A golf ball has a core, an inner cover, an outer cover, and dimples. The golf ball satisfies the following mathematical formulas.
Sa=4500+10(A−0.5B−2Cs)≥4000
0.04Sa+160−20≤D≤0.04Sa+160+20 A: a compression (Atti) of the golfball B: a hardness difference (Shore C) between a surface and a center of the core Cs: (Hi×Ti+2Ho×To)/(Ti+2To) D: a total volume (mm.sup.3) of the dimples Hi: a hardness (Shore D) of the inner cover Ho: a hardness (Shore D) of the outer cover Ti: a thickness (mm) of the inner cover To: a thickness (mm) of the outer cover

Golf ball having a generally spherical surface and comprising a plurality of dimples separated by a land area formed on the ball surface, wherein the plurality of dimples includes at least one non-spherical dimple having a non-axially symmetric plan shape and a defined point of maximum dimple depth, wherein: (i) each dimple cross-section of the non-spherical dimple consists of two arcs, each arc extending from the defined point of maximum dimple depth to a point at the land area of the golf ball; and (ii) every point on the perimeter of the non-spherical dimple is located at a radial angle, θ, about a unit circle, where 0≤θ≤2π, and the edge angle value of the non-spherical dimple at any given point on the perimeter is defined by the solution of an edge angle function f(θ), wherein f(θ) is a non-periodic, continuous, differentiable function.

A golf ball 2 includes a core 4, a mid layer 6, a cover 8, and dimples 10. A difference DH in hardness between a surface and a central point of the core 4, a thickness Tm and a hardness Hm of the mid layer 6, a thickness Tc and a hardness Hc of the cover 8, and an amount of compressive deformation Sb meet the following mathematical formulas.

(DH*Hm)/(Hc*Tc)>80

((Sb*Tc)/(Hc* Hm*Tm))*1000>0.75

An area ratio So of dimples 10 and a ratio Rs of a number of the dimples 10 each having a diameter of equal to or greater than 9.60% but equal to or less than 10.37% of a diameter of the golf ball 2 meet the following mathematical formula (3).

Rs≧−2.5*So+273   (3)

A golf ball 2 has a large number of dimples 10 on a surface thereof. The contours of the dimples 10 are non-circular. A standard deviation of areas of the dimples 10 is equal to or less than 1.7 mm.sup.2. A ratio of a total area of the dimples 10 relative to a surface area of a phantom sphere of the golf ball 2 is equal to or greater than 80%. By comparting lines CS obtained by projecting sides of a regular dodecahedron, which is inscribed in the phantom sphere, onto the phantom sphere, a surface of the phantom sphere can be divided into 12 units Ut each of which meets the following mathematical formula (I):
−2≦(Nt/12)−Nu≦2  (I),
where Nt represents the total number of the dimples 10 and Nu represents the number of the dimples 10 on one unit.

A golf ball having the contour wherein at least one dimple has the cross-section of the dimple surface based on a modified witch of Agnesi curve and defined by the equation in the form of: $y\left(x\right)=\frac{-C_1{a}^3}{x^2+C_2{a}^2}+\frac{C_1{a}^3}{{\left(\frac{d}{2}\right)}^2+C_2{a}^2}$ wherein: y is the vertical distance from the dimple apex, x is the radial distance from the dimple apex, a is equal to the radius of the circle in the witch of Agnesi, d is the dimple diameter, and C.sub.1 and C.sub.2 are constants that will produce a variety of dimple surfaces from a variety of functions.

A golf ball according to an aspect of the present invention is a golf ball having a large number of dimples, a surface of the golf ball is covered with a plurality of virtual flat surfaces each having a triangular shape, one or more dimples are arranged so as to correspond to each of the virtual flat surfaces, and an edge of each dimple is formed in a linear shape. Each dimple may have a triangular pyramid shape or a triangular frustum shape.

Golf balls according to the present invention achieve flight symmetry and overall satisfactory flight performance due to a dimple surface volume ratio that is equivalent between opposing hemispheres despite the use of different dimple geometries, different dimple arrangements, and/or different dimple counts on the opposing hemispheres.

A golf ball can have a large number of dimples on a surface thereof. A trajectory of the golf ball can be calculated under conditions of an initial speed of 260 ft/s, a launch angle of 15.0 degrees, and an initial backspin rate of 3000 rpm satisfying the following mathematical formula,

[00001]$\text{Amax}\ge \text{4}\text{.0}\text{*}\text{Vave + 13}\text{.10,}$

wherein Amax represents a maximum value (degree) of a vector angle A in the trajectory, and Vave represents an average volume (mm.sup.3) of the dimples. The vector angle A can be calculated by the mathematical formula

[00002]$\text{A}\text{=}\text{ATAN}\left(\text{Vy}/\text{Vx}\right),$

wherein Vx represents a horizontal component of a speed of the golf ball, and Vy represents a vertical component of the speed of the golf ball.

Golf ball having a generally spherical surface and comprising a plurality of dimples separated by a land area formed on the ball surface, wherein the plurality of dimples includes at least one non-spherical dimple having a non-axially symmetric plan shape and a defined point of maximum dimple depth, wherein: (i) each dimple cross-section of the non-spherical dimple consists of two arcs, each arc extending from the defined point of maximum dimple depth to a point at the land area of the golf ball; and (ii) every point on the perimeter of the non-spherical dimple is located at a radial angle, θ, about a unit circle, where 0<θ<2π, and the edge angle value of the non-spherical dimple at any given point on the perimeter is defined by the solution of an edge angle function f(θ), wherein f(θ) is a non-periodic, continuous, differentiable function.

A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is formed in a mold having support pins by injection molding. A ratio (V/S) of a volume V (mm.sup.3) of the cover 6 to an amount of compressive deformation S (mm) of the core 4 is not less than 1000 and not greater than 1900. The cover 6 has a shore D hardness of not greater than 62. The golf ball 2 has a plurality of dimples 8 on a surface thereof. A total volume W of these dimples is not less than 490 mm.sup.3 and not greater than 620 mm.sup.3. A ratio (α/P) of a latitude α (degree) of each support pin to a total cross-sectional area P (mm.sup.2) of the support pins is not less than 0.35 and not greater than 0.60.