SPRING FEVERDick Rugge Q&A - The head of the USGA Test Centerfields some frequently asked questions.

The USGA's test to determine its coefficient of restitution (COR) measures the reboundvelocity of a golf ball fired at a club head.

Ed. Note: This presentation summarywas originally published in the MarchiApril 2001 Golf Journal magazine.

SINCE Dick Rugge first heard the:words "spring-like effect" a fewyears ago, he has read and seen

as much fact as fiction on one of theindustry's hotly debated topics. Everygolfer Rugge meets, it seems, has anopinion on the subject, and not all ofit is based upon scientific research.Rugge, who in early 2000 becamethe USGA's senior technical director,recently sat down to discuss the physicsand philosophy of the matter. An 11-year veteran of club development for amajor equipment manufacturer, Ruggediscussed how and why his Test Centerstaff examines clubs for spring-likeeffect, as well as why the game's two

governing bodies are not in completeagreement on the matter. The questionsincluded those posed most frequentlyto the USGA. ,

Q: What is spring-like effect?'A: I can best describe it by describ-

ing the test. We fire a golf ball at theface of a clubhead, and we measure the'velocity of the ball just before it hits theclubhead. It strikes the clubhead andrebounds in the opposite direction:Wemeasure the velocity again after itbounces off the clubhead. For example,if the ball started at 100 mph coming in,bounced off,the head, and went back at75 mph, we would say that club has acoefficient of restitution, or COR, of 75divided by 100, or .75, or 75 percent.

If we put a persimmon clubhead inthat test, the ratio of the outgoingvelocity to the starting velocity is'about .

78 percent. When we replace that clubwith the first generation of steel clubs,it's a tiny bit faster going out, about 78.5percent. First-generation titanium clubsare about 79 percent, maybe 79.5. It'shard to notice a difference. But thentitanium clubs started to evolve; theybecame larger and the face becamethinner. What started out at 78 percentwith wood, and 79 percent or so withfirst-generation titanium, went to 80, 81,82 percent. So the ball's going out fasterthan it had with previous models.

The USGA developed this COR testand put a limit in of 83 percent. Thathas been the limit for more than twoyears. Since that limit was put in place,some clubs have come on the market-place that have exceeded that limit.They've gone up to 84, 85, as much as86 percent.

Q: Is it possible that further develop-ment will take those numbers evenhigher?

A: We've studied it with very goodengineers we have working at theUSGA, and consultants and physicsand mechanical engineering professorsfrom places like the MassachusettsInstitute of Technology, Princeton Uni-versity, and Lehigh University. Theyhave studied this at length and havetold us we can expect a limit of perhaps88 percent.

So where we started out was 78 per-cent. Where we think it can end up is88 percent. We drew a limit rightsmack in the middle, at 83, and clubsso far have gone to about 86.

Q: What does this mean in terms ofadditional yardage a player may get?

A: Let's assume a good PGA Tourplayer swinging that wooden club hitsit 289 yards - a long poke. As he

~ changes his club and increases his; COR, let's say he goes to the USGA

conforming limit of 83 percent. He'llget another 10 yards and that 289 willbecome 299. If he continues on withthe highest COR club we've seen so far,that will be a 305-yard hit, and if hecontinues on with,what we expect to be

" the maximum, it''llbe about 309. So hewill have gained 20 yards from thewood. We've drawn a line at 10 yards,and he can get another 10 on top ofthat.

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Q: What does any of this mean tothe average player?

A: A player who hits the ball 220yards is going to get about three-quarters of the benefit. In other words,that player's going to see an increase ofabout seven or so yards at the conform-ing limit of 83 percent and about 15yards at the ultimate.

Now that is if - and that's a big "if"there - the player happens to hit it rightsmack on the sweet spot, because thatis where this effect occurs. What I meanby that is, within the half-inch diametercircle of the sweet spot is where thiseffect works. Outside of that, the above-the-limit COR goes away. So you've gotto be able to swing it pretty hard, butmore importantly, you've got to be ableto put it on the sweet spot reliably andrepeatedly.

Q: Some people have said the USGAis stifling innovation. Is that true?

A: No, not at all. Consider in the past20 years some of the equipment inno-vations: metal woods, shafts of exoticmaterials, long putters, square grooves.Those help golfers of every ability. Butspring-like effect doesn't do that; itgenerally helps the very best playermost and rarely helps the lower-abilityplayer.

I'll give you an example of a tech-nology that has had just the desiredimpact. The perimeter-weighted ironhelps the lower-skilled players far morethan it helps elite players. Elite playersreally don't need it because they alwayshit the ball very close to the sweet spot.The benefit of the perimeter-weightediron is that when you hit it off center,you get a better shot than you wouldhave gotten without perimeter weight-ing. And that makes the game more

Iron Byron,the mechanical

golfer, repro-duces a golfer's

swing. It can beused for both

indoor andoutdoor testing.

16 USGA GREEN SECTION RECORD

enjoyable for those players who can'treliably put it on the center of the club-face. That's the kind of technology theUSGA likes to see.

Q: Is excess spring-like effect pos-sible because of the thinness of a club-face?

A: I'll give you the recipe to make aspring-like driver: Make it from tita-nium, make the clubhead broad, andmake the clubface thin.

Why titanium? Because titanium isstrong and light and allows you to makeit big. But titanium is also springier; ithas a higher elasticity than steel. Thenyou make a big face; by the same tokenthat a long diving board is springierthan a short one, the bigger face isspringier than a small one. Think abouta diving board that's a foot long versusone that's 15 feet long. You're goingto get a lot more spring out of the 15-footer. And the third thing is, make theclubface thin. Thin gives more thanthick does.

Q: How thin are we talking about forthese clubfaces?

A: They're a little bit more than atenth of an inch, or less than thethickness of a compact disc.

Q: Why does the USGA believe thatregulating this effect is so important?

A: Golf is meant to be a broad anddeep challenge for a golfer, and wewant to make sure equipment doesn'talter the balance it should have withskill in such a way that the challengesbecome less in the game. We have to dosomething before it happens ratherthan after it happens. Our mission is toprotect the game.

There are two examples I'll cite - twosports that have been longtimecompetitors for participants with golf.

One is bowling. If we went back30 years, we would find a couple ofinteresting things. There were about9.5 million serious bowlers, as definedas people who belonged to bowlingleagues and bowled every week. Therewere about 900 perfect games rolled inthe United States in 1969. During theensuing decades, there have been a lotof technical changes made to bowlingequipment, to balls and the lanesthemselves. Bowling ball ads todaylook like golf club ads. They talk aboutmoment of inertia and the use oftitanium, believe it or not, and havingdifferent surface treatments that grabthe lanes better, all for the purpose ofallowing for control and supposedly togive the bowler more enjoyment of thegame. Well, they've made the gamemore "enjoyable" in a couple of ways.Those 900 perfect games in 1969? In1999, the number had swelled to35,000. Many lanes never saw one in ayear and now it just happens all thetime. And by the way, those 9.5 millionserious bowlers have shrunk to about3 million.

Another example: tennis. In 1975,the high-water mark of tennisparticipation in the U.S. reached about34 million players. About the sametime, the oversize racket was brought tothe U.S. to make the game moreenjoyable and easier to play and morefun and all those kinds of things. From1975 to 1985, one decade later, the elitegame of tennis had markedly changed.It became a power game. The finessethat had been present before waslargely gone, and it wasn't so interestingto people anymore. And that 34 millionhad shrunk to about 13 million - inter-estingly enough, about the same ratio asbowling. And according to people atthe United States Tennis Association,the hard core tennis players stayed. Theones lost were the marginal players, theones the game was trying to turn intohard core players. They disappeared.

Now I can't say for sure it was theoversize tennis racket that drove themall away, but it sure didn't keep them inthe game. I think it's our responsibilitynot to allow unchecked technologyexperiments, like they had in bowlingand tennis, to come into golf. To be trueto our mission of protection, we can'ttake these kinds of chances, especiallywhen other sports have shown that aneasier game resulting from equipment"advances" is not the road to moreparticipation.

Q: Why have the USGA and theRoyal & Ancient Golf Club, the two

governing bodies, taken different posi-tions on the need to test for excessspring-like effect?

A: The USGA and the R&A havetaken different positions based not onscience, but on philosophy. The R&Alooked at the same data and said, "Well,the highest COR clubs today gain onlyabout six yards on top of the USGAlimit." The USGA looked at the samedata a little differently. The USGAsaid, "Wow, that's six yards and that'salready on top of 10 we allowed bysetting the limit at 83 percent. So that's16 yards. That?s a bunch."

The other part of that philosophicaldifference is that the R&A looks at theclubs that have been made so far andsaid, "Well, that's about as much asthey're going to get. They're not goingto go to 088 percent as the USGA saidthey might."

Driven primarily by my years ofworking at a major club manufacturerwith multi-million-dollar research-and-development budgets and 50 engineersworking away, I tend to think themanufacturers will continue to exceedthe results with their second, third, andfourth models. I have a more optimisticview of their abilities than the R&Adoes. I don't think they are finished. Ithink they're just beginning. The R&Athinks the future is already here.

Q: What supports your view?A: My experience in the business.

You find something, get a first try at it,then keep working at it. You don't stopuntil you really have nothing more inthe well. And I think they have some-thing more in the well.

COR is not the crux of club design.To my way of thinking, it's one smallpart. There are many opportunities tomake clubs that are more enjoyable toplay, that work better for any specificgolfer. To focus so much on this oneissue is not in keeping with the historyof golf. The history of golf proves thatnew development comes from allangles, and I would say the recentmerchandise show in Orlando showedthat. There wasn't much of a focus onhigh-COR clubs, if any at all, yet wesaw some new, interesting develop-ments in shafts, grips, and clubheads,all within the Rules.

Q: The way clubs are developed forthe marketplace has changed drasti-cally in recent years. How would youcharacterize the changes in this era ofclubmaking?

A: Certainly it has been a more engi-neering-driven era in the past 10 or 15years, which is the era I've been in-

"Equipment innovationsof the past 20 years havehelped golfers of everyability. But spring-likeeffect doesn't do that;it generally helps thevery best player mostand rarely helps thelower-ability player."

The USGA Research and Test Center testsmore than 20,000 golf balls each year.

volved in golf. And that's driven by acouple of things: significantly more in-vestment from publicly owned com-panies, a lot of aerospace engineerswho like to play golf, and the advent ofusing computerized tools, analysis, cad-cam equipment - virtual designing onthe computer - bringing those toolsfrom other industries into golf. Peoplehave seen that you can make improve-ments.

The game has a history 500 yearslong or more, and that's 500 years ofnot just playing, but also tinkering withclubs. And that tinkering continues. It'san important part of the history and thefuture of golf. Only the tinkering that'sdone today isn't done in somebody'sworkshop. It's done in front of cad-camcomputers by Ph.D.'s, and that acceler-ates the pace of tinkering. It also allowsthem to weed out the bad ideas fromthe good ones much more easily,

quickly, and inexpensively. But there'snothing like the good 01' creativity thatcomes springing forth from the humanmind, and that will continue forever.

Q: Are all of these equipment ad-vances possible because the clubs aremade of metal and not wood?

A: The whole reason metal clubscame to replace wood clubs was be-cause they had a more forgiving char-acteristic. They were tolerant of off-center hits, and that's simply becausetheir moment of inertia, which is abody's resistance to twisting, is higherthan wood clubs. The weight is locatedfurther away from the center. And thesame thing is true when drivers becamelarger in the early '90s, and continue togrow larger, with titanium.

It was a story of the two Ps: physicsand psychology. The physics is a highermoment of inertia, allowing for moreforgiveness on off-center hits. The psy-chology is looking down at a small, olddriver head, and one of the thoughtsgoing through a player's mind beforehitting that would be, "Don't whiff."With a big driver of today, that thoughtis no longer there. There's a much morerelaxed sense, and people know thata relaxed golfer is generally a bettergolfer.

Q: The Rules of Golf would infer thatno spring-like effect is allowed. Bydrawing a line at 83 percent, is theUSGA saying that some spring-likeeffect is allowed, but only up to acertain point?

A: Let me give you the exact wordingfrom Appendix II in the Rules: "Thematerial and construction of, or anytreatment to, the face or clubhead shallnot have the effect at impact of aspring."

What we have is a pragmatic appli-cation of an extreme Rule, and I'll giveyou another example of that. We say inthe Rules that a shaft must be straight.I guarantee you that if we make a fineenough measurement, no shaft evermanufactured or made in the history ofthe world, or the world to be, wouldbe straight. So we make a pragmaticapplication of a severe Rule. That'sthroughout the Rules book. That's whatwe did here.

DICK RUGGE, USGA senior technicaldirector, coordinates the USGA Test Centeractivities from Far Hills, N.J.

More information on the USGA's TestCenter, including how it conducts con-formity tests, can be found on the USGA'swebsite at www.usga.org/tesCcenter.

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