eagle, wabisabi, et al
Sorry that the following is lengthy, I have tried to keep it compact but there is a lot to cover and it is pretty complex. For those with higher education or engineering type backgrounds remember that you are, by far, the minority here and this is written so that the majority might find it easy to deal with. Had I been writing for you minority, I would have written ti quite differently.
This is not te be considered as a golf swing theory, tip, or the like, just an explanation of how and why some things happen
Here is the first part of the riddle, the Bobby Jones 113.2 mph clubhead speed dilemma as compared with swing speeds of today, with Tiger Woods @ 119mph clubhead speed.
As previously stated Bobby's driver specs were;
dead weight 387gms
shaft weight 207grams.
Subtract shaft weight from deadweight = 180grams
At this point I have an area of uncertainty. In all modern golf club assemblies the weight of the head, shaft and grip are considered separately and I have never seen anything to the contrary. I have checked in every possible way to clarify this further but cannot find any reliable information. The problem is; in the days of hickory shafts and Bobby Jones’ driver, was the 207grams inclusive of, or in additional to, the weight of any and all whippings and grip materials. Did it weigh 207grams all up or did it weight 207gms plus the weight of all extras attached to it.
If anyone can clarify that point I would be most appreciative.
However, it really doesn’t change the fundamental concept, either way, it merely adds a minor complication to be absolutely specific.
Let’s accept the first scenario.
The shaft was fitted with the grip of the day which was (almost certainly) made of oiled leather strap with a tar paper or cloth underlay. There was considerable whipping (binding) on his driver. I think that we could safely assume that it should weigh a minimum of (say) 30grams.
180gms - 30gms = 150gms.
By elimination we find that his head weight was = 150grams.
Second scenario; If the 207grams is inclusive of the ‘extras’ then we have a shaft weight of 207grams and a head weight of 180grams on a shaft length of 43 3/16”
Steel and composite fiber shafts are tubular in construction and usually have a balance point pretty close to the center of the shaft.
Conversely, hickory is a solid, straight grained timber mass. Cut to make golf shafts it’s tapered and considerable larger in diameter at the butt end half length than it is at the tip end half of the shaft. The balance point of the hickory shaft is considerably closer to the butt extremity than it is to the head.
The weight of today’s composite ‘wonder shafts’ is, on average, around 60 grams. The average head weight seems to be in excess of 200grams by 5 to 10gms.
205 + 60 + 50 (grip)= 315gms which represents a ‘ball park’ figure for the average dead weight of the modern driver.
You cannot have too low a dead weight as the player cannot then ‘feel’ the golf club. Also the shaft is now so absurdly light that weight must be allocated to the head to maintain swingweights, as well as deadweights.
Shaft lengths for drivers are no longer 43’’, as they used to be. The standard now is 45’’.
In the swingweight system one inch in length has a value of approximately 6 swingweight (SW) points. Additionally, a half inch in length difference is compensated for by 7grams in weight. A modern five iron is a half inch longer than a six iron so the six iron head is 7 grams heavier to bring both to the same swingweight value (say D1).
In comparisons therefore between Bobby Jones and the average modern tour pro we might find a 2’’ difference in driver length and that’s 12 SW points. Two inches would also indicate 1/2’’ = 7grams and 2’’ = 4 x 7grams which = 28grams . Obviously you need to know exactly how to apportion and allocate all of these factors but they are critical.
In summary at this point, Bobby Jones was certainly swinging a driver with a deadweight that was about 50 to 60grams heavier than current drivers. But he had a shaft that weighed about three times the weight of a modern composite fiber shaft, constructed of SOLID MASS. After a length of parallel section under the grip, quite considerable tapering took place from his end, the butt end. It then continued to the tip end and that shaft was married to a head that was either about 25-30grams lighter or even 55-60 grams lighter. Plus the shaft was 2’’ shorter.
The masses that Jones swung were considerable closer to him than the masses are to the modern tour pro. The greater a mass/ weight is and the further it lies from the energy that accelerates it, the greater the amount of energy that must be provided/ expended to maintain the value of the acceleration.
Let’s change this particular wagon wheel about a bit and see what happens. In this experiment the wheel always remains the same weight, overall.
First…let’s reinvent the spokes. Here we are going to take weight from the RIM and move that weight up to the top half of the spokes. Obviously, the more weight we shift from the RIM and the closer we fix it to the center, the greater the acceleration potential, from a given energy source.
Let’s now go the other way. We shift every gram we can out of the spokes and place it in the RIM. The more we shift, the more energy we are going to need to maintain the same acceleration potentials. This is the flywheel effect.
Second part of the answer.
Consider the principle of the flail.
Take two lengths of material at (say) 44’’ long that are equal in all weight and mass distribution factors. Both measure the same and weigh the same and the distribution of mass/ weight is constant.
Leave length A as it is. Cut length B into two equal parts and hinge them in a theoretical manner so that the hinge can be set and fixed at a given angle or it can be a free hinge.
First…fold B to zero angle at the hinge so that both (lever) arms lie parallel and touching. (This is theoretical so ignore grips and comfort levels). Obviously you have placed half of the original mass closer, by proportions, to the energy at the center.
Now swing it as a free hinge in the flail principle. As the angle commences to open, the lower arm moves outwards tangentially to the upper arm. It’s moving away from the direction that the primary or top arm is moving in. By doing so it must create DRAG on the upper or primary arm, causing deceleration of that arm.
Now take the other theoretical length, Part A. It has the bottom half in line with the top half. Therefore the bottom section requires proportionally greater energy to accelerate it than the top half does. And not to be overlooked either, it has a surface that must pass through atmosphere and it will lose potential acceleration through friction by having to do so. Conversely B will have its lower half ‘end on’ to its earlier line of travel and will be effected much less by friction.
Both Jones and Hogan, especially Hogan, consciously held or retained the angle between the left arm and the shaft for far longer than most. Would this not encourage all of the ‘good things’ mentioned above?
If one can get the butt end past the ball faster then would this not also allow the probability that the head end can get to and through the ball faster too?
This is not about Radial Accelerations of the head end so I’m not entering into that. This is enough, for the time being.
There is an even further factor and that is the ‘feel’ effect that it has on the persona swinging it.
Thanks to all who gave it some thought, I hope the experience and the experiment helps you. I also hope that it points you in a direction where you get to enjoy thinking for yourselves.
Regards
Gerry.
Copyright(c) all rights reserved. Gerry Hogan December 2009.
