The Golf Swing
is a wonderful article, guest-authored by Rod White, a physicist with
the New Zealand Measurements Standards Laboratory. It starts from basic
Newtonian physics (like we learned in the tutorial) and shows how a
good golf swing works. With animations, videos, graphs, and [completely
optional] equations, the article covers both swing technique and club
technology and how they combine for power drives.
the Golf Swing
with the double-pendulum model discussed by Cochran & Stobbs
1970, mathematical models and engineering models have given us insight
into how the golf swing works. Here is a multi-page survey of important
the swing, and how each further refinement of the model refined what we
know about how to swing a golf club.
Through Impact: Mandate or Myth
Every golf instructor I've ever read or
heard says you
accelerate through impact.
Then they extend this advice to mean that you will hit the ball farther
-- more ball speed -- because you are accelerating the clubhead through
than if you were simply coming into the ball at a constant clubhead
speed. The first is good instruction. The second is not good
Opening the loop -- instrumented grips
Until now, kinetic analysis of the golf swing has been limited by the
lack of a way to deduce mathematically which hand, arm, or shoulder --
right or left -- was producing a given force or torque on the golf
club. Recently, there have been studies that placed instrumentation
inside the grip of the club, strain gauges or sensors to measure more
directly what the hands do to the club. This article evaluates two of
those studies, by Choi & Park and Koike respectively.
Nesbit or Kwon or MacKenzie?
favorite swing modelers are Doctors Young-Hoo Kwon, Sasho MacKenzie,
and Steven Nesbit. So it pains me to see a rather fundamental technical
issue where they are on opposite sides of the question. Let me detail
what the dispute is, and finish with where I stand on it and why.
Required grip pressure
How tightly does a golfer have
to grip the club in order to make a swing? It is dominated
by the force the golfer needs in order to hang onto the club, but there
are other forces that might have something to do with it as well.
Why do tall golfers hit it
a fact; they do. But you maybe surprised why they do. It's not "longer
arc", "bigger wheel", or "leverage", which is what most golf
instructors responded when asked.
Stability of the swing plane
Dugan asked me if the swing plane is most stable with the hands moving
in the same plane as the clubhead (and therefore, of course, the
shaft). I asked him what he meant by "stable". Here is the outcome of
that discussion. And the answer is yes for a full swing and not so much
for a putt.
Double Pendulum Model and the Right Arm
instructors and some golfers criticize the double-pendulum model of the
golf swing as inadequate. The most frequent complaint is that
fails to reflect the role of the right arm (in the right-handed swing).
Interestingly, physicists and engineers seldom offer this criticism,
because they know how to incorporate the effect of the right arm.
Here's what they know that the instructors don't.
Comeaux, and the Right Hand Hit
Ben Hogan advocated hitting with
the right hand at impact. Recently, Texas instructor
Lee Comeaux has been teaching his students a "right-hand slap", which
seems very Hogan-esque. One of his students, who has seen marked
improvement in his distance, asked me to investigate the physical
basis of the improvement. My brief study concludes that, from a physics
viewpoint, hitting with the hands at
impact produces no additional clubhead speed -- none.
That might not prevent it from being effective instruction,
the Right-Side Swing
better description of Leecommotion, Lee Comeaux's swing, is a swing
driven by the right side. One of his students reported significant
distance gains, and wanted me to explain why that should be. It took a
while, but I think I have an analytical model that explains it. I also
have a critique of the swing itself.