Anyway, Strange also mentioned the magic term "smash factor", but never went beyond saying the words once. And they never showed the smash factor on the screen. But it's a very interesting quantity, and is just the ratio of ball speed to clubhead speed. What does that tell us? It says:
(1) How pure the hit is. (Centered on clubface, square clubface)
(2) How springy the head is.
What is the maximum feasible smash factor? That depends on the weight of the ball and the clubhead, and the coefficient of restitution (COR) of the clubhead. Let's assume:
* Maximum weight ball of 46g. (Everybody is real close to that.)
* Clubhead at 200g. This may not be accurate, and may vary markedly from player to player. The guys going for the long drivers are probably around 195g, and some do. The guys going for control (like Tiger) are using a shorter driver; they get there with a heavy shaft and/or extra weight added to the head (I once got a 44" driver correctly swingweighted, but only after getting head weight over 210g).
* COR as close as possible to the legal limit of .830.
With these parameters, physics tells us that the maximum smash factor is 1.488. If we see how that varies with the clubhead weight, we get:
195g 1.481
200g 1.488
210g 1.501
So how did the players do with their smash factors? Oh yeah, and they also took a swing from George Lopez, a 13-handicap TV comedian, as an "average hacker". (Actually, I was impressed with his swing, and the numbers bear it out.)
EARLY HOLE:
GOLFER CLUBHEAD BALL SMASH
SPEED SPEED FACTOR
(Lopez) 101 142 1.406
Garcia 125 176 1.408
Mickelson 129 181 1.403
Woods 124 183 1.476
Els 126 187 1.484LATER HOLE:
GOLFER CLUBHEAD BALL SMASH
SPEED SPEED FACTOR
Woods 129 184 1.426
Els 120 170 1.417
Garcia 121 173 1.430
Mickelson 128 182 1.422OBSERVATIONS:
(1) On the early hole, Garcia, Mickelson, and the "hacker" all had the same smash factor to well within the accuracy of the speed measurement.
(2) Woods and Els were both significantly better in their hit. In fact, Els was probably close to the limit of what his driver can do, a near-perfect hit.
(3) While Strange and Tirico made much of Mickelson's clubhead speed on the early hole, he was outhit (ball speed, distance, and BTW direction; he wound up in really bad rough) by both Woods and Els.
(4) On the later hole, there was a bigger variation in clubhead speed (and ball speed, and distance), but much smaller variations in smash factor. The smash factor range was 1.417 to 1.430, or less than 1%. Given that the speed measurements were between 1% and 2%, all four golfers had essentially the same smash factor.
(5) This suggests that the superiority of Woods and Els on the early hole was not due to their equipment, but that they were hitting the ball really well on that tee.
Just thought it was interesting.
Cheers! DaveT
