Book contents
- Frontmatter
- Contents
- PREFACE
- 1 MOTION UNDER GRAVITY ALONE
- 2 MOTION IN A LINEAR RESISTING MEDIUM
- 3 MOTION IN A NON-LINEAR RESISTING MEDIUM
- 4 THE BASIC EQUATIONS AND THEIR NUMERICAL SOLUTION
- 5 SMALL DRAG OR SMALL GRAVITY
- 6 CORRECTIONS DUE TO OTHER EFFECTS
- 7 SPIN EFFECTS
- 8 PROJECTILES IN SPORT AND RECREATION
- REFERENCES
- INDEX
7 - SPIN EFFECTS
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- PREFACE
- 1 MOTION UNDER GRAVITY ALONE
- 2 MOTION IN A LINEAR RESISTING MEDIUM
- 3 MOTION IN A NON-LINEAR RESISTING MEDIUM
- 4 THE BASIC EQUATIONS AND THEIR NUMERICAL SOLUTION
- 5 SMALL DRAG OR SMALL GRAVITY
- 6 CORRECTIONS DUE TO OTHER EFFECTS
- 7 SPIN EFFECTS
- 8 PROJECTILES IN SPORT AND RECREATION
- REFERENCES
- INDEX
Summary
“______, when I remembered that I had often seen a tennis ball, struck with an oblique racket, describe such a curveline. For, a circular as well as a progressive motion being communicated to it by that stroke, its parts on that side, where the motions conspire, must press and beat the contiguous air more violently than on the other, and there excite a reluctancy and reaction of the air proportionably greater …..”
Sir Isaac Newton (1642 - 1727)Overcoming Yaw
When a non-spherical projectile is fired or launched its longitudinal axis rarely lies along the tangent to its trajectory, so there is a non-zero angle of yaw. As a result of yaw the air acts on the projectile to produce
(i) an increased drag compared with the drag at zero yaw,
(ii) a deviating force which tends to alter the projectile's trajectory,
(iii) an overturning moment which rotates the projectile about its centre of gravity.
The last was discussed in Section 6.7, and may increase or decrease the yaw depending on the design of the projectile. A decrease in yaw is obtained by fitting fins to some projectiles (darts, arrows, bombs and mortar shells), so providing a method of stabilising the projectile and its trajectory. This method of stabilisation has some disadvantages however, the principal one being that a cross-wind tends to interact with the fins and push the projectile well off course.
- Type
- Chapter
- Information
- The Mathematics of Projectiles in Sport , pp. 119 - 134Publisher: Cambridge University PressPrint publication year: 1990