head weight (or more correctly, club head mass) is one of the
contributors to distance off the tee. The greater the mass
of the club head and the great its speed, the farther the ball
will go. Unfortunately, the greater the club head's mass, the
slower will be its speed at impact. One can't swing a more
massive (heavier) club head as fast.
physics of the interaction between club and ball is quite well
understood. At play are the laws of momentum and energy. A
given player (let's say you) is capable of swinging a club
with a some maximum speed. The more massive the club, the
slower will be this maximum speed. The speed of the ball is
a result of the mass of the club head and its speed. So, as
the mass increases, so will the resulting ball speed. But,
since the club head is more massive, its maximum speed is less.
There is actually an optimum mass for each golfer that produces
the greatest ball speed. For most golfers, that mass is about
200 grams. A physics equation that determines the resulting
ball speed is:
U = club head speed, m = mass of ball, M = mass of club head
is called the coefficient of restitution which is a measure
of the efficiency of the kinetic energy transfer between club
and ball. e has a value between 0 and 1. A collision with e=0
would be like a club hitting a putty ball, with the ball sticking
to the club (maximum loss in kinetic energy). A collision with
e=1 is called a perfectly elastic collision (no loss in kinetic
energy). There would be no heat or sound produced at all, so
of course is completely hypothetical.
the past 10 to 15 years, club and ball manufacturers have made
great leaps in increasing the e of the collision due mainly
to the hollow, metal faced drivers whose faces can "spring
back" upon collision. So much so that the USGA has put
in place a legal maximum which is about 0.83. Club testers
have found that e decreases with increased club head speed.
Tiger Woods' drives, therefore, are not as efficient as yours
or mine. He makes up for this by having significantly more
club head speed.
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||One of the ways manufacturers have increased
the ability of the face to spring better is by producing
variable thickness club faces. The club face gets progressively
thinner at distances farther from the sweet spot.
take the example that your club head speed is 110 mph (48.9
m/s), which means you are a relatively long hitter. A typical
value of e (exact value depends on the club) would be about
0.83. According to the equation above, the resulting ball speed
(assuming a solid hit) would be:
= 110*(1+0.83)/(1+46/200) = 110*1.49 = 164 mph
a 200 g club head hitting a 46 gram ball. The ball speed ends
up being 1.49 times the original club head speed. Let's assume
the amount of energy you can deliver to the club is the same
no matter what the mass of the club.
Light clubs would have high speed, heavy clubs would have low speed, but the
energy of the club would be the same in each case. The equation for kinetic
= 0.5*m*v*v = 0.5*0.19*48.9*48.9 = 227 Joules
mass must be in kg and speed in m/s. In the table below are
the resulting values for club head speed, e, and ball speed
using different mass clubs, assuming constant kinetic energy
of 227 Joules . . . . . . . .
. . . . . . . . . .
that it appears that the less the mass of the club, the greater
the ball speed. The assumption made, however, is that the kinetic
energy of the club is the same in all cases. Realistically,
a golfer cannot obtain such speeds with light clubs. As determined
by tests published in "Search for the Perfect Swing," the
speeds of the clubs and the resulting ball speeds would be:
speed actually peaks when using a club head with mass 0.210
kg or 210 g. This result is for a kinetic energy of 227 Joules.
Different players with different swings and strengths would
all have a slightly different optimum club head mass. For most,
it is around 200 g, thus most drivers have club head masses
that correspond to this.
most, experimenting to find the optimum mass . . .
. . . . . . . . . . . . . . . . . . . . . . . . .
than environmental conditions, the three major determinants
of distance for a golf ball are:
club head speed
initial trajectory angle.
the most part, the club can't do much for your club head speed
(as long as it
has optimum mass, see above), but it can play a major roll
trajectory angle and backspin. If there were no air, the
would not have any effect and the optimum launch angle
would be 45 degrees. The ball would not go anywhere near
it goes in air. Backspin creates a lot of lift for
the ball which keeps it in the air longer, so it can fly
out the graph below of a golf ball hit with a driver under
3 different conditions . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . The spin on the ball
creates lift which increases the height reached
and increases the time of flight so that the ball travels
further. If there were no air, spin wouldn't matter at all.
If the air is changed (pressure, temperature, density) the
height and distance travelled will change.
initial trajectory angle and backspin are greatly affected
by the loft of the club and its center of mass (the path
of the club, ascending or descending, also plays a role). The
loft which optimizes distance depends on club head speed.
greater the club head speed, the lower the desired loft angle.
For a short hitter, the optimum loft might be 16 degrees
(which means a 3 wood loft), while for a longer hitter, the
angle might be 10 degrees . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . Most
golfers should play a driver which has a center of mass that
is low and back from the face of the club. This will promote
higher trajectory without having to have too much loft. The
greater the loft of the club face, the smaller will be the
ball speed. One wants optimum trajectory
with maximum ball speed.
Having the center of mass back from the face will also mean
the club will twist less on off center hits (which occur more
often than not).
presented earlier, to achieve maximum distance,
the golfer must provide the club head with as much energy (and
thus speed) as possible. Because of the very short duration
of impact (about 0.0005 seconds), the golfer has no influence
on the transfer of energy between the club and the ball. It's
as if the club head were not attached to the shaft at that
point. In fact, very little of the shaft's mass contributes
to the transfer . . . . . . . . .
. . . . . . . . . . . Many
think that the kicking forwards of the club head increases
club head speed, thus one wants a shaft that is stiff enough
twist and but not too stiff to reduce club head speed. In actual
fact, it has been found through high speed camera measurements
that . . . . . . . .
. . . . . . . . . . . . the position of the
kick point of the shaft also influences how
soft or stiff it feels, although it makes no significant difference
to . . . . . . . . . . . .
. . . . . . . . . . . for a long hitter,
a steel shaft driver would yield about . . . . .
. . . . . . . yards less
distance. A short hitter would find similar differences.
Driver Club Face Area
often do you hit the ball from the center of the club face
of your driver? You know you've
gotten all of the ball; you've smoked it. Next time you play,
keep track. If you're a high handicapper, you probably don't
make solid contact all that often. In fact, it has been well
documented from tests that the higher the handicap of the golfer,
the greater the percentage of mishits and the greater the degree
of error of the mishits.
order to hit with maximum distance, the ball must strike
the club face on the "sweet spot." The actual
position of the sweet spot depends on the center of mass
of the club. If the ball strikes at a position away from
that point, the club will twist, the ball will spin and
there won't be optimum transfer of energy.
new, large club heads have larger moments of inertia. The
mass of the club is distributed over a larger area
making the sweet
. . . . . . . . . The actual center of the sweet
spot is not geometry center of the
club face. For most new drivers, the sweet spot is a little
higher, and thus maxium distance results from balls striking
high on the club face, not low. This is why most players
use longer tees today when using the large face drivers.
needs to be teed a little higher. Examples shown above right
are the Ping Tsi and Titleist 975D. See more
examples here . . . . . . . . . . . . .
much like to switch from small to large tennis rackets back
in the 80s. The tennis ball is easier to hit with a larger
racket. Likewise, the golf ball is easier to hit with a large
face driver. One might think that the increased head size
would increase air resistance and thus decrease club head speed
significantly . . . . . . . . . . . . .
. . . . . . . . . . . In summary, this section has introduced
and discussed reasons
why new driver technology has increased distance. The right
club head weight, loft, center of gravity and shaft for the
individual golfer can optimize distance . . . . . .
. . . . . .
Play with my Driver
Distance Calculator. You can input such variables as
loft and club head speed to determine the optimum loft.
Optimize in All Weather
you have a driver that optimizes distance for your swing,
other than how you swing
on a day, the next major factor that determines how far you
drive the ball is the weather. Distance depends on air temperature,
humidity and air pressure. A golfer can modify his/her game
slightly in different weather conditions to optimize distance
on any given day . . . . . . . . . . . . . . . . . ..
. . . . . . .Temperature affects distance in two ways. Firstly,
. . . . . . . . . .
New Driver Checklist
you ever had the experience of trying a new club, say a driver,
hitting it really well, and then buying it? Then, after that,
you never really hit it that well again? Your old driver
was just as good. Many of my friends and playing companions
have had this experience. You're not alone.
a new driver requires a lot of serious thought. You needs
to try many before you decide. The new driver technology
is very expensive. One hates to feel they've thrown their
money away. One positive step you've made is purchasing this
guide; a small investment to inform yourself before an expensive
is an itemized checklist for buying a new driver .
. . . . . . . . . . . . . . . . . . .
The Golf Ball
things have led to PGA Tour players hitting the ball significantly
farther in the last
15 years: new driver technology and new golf ball technology.
Most of this article has focused on drivers.
This section will focus on the new golf ball and its benefits
to all golfers.
Hogan and Snead's era, the golf balls used were . . . . .
. . . . . . .
This photograph shows a brief instant during
the 0.0005 second impact. The ball has just begun to move
off of the tee. Note how compressed it is. It is during
the compression and expansion of the ball that kinetic
energy (energy of motion) is transformed into thermal
energy. Thus the ball's temperature rises (although not
Tour players now hit it farther because of the much better
driver technology (most significant reason) and because they
can now play a high spin ball without the ball being a wound
ball with a balata cover. Amateurs, on the other hand, have
been playing with harder 2-piece balls for years, therefore
their new found distance is mainly the result of club technology.
Better amateurs that previously played with soft, wound balls
have realized additional gains, like the pros, since they can
now play a soft, high spin ball that is still durable and goes
a long ways.
is the longest golf ball out there? That's a very popular search
by surfers with the search engines. Pretty well every ball
manufacturer claims to have the longest ball. They can't all
be the longest. I'd like to suggest to you two avenues to pursue
if this question is important to you.
1. Purchase my Longest
Golf Ball Report in which I statistically analyze distances
of over 70 different golf balls with differing constructions.
The balls were hit using a mechanical hitting machine.
Take a look at the results of
an independent golf testing company. They have tested many
of the new golf balls using golfers and launch monitor equipment.
Below is a sample of their results.
Pro V1 and the Nike One are both . . . . . . . . . . . .
Golf Ball Report explains what this uncertainty does
to concluding whether one golf ball is in fact longer than
for all golfers.
Another characteristic of a golf ball that has
a slight effect on distance is the size and depth of the dimple.
Without any dimples at all, a drive would only carry about
100 yards. It has been
determined that the deeper the dimple, the greater the distance,
although it is only a few yards. On today's new balls, the
size and number of dimples does not affect distance significantly.
The different patterns are mainly for aesthetics.
Play with my Driver
Distance Calculator. You can input such variables as
loft and club head speed to determine the optimum loft. I'll
be adding to it soon so that you can input different golf
ball parameters such as speed and spin.
Backspin and Distance
you've been a Probable Golfer long, you know that most of
the analysis that I do is using
a golf ball trajectory computer program that I have written
to simulate golf ball flight. The most difficult things to
factor in are the changing drag and lift forces that occur
on the ball. Both are dependent on ball speed and backspin.
They are ever changing. I have accomplished this task by
using a spreadsheet. My model agrees very well with experimental
results. To see more, go here .
. . . . . . . . . . . . .