Gravity Games

Why does having a lower center of gravity matter on a driver when I can tee up the ball?

–C.S., Pa

C.S.

Moving the center of gravity (CG) has become a hot topic for clubmakers and designers because there is little room for improvement elsewhere. The clubhead’s moment of inertia (resistance to twisting) has been constrained by the U.S. Golf Association’s 460 cubic-centimeter head-size limit and the rule curbing springlike effect.

So the last thing to work on is optimizing launch conditions. Optimal launch requires a high launch angle with a low spin rate, two conditions that normally can’t be achieved together.

The reason? As the launch angle goes up so does the spin rate (a wedge shot spins more because of its loft, for example). To get closer to optimum launch conditions, some golfers have tried to take advantage of the vertical-gear effect by hitting the ball high on the face (above the sweet spot). That will increase the launch angle and provide a spin rate that’s slightly lower than what you’d expect from that kind of trajectory.

 The problem? This impact point decreases ball speed because the maximum springlike effect is usually in the center of the face, not high on the face. Therefore, here’s the real benefit of lowering the CG: It helps get more ball speed from the driver’s trampoline face while maintaining the desirable benefits of vertical- gear effect. Instead of intentionally having to hit the ball in an inefficient place on the clubface, you can hit it in the center and get the same benefit. All other things being equal, this overall collision will be slightly more efficient than one where the clubhead has a higher CG.

Frank

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