| 摘要 |
A putter-head ( 1 ) giving positive ball-topspin (S) for impact-heights (h<SUB>i</SUB>) above 5 mm from its sole ( 6 ), has its center of mass ( 9 ) located p mm behind its impact face ( 8 ) at height h<SUB>c </SUB>mm above the sole ( 6 ), a mass M kgm and a radius of gyration K mm about the heel-toe axis ( 4 - 5 ) through the center of mass ( 9 ). The loft (alpha) of the impact face ( 8 ) increases monotonically with height from 5 to 15 mm above the sole ( 6 ), where (K<SUP>2</SUP>/p) is greater than 5 mm and S=S<SUB>G</SUB>+S<SUB>L </SUB>where S<SUB>G </SUB>and S<SUB>L </SUB>are percentage spin rates based on: <?in-line-formulae description="In-line Formulae" end="lead"?>S<SUB>G</SUB>=(250xh)/[(3.2+70xM)x(K<SUP>2</SUP>/p)+p]<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>S<SUB>L</SUB>=(-0.76xalpha<SUB>i</SUB>)/[1+0.04x(p/K)<SUP>2</SUP>]<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>for which: h=h<SUB>i</SUB>-h<SUB>c</SUB>-pxsin(a<SUB>i</SUB>) <?in-line-formulae description="In-line Formulae" end="tail"?> and alpha<SUB>i </SUB>degrees is impact-face loft at height h<SUB>i</SUB>. From the sole ( 6 ) upwards, the impact face curves ( 16 ) from negative- to positive-loft and merges into an upper flat-portion ( 15 ) of positive loft. Alternatively, it has upper and lower flat-portions ( 21, 22 ) of positive- and negative-loft respectively. A hosel ( 30, 31 ) gives high compliance at impact for head-rotation relative to the shaft ( 33 ) about the heel-toe axis ( 4 - 5 ), and allows choice of lie in shaft-attachment.
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