Hitter's corner

A technique for additional clubhead speed.

How about getting into the swing of things and obtaining a flail boost factor.

Hitting and swinging, what exactly is the difference? Is Moe Norman a hitter or a swinger? A great subject for DGs. George Hubbard uses an interesting expression - 'invisible exertions'. It is indeed not easy to distinguish between the two styles if done by the same golfer, demonstrating these two styles.

Is the difference mainly a matter of feelings overriding the real muscular exertions? When comparing the swing of Ernie Els with Craig Stadler's swing it seems there is more than just a difference in feelings. However, when looking at Yoda's swing, lengthy discussions indicate that the 'experts' have a hard time deciding one way or another.

Swinging is more circular, a bottom-up approach, from the center out towards the periphery, the traditional kinetic linked chain. Hitting, usually there is a short backswing, the downswing starts at the periphery (hands), trunk /shoulders more of a launching platform for trail arm extension, hence more of a top-down, outside-in approach. Croker's A to B, Kelley's straight line delivery, Norwood's working from out of the shoulder. This action doesn't correspond quite to the traditional kinetic linking.

The swinger pulls with the lead side,the hitter hits with the trail side. However due to the Checkrein effect pulling or pushing is not such an important distinction between the two type of swings. Many things can be said about what sets a swinger aside from a hitter. However we will assume here, as a reasonable work hypothesis, that the hand's trajectory for a swinger is more like depicted in Fig1a and for a hitter resembles more Fig1b.


The difference in downswing trajectory as pictured in Fig1b vs Fig1a has some interesting consequences.
-1- inertial forces in top half of downswing are reduced
-2- a transition point with a sudden reduction in swing radius

We will here only be concerned with the shortening of the swing radius at the transition point and the effect it has on clubhead speed. I will tackle the dynamic effects due to the specific clubhead trajectory later on when I have completed a dynamic model specifically for hitting. A simple model to analyze the transition only is shown in Fig2. To be very clear, it is not a golfer, it is a simple mathematical model to illustrate the peripheral velocity increase due to shortening the swing radius at the transition point.



Two segments and a point mass represent the 'arms', shaft and clubhead. This ensemble moves with constant velocity V1 along a straight line till the hook catches the pint at t=t0. Then the straight line motion is diverted into a pure circular motion. The angle β is kept constant. The velocity for the point mass M3 changes very rapidly form V1 to V2.

To give some flesh and blood to the model one can think of the hook catching on to the pin as being the trail elbow hitting the front or side of the hips. This is than rather similar as in the pics of Ben Hogan posted by Peter. In general think of it as directing the hands straight towards some aiming point - eventually it has to resort to a more circular path.

The mathematical expression derived for the ratio k = V2/V1 is shown below.

Being a mathematical model it is very convenient to play with different parameters. The values of the parameters in the equation above are taken to be reasonable close that of a real golfer , but can be chosen any arbritary values. The angle β is kept constant at 90 degs. The angle α was taken as the main variable with the mass M1 used as a parameter. The results are show in Fig3.

Fig3 gives an clear indication as to why hitters are usually stocky and muscular. Using a short backswing they more readily control a straight delivery and with M1 large will have a large k factor. Female and junior golfers are immediately at a disadvantage if they would go for a hitting procedure.

For each value of M1 there is an optimum angle α. The dashed line shows the locus for these optima. For heavy built golfers, with M1 large, this optimum angle tends be close to zero, hence segment L1 more aligned horizontally.

From inspection of Fig3 it is immediately clear that there is a definite advantage in trying to obtain an abrupt transition - one reaps as benefit an interesting potential increase in clubhead velocity. It is interesting that many instructions/observations can be logically tied  to the transition point in the downswing.

-1- Trail forearm in line with clubshaft. This is very important for the SA golfer right from address position and for all good golfers nearing impact. It can be intuitively seen immediately that having the trail arm mass aligned with the clubshaft increases its effective mass (M1).

-2- Instructions such - vertical drop into slot, getting trail elbow against hip, TGM’s straight line delivery are related to obtaining a sharp transition point hence increasing k, the flail boost factor.

-3- The instruction to make a slow, heavy, deliberate and continuous thrust with the trail side can be seen in two ways to increase the k factor.
a) A slow deliberate start makes it easier to obtain a straight line delivery for the trail side favoring a sharp well defined transition point. b) It promotes connectivity in the trail side augmenting the effective mass (M1) behind the mass at the transition point

-3- Yoda’s instruction - Per 1-L-15, the Club starts Up-and-In after Low Point, but the Thrust continues Down Plane, when put into the light of human reaction time, helps producing a sharper defined transition point, BEFORE IMPACT, resulting in a larger k value.

-4- Maintaining pressure on the shaft through impact, e.g., TGM, Mindy Blake’s pressure swing, etc., due to reaction time can be seen to really operate earlier on in the downswing and as above through better connectivity increase the effective mass of M1.

The transition point is what it is, a single point along the downswing trajectory, yet it seems to shed some light onto various instruction usually given without much rational explanation.

Since our friends from the various TGM forums are occasionally coming over to visit I have included Homer Kelley's endless belt effect.  He was intuitively very much on the right track, even if the endless belt effect is not very realistic.

The mathematical formulation of the endless belt effect is very straightforward:

The belt traces the trajectory of the hands and has constant speed. However, hands in a downswing do slow down indicating proximal-distal energy transfer and hence an energy efficient swing. Moreover very large forces have to be generated at the belt club interface to satisfy the model. Dynamic interaction is thus ignored, the rapidly rotating club shaft exerts a large reaction torque back onto the hands/belt.

All a golfer can do is try to ceate a trajectory with a sharp transition and let the swing unfolds itself through the boundary conditons set up by the trajectory change. At the transition a rapid transfer of angular momentum occurs towards the periphery resulting in a boost of clubhead velocity.

In Such a little Secret (Barrett), The Secret of the Golfswing (Dunigan), LPG, and likely other sources, one is asked to make, from the top of the back swing, initially a motion away from the target. Here, I think, we have something quite similar to the transition point of the hitter. It tends to create a 'sharp' transition. The initial backward impetus is running very fast out of steam and has to revert to a forward flow. There is a transition point created between these two antagonistic motions with the potential to augment the peripheral velocity, i.e., clubhead speed.

Conclusions

The mathematical model described above is close and yet far away from reality. It however points clearly to a possible underlying mechanism which explains at least partly why a hitter with a short backswing can still generate so much clubhead speed. The underlying mechanism technically has to do with creating a downswing trajectory which includes a distinct transition from a large to a small swing radius. When this is done with substantial mass at the center and little mass at the periphery one obtains an interesting flail boost factor k.

mandrin