GARY: yes, you are right - but you also hit on something that is almost as important, that being the feel of the shot. While the less 'squashing' is better for energy loss minimization, if you absolutely hate the harder feel that you might perceive that comes with it, then you might tense up and do other things in the body that would make for worse shot making than what the ball energy loss minimization would be worth. Still so you don't feel compelled to change to a ball you hate the feel of - this is a very small difference. TOM W
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Gary Tarbet Sent: Tuesday, July 02, 2002 1:09 PM To: [EMAIL PROTECTED] Subject: RE: ShopTalk: Swingspeed vs. trampoline effect Tom, Appreciate the input. The one question I have from your information is what affect does different types of balls have on this energy loss/exchange? If it is important that we do not squash the ball then it would seem that a 110 compression ball would be better than an 80 compression ball to maximize energy transfer. At least for me, with my senior swing speed, I seem to get more distance and a much more pleasant feel from a mid/softer ball. A 110 feels like I am hitting a frozen marble. Is there an optimum ball type to use with these high COR drivers? Should different speed ranges use different ball types? Gary T. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tom Wishon Sent: Tuesday, July 02, 2002 12:21 PM To: [EMAIL PROTECTED] Subject: RE: ShopTalk: Swingspeed vs. trampoline effect Guys: Been reading your comments on spring face with interest. Lots and lots of things to comment on but don't want to make this too long, so I will try to hit the high points about which I think mine and my engineering consultant's knowledge is pretty solid. 1. Perhaps the worst piece of misinformation in all this is the actual term trampoline effect, for the reason it gives you the mental image of the face acting like a 'slingshot'. What happens to increase ball velocity off a so-called spring face is that when the head is allowed to lose more energy by the face deflecting more, then the ball loses less energy - and then can leave the face at a higher velocity relative to the head's velocity. If you have less face deflection for the speed of the head, then the ball is deforming (squashing) more, the ball then is losing more energy and it cannot leave the face as fast. 2. Remember - it is the BALL that is the source of almost all of the energy loss at impact. The greater the squashing of the ball, the more the ball energy loss. This matter of loss VS ball squashing is NOT linear. If it were, then twice the squashing of the ball would produce twice the energy loss. What happens is as the deformation of the ball doubles, the losses more than double. 3. Yes, it was me and my engineer who came up with the idea of different swing speed limits for the different head designs when I was with Golfsmith. Reasoning for this was based on #1 and 2 above. Higher swing speeds cause more face deflection for any particular face thickness. No matter what, a slower swing speed will deflect a face less. And the less the face deflection, the more the ball loses energy for that particular golfer. If you make ONE face thickness to fit all golfers, the more the golfer's swing speed decreases from the highest swing speed the face is built to withstand, the less ball velocity to swing speed improvement will be realized. To maximize the potential for the slower swinger, you have to reduce the face thickness to allow their slower swing to deflect the face more - but the downside is if that club is used by a golfer with a much higher swing speed, they will "over-flex" the face past its stress limit and cause permanent damage. Hence the reason for the WARNING stickers on the faces of those drivers we designed for GS. 4. If you plot a curve of the COR VS the Spring Rate of the face, the COR starts out at a low value with a face that is very flexible and increases as the face assumes a higher spring rate until the peak is reached at about a 0.86 COR value. Continued increase of the spring rate results in a LOWER COR until the idea levels out to a point where the face would be totally rigid, at a COR of about 0.76. 5. The keys to higher COR drivers that can maximize the ratio of swing speed to ball speed, are, a) larger faces that are more TALL than wide. Our studies indicate that face height is 3 times more influential on the ability of the face to deflect than face width. B) face materials with a high yield strength + low modulus of elasticity AT THE SAME TIME TOGETHER. This is why Beta Ti alloys are so good to use. But do not forget, super high strength steels that allow less face thickness than the beta ti alloys are good too - we were able to make an Aermet face driver that had the same 0.845 COR as the Beta Ti back in 2000. Their only drawback is their higher density - as the face area increases the weight does too - which puts limits on how large you can make a steel head and still have the desired headweight for swingweighting purposes. 6. It is possible for a slow swinger to get more ball velocity from a thin face big head than if that same slow swinger was using a much thicker faced driver. But do not even think they are getting close to what the faster swinger is getting in terms of face deflection/ball energy loss reduction. Use common sense - a 50 mph swing is still going to deflect a thin face more than it will a thick face. It won't get the MOST out of it like the 100mph swing will, but it will still get some improvement over what happens with the thicker face. TOM W
