Discussion on 'Effective CG' - Mark Crossfield

[b101]

So, this popped up today in my YouTube feed. I'll freely admit, I'm a bit addicted to his stuff and watch everything, but this is the first video in a long time (since the shaft video) that has actually made me think a bit rather than just repeating things I'm pretty well-aware of. More than that though, I didn't really know what to make of it at all, and thought I'd see what others thought. Basically, they try to hit various types of shots (fades/draws) and discuss where they feel the sweet spot is. I feel like it'd have been more interesting to see high fade vs low fade etc. Quite frankly, I'm happy with pretty much anything out of the centre of the club.

Anyway, here's the clip - interested to know what you all make of it.

[saevel25]

To me it makes sense in a way. Physically the CG is a static point. Yet that point does move in the golf swing. How the face is angled and traveling will effect how that CG moves. Even the MOI of the club can effect how it moves because the club is resisting turning due to impact.

If you hit the ball with an open face, that CG should be more inward (towards you). So to deliver the ball with a solid strike the CG should be moving outward to meet the ball.  If the CG is moving inward with an open face then the strike might feel very slight.

I am not sure the correct impact zone on the face should change depending on the shot you hit. If you have a very neutral path then a strike that is low and heel will start off lower, spin more, and curve to the right do to the gear effect. Does the shot feeling good actually correlate to the intended shot?

It would be interesting to test this out on the range sometime with some impact tape.

[Lihu]

So, this popped up today in my YouTube feed. I'll freely admit, I'm a bit addicted to his stuff and watch everything, but this is the first video in a long time (since the shaft video) that has actually made me think a bit rather than just repeating things I'm pretty well-aware of. More than that though, I didn't really know what to make of it at all, and thought I'd see what others thought. Basically, they try to hit various types of shots (fades/draws) and discuss where they feel the sweet spot is. I feel like it'd have been more interesting to see high fade vs low fade etc. Quite frankly, I'm happy with pretty much anything out of the centre of the club.

Anyway, here's the clip - interested to know what you all make of it.

Funny, I was just watching this at lunch.

Great video.

[golf-noob-bruce]

http://thesandtrap.com/t/33326/sweet-spot-shifts-fade-vs-draw

I find the references to COG confusing though. Isn't it really the center of mass?

[saevel25]

http://thesandtrap.com/t/33326/sweet-spot-shifts-fade-vs-draw

I find the references to COG confusing though. Isn't it really the center of mass?

When gravity is a constant then yes the Center of Mass equals the Center of Gravity.

In physical terms center of mass is how the mass is distributed. Center of Gravity can change if the gravity is not uniform. That is more important in astrophysics.

[golf-noob-bruce]

When gravity is a constant then yes the Center of Mass equals the Center of Gravity.

In physical terms center of mass is how the mass is distributed. Center of Gravity can change if the gravity is not uniform. That is more important in astrophysics.

Ah, ok. So for everywhere in the universe where golf is currently being played (presumably) the distinction is academic.

[saevel25]

Ah, ok. So for everywhere in the universe where golf is currently being played (presumably) the distinction is academic.

I don't know there could be a planet with a fluctuating gravity.

[Pretzel]

I think I understand this, after thinking through it.

If you normalize the path relative to the clubface (in other words finding out how far right or left your path is relative to the face angle), then you can draw a line along that path through the CG to find the effective sweet spot is what appears to be happening. All you're doing is making sure that the center of mass is directly behind the point of contact when you're swinging to find the effective sweet spot. At least this is what appears to be happening when I think through it.

So long as you normalize the path relative to the face and draw the path to bisect the center of mass, you should be able to predict where the sweet spot can be found if my guess is correct. My guess is assuming that the feeling of solid contact comes from effectively delivering the center of mass directly behind the ball. This would also explain why longer hitters say they prefer to hit the ball on the upper half of the clubface, since they would be swinging up (and thus delivering the center of mass directly to the ball by hitting higher on the face).

Any engineers able to tell me if this sounds plausible?

[motsco]

the way I see it, using billiards, the cue ball is the golf club, the pool stick is the ball. reverse action? so in billiards you use the stick on points of the cue ball to get certain movement. in golf the club head is bigger then the golf ball so the club head becomes the cue ball.?