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Sports Engineering

, Volume 6, Issue 2, pp 81–93 | Cite as

Topspin in putters — a study of vertical gear-effect and its dependence on shaft coupling

  • N. M. Lindsay
Article

Abstract

Imparting topspin on a golf ball from putter impact can be achieved either by oblique impact from negative-lofted putter faces or by vertical eccentric impact (commonly referred to as ‘vertical gear-effect’). Negative loft gives a small amount of topspin but should preferably be combined with positive putter-head trajectory to give the ball lift at impact. Vertical gear-effect can provide high spin rates for impacts above the sweet spot and desirably gives the ball a small upward lift at impact. This paper outlines the theory of spin generation in putter impact, discusses how high vertical gear-effect can be implemented and considers the effect that such designs have on putt length control, directional accuracy and impact vibration. Ballistic measurement techniques to validate putter designs are described and an unexpected experimental result dependent on shaft coupling is analysed.

Keywords

ballistic gear-effect inertia putter shaft topspin 

Nomenclature

αi

putter face loft angle at impact

δ

impact point lateral offset towards heel or toe

D

distance between shaft axis and putter-head rotation axis

dr

ball roll distance on green

ds

ball slide distance on green

Φ

putter-head rotation angle due to offset impact

g

acceleration due to Earth’s gravity (9.81 m s−2)

h

distance between line of impact and putter-head centre of mass

hc

height of centre of mass above extreme bottom surface of putter head

hi

impact height above extreme bottom surface of putter head

hs

height of sweet spot

Ix

putter-head moment of inertia about heel-toe axis through centre of mass

Iz

putter-head moment of inertia about vertical axis through centre of mass

Kx

putter-head radius of gyration about heel-toe axis through centre of mass

Kz

putter-head radius of gyration about vertical axis through centre of mass

L

effective length of shaft during impact

M

putter-head mass

μr

coefficient of rolling friction of golf ball on green

μs

coefficient of sliding friction of golf ball on green

p

distance of centre of mass behind putter impactface

r

radius of shaft

R

ball peripheral velocity due to vertical spin as a ratio of its linear velocity (roll ratio)

t

wall thickness of shaft

ts

duration of skidding phase

v

ball launch velocity at eccentric impact

vc

ball launch velocity at central impact

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References

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Copyright information

© isea 2003

Authors and Affiliations

  1. 1.Lindsay Golf LimitedAmershamUK

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