Hmm that's really interesting Mafa, and extremely nerdy I have to say :-D
Bradley, I was bothered by the same thing as mafa in your reasoning;
Bradley said:
wide rim discs are much harder to snap, because the MOI of the disc around the lock point is so much greater...From my tests, the wider the rim, the lower the initial velocity. In other words, a Wizard goes 65 MPH, a Teebird, 60 MPH, and a Boss 55 MPH OUT OF THE HAND. I, at first, believed this was all grip related, but I now believe that the wide rim discs simply have a much much greater weight "in the head of the hammer" that must be swung around the arc of the disc pivot
Two things actually; as mafa showed the MOI should not be greater in wide-rimmed drivers. In addition to most of the mass in the rim being towards the center (the sharper/wider the rim, the more pronounced this would be of course), a smaller diameter would make the "lever" shorter as well - so the net result has to be a smaller MOI.
Then it's the idea of exerting energy to make the disc rotate, "leveraging" MOI. I would think that it's actually the other way around, MOI in a larger diameter putter or midrange would
contribute to speed and spin. This might seem counter-intuitive if you think that most of the force in the disc pivot is intentional, but it's consistent with the mechanics of the hit and the motion of the disc as I understand it:
- Disc moves forward without rotation
Rotation starts when arm extends (no conscious effort needed to start rotation)
Rotation amplified and partially converted back to more disc speed through wrist extension (very little conscious effort here as well - wrist closes because of disc inertia, extends because of tendon bounce. This might be controversial but I believe that even though some conscious extension is possible, it will mostly be too slow to make a lot of difference.)
This theory is also consistent with your own speed measurements.
Power (especiallys static power) in the hand and wrist makes it possible to transfer more energy to the disc (without slipping, as JR has pointed out) and technique would make it possible to time this use of power to some extent and optimize the effects through proper placement of the disc. But I would think the higher speed of putters and midranges is
because of a higher MOI.
It would be very interesting if you have some speed measurements on putters or mids with similar rims but distinctly different diameters, If I'm correct the larger diameter should lead to higher initial speeds, this might of course be cancelled by necessary form/grip/wrist extension changes though...
Bradley said:
It is much more difficult to accelerate a golf club of swingweight e8 than it is a c9... it is the same principle. The more plastic concentrated in the rim, the heaver the head of the hammer.
Well, it takes more power to accelerate a heavy hammer but it can reach a higher speed... provided you have the strength to hold on. Since it's harder to maintain the grip with a wider rim, and this theory stipulates that grip and technique are the limiting factors here, NOT dynamic wrist strength, this is still consistent I think.
The Finn's got it figured out;
JR said:
there's a benefit of having the finger pinch strength of an Olympic athlete.
Now, I need a real nerd (that is someone who really understands mechanics/physics) to cut me down at once if any of this is wrong :lol:
PS: JR - jeg er norsk så svensk er ikke noe problem å forstå heller, men en osaa puhua suomea ;-) but enough of the code speak
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
I've seen the Avery vids and they're awesome but I wouldn't know where to begin analyzing them... Now,when you put up the other vids you mentioned as well and we can start comparing, that should be interesting! I really love those top-down vids, that's really made a difference in figuring out what the hit should be like.