Optimizing a Driver's
January 24, 2011
This is a rework of an article written four years earlier (January
2007). That article drew criticism not so much for the conclusion as
for incorrect distances in the examples. Subsequent investigation
showed that the program I used to generate the numbers, Tom Wishon Trajectory
Profiler 2.0, was not accurate for higher clubhead speeds.
(See my study of
trajectory programs which resulted from this observation.) I
have more confidence in the numbers presented herein. The conclusions
are basically the same as the original study, though the numbers are
not quite as compelling.
hear a lot about how the optimum launch parameters for a driver mean
you should be going for higher launch angle and lower spin.
This seems to be a consequence of the sudden prevalence of launch
monitors in clubfitting shops. As an engineer, I have been trying to
make quantitative sense of that for some time now.
think I have finally found a way to look at it that tells me what's
going on. What it tells me is that the conventional wisdom of
launch and lower spin is an over-worrying of the situation.I'm
convinced that fine-tuning the spin and launch angle is mostly
a waste of time. If you get the loft right for the golfer's swing, the
amounts to a hill of beans. I'll show you the numbers that lead me to
conclusion. But first let's go over what I think is the right
way to fit a driver with the aid of a launch monitor.
Here's my technique, which has the backing of
numbers that you'll see later.
- Find the
shaft and head combination that the golfer hits the best. "Hits
the best" means things like:
Notice that I haven't said a thing yet about loft. As long as
the loft is vaguely in the ball park for the golfer, you can fit the
other things. Yes, loft matters -- and we'll deal with it in the next
step. But the properties in this step must be correct first!
Now try out the combination with a variety of lofts. If you
have interchangeable heads of the model you're going to use, that's
obviously a big advantage. The goal here is:
- Highest ball
- Best consistency of impact on the
sweet spot, which is centered heel-to-toe and above the middle of the
- Consistently good swing path and
clubface angle (open/closed).
- Good subjective feel.
launch angle and spin. On second thought, don't bother!
You are not going to get a lot of distance out of this step -- if
you did #1 and #2 right. A little tweaking may give a little
improvement. But there is much more to be gained by choosing a driver
where the golfer can make consistent contact just above the middle of
the clubface. Any other spin/launch tweaking is small potatoes by
Basically, what I'm
saying in #3 is: If
you got the loft to give the launch angle for maximum distance for that
player's ball speed, there is not much left to be optimized by
further tinkering with launch angle and spin. Theoretically,
perhaps there is. But equipment does not give much ability to hunt down
that theoretical improvement. The high-yield ways to find it have to do
with the golfer's swing: consistent contact at the proper point on the
clubface and with a good angle of attack.
distance, as measured by the launch monitor -- or even by eye on the
range, if your range is well enough marked to do it accurately. This
is most likely to give the best result.
you don't have interchangeable heads, you may have to choose a loft "by
table". See how the golfer's loft compares with his/her launch angle
(for this you'll have to measure the launch angle), and extrapolate to
the optimum launch angle in one of the common tables. There are lots of
such tables around; I just whipped up the following one, which is as
good as any.
Be sure you do this with at least the same model head and the same
model and flex of shaft. For flex, you should take measurements and not
just rely on the LARSX markings. BTW, this table does not deal with
swing variations that change the effective loft at impact -- such as
the wrist cupping common to high handicappers. That can only be
accounted for by measuring the actual launch angle and spin.
in this study were done using the TrajectoWare Drive
program, version 1.0. This program provides carry distance only, so
that is what is being optimized here. As a practical matter, ground
conditions vary so much that it is hard to optimize for total distance
(carry + roll) with any great precision -- but we are working on a way
to include it in the next version of the program. My rough and ready
approach is to use about a degree less loft than the optimum, to
reduce the spin and angle of descent.
hear the words, "You should aim for higher launch angles and lower
spin," I visualize the following chart:
numbers on the chart are yardages. Moving in the direction of the green
arrow -- toward higher launch angles and lower spin -- should give the
fastest improvement in distance. The yellow arrows -- one with just
higher launch angle and the other with just lower spin -- show more
That is what the words imply.
real world is more complex. Here are the actual yardages, for a golfer
with a 124mph ball speed. (That's a fairly typical male golfer with
85mph clubhead speed and consistently good impact with a "standard"
driver. Note that, as the loft goes up, the more-glancing blow means a
loss of ball speed. Thus it takes a little more clubhead speed to
ball speed as the loft goes up.)
for spin and launch angle
a little hard to understand the shape of this "launch space" just
looking at a
sea of numbers. So let's enhance it graphically. Here is a 3D picture
of the yardage contour.
shape looks as if you
had taken a paper rectangle and curled it along the diagonal. There is
a top diagonal line going from the high-spin, low-launch corner to the
low-spin, high-launch corner. The two corners bent down are high launch
and spin, and low launch and spin. The whole paper is tilted along the
diagonal, so the highest corner is at high launch low spin.
first glance this does seem to say, "Go for high
launch, go for low spin". But a closer look (below) is going to tell us
to be somewhere on
that high diagonal. We will see that moving off the
diagonal, even if
it is for higher launch or lower spin, is going to cost distance. So
going for high launch and low spin helps only
if we manage to get both, and in
proper proportions to stay on the diagonal.
This 3D graph shows us what is going on very intuitively. But we'll
need another way of
looking at the surface to get enough detail to be useful.
that other way. The table below is color-coded according to the
distance. The warmer the color (red is the warmest), then the longer
the drive. Conversely, the purple entries are the shortest drives. This
is a 2-dimensional representation of the 3-dimensional surface shown
for spin and launch angle
is the "lay of the
land" that we're looking at?
re-phrase that in terms of driver performance:
- There is a "ridge" of
maximum distance. Here's the same table with the ridge shown
explicitly. It is the black dotted line, which is the maximum distance
for a given launch angle.
- If you move along the line, the yardage changes
you move away from the line, you lose yardage more quickly. That's
what makes it a ridge.
ridge is slanted compared to the east-west and north-south axes of the
map. It goes from high-launch/low-spin to low-launch/high-spin.
- There is no "peak" on the chart. As you move down and
the right, the distance continues to increase -- but the increase slows
to a crawl at the bottom right. (A bit more exploring with TrajectoWare
Drive shows a maximum just under 210 yards, at a launch angle of 30°
and a spin of 1000rpm.)
long as your launch angle and spin are "on the ridge", you are fairly
close to the maximum distance you can get with your swing.
you do something to reduce (or, for that matter, increase) the spin,
do something to also change the launch angle, or you will fall off the
ridge -- that is, lose distance. Just lowering the spin by itself with
not help and will probably hurt. You have
change both to stay on the ridge.
- If you just raise the launch
angle things, are a little better -- but not much. You may get a slight
increase for a few degrees, before the distance goes down again.
talking as if we can design a driver to place us anywhere we want in
the chart. But that is not true. There is a "natural" area of the chart
for drivers to live, and we have to work hard to get away from that
look at how real drivers behave. Here is the performance of a set of
drivers, showing launch
parameters and yardages. The table is based on a very simple
set of assumptions:
only thing we vary in this table is the loft of the driver. And we
record the calculated
distance, launch angle, and spin. The highlighted row is the
driver with the best distance. Our 86mph golfer can get 189 yards with
15º driver. Let's see how the collection of feasible drivers maps onto
the launch space, how it
fits on the ridge of maximum distance.
- 86mph clubhead speed (because 85mph is not enough to keep
the ball speed at 124mph, at the loft we are going to need).
- 200 gram head weight.
angle of attack; the club is at the bottom of the swing at impact.
- The loft listed is the "dynamic" loft, defined at the
difference between the direction the clubface is pointing and the
clubhead is moving at impact. That means it includes not only the loft
built into the driver but also:
- Shaft bend, tilting the head up at impact.
- Face roll, providing more loft as the impact point is
higher on the clubface.
- Cupped or bowed left wrist at impact, to the extent that
this provides loft and not angle of attack.
- No increase nor decrease of spin due to
vertical gear effect. (Here are links for an explanation of gear effect and vertical gear effect.)
normal conditions otherwise: a ball fitting the TrajectoWare Drive
model, normal temperature, altitude
the rows of the driver table include launch angle and spin, we can plot
row as a point on the launch space table. Those points are the little
golf balls. The dotted red line connecting them is the path of all
could build for our 86mph golfer by varying just the loft.
Important points to note about this diagram:
The lesson here is that the line of feasible drivers and the
line of maximum distance are sloped in opposite directions. Where they
intersect is the driver that gives the best carry. We may be able to do
some fine tuning and add a few yards. But not many yards, and probably
not with most golfers.
loft does not takes us along the ridge; it takes us almost
perpendicular to it, straight across the ridge.
That means that there
is a fairly
well-defined optimum loft. In the case of our golfer, the maximum is at
12.8º of launch angle (corresponding to 15º of loft).
surprisingly, the maximum distance occurs where the
red line meets the
ridge (the black line). That's not surprising
because the ridge
represents the best spin for a given launch angle, or the best launch
angle for a given spin.
- The maximum distance
the intersection between the black and red lines -- is
a long way in launch space from the maximum distance possible.
It misses the peak (of 209.7 yards) by 17º worth of launch angle and
2500rpm worth of
- If we could somehow traverse this distance of launch angle
and spin, there is about 20 yards to gain -- about 10% of the distance
of the drive. That is a lot, if we could somehow obtain it. (But, as we
shall see, this is not easy. Moreover, it has less to do with club
design and more to do with the golfer's swing.)
Before we leave this point, here is a
table giving the slopes of the two lines -- the ridge and the feasible
drivers -- for some representative ball speeds.
||Slope of feasible
many rpm of spin
must be removed
degree of increased launch?
many rpm of spin
degree of increased loft?
At this point,
the numbers for steps #1 and #2 of my recommended fitting procedure.
That's the "lazy" use of the launch monitor. Now it is time to see just
how much we can get from "fine tuning" the launch angle and spin: step
know there is about 20 yards more distance, a full 10% of the drive,
out there somewhere. Is it accessible, or is it the pot of gold at the
end of the raibow?
There is a fundamental fact of life we need to realize before we start
fine tuning, if for no other reason than to set our expectations.
It's really hard
the launch angle 5º at the same time you're lowering the spin
by 500 rpm. (That's what it would take for our 86mph golfer to get 10
extra yards.) The loft is your strongest tool for dealing with launch
angle. But loft takes spin in the wrong direction to stay on the ridge.
Increase launch angle using loft, and you'll raise
spin, not lower it. You have to find other methods. Such methods are
they generally make more modest adjustment of spin or launch
That said, let's look at the approaches club designers can use to
increase launch while they decrease spin.
As we said, this story is good news, bad news:
That means that we can easily increase the launch angle, but now we not
only have to reduce the spin to stay on the ridge, we have to reduce
hundreds or even thousands of RPM of spin just to make up for the
launch angle gain. That's a high price, considering we must accomplish
both higher launch and lower spin; one without the other is distance lost, not gained.
- First the good news: loft increases launch angle by almost
a degree for every degree of loft. (Actually, it is not quite
one-for-one, more like 80%-90%.)
- Now the bad news: loft also increases the spin. For our
86mph golfer with typical driver lofts, the spin increases by 270rpm
for each degree of increased launch angle.
Angle of attack
not a club design issue, but a golfer-training issue. It requires
learning how to hit the ball on the upswing, which implies placing it
further forward in the stance and teeing it higher. It works because
you can increase the launch angle without increasing loft. Every degree
of angle of attack gives a degree of launch angle with no effect on
How much can you gain through angle of attack? I don't have a lot of
data on what golfers who try to hit up on the ball accomplish. But here
are a couple of ways to estimate an answer:
In any event, this is not a clubfitting parameter. The job of the
clubfitter is to specify the best club for the swing the golfer has.
That will have some amount of angle of attack (perhaps zero or even
negative), so let's move on to considerations the clubfitter can do
- Long drive data: These guys have a lot of athletic ability,
plus a strong motive to learn an upwards angle of attack; they need
both in order to compete. So we can look at the actual data from the
high finishers in elite long drive competition and get an idea of the
AoA that they manage. I plugged the launch data from two drives from
the 2006 ReMax finals into TrajectoWare (they were drives Jason Zuback
and Erik Lastowka), and worked backwards to the loft and angle of
attack that they must have used. In both cases, the angle of attack was
under 1º. I was surprised it was so small.
- More long drive data: Tom
Wishon points out that "the long drive
competitors can use a head with 5-6 degs and still generate a launch
angle of 11-12 degs." Even allowing for a reasonable shaft
bend increasing the loft by 3º, this is still 3 or 4 degrees of upwards
angle of attack.
- Geometry: If you can somehow tee up the ball 6" farther
forward in your stance, the natural arc of a 45" driver will allow
hitting up on the ball by an angle of 8º. That is a lot. It will also
involve teeing the ball up almost a half inch higher. This is probably
an extreme upper limit to angle of attack, nowhere near available to
most of us.
Vertical gear effect
We usually think of gear
effect in terms of sidespin: hooks and slices. But the same
effect can work for backspin as well. Hit the ball high on the face and
the clubhead rotation will reduce the nominal spin, compared to a
center hit. (TrajectoWare Drive assumes a center hit when computing
launch parameters from impact information.) Conversely, a low-face hit
will experience increased backspin.
How much can we expect from gear effect? Until a couple of years ago,
most people (myself included) didn't think vertical gear effect was an
issue at all. Even today, there does not seem to be much agreement on
the specifics. For instance:
Making use of vertical gear effect is a combination of the golfer's
swing and a driver fit to that swing:
Wishon has reported a difference of 425rpm for a 1/2"
vertical difference of impact position on the clubface, with a 105mph
clubhead speed. A difference of 1.5" from a very low on-face hit to a
very high on-face hit allows 3/4" from a center hit to a high hit. With
Wishon's numbers, that allows a little over 600rpm to be saved by
vertical gear effect.
Upshaw has reported a difference of 3300rpm between a
high-face hit and a low-face hit, corresponding to a difference of
1650rpm from a center hit to a high hit. That is almost 3 times
Wishon's data. Upshaw's data was at a ball speed of about 145mph,
corresponding to a clubhead speed of 98mph, making the difference even
- The golfer must have a repeatable impact high on the
clubface. High enough to get maximum benefit from the gear effect, but
still low enough not to lose COR.
- The golfer can be helped a little by a low center of
gravity for the clubhead. A low CG increases the range and efficacy of
hitting "above the center".
- Shaft flex. (Finally, something we clubmakers can relate to
has reported an anecdote involving a long drive champion
getting much better runout after landing after going to a flexible-tip
shaft (generally considered high-launch and high-spin) and a lower loft
in the clubhead. The explanation Dana gives is that the
clubhead was more free to rotate and exercise vertical gear effect with
the tip-flexible shaft. I'm not sure if I agree; my inquiry suggests that
tip stiffness has much less impact on vertical gear effect than Upshaw
reports. But Dana's data is what it is, and I can think of no other
explanation for it.
There are other factors sometimes cited as ways to get high launch and
low spin which, unfortunately, do not do what the proponents would have
- Head weight distribution
- A low center of gravity is reputed to give a high launch angle
without adding spin. Vertical gear effect is a technical explanation
for why that should be. A low CG
enhances the vertical gear effect as noted above.
yeah. There's also the possibility of raising the launch angle by
the center of gravity back away from the face. That definitely works to
raise the launch angle. But it has the same effect as loft --
increasing the spin as well -- so it's not
helpful this time.
- Shaft flex - Stiff
shafts, and especially tip-stiff shafts, have a reputation for being
low spin. (Also low launch. That is not what we want right now, but
remember that because it's important.) The biggest launch effect of
shaft flex is on the dynamic loft of the clubface. So if you reduce
spin, you also reduce the launch angle. The only valid use of shaft
flex to reduce spin without lowering launch is as Dana Upshaw revealed;
use a tip-flexible shaft in
conjunction with a lower loft clubhead to take maximum advantage of
gear effect. The shaft flex will increase the loft, the lower-loft
clubhead will get the loft back down, and a high-face hit might
backspin because the shaft will allow more clubhead rotation and the
resulting gear effect. (I qualify it with "might", not "will". My
analysis does not support the substantial effect that Upshaw noted. So
I accept his data with considerable reservation.)
- Low-spin face - I
don't know of a single instance of face design or face treatment that
reduces spin. (At least none that is legal. Adding some sort of of
slime when you play is not legal.)
We are not left with many tools to do fine
tuning -- to try to move along the ridge and simultaneously raise the
launch angle and lower the spin:
of all, the golfer must have a sufficiently repeatable swing that we
can depend on high-face contact. (Maybe not all the time, but often
enough to be worth fitting to.) To do such a fitting:
- Loft moves across
the ridge. Wrong direction.
- Angle of attack is either there in the golfer's swing or it
isn't. If it is, we already accounted for it in step #2.
- Vertical gear effect is all that is left. Let's look closer.
impact tape or powder to determine ball impact. If impact is scattered,
don't even to try to tune any further; this golfer needs lessons and
practice, or at least attention to the gross driver fitting (step #1)
that would give consistent high-face impact. Continue only if the
- Find the proper tee height for high impact that still
retains full ball speed. This will take a launch monitor and impact
tape or powder.
- Experiment with shafts to find the one that gives the greatest
for the ideal impact. We're still monitoring impact here.
draw conclusions based on lower or higher impact. That will "churn"
your shaft selection. If you can't get stable enough impact for this
step, stop trying to fit for vertical gear effect.
- Now that the
spin is lower, we have to get back to the ridge of maximum distance by
adjusting the launch angle. We use loft to do this. We may need to
decrease loft; that's a good thing, because it also decreases spin. Or
it may be increased loft, in which case we have to spend some of our
spin reduction to get back to the ridge.
In closing, let me review my recommendations and the reasons for them:
Remember that errors in step #1 can cost 5-20 yards consistently, or
even the ability to hit consistent drives. Don't get caught up in step
#3, where fewer yards are harder won.
by finding the length, shaft, and clubhead that the golfer hits
consistently, at high ball speed, in a consistent place on the
clubface. Use a loft within 2-3º of what
the golfer needs, but don't worry too much about loft now -- just
consistency, ball speed, and comfort. This is the step where you have
to be good at the clubfitting art, and it is necessary to get this
right if the rest is to follow.
- Now vary the loft, using these components, to give the
maximum distance for the golfer.
- You are now within 10 yards -- 15 at the
most -- of
what is "on the table" for that golfer's swing. You might be able to
get a small fraction of this distance using a launch monitor and
shafts. Bigger improvement can be made if you can get the golfer to hit
the ball consistently high-center on the clubface.
like to thank Jeff Parrott of Golf Provisions (Largo, FL) for getting
me serious about resolving this mystery. (Below you can see a partial
transcript of the emails that got this work started.)
also like to thank David Bahr (from the GolfDiscussion forum) for
pointing out the problems that the Wishon program had inserted into my
numerical data, and Todd Kos for providing correct real-world data so I
could test the various programs I use for validity.
but definitely not least, is Frank Schmidberger. Frank saw my study
comparing existing trajectory programs, and started building a tool for
his own use. Our correspondence grew into a joint venture that resulted
in TrajectoWare Drive. It would have been very tedious to repeat all
the calculations for this driver optimization project without our new
program -- so much so that this update might never have happened at all.
On Jan 15, 2007, Jeff Parrott emailed me:
Dave! Have you ever looked into ideal launch angles and spin rates
based on ball speed? I do a lot of Vector fittings (with good results,
I might add), but wondered if you'd ever taken any interest in the
I responded in part:
have never played with shafts or weight distribution trying to change
the spin at a given launch angle. From what I have seen, the strategy
I decided that I needed to a more precise
justification for my method. It jibed with my experience, but I didn't
have a very good grasp on why it worked that way. As I proceeded with
my investigation, Jeff and I exchanged a few more notes. By Jan 17, I
had written the first draft of this article and gave Jeff a private
link to it. His response was:
know that's backwards from what a lot of professional fitters do. They
tend to start with a loft that gives the "proper" launch angle, then
play with heads and shafts to get closer to the optimum spin for that
- Find the shaft and
head style that the golfer seems to hit well and feel good with.
lofts for that head and shaft, to find the optimum loft for the golfer.
Use only center hit data, determined by impact tape and consistency of
the numbers on the LM.
- You will find a
pretty broad maximum, with essentially the same distance over a 3-4*
loft range. Use a number toward the lower end of that range. Don't
worry about exact launch angles or spin at this point; there aren't
more than 2-3 yards to be wrung out of it now anyway, and the golfer's
consistency (with a head and shaft that feel good and suit his eye) are
more important at this point than those last 2-3 yards.
Dave: I may have
argued the importance of spin 6 months ago (which is why I emailed you
in the first place), but my findings after many Vector fittings agrees
with what your article states completely. In the past, I'd
great launch/distance results, but would waste additional time with the
customer because the spin rates just didn't make sense. Now I know why.
also solicited Charlie Badami's opinion, and he concurred that
was what he saw in the fitting cage. Thus encouraged, I'm
the information generally available.
Thanks for your input (as I'm sure many others will also do). Now I can
spend a lot less time trying to get loft & spin to match so
Last modified - Jan 24, 2011