The Shaft is stressed by the Impact Collision of Club and Ball. In the Start-Down Loading, the Hitter Pre-Stresses the Shaft with Clubhead Lag Pressure Point Pressure via the Right Elbow. The Swinger's Loading allows Centrifugal Force and its efforts to Straighten the Shaft to do that job via the Left Wrist. This is the "flexed, stressed Clubshaft (Hitters) and the wallop of Centrifugal Force (Swingers)" of 6-F-1.
Agree that the shaft is stressed by the collision with the ball. Another question is the shaft condition at impact.
Inspired by your post, I opened the yellow book. I think 6-F-0 Timing - General sheds some light too:
... "So, the Clubhead is not picking up speed during the Overtaking (release) Interval, either when Hitting or Swinging."
What does this implicate?
A prestressed spring will start bouncing back as soon as the force that stressed the spring is being reduced. Similarly, a prestressed shaft will bounce back as the accelleration drops and swing speed reaches max during the release.
If thrust is maintained (according to Homer it should be) during the Overtaking, the clubhead will be forced to catch up with the hands. If thrust is aborted, the hands will simply wait for the clubhead that and potential speed increase is lost.
Originally Posted by Burner
They (True Temper) do, however, also mention that most swings have achieved their maximum velocity some little while before impact.
This is exactly what Homer says in 6-F. In fact I see no conflict between 6-F and the shaft loading profiles from the True Temper shaft lab. On the contrary, they are complimentary.
If my understanding of Homer and True Temper is correct, the player should do his/her best to maintain a prestressed shaft all the way to impact. But the appropriate shaft should nevertheless straighten out juust in time for max clubhead velocity at impact.
Inspired by your post, I opened the yellow book. I think 6-F-0 Timing - General sheds some light too:
... "So, the Clubhead is not picking up speed during the Overtaking (release) Interval, either when Hitting or Swinging."
Remember, as Mike O pointed out in a post last year, Homer Kelley is not referring here to the Clubhead's Surface Speed (miles per hour). That Speed does indeed increase during Release. However, because of the Flat Left Wrist, Angular Speed, i.e., Hand Speed versus Clubhead Speed as measured in revolutions Per minute around the Left Shoulder Axis, does not increase. A readily understood example of Angular Speed is that exhibited by the various components of a merry-go-round all rotating at the same RPM around a common axis.
For the Swinger, after the initial Acceleration in the Start Down, Angular Speed is constant from Release until Impact. For the Hitter, the deceleration begins immediately at Release. For both Swinger and Hitter, the Impact collision slows Angular Speed and Surface Speed.
Hybrid Mode
