I have picked up the final understanding from your book Ralph. Thanks !
VCOG
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12:53AM - Jun 3, 2008RE: VCOG
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Report Thisjonag
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Quote:
Originally Posted by Ralph Maltby
jonag and keyser, I was reading the entire thread here and jonags are the correct ones. I have a series of 9 full page illustrations of all of this in my “MPF for Irons” book showing 3 different design irons at impact with explanations on each illustration. It’s too much to add in here.
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10:26PM - Jun 2, 2008RE: VCOG
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Thank you all, now I think I understand this better. I have a related question. I would like to put a mark on my clubface marking the exact sweet spot. Can I just measure in from the shaft center for the C and up for the acog? Or is this going to change for each different loft? Or is this a useless effort because the precise sweet spot changes based on the angle of attack—sweeper verses digger?
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4:05PM - May 28, 2008RE: VCOG
#12
Report ThisRalph Maltby
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keyser, the key is the force path direction of the clubheads center of gravity in relation to the golf balls center of gravity. More specifically how much lower is the CG of the clubhead on this path than the balls CG. Next, the more rearward the CG (comparing two irons with the same vertical center of gravity), the greater the forces from the head acting on the golf shaft to dynamically increase the loft. Of course, this force as we all know is referred to as “centrifugal force”.
From a playability and fitting standpoint, you only need to focus on the actual vertical center of gravity and the rearward center of gravity. These two mass and dimensional qualities of the head along with the moment of inertia control MPF. So, an understanding of how they work is very helpful in proper clubfitting.
Note here that we are talking about the mass and dimensional properties only, because there are many other factors to consider in iron playability and fitting. keyser, I added in this “note” line in case a reader was reading this post for the first time.
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6:26PM - May 26, 2008RE: VCOG
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I looked through the book. If I understand this correctly, it´s not how how the CG is aligned with the ball upon first contact of the ball and the clubhead(then a deeper RCOG would appear to be higher than a shallower one), it´s actually the path of the CG(the path of a deeper RCOG is going more behind and lower). If that´s the case, then I understand how a deeper RCOG can work dynamically as a lower one.
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7:43AM - May 26, 2008RE: VCOG
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Report ThisRalph Maltby
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jonag and keyser, I was reading the entire thread here and jonags are the correct ones. I have a series of 9 full page illustrations of all of this in my “MPF for Irons” book showing 3 different design irons at impact with explanations on each illustration. It’s too much to add in here.
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4:43PM - May 25, 2008RE: VCOG
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Keyser, you are placing extra limitations to the equation here. When the club is released down into the ball, a deeper COG is on its way heading to the ground more behind the ball than a less deep COG. The clubhead is not moving straight, it is moving on an arc and the deeper the COG the lower the attack on the ball.
For a player hitting to level or up on the ball to get height (releasing, not getting the hands in front, picking the ball, sweeping), the dynamic loft will help, but will not fix the fact that the swing is sweeping. If you hit flat or up on the ball the problem is tha the COG is attacking to much to the middle of the ball. A deep COG will help in attacking lower due to the arc-path described above.
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5:17AM - May 24, 2008RE: VCOG
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A more rearward COG at a descending blow will attack lower on the ball than a less rearward COG How you figure? The further the CG is back, and if the head is tilted forward(like in a descending blow), the HIGHER the CG is.
teh rearward COG will bend the shaft and give dynamically more loft. The result is a more solid hit and more loft = higher and longer I agree that it will cause more bending of the shaft hence more dynamic loft, but that has nothing to do with a “solid” shot, and there are many that struggle with too high of a ball flight, and they´ll just hit it shorter.
This is perfect for the more sweeping swing. I agree with that. Many gofers don´t hit down well enough on the ball, but most good golfers will take divots with most irons and a deeper RCOG will only benefit them in a driver(and possibly the long irons).
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4:36PM - May 23, 2008RE: VCOG
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guys…
A more rearward COG at a descending blow will attack lower on the ball than a less rearward COG. In addition teh rearward COG will bend the shaft and give dynamically more loft. The result is a more solid hit and more loft = higher and longer. This is perfect for the more sweeping swing. For a good player he might have problems with a too high trajectory.
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6:55AM - May 23, 2008RE: VCOG
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What a great thread:)
So a more rearward CG on an downward strike(most everything except a driver for many), will actually raise the VCOG at impact because of the way the club is going down at the ball. Is that correct?
That means that for irons that more rear CG can never be a good thing, the only good thing it does it will likely raise X-axis MOI by getting more weight into the heel and toe, like the nicklaus polarity iron, or square designs are good because they can achieve a higher MOI without getting the weight too much back">MOI.
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10:21AM - May 5, 2008RE: VCOG
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Report ThisRalph Maltby
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chuck, the rearward center of gravity (rcog), the balance point on the face which is the basic vertical center of gravity (bvcog) and the loft of the club are used to calculate the actual vertical center of gravity. This is a simple trigonometry calculation. What happens is when the rcog is not very far back and/or the club has a higher loft angle and/or the bvcog is higher up the face, you may start getting positive correction factors which when added to the bvcog will raise the avcog (actual vertical center of gravity) instead of lowering (most common scenario) the avcog.
You will notice that most every 5 and 6 iron that I list is a negative correction factor, so some of you have guessed that this usually indicates a more rearward center of gravity. The Ping G10 that I measured was .456 rcog and this mostly accounted for the +.013 adjustment to the bvcog to get the avcog.
Boy, you guys really know how to get into some complicated stuff. In my book, “The Maltby Playability Factor for Irons”, see page 90 for an explanation of this.
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