How many dimples are on a golf ball?

Number of Golf Ball Dimples

Most balls on sale today have about 300 to 450 dimples.

There were a few balls having over 500 dimples before. The record holder was a ball with 1,070 dimples -- 414 larger ones (in four different sizes) and 656 pinhead-sized ones. All brands of balls, except one, have even-numbered dimples. The only odd-numbered ball on market is a ball with 333 dimples.

Officially sanctioned balls are designed to be as symmetrical as possible. There was a ball that had six rows of normal dimples on its equator, and very shallow dimples elsewhere. This asymmetrical design helps the ball self-adjust its spin-axis during the flight. The USGA did not sanction it and changed the rules to ban aerodynamic asymmetrical balls. The ball supplier sued the USGA and the USGA paid U.S. $1.375 million in an out of court settlement.

(clipped from Wiki, at http://en.wikipedia.org/wiki/Golf_balls )

Also see golf ball history at: http://www.golfeurope.com/almanac/history/golf_ball.htm

And the Kid version, on page: http://www.kidzworld.com/site/p1147.htm

or try looking via Google: http://www.google.com/search?hl=en&lr=&safe=off&q=%22golf+ball%22+dimples&btnG=Search

Answer

The number of dimples on a golf ball varies, depending on the manufacturer and may even be different for different models made by the same manufacturer. The dimples are usually the same size as one another, but some golf balls have several different sizes of dimple on the same ball. Any number between 300 and 500 dimples is reasonable, and 336 is a common number. Not just any number will do. Golf balls are usually covered with dimples in a spherically symmetrical way, and for many values of N, it is impossible to cover the golf ball uniformly without gaps. Symmetry is important or the ball will wobble or its flight will depend on which part of the ball is forwards or sideways as the ball spins. You can get an idea of how to space dimples uniformly around a sphere by thinking about the "platonic solids" -- the tetrahedron, cube, octahedron, dodecahedron and icosahedron, and placing a dimple at the corners of an inscribed platonic solid. Variations on this theme give the corners of Buckminster Fuller's geodesic domes, and also the possible symmetrical locations of dimples on a golf ball.

Why does a golf ball have dimples on its surface?

When a golf ball is flying through the air, it has three forces on it. Two of them are gravity and drag from the air. In addition, if the golf ball is spinning, there will be a Magnus force on it (which may point up or down or either side, depending on how it is spinning -- the Magnus force cannot point along the flight path of the ball however -- see our answer on the Magnus force for more information).

The main goal of making a golf ball go farther however is to reduce the force of drag as it flies throught the air. In general, turbulence increases drag, because the energy needed to stir the air up and make it swirl around is energy that the ball has lost. One might think that a rough ball will induce more turbulence in the air than a smooth one, but it depends on how fast the ball is going. For balls going slowly through a viscous fluid, then the fluid just moves a bit to the side as the ball passes, and then it returns more or less to where it was. If the fluid motion is smooth, we call the motion "laminar", otherwise it is "turbulent." A ball moving quickly through a fluid like the air will have air flowing in a laminar fashion in some places and in a turbulent fashion in others. Directly behind the ball there will be a turbulent "wake", and surrounding that will be smoothly flowing air. The whole idea behind reducing the drag is to make the turbulent wake small.

The air that slides past the ball very close to it is called the "boundary layer". At the place where the turbulent wake starts is called "separation of the boundary layer" where the smoothly flowing air departs from the ball and does not close up behind the ball nicely but rather swirls around in small vortices. If the boundary layer can be encouraged to stick to the ball a little longer, then the turbulent part of the wake can be reduced. It turns out that adding a little extra turbulence in the boundary layer itself all over the ball allows the main smoothly-flowing air currents to stay closer to the ball and delays the separation of the boundary layer. Some nice pictures of balls in wind tunnel showing this effect can be found here.

There is also an increase in the Magnus force, giving the ball some lift when it is spinning in the correct direction. This force helps keep the ball in the air longer, allowing it to travel farther.

People have thought of putting dimples on everything from swimsuits to cars to airplanes. You only get an advantage from these dimples if the boundary layer can be made to stick longer to the object. Some cars just have vertical flat ends to them where the trunk comes down and there is no way to reduce the turbulent wake of these no matter how dimpled the paint is. And the boundary layer stays with airplane wings except maybe a bit at the ends (some gain can be made by putting small rods out on the tips or on the trailing edges of the wings).

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First answer by ID1133412878. Last edit by G00bers. Contributor trust: 103 [recommend contributor]. Question popularity: 172 [recommend question]