The momentum of a well-hit drive just after impact is roughly equivalent to that of a bullet fired out of a typical 22-caliber rifle. The golf ball which weighs 1.62 oz. can exceed 150-mph after impact with a driver swung at 110-mph. Just after impact, a person hit by a golf ball would experience similar contact forces as that of being struck by a 22-caliber bullet fired from a rifle with the speed of 750-mph. Remember that next time you hear "fore" or you're thinking about to hitting into a slow playing group in front of you. However, a golf ball does experience drag force during flight that reduces the velocity by more than 50% by the time it lands.
5 Hours in Less than a Second
The total contact time, between a golf ball and clubface during impact is approximately 0.0005 seconds. In fact, by the time the shock wave caused by impact travels up the shaft into a golfer's hands and into the nervous system-the ball has already left the clubface. In other words, by the time a person senses the impact, the ball is already in flight. In fact, the clubhead travels at most ¾" during impact. Even more amazing, for a 72
stroke round, the ball is in contact with the clubface for approximately 0.036 seconds. Next time you're playing a 4 or 5 hour round of golf, remember it's only that 0.036 seconds that matter.
During collision between the ball and driver, peak force applied to the ball can be as high as 4000 pounds. A swing of 110-mph can result in the ball going from rest to 150-mph in 0.0005 seconds. In fact, during certain stages of impact, the ball experiences more than 50,000-g' is of acceleration. One
g of acceleration is equal to the acceleration of gravity. These very high peak forces and accelerations occur over such a short duration of time, that one does not actually feel that kind of force. Golf ball impact is certainly an amazing phenomenon.
An oversized driver can increase distance up to 2% for a 1" OFF CENTER hit when compared to that of a normal-sized driver. The benefit of having an oversized driver is only for OFF CENTER hits. In other words, hitting the "sweet spot" of an oversized clubhead will result in no advantage in terms of driving distance.
One of the advantages of using a composite shaft is that it can be made lighter than steel shafts. Typical steel shafts weigh about 4oz. The lightest composite shafts weigh about 2 oz. A composite shaft weighing 2 oz. would result in approximately a 3-mph increase in speed for most golfers
compared to that of a 4-ounce steel shaft. A 3-mph increase in swing speed can result in about a 3% increase in distance of a typical drive. On a 250-yard drive that's about 8 extra yards.
The shaft kick velocity can contribute up to 10% of the total clubhead velocity at impact. During the downswing for a driver, the shaft can deflect up to 7 inches. This stored energy is released at impact and contributes to the clubhead speed at impact. So, if one swings at 100-mph, the shaft could be contributing up to 10-mph of that swing.
Load It Up
The amount the shaft deflects during the downswing is NOT dependent on the swing velocity. The deflection of the shaft is dependent on how much the player LOADS or ACCELERATES the shaft. For instance, a golfer that achieves a 100-mph swing speed with a ¾ backswing loads the shaft more than a golfer who achieves a 100-mph swing speed with a John Daly type of swing. In other
words when considering the amount a shaft deflects, it's not how fast you swing, it's how you swing it fast.
A golfer that swings 100mph in 0.25 seconds generates at most 1.25 horsepower. A horsepower, an old British unit, represents the power required to lift 550 pounds, a distance of 1 foot, in 1-second, using a pulley. This is supposed to be the amount of power a typical horse could supply. A 100-mph swing in 0.25 seconds can actually generate enough power to raise 550 pounds, 1.5 feet, in 1 second. However, generating power with a golf club would require swinging a club 100-mph, 80 times to light a 60 Watt light bulb for around 5 minutes.
Revolutions Per Minute
A ball hit by a pitching wedge can have a backspin of 180 revolutions per second or 10,800 Rpm's. This is much faster than the allowable Rpm's for most sports cars. In fact, NASCAR racers average around 8000 Rpm's while Indy car's can go as high as 12,000 Rpm's.
Tangential club acceleration can approach 20 g's during the beginning phases of the downswing. This means a 7-oz. driver head feels like it weighs almost 9 pounds. Just prior to impact, centripetal accelerations can be as high as 100 g's. This makes the 7-oz. driver feel like it weighs 43 pounds. This is perhaps one reason why people decelerate the club just prior to impact. Many people think, on the contrary, that they are accelerating the club just prior to impact. We have not been able to find a single person who accelerates a club just prior to impact. The fact is, the clubhead is slowing down at a small rate just prior to impact.