Perimeter Weighting and Impact Dynamics

[rainbow_in_the_dark]

Thru science the notion of the "heavy hit" has been refuted.
The ball is on the face such a short interval there's very little that can change between impact and seperation.
Does this also diminish the claims that perimeter weighting will result in a more forgiving club because it's less resistant to twisting? If the interval is so short, how much twisting can occur?

 

[Brian Manzella]

Thru science the notion of the "heavy hit" has been refuted.
The ball is on the face such a short interval there's very little that can change between impact and seperation.
Does this also diminish the claims that perimeter weighting will result in a more forgiving club because it's less resistant to twisting? If the interval is so short, how much twisting can occur?

The "resistance to twisting" is on OFF CENTER HITS.

And the answer is A BUNCH!!

 

[savydan]

The heavy hit dispute has to do with the properties of the steel (or graphite) shaft that there is not enough time for any wave to travel up and down the shaft in order to add any effective mass to the clubhead.

The perimeter weighted head/off-center hit situation does not have to factor in the shaft properties.

 

[Virtuoso]

When it comes to the launch parameters of the ball, here are the 4 things that matter:

1. Mass properties of clubhead
2. CG location vs hit location
3. "Obliqueness" of impact (dynamic face normal and path/attack)
4. Clubhead speed

So, in terms of mass properties, increasing the MOI (perimeter weighting) vs concentrating the mass at the cg (muscle back) has an enormous effect on launch parameters when the clubhead cg and ball cg are not lined up.

Side note: Shaft properties are incredibly overrated in terms of directly affecting launch parameters, but not in terms of their effect on clubhead delivery.

 

[rainbow_in_the_dark]

So then is there any benefit to using blades?

 

[Virtuoso]

So then is there any benefit to using blades?

There is less drag in deep rough when using blades, assuming they are smaller in size (this has nothing to do with MOI) and as a result there is less clubhead speed loss (might be one reason why they are still used on the PGA Tour).

Also, blades typically have cg location very high heel, so even a chopper that hits everything high in the neck will get better ball speed on avg from that type of club compared to a typical game improvement club which has cg location more low/center. In other words, their hit location is close enough to the blade cg to have a net gain in ball speed vs a bigger mis-hit on the club with the high MOI.

 

[Virtuoso]

Where is the sweetspot on a large cavity back iron?? Genuine question .. can't wait to hear the answers .
Point is, if your on a tight fairway lie, why the hell would you wanna hit a large faced club over a small one without perimeter weighting, assuming you're not a hack.

Chops usually have a shallow angle of attack with the irons and steep with the driver which is the opposite of what you want. If the ball sits tight, instead of fluffed up, then most chops want a cg as low as they can get, because when they bottom out too soon, if they miss the ground and don't chunk it, then they will likely hit it thin. Whatever club has the lowest cg will be best, not because they launch it higher, but because they get better ball speed on a thin impact.

If they are a little better and attack the ball at say neg 4 or 5 degrees, then they can use a more traditional design with higher cg.

 

[Virtuoso]

Cool , so technically a blade (or a VERY narrow cavity back, relatively speaking) will always be better for a good player on a tight lie. PERIOD ??
If not, the why do no PROS play driver off the deck anymore? See, it shoud be easier rigth cause they are 460cc compared to 250cc ... LOL .
Everytime I walk into a proshop and a KNUCKLEHEAD tells me a 460 cc club is better than a 300cc one , or one of those huge ping shovels are better for me than a blade , I want to get hold of the nearest club I see and do a very nasty thing to the said pro ! . CLUELESS like most other things in golf .

A blade will always work fine for a better player IF they don't hit it on the toe or thin. If they hit it toe-ward at all, or catch it low on the face, a blade is a big mistake.

A 460 cc driver is horrible off the ground. The CG is way too high. You just can't get the ball to impact high enough on the face. If you make a perfect swing, you will still hit it below the cg, lose a bunch of ball speed, have a low launch angle, and have very high backspin. A shallow faced 13-14 degree 3-wood, even struck with a clubhead speed a couple mph slower will go much farther.

 

[birdie_man]

Good posting Virtuoso.

 

[birdie_man]

I don't have much experience with em but...

Titleist 690MB...freaking sweet...didn't find them that hard to hit.

MacGregor Muirfield Custom...freaking SWEET (points for old-SKOOLE flavour)...not bad- not bad at all. (ease-wise)

Newest Hogan Apex...been a long time but...quite nice...ball felt too soft on impact though (and range balls at that) and flew too high. (probably soft shaft)

Spalding Executives...meh...really old irons. (they are 1960-something)

(first set my dad ever bought)

I think those are the only ones I have hit...

They sure look purDy though...and believe it or not that IS something.

Same deal with "in hand feel."

I hear you on tight lies Danny...esp. with irons with lots of bounce. (apt to hit thin)

(you have to add more lean)

Again, I won't have nearly as much experience as some...but so far pretty good for blades.

 

[Virtuoso]

Excactly . Well, I edited my post . The sweetspot is the issue. And if you're on a tight lie a big cavity back iron is a DISADVANTAGE, PERIOD. Unless you're a hacker.
It's about time these idiots who claim blades are so TERRIBLE got their heads out the sand. And lets face it most blades are not like they used to be.
Oversize heads are the worst thing that ever happened to golf, and all the clueless bunch that thought they were so great when they arrived.

Well, i understand if you think blades have been given a bad rap. Certainly, there are situations where blades are more optimum than large cavity backs. But I would completely disagree that oversize heads are the worst thing that happened to the game. Some of my students come to me hitting the ball soo badly that I would gasp in horror to watch them try to hit an old steel shafted persimmon driver or an apex pc 3 iron.

 

[birly-shirly]

Danny - I think you're well wide of the mark on this one.

I've got nothing against blades, but you seem to be saying that oversize iron heads have a higher CoG than blades. In the case of most oversize, perimeter-weighted irons, I think that's just not true. Those wide soles are there in large part to move the weight lower - and if you re-read Virtuoso's 2 posts above, I think you'll see him saying the same thing.

Look also at Maltby's playability factor ratings for iron design. I'm not defending the concept of MPF per se, but Maltby thinks that a lower CoG is critical to playability, and his "most playable" categories are stuffed with oversize perimeter weighted irons with a low CoG. (Curiously, he doesn't rate many of the "classic" generation of Ping irons - which he thinks have too high a CoG. Maybe it's not a coincidence that for years Pings were the better player's shovel of choice.)

460cc drivers off the deck are a different case entirely - those are designed to be optimal off a tee (quite a long tee nowadays, I think).

Even the issue of bounce on the soles of these shovels - I kind of want to agree, but then you've got Stan Utley arguing that 12* bounce is no handicap on a pitch off hardpan.

This isn't meant to be down on blades at all, but I totally disagree with the statement that any non-hacker is at a disadvantage playing cavity-backs.

I don't think I agree either that blades these days are much different to those of 30 years ago. I just don't think there's much scope for moving significant amounts of weight around within a traditional design. I've got sets of Hogan, Wilson, MacGregor and Mizuno blades and maybe one set is less than 20 years old - but I think they'd all easy stand up against any of the modern blades for playability.

 

[Virtuoso]

You completely nailed it Birly-shirly. Nice job.

Incidentally, spent some time with Maltby and was very impressed by his knowledge and methods. But he's a racer too and we spent as much time talking about shifter karts and racecars as we did golf, LOL.

 

[rainbow_in_the_dark]

Seems like most cavity clubs dont really have much of a cavity anyway. Sure there are some exceptions like Ping Eye 2's. It seems most of the weight when you go from a MB to CB model goes to the sole and not the heel and toe anyway.

What are the physics of building up the sole?

 

[Matt 4-L]

Question: If you hit a cavity back in the center of the club face are you hitting it above the sweet spot and are you going to lose ball speed? Are they designed to have optimal ball speed hit low on the face or thin?

 

[rainbow_in_the_dark]

Is the performce of this MB model ...

http://www.titleist.com/golfclubs/irons/MB.asp

... really different than this CB?

http://www.titleist.com/golfclubs/irons/CB.asp

 

[birly-shirly]

Seems like most cavity clubs dont really have much of a cavity anyway. Sure there are some exceptions like Ping Eye 2's. It seems most of the weight when you go from a MB to CB model goes to the sole and not the heel and toe anyway.

What are the physics of building up the sole?

I think this can do three things. It can move the CoG lower in the clubhead by putting a greater proportion of the clubhead mass low down. Balls can then be hit lower on the face and not be so "clanky". Speculating here, but I'm guessing that people who struggle to make consistent contact will instinctively err on the thin side in preference to dumping the club fat behind the ball. A low CoG is going to help them somewhat hit better feeling, better flying shots.

Second thing is, building up the sole at the expense of the cavity - but leaving a thicker top-line - is perimeter weighting in the vertical dimension, rather than heel-toe. That will increase the clubhead's resistance to twisting around the heel-toe axis - making the clubhead more forgiving of mishits either too high or too low on the face. I believe that for a given amount of miss, say 1/2 inch from the sweetspot, misses in the vertical dimension are more costly in terms of lost distance than misses in the heel-toe direction.

Third, sole weighting from a wider (front to back) sole may help move the clubhead's CoG rearwards, away from the face. I think this helps launch the ball higher, and I suppose must increase the clubhead's MoI too (although I have no idea whether the increase in MoI is significant)

 

[birly-shirly]

Question: If you hit a cavity back in the center of the club face are you hitting it above the sweet spot and are you going to lose ball speed? Are they designed to have optimal ball speed hit low on the face or thin?

I don't know - it must vary from club design to club design. See my comments about Maltby and Ping irons above.

An alternative answer is that I'm not sure that it helps to know "visually" where the CoG is. My basic belief is that, if you're going to find the sweetspot consistently, you'll do it by trial and error, feedback and feel rather than being able to pinpoint the precise spot with a marker pen.

Then again, I'm sure Kevin Shields posted here a while back that he liked to use impact tape when practicing with his wedges - and I suspect that Kevin knows a bit more about where to find the sweetspot than I do...