Distance Differences: Cavity Backs vs Blades

Frank,

Would a tour pro hit each iron farther if he used cavityback, oversize irons instead of small blades?

–Eric, Orlando FL

Eric,

The size or forgiveness of the iron does not dictate the distance the ball will travel if the head weights, lofts, head speeds, and head paths are the same, and the ball is impacted on the sweet spot – which is directly in line with the center of percussion.

The advantage of an oversize iron is its higher MOI (moment of inertia, or resistance to twisting at impact), but that comes into play only on an off-center hit. Obviously there are other differences between irons (typically, oversize cavity-backs have stronger lofts than blades do), but all things being equal a cavity-back iron will hit the ball the same distance as a blade.

Having said this, I have not taken into account some recent designs of cavity back irons, which are now designed to have a spring-like effect which allows the face of the iron club to act like a trampoline and contribute to the efficiency of impact by increasing the COR (coefficient of restitution) which increases the ball speed. This phenomenon of the trampoline effect is difficult – if not impossible — to design into a blade because we define a blade as solid mass. A cavity back club – like a window frame — lends itself to a trampoline type design.

Many of the most elite professionals use a blade, or some design close to it and don’t need the forgiveness of miss-hits as they don’t miss very much and they enjoy the ability to work the ball with a blade and the consistency in the distance they get.

So, should you get irons with spring like effect?

My answer to this is I don’t know why you should because the miss-hits will be a little more erratic as far as distance is concerned, even though the club is more forgiving. So yes to cavity back irons but a “maybe†to those with spring-like effect. If the seven iron doesn’t go far enough take out your six-iron. A spring-like effect is great in a driver – the distance club – and maybe some fairway woods (not “metals†as some announcers have tried to rename them) because there is not another club available to get more distance.

Have fun and I hope that I have answered your question. For additional, useful insights into golf equipment, its performance and the game you may want to add my book “Just Hit It†to your reading list.

Frank      

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