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Driver Technology Explained
Dominic Pedler
Modern driver marketing involves an ever growing barrage of technical features to help you decide which might suit your game, Dominic Pedler deciphers a dozen examples of essential jargon you will inevitably encounter among the big sticks of 2009 and onwards...
With their huge 'footprints', geometric heads, sunken crowns
and 'hot' – and now adjustable – faces, today's drivers are
strange beasts indeed.
But how do their ambitious designs really affect performance
and which Unique Selling Points will really
improve your game?
Here is a guide to the most common techie terms, illustrated
with the latest models that you can read up in more
detail elsewhere this issue and on our more extensive website
pages. While several drivers potentially fall into each
category under discussion (and some span several categories) we
have chosen just a few examples that best capture each concept. MULTIPLE HEAD OPTIONS
The golf industry's growing appreciation of the individual
nature of a player's swing has led to the rise of multiple
head designs for a given model of driver, truly
tapping into the needs of different types of golfer.
Leading the way is the Titleist 909 which comes
in three distinct versions each with its own
design rationale and some of the most high spec,
premium shafts as standard.
This is an important evolution from the
more conventional practice of merely offering
one driver head style, perhaps with different
weighting configurations according to loft
option. After all, a golfer may require a higher loft but not necessarily the draw-biased weighting that is often
packaged with it.
'Golfers have different swing speeds and angles of
attack which dictate different head constructions, with players
increasingly looking for different performance characteristics
beyond distance,' confirms Richard Temple, Titleist's
Senior Product Manager referring to the 909 DComp, D2 and
D3 each with their own head size, shape, materials, construction
and shaft options 'They want various types of ball flight, levels of
accuracy and workability – and they are now much more particular
about sound and feel.
You can't meet these requirements with
a single driver.'
Cobra adopts a similar philosophy with eight versions of the
King Cobra S9-1, including Pro heads with both shallow and
deep faces, dedicated Senior's and Ladies heads as well as the
variously lofted, weighted, and face-angled M and F versions.  INTERCHANGEABLE
HEAD/SHAFT TECHNOLOGY
The biggest equipment story of last season was the retail debut of
drivers with interchangeable heads and shafts, now deemed conforming
courtesy of the R&A's rule relaxation.
Techie-minded golfers no longer have just moveable weights to
tinker with, but can now dismantle the entire club and mix'n'match
heads and shafts in a brave new world of self-customization.
It allows a new generation of golfing perfectionists to tailor their
equipment not merely to their swing but also to the course and the
weather conditions, with different shafts and (indeed heads) offering
different trajectories and patterns of roll.
The Callaway iMix and Nickent 4DX Evolver pioneered the
concept at the 2008 Orlando Show with standard packages of a
head and two shafts offering differing kick-points and flight trajectories.
Taylor Made joined the club of with their R7Limited and R9
drivers, while the new Callaway FT-iQ is among the most exotic.
While the Callaway clubs fasten the two components with a
carefully engineered rotating hosel, TaylorMade and Nickent use
a high-tech bolt that screws in from the sole. Either way, traditional
epoxy glue is now made redundant by a few turns of a wrench. ADJUSTABLE FACE ANGLES
Arguably more practical to the average golfer are the very latest
drivers whose heads and shaft can be manipulated more specifically
to adjust the face angle of the clubhead.
The King Cobra L5V won an award for its Adjustable Flight
Technology that allows you to unscrew the head and rotate it so
as to close the face by one degree relative to the factory preset.
Of course, many other drivers sport varying degrees of (nonadjustable)
face angle in what is a variation on the anti-slice
theme. But the beauty of adjustability is, obviously, that once you
have worked on your swing you can then just turn the face back
to neutral, effectively giving you two drivers for the price of one.
Or, in the case of the more sophisticated offerings, several drivers
in one.
The Nike SQ Dymo STR8T-FIT gives you eight
options of face and lie angle, with three closed positions alongside
neutral and open-faced options. Most elaborate is the 2009 version
of the Nickent 4DX Evolver with its special hosel insert that
rotates to encompass 26 different settings of face angle, lie angle
and loft. [See also the Taylor Made R9 under section 7, below]
Indeed, the wizardry of all these clubs is in the way the shaft fits
into the hosel sleeve at a slight angle, rather than being perfectly
parallel.
In this way, golfers should be aware that there is
inevitably a loft ramification to a change in the face angle – the rule
of thumb being a half-degree increase in loft for every full degree
of face closure. CENTRE OF GRAVITY
Here's a term that crops up in the descriptions of just about every
driver (and indeed fairway wood, hybrid and iron) these days.
Basically, the lower and farther back the CG is from the clubface,
the higher the shot trajectory for any given loft.
With many golfers
struggling for height at low-to-moderate swing speeds, most drivers
are preoccupied with shifting the CG low and rearwards by
various means.
Most popular are the lightweight crowns (either composite or
wafer-thin titanium now pushing the 0.5mm barrier), along with
both rear weight plugs and 'limit dimension' bodies that can
stretch some five inches back from the face.
Nicklaus Golf claims a similar approach in their Dual Point
FastBack driver named after the 'precise alignment of the optimal
face flex-point with the centre of gravity in order to enhance energy
transfer and ball velocity'.
This is in contrast to the many conventional,
deep-faced heads requiring an unduly high tee to strike
the ball with an efficiently high launch angle and low spin rate.
But you don't always need an extreme shape to lower the CG
and get the ball up, as Ping have shown with their V2 Rapture
which does the job through more subtle tapering of the crown and
a pair of relatively heavy tungsten weight pads in the rear sole.
Remember, while super-low CG works for many golfers, it's not
for everyone, hence the rise of 'progressive internal weight distribution
'.
The Crews TourLink D-460 is a good example, with its
elaborate internal 'rib and dimple' pattern and external rear weight
pod being configured individually for each of the three loft options
so as to optimise their respective spin and launch angles. MOMENT OF INERTIA
'High MOI' has now replaced the rather tired 'perimeter weighting'
among the essential marketing mantras – though in many ways
they both promise the same thing: a more stable clubface with a
less-than-perfect contact.
You don't need to be square to have a high a MOI – the
Benross Innovator X is more triangular – but boxy shapes have
breathed new life into the driver market by clearly conveying how
weight is directed to the 'corners' of the club for extra stability.
Nike even named their SQ Sumo2 5900 after the R&A's MOI
limit of 5,900 grammes-per-cm2 with the concept refined further in
the Nike SQ Dymo2 (whether in non-adjustable or STR8-FIT versions.)
It's important to specify that this particular measured definition
of MOI relates to a club's resistance to rotation about the axis that
goes vertically down through the point of the clubhead's centre of
gravity. A high figure MOI will make your drives straighter on off centre
hits – but only if you mange to square the face at impact.
Nike, along with Callaway's square Big Bertha Fusion FT-i
models paved the way for dozens of exotically shaped rivals, albeit
with varying degrees of angularity, and nowadays at all price points.
MD Golf's High MOI offerings are particularly good value whether
in the square model of the Ti-460 series or the more conventionally
shaped Seve Icon driver designed by the Spaniard himself. ‘HOT FACE’ TECHNOLOGY
With the new rules limiting the efficiency of energy transfer
between clubface and ball having finally come in on Jan 1, 2008,
the old 'High COR/Hot Face' chestnut is being gently relegated as
a marketing mantra. Leading drivers are now on, or near, the 0.83
maximum (or the equivalent in terms of the Characteristic Time
measurement which the R&A now specifies). But they still achieve
the maximum allowed ball repulsion in a variety of exotic ways.
The Mizuno MX-700, for example, showcases a 'hot metal'
construction using the advanced Ti9 grade of titanium whose
grain structure in the 3mmthin face allows for more flexibility in the
sole-to-crown plane – traditionally the most rigid area that limits
the scope for maximising ball speed.
This appears to be a sophisticated
evolution of the tapered titanium alloy insert which debuted
in the Titleist 907 series, thinner at the top where it meets the
crown precisely to promote the latter's flexibility at impact.
The rationale is, paradoxically, that thin crowns are the key
route to powerful ball speed as, being far thinner than the face
itself, they can deform upwards on impact before recovering –
hence the 'spring-like effect'. This works by causing less deformation
– and therefore less energy loss – of the golf ball itself,
leading to more distance (even if calculations of non-conforming
faces range merely from an extra 2-12 yards). Look out, then, for modern crowns of just 0.5mm, like the
Cleveland Launcher and Ping Rapture V2 – or 0.3mm in
the case of the magnesium alloy crown of the Nickent 4DX
Supermag – even though these are usual marketed for their
lower centre of gravity and higher ball flights.
Arguably the most cutting-edge concept is the nitrogen-filled
chamber in the head of the PowerBilt Air Force One designed
to create high-pressure support for the ultra-thin face – just 2.8mm
– that can itself flex to provide a more effective and faster ball speed
 EFFECTIVE HITTING AREA
Once you have your maximum 'COR', the trick is then to apply it
not just to a single point on the clubface but across the widest possible
area.
Hence references to 'effective hitting area' (updating the affectionate
'sweet spot') which we can look at in terms of both the
physical dimensions of the face and the specific technologies
that ensure off-centre hits perform more solidly.
Among the largest club faces for 2009 are the mighty
48.5cm2 surface area of the Taylor Made Burner and the
46.8 cm2 of the Cleveland Launcher. Seriously confidence
inducing dimensions.
Meanwhile, elaborate ways of ensuring a wide effective hitting
area even on slightly smaller surface areas usually involve
'variable face thickness': typically thinner at the traditionally less
flexible outer areas and thicker at the naturally more flexible centre.
The Ping Rapture V2 has a precision-machined variable thickness
face to achieve a more consistent performance for impact
points all over the face, as does the Wilson Smooth which
Padraig Harrington recently put into play.
Callaway have had particular success with their Hyperbolic
Face with its 'X'-shaped internal configuration milled into the back,
again to increase impact efficiently across the area. Debuted in
last year's Hyper-X, the structure is back in the FT-9 and the driver
of the brand new Big Bertha Diablo range. ADJUSTABLE WEIGHTING
Taylor Made got the ball rolling back in 2005 with the r7 Quad featuring
four external weight bolts that were adjustable (between
rounds only, of course) to encourage your preferred shot shape.
Not to be confused with pre-configured factory weightings (see
below), such drivers come complete with a tool kit and a selection
of weights to help you dial-in both your preferred trajectory and
draw/fade bias.
Taylor Made simplified their own concept in the r7 Limited, and
also the latest R9 both using three weight ports (heel, toe and central
rear plug) allowing for three separate weighting configurations
using the 16g and pair of 1g weights. When you include the further
eight set-up combinations of adjustable face and lie angle,
the R9 can display some 75 yards of ball flight variation (in terms
of horizontal dispersion) depending on how you set it up from the
club's total of 24 potential settings.
Somewhat simpler is Mizuno's MP-600 which adopts an effortless
FastTrack system of sliding weights where you simply loosen
the two 8-gramme pegs and slide them to one of the six numbered
positions along a semi-circular groove running around the
rear. The 15 possible flight variations promote varying degrees of
bias from fade to draw, and also influence trajectory and spin rate.
The Snake Eyes Viper TI Tour is another that comes with a
handy guide to exploiting the twin 2g and single 6g weights; while
special mention also for the Benross Innovator X for the single,
centrally-located rear port which accommodates interchangeable
3-gramme and 9-gramme weights. This restricts the user to
tweaking only the vertical trajectory, rather than also lateral dispersion,
but the latter can be far more fickle and consequently difficult
to harness through weight adjustment alone. AERODYNAMICS
Driver aerodynamics are back in fashion with some scientists
claiming that many 460cc drivers suffer undue wind resistance
from their deep faces, thereby compromising stability and clubhead
speed.
The Yonex Nanospeed-i aims to correct this with an intricate
rear sole section that ensures the air flows closer to the structure
at high speeds for a faster,more stable flight. The rather elaborate
undercarriage is obscured at address, leaving a crown whose
pentagonal lines are much less space-age than they sound.
The Adams Speedline is another whose various curves and
'scoops' are claimed to create less drag and airflow turbulence.
'Extreme geometry drivers continually test with higher drag and
lower club speed,' said Scott Burnett, Director of Advanced
Product Development. 'By changing the aerodynamic properties
of the face and crown in order to keep the airflow attached, we
were able to deliver a significant distance advantage for the average
player and tour pro alike.'
As with the Yonex, Adams claims a figure of 3-4mph extra clubhead
speed – equating to an extra three to nine yards – according
to the wind tunnel aero-physicists at Texas' A&M University.
It certainly worked for Bernhard Langer when he won on the
Champions Tour, last Autumn, with a Speedline prototype and
again this season with the commercially available model. INTERNAL DRAW AND WEIGHTING
With the vast majority of
golfers suffering from a
slice, dedicated draw designs have snowballed in the last few
years – with Taylor Made even developing an entire Draw family
of clubs led by a Burner Draw driver.
Technically speaking, we need to revisit centre of gravity –
though this time not in the 'high/low' or 'front-to-back' plane but
the 'heel-to-toe' plane, with draw designs typically loading up the
heel with extra weight allowing the lighter (and therefore faster moving)
toe to square more effectively at impact.
This is the rationale behind the Callaway Opti-Fit weighting
system whereby golfers can choose heads for drivers such as the
new Big Bertha Diablo and FT-9 in either Draw or Neutral versions,
each with pre-configured stainless steel 'web' weights precisely
positioned for the appropriate performance.
Other manufacturers offer similar opportunities – though these
are often determined by the choice of the loft, the assumption
being that golfers requiring a more draw-friendly construction tend
to be those who also require a higher launch angle off the tee. GEAR EFFECT/BULGE AND ROLL
Another 'blast from the past' (being traditionally associated with
persimmon drivers), gear effect has made a comeback in recent
years as both a design and a marketing tool.
The term describes the compensating side spin, and resulting
curving shot shape, that causes a shot off the heel to display a
fading ball flight – and vice versa off the toe. This is a potentially
confusing concept as you would intuitively expect the exact opposite
– i.e. a shot off the toe to have inherent clockwise slice spin.
The phenomenon is down to the off-centre strike causing the
clubhead to twist about its center-of-gravity promoting the ball to
slide and roll slightly sideways across the face – literally with a
gear-type effect on the face – and to launch with draw-biased
side spin.
Hence most woods have a slightly curved face (horizontally
from heel to toe), known as 'bulge', which allows the ball to start
its flight slightly away from the target line, before the opposing
side spin kicks in.
Bulge is usually paired with 'roll' referring to face curvature now
in the vertical plane.
While perimeter weighing has made the gear effect principle
and hence the bulge and roll of metal woods far more subtle than
their persimmon predecessors, the terms are still relevant, with
Srixon showcasing in the latest WR drivers that claims to reduce
side spin in conjunction with the thin walls of the high-impact
Powerface.
The Bridgestone J33 is a 460cc driver with a super-thin Low
Modulus Crown which flexes slightly at impact to add effective loft
and enhance the vertical gear effect of the face which, in turn,
decreases the unwanted backspin that can compromise distance. OFFSET HEADS
Offset club heads were one of the earliest anti-slice measures and
remain one of the most popular – being also found in dozens of
models of irons.
They work through simple physics dictating that the toe of
the clubhead tries to align itself dynamically at impact with the
line of the shaft as it meets the hands. This ensures that in an
offset club, the toe has slightly further to travel to catch up and
will therefore necessarily cause the face to be slightly closed
face at impact.
Many drivers either highlight the offset feature or offer it as an
option to the main range. Our favourites are the Nicklaus Golf
DrawBack, the MD Golf Superstrong Ti-460 Offset and the latest
12o offset option of the Wilson Spine, all especially marketed
for their right-to-left ball flight – for right-handers, of course....
Reproduced with kind permission of Golf International.
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