Thanks for the reply. I think that head speed has a direct bearing on the centrifugal force that pulls the toe down, into the first half of a "bob". If I am wrong, stop reading, because I am basing my comments on that. If it is true, then I would make a layman's guess that by either increasing or decreasing the head speed would cause a change in the amount of toe bob / deflection. I always thought the acceleration and deceleration was changing speed. What am I missing? Thanks again.
Al
At 06:10 PM 1/2/2003, you wrote:
Al Acceleration through impact would have nothing to do with toe up toe down deflection its the centrifugal force pulling down on the head and the flexing of the shaft in the toe up toe down direction initiated at the top of the swing. These deflections are normal to a players acceleration at impact. The acceleration component normal to the toe up toe down flexing would have no or at least very little affect on toe up toe down deflections. The fact that the good player takes the club away from to top slower or more smoothly would substantially reduce that component of toe bob which I believe is the major factor in the toe deflection problem.llhack ----- Original Message ----- From: "Al Taylor" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, January 02, 2003 10:16 AM Subject: Re: ShopTalk: shaft flex v.s. frequency > Lloyd, > I hate to argue with an engineer since I am out of my league then, but I > believe that the TT shaft lab results do show that higher head speeds have > greater toe down. Along this area, the Pros usually are still accelerating > into impact and, as a result, have little to nil toe bob. The amateur > often starts to decelerate prior to impact and the toe then starts back up, > or bobs. The TT graphs show that somehow there is often a series of toe > ups and toe downs on the later example. > > I know that my irons profile is similar to pro iron profiles (wonder why my > shot results aren't the same?) but my driver shows some toe bob. > > Al > > At 09:40 AM 1/2/2003, you wrote: > >Royce and Alan > > > >The centrifugal force is certainly part of the Toe down deflection at > >impact. Since toe down deflection is dependent on club head speed this > >would make the better players with the high clubhead speeds have greater toe > >down deflection ( opposite True Temper results ). What I described earlier > >is the other component of toe down defection at impact. As can be seen in > >all of the Shaft Lab data there is initially a toe up deflection at the top > >of the swing. This deflection along with the time from the start of the down > >swing to impact gives the shaft time to go through 1/3 to 2/3 cycle of its > >natural frequency resulting in some degree of toe down deflection. This > >resulting defection is a function of how much the club is loaded at the top > >of the swing to produce the initial toe up deflection. Herein lies the > >difference between the good player and the others. > > > >Allen, I follow your 1/2 cycle argument and our only difference is in the > >definition of the cycle. As an example, if I mount the club in a frequency > >analyzer and pull the head down and hold it in that position before > >releasing it, it dose not complete a full cycle until it returns to the max > >down position again. A 1/4 cycle would bring it to shaft straight with max > >upward velocity. As in the swing I do not consider the loading of the shaft > >as part of the cycle because it is not a function of natural frequency or > >spring properties. > > > > > >----- Original Message ----- > >From: "Royce Engler" <[EMAIL PROTECTED]> > >To: <[EMAIL PROTECTED]> > >Sent: Tuesday, December 31, 2002 10:07 PM > >Subject: FW: ShopTalk: shaft flex v.s. frequency > > > > > > > Alan said.... > > > > > > <snip> > > > As far as 'toe bob' goes I am not sure that I know what you mean by > > > this. I think it is probably the toe down deflection of the club head > > > caused by the centrifugal force on the offset cg of the club head. This > > > force increases very rapidly near impact (it's proportional to the square > > > of the head velocity) and is resisted mostly by a relatively short section > > > of the shaft near the tip. > > > > > > </snip> > > > > > > As I understand it there are two forces acting here, both the result of > >the > > > CG of the clubhead being offset from the centerline of the shaft. First > > > there is a moment working to align the CG of the clubhead with the shaft, > > > which has the effect of rotating the trailing edge of the clubhead under. > > > This has the effect of increasing the loft of the club as it goes through > > > the ball, and acts in the plane of ball flight, commonly called dynamic > > > loft. According to Tom Wishon's book, moving the CG 1/8" further back > >from > > > the face will add about 7 feet to the trajectory. > > > > > > What is commonly called toe bob is the result of a similar, but orthogonal > > > moment trying to align the CG of the club with the shaft in the direction > > > from the toe to the heel. The net effect is to rotate the toe of the club > > > around the CG, which bends the tip towards your toes i.e. in a plane that > >is > > > orthogonal to the plane of ball flight. This is the effect that causes > > > dynamic lie angle to be different from static lie angle. > > > > > > All of which combines to make it amazing to me that any of us can ever hit > > > the ball "on the screws".... > > > > > > Royce > > > > >
