2 degrees.
A 1000 rpm increase in spin is only a half metre longer (Flight D) than the Standard Launch Conditions. The ball flight picture shows an increasing ballooning of the ball flight with steeper landing angles. Higher ball speeds favor lower spin rates to produce desirable ball flight distances and minimize ballooning of shots.
The 2520 rpm amount of spin for USGA Standard Launch Conditions is producing near optimal ball flight results at 10° launch and 160.2 mph of ball speed. This result will be looked more closely in a follow-up article.
Spin is a by-product of ball speed and the angle the ball is being struck. However ball types and shaft profiles are variables here too. The type of ball to be played can be tuned to the player’s equipment.
The comparison of two clubs can benefit from a performance study with a launch monitor. We can discover which club allows the ball to be launched consistently and take a closer look at two examples: an inconsistent set of shots with a club versus a consistent set of shots.
An inconsistent club has increased shot to shot variation, as shown in Fig 7. There may be a number of reasons why this is happening. It could be the shaft, club swing weighting, the golfer’s swing or a combination of all three. Gathering this information is often interesting to see what feels right and what may perform better.
A consistent performing club produces similar ball flights and distance results, as shown in Fig 8. The player is able to load, hit, and release the ball into the air well. Now we are into the realm of possible coaching information. If a player was previously very consistent with the club in hand and their swing has changed, a coach now has the ability to quantify the before, current and after results.
Feel will continue to be an important part of our golf equipment and swing feedback.
A few examples of how small changes in launch conditions can affect distance results have been presented. It is hard to measure feel. Advances in technology are making it easier to measure launch conditions and integrate ball flight science.
When launch monitor feedback is used properly, it aids the learning process of our capabilities with golf equipment, from Driver through SW, what’s working, and how consistent it performs. On course testing and validation helps confirm out the better result than the better feel.
This process can be accelerated with a club-fitter on hand who can observe the total golfing picture (swing, launch monitor, and actual results) to properly fit a club.