Why are Golf Balls Dimpled?
July 11, 2009 by Golforbis Admin
Filed under Golf Balls, Instruction, Latest News, Other
So Why are Golf Balls Dimpled? Who knows, i guess someone somewhere down the line started
making them like that and everyone just started using them! Not quite, but close enough!
In a way, the reason why golf balls have dimples is a story of natural selection. Originally, golf
balls were smooth; but golfers noticed that older balls that were beat up with nicks, bumps and
slices in the cover seemed to fly farther. Golfers, being golfers, naturally gravitate toward anything
that gives them an advantage on the golf course, so old, beat-up balls became standard issue.
At some point, an aerodynamicist must have looked at this problem and realized that the nicks and
cuts were acting as “turbulators” — they induce turbulence in the layer of air next to the ball
(the “boundary layer”). In some situations, a turbulent boundary layer reduces drag.
The dimples, paradoxically, do increase drag slightly. But they also increase what is called the
“Magnus lift”, that peculiar lifting force experienced by rotating bodies travelling through a medium.
Magnus lift is present because a driven golf ball has backspin. The same Magnus effect can cause a
ball to hook or slice if it has sideways spin.
impetus trajectory
Contrary to simple ideas of trajectories in a vacuum, golf balls do not travel in inverted parabolas. They follow what is called an “impetus trajectory”. This is because of the combination of drag (which reduces horizontal speed late in the trajectory) and Magnus lift (which supports the ball
during the initial part of the trajectory, making it relatively straight). The trajectory can even curve upwards at first, depending on conditions!
A golf ball leaves the tee with a speed of about 70 m/s and a backspin of at least 50 rev/s. The
Magnus force can be thought of as due to the relative drag on the air on the top and bottom
portions of the golf ball: the top portion is moving slower relative to the air around it, so there is
less drag on the air that goes over the ball. The boundary layer is relatively thin, and air in the
not-too-near region moves rapidly relative to the ball. The bottom portion moves fast relative to
the air around it; there is more drag on the air passing by the bottom, and the boundary (turbulent)
layer is relatively thick; air in the not-too-near region moves more slowly relative to the ball. The
Bernoulli force produces lift. (Alternatively, one could say that “the flow lines past the ball are
displaced down, so the ball is pushed up.”)
A difficulty comes near the transition region between laminar flow and turbulent flow. At low
speeds,the flow around the ball is laminar. As speed is increased, the bottom part tends to go
turbulent first. But turbulent flow can follow a surface much more easily than laminar flow.
As a result, the laminar flow lines around the top break away from the surface sooner than
otherwise, and there is a net upward displacement of the flow lines. The Magnus lift becomes
negative.
dimples vs. smooth
The dimples aid the rapid formation of a turbulent boundary layer around the golf ball in flight, giving more lift. Without them the ball would travel in more of a parabolic trajectory, hitting the ground sooner (and not coming straight down). This was discovered by accident in the early days of golf when golfers noticed that old roughened golf balls went farther.
Despite the drag, a dimpled golf ball can even go farther in air than it would in vacuum given the same initial velocity and low angle. However, a golf ball shot at 45° and 70 m/s in vacuum would go 500 metres to the first bounce, which exceeds all records!
References:
Lord Rayleigh, “On the Irregular Flight of a Tennis Ball”, Scientific Papers I, pg 344.
R. Watts and R. Ferver, “The Lateral Force on a Spinning Sphere Aerodynamics of a Curveball”, Am. J. Phys. 55, 40 (1986).
Steve Haake, “Physics and Golf? You must be joking!” Physics World 10, 76 (1997).
Journal of Applied Physics 20, 821 (1949) by Davies.
American Journal of Physics 56, 933 (1988) by McPhee and Andrews.
“The Physics of Golf” by Theodore P. Jorgensen
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P10G Set of Iron Heads (Ping® G10™ clone)
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Taylor Made Golf- Ladies R7 CGB Max Driver
SuperFast Technology reduces total club weight and promotes faster swing speed for added
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Nike Tiger Woods Kids Golf Club Set
Nike Sumo Squared 2 5900 Driver
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New Mizuno MP-600 Driver
Mizuno has long been known for their forged irons for better players. However, that reputation has largely failed to carry over into the world of woods. Their previous driver offering for low handicappers (the MP-001) had a small, but loyal following (at the range one day, a guy with an MP-001 couldn’t help but come over to check out the MP-600). In fact, only 16 of the nearly 800 Sand Trap forum members who responded to a driver survey, or just over 2%, use a Mizuno driver.
New Titleist AP1 And AP2 Irons
AP1 Technology
- Dual Cavity, Multi-Material Design: Upper and lower cavities optimize weight distribution to the perimeter, while the precise cast 431 stainless steel body with high density tungsten nickel box provide both feel, forgiveness and performance. Elastomer cushion on central support bar dampens vibration for outstanding feel.
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New Callaway Big Bertha Diablo Drivers
The El Diablo Driver is currently the #1 driver in the Sport of Long Drive with a World Long Drive Championship win, numerous Long Drive Tour wins and hundreds of local and regional Long Drive event wins. There has never been a driver so dominant in the Sport of Long Drive. We are asked all the time, what is the difference between a Long Drive Driver and a regular driver used to play golf? The simple answer is the shaft. In Long Drive we use longer and stiffer shafts. In Golf we use shorter and less stiff shafts. The driver head in both is the same.
New Scotty Cameron Studio Select Kombi Putters
Studio Select Kombi™
The Scotty Cameron Studio Select Kombi™ putters add advanced mallet designs in Standard (33″, 34″, 35″), Mid (42″, 43″, 44″) and Long (48″, 50″) models to the Studio Select family.
Kombi putters feature Studio Select heel and toe weighting technology to ensure proper headweight-to-length properties and provide multiple length options per model. A third weighting point (factory adjustable for Kombi, non- adjustable for Kombi Mid or Kombi Long) pushes the CG deep to stabilize the putter throughout the stroke for a great roll and unmatched feel and sound.
The player-preferred shape flows into the ground from topline to rear, giving the Kombi putters a pleasing look in the playing position. The clean, misted topline with high-contrast T-shaped sightline reduces visual thickness and makes face alignment easy. Additionally, Kombi putters feature a clean, double-bend stepless shaft with a full shaft of offset for an unobstructed look at address.
Studio Select Kombi H putters, available in 34″ and 35″ models, feature a heavier head (+10g) to provide a heavier feel preferred by some players. Studio Select Kombi H models are custom built at Titleist and are differentiated by a special Circle H shaft band.
Head of Titelist Golf Ball Tech Goes To Taylormade
TaylorMade Golf Company has announced that global golf icon Greg Norman has joined its Tour Staff. Norman, 54, will play TaylorMade clubs, a TaylorMade TP golf ball, use a TaylorMade staff bag and display the TaylorMade logo on the side of his headwear.
Norman chose on his own accord to play TaylorMade’s TP Red golf ball with Low Drag Performance (LDP) Technology during his remarkable run at last year’s Open Championship at Royal Birkdale, where he held a two-stroke lead going into the final round and finished tied for third. It was his 30th career top 10 finish in a major. Soon after a conversation began between Norman and TaylorMade that resulted in their new relationship.
