• Introduction to Principles of Aerodynamics
• History of Golf Ball Aerodynamics
• Aerodynamics Basics
• Common Myths
• Epilogue

Sort of like a snow tire? This is one which appeals to our common sense notions about airflow. Unfortunately, common sense is often wrong about aerodynamics, and that's the case here. Truth #1 taken from Intro to Aerodynamics I: When a golf ball or any other solid object moves through the atmosphere, a thin layer of air (the boundary layer) sticks to it and is dragged along with it. There is no slipping between the object and the air. Therefore, the issue of "traction on the air" is completely irrelevant and without a shred of meaning. Slipping never occurs, no matter how smooth and slick the surface of the ball may be.

Amazing but true: A smooth golf ball will only fly about half as far as one with dimples. But why does this happen? Many a golf ball guru would explain that a ball without dimples creates no lift. But more than 250 years ago, B. Robins was able to demonstrate the lift force on a spinning dimpleless musket ball. And any serious table tennis match will provide example after example of wildly curving, floating, or diving shots produced by lift forces acting on spinning smooth balls. The common factor here is spin, not dimples. As we saw above, it's the spinning action of the ball which warps the airflow and makes the ball act like a wing.

This is not to say that dimples have no effect on lift. To the contrary, they can affect both the amount and the direction of the lift, especially at low speeds.

This notion is only half wrong. It probably traces back to the early 1970s, when the so-called "Big Dimple" Titleist was introduced. This ball had a noticeably higher trajectory than many of its contemporaries, and its novel dimple pattern had noticeably large and shallow looking dimples, and thus was made the connection. But the truth is somewhat different: All else being the same, its true that shallower dimples will generally make a golf ball fly higher. But larger dimples will actually make it fly lower. Why, then, was the "Big Dimple" Titleist a high flier? Because even though the dimples were large, they were also very shallow for their size, shallow enough that the net result was a higher trajectory.

In 1983, Titleist introduced the 384 Tour, a new generation ball which had 60 more dimples and, for many golfers, significantly more distance than its predecessor. This ignited a "dimple war" in the industry, when many companies' marketers went for the easy sell with "more dimples = more distance" campaigns. If this sounds entirely too easy (Want more distance? Just put more dimples on the ball . . . ), well, it is. Just a little thought will reveal that it doesn't even make sense. If it were true, then thousands of tiny dimples would make a very long ball. And millions of microscopic dimples would let anyone reach par fives in one. But aren't these balls becoming more like smooth balls? We already know that smooth balls only go about half the distance of dimpled ones.

The truth is that the number of dimples is not a very important parameter. Any number from around 300 to around 500 works quite well. It's far more important to carefully optimize the dimensions of the dimples to provide the desired lift and drag characteristics.

This is another one that is easy to believe because it agrees with our common sense. Humid air feels heavy, and therefore the ball should have a tougher time punching through it. But in truth, humid air is actually lighter than dry air, and the ball will actually fly farther. Strike three. But don't bother seeking out muggy days to do a John Daly impression, because the advantage is truly minuscule. The best one could hope for would be a gain of about 18 inches.

There are television golf commentators who time and again will attribute a particularly long carrying and/or rolling shot to the player "putting a lot of overspin on the ball." This is utter nonsense for two reasons: first, it is impossible to put any overspin on any shot other than a cold-topped one, and second, even if it could be done, the shot would be much shorter than one with backspin. With overspin, the lift force, which normally helps hold the ball in the air against gravity, reverses and helps gravity pull the ball down. Such a shot would only fly a small fraction (perhaps 1/4) of the normal distance, and even with a lot of extra roll will still wind up short by about half.

Guess what? Another appealing notion, and another wrong one. A well engineered golf ball creates the correct amount of lift and drag to achieve the desired trajectory shape while maximizing distance. A blind pursuit of maximum lift and minimum drag will usually produce a very high flying ball with an annoying affinity for the dreaded upshoot. Given the right conditions, such balls can achieve a carry distance improvement, but it comes at the cost of wind-performance you wouldn't wish on your favorite sandbagger And the loss of roll distance brought on by the high trajectory usually means that the total distance is no better, and often worse.