Question:
Hello! Please, if you can help me to find a physical/mathematical explanation for this fact: Why a perfectly spherical golf ball does not go as far as a usual golf ball (which has dimples) ? Thanks a lot for your answer about this fact or about the way to find the solution. Michel Gogny-Goubert.
Response:
It’s physics, has to do with air drag. The dimples move the air around the ball in such a way as to create lift and keep it airborn longer. Similar to a base ball’s stiching needed to create a curving pitch. Crack open a good physics book to get the details. Have fun! Remove ALL the zz’s to repoond:
Response:
– Hide quoted text — Show quoted text – It’s physics, has to do with air drag. Right! The dimples move the air around the ball in such a way as to create lift and keep it airborn longer. Wrong! – the dimples brake up the turbulant boundary layer and reduce the airflow breakaway thus REDUCING drag. A spinning ball will create lift whether it has dimples or not. It is the reduced drag ( which is relatively substantial) that allows the ball to remain in the air longer! David Similar to a base ball’s stiching needed to create a curving pitch. Crack open a good physics book to get the details. Have fun! Remove ALL the zz’s to repoond:
<a few snip’s Check out http://www.sciam.com/0197issue/0197moinbox3.html or,if you have some time go to Yahoo.com and enter "golf ball dimples" in search block. Rich
Response:
It’s physics, has to do with air drag.
Right! The dimples move the air around the ball in such a way as to create lift and keep it airborn longer.
Wrong! – the dimples brake up the turbulant boundary layer and reduce the airflow breakaway thus REDUCING drag. A spinning ball will create lift whether it has dimples or not. It is the reduced drag ( which is relatively substantial) that allows the ball to remain in the air longer! David – Hide quoted text — Show quoted text -Similar to a base ball’s stiching needed to create a curving pitch. Crack open a good physics book to get the details. Have fun! Remove ALL the zz’s to repoond:
Response:
Please, if you can help me to find a physical/mathematical explanation for this fact: Why a perfectly spherical golf ball does not go as far as a usual golf ball (which has dimples) ?
It has to do with a drag coefficient and dimples. As the ball flies through the air the air flow across the surface creates a boundary layer. Dimples help create turbulence in this boundary layer. A turbulent boundary layer clings better to the ball, reducing the size of the wake behind it reducing the drag. Lift is created by something known as the magnus effect. As the ball spins backwards it turns against the air passing below it, and it turns with the air passing above it. The air flows faster and with least resistance pass the upper half of the ball where as the air flows slower and with more resistance pass the lower half. The push is always in the direction of least resistance, and in this example the push will be upwards creating lift. If the spin becomes reversed, top spin, the effect is opposite, the ball dives into the ground. If this spin leans to either side of vertical a hook or slice will be produced. David Golf Instruction Homepage http://www.geocities.com/Augusta/3628/
Response:
It has to do with a drag coefficient and dimples. As the ball flies through the air the air flow across the surface creates a boundary layer. Dimples help create turbulence in this boundary layer. A turbulent boundary layer clings better to the ball, reducing the size of the wake behind it reducing the drag.
I’ve seen that several ball manufacturers have balls on the market with "extra" dimples, David. Do you know if this would increase the turbulence effect even more, or is there an optimal number of dimples for a ball? If I recall correctly, another manufacturer has come out with eliptical shaped dimples, instead of the traditional circles. Any info on what such an odd-shape might do?
Response:
Don, I believe that you reach a point of diminishing returns. The more dimples you put on a ball the samller the dimples have to become in order to fit. At some point around 400 I think you reach the maximum effectiveness of dimples. This is round dimples. I don’t know what the effect of oval dimples would be. I suspect that any difference would be too small for a player to notice, although it might be measurable in a wind tunnel. Good Golf Dan – Hide quoted text — Show quoted text – I’ve seen that several ball manufacturers have balls on the market with "extra" dimples, David. Do you know if this would increase the turbulence effect even more, or is there an optimal number of dimples for a ball? If I recall correctly, another manufacturer has come out with eliptical shaped dimples, instead of the traditional circles. Any info on what such an odd-shape might do?
Response:
The more dimples you put on a ball the samller the dimples have to become in order to fit. At some point around 400 I think you reach the maximum effectiveness of dimples. This is round dimples. I don’t know what the effect of oval dimples would be. I suspect that any difference would be too small for a player to notice, although it might be measurable in a wind tunnel.
When you look at the dimples on many balls, the pattern of the layout and the size of the dimples varies around the ball. This is done because the size of the dimples and the number which is optimum for reducing drag is dependent on the speed of the ball. Therefore, ball manufactures have tried for years to develop the size, quantity, and shape dimples which will work for the greatest range of speed. As for lift, the spin on the ball creates an effect where the air pressure above the ball is lower than the pressure below the ball. Therefore, the ball will tend to move away from the high pressure and into the lower pressure. This same effect can cause hook and slice when side spin is put on the ball. It is true that a wind tunnel with very precise measurement equipment would be needed to measure the difference in most dimple changes.
Response:
If I recall correctly, another manufacturer has come out with eliptical shaped dimples, instead of the traditional circles. Any info on what such an odd-shape might do?
The eliptical shaped dimples are found on a ball called the Top Flight "Aero" here in Australia, presumably the same elsewhere. Not all the dimples are that shape, some are conventional round. Marketing claims a reduced amount of drag with this arrangement. I have played with the ball but cannot live with the "feel" of the ball on a green – but that’s just me! I have to say that, if nothing else, these balls do seem to be less affected by windy conditions and are particularly easy to hit directly into the wind. Other than that they are just another relatively cheap ball. David A
Response:
The odd-shaped (usually ellipitcal) dimples are distributed in a regular, repeated pattern. The principle is to increase the average time that the dimples are on the top of the ball as it spins, thereby increasing the lift. All modern jet fighters incorporate a similar concept. The F16, on which I was an engineer, has "strakes" on the front of wing where it attaches to the fuselage. They creat vortex (tornado-like swirling) turbulence at low speeds. The turbulent air reduces the air pressure on the top of the wing (near the wing root, which is the first place to stall during a low-speed, high bank turn) further than the normal airfoil does, thus increasing the lift of the wing. The dimples do the same; they create increased turbulence on the top of the ball, reducing air pressure (fewer air molecules in contact with the surface of the ball) and increase the lift. Reduced drag is also a byproduct. What happens, in detail, is that the air is not able to flow into the dimples fully, creating a tiny near-vacuum in each. Another writer was correct in that there is diminishing return as the dimples get smaller. Computer modeling has led to the discovery of improved patterns using ellipses and other patterns. I can’t recall which ball it is, but if you look at it, you’ll see a repetitive patern of triangular areas. There’s a lot of technology in today’s golf ball! Mark – Hide quoted text — Show quoted text – It has to do with a drag coefficient and dimples. As the ball flies through the air the air flow across the surface creates a boundary layer. Dimples help create turbulence in this boundary layer. A turbulent boundary layer clings better to the ball, reducing the size of the wake behind it reducing the drag. I’ve seen that several ball manufacturers have balls on the market with "extra" dimples, David. Do you know if this would increase the turbulence effect even more, or is there an optimal number of dimples for a ball? If I recall correctly, another manufacturer has come out with eliptical shaped dimples, instead of the traditional circles. Any info on what such an odd-shape might do?
Response:
Any effect of dimples shape / number / deepness / disposition in striking a putt? I always blame a edge-dimple contact for off-line putts… 
Ciao. Marcello Hello! Please, if you can help me to find a physical/mathematical explanation for this fact: Why a perfectly spherical golf ball does not go as far as a usual golf ball (which has dimples) ? Thanks a lot for your answer about this fact or about the way to find the solution. Michel Gogny-Goubert.
Response:
– Hide quoted text — Show quoted text – It’s physics, has to do with air drag. Right! The dimples move the air around the ball in such a way as to create lift and keep it airborn longer. Wrong! – the dimples brake up the turbulant boundary layer and reduce the airflow breakaway thus REDUCING drag. A spinning ball will create lift whether it has dimples or not. It is the reduced drag ( which is relatively substantial) that allows the ball to remain in the air longer! David Similar to a base ball’s stiching needed to create a curving pitch. Crack open a good physics book to get the details.
When a golfer hits a golf ball that tends to hang in the air defying gravity or when a pitcher throws a curve ball, they are taking advantage of the beneficial effect of aerodynamic drag. Formula based text say this effect is the result of lift and the definition of drag is a force that impedes forward movement and is not beneficial and dimples are put on golf balls to reduce drag. Once again actual occurrence is fashioned to fit formula instead of the other way around. When a golf ball is hit in such a way that causes it to spin the golf ball will generate a force perpendicular to the flow caused by the forward movement of the golf ball. This would certainly be lift if it were not for the fact that this force is not directly caused by the airflow generated by the forward movement of the golf ball. This force is created by the airflow generated by the rotation of the golf ball (drag). Imagine a paddle boat running while the paddle wheel is being held out of the water. Drag is reflected in a uniform torque force that opposes the rotation of the paddle wheel. When the paddle boat is set in the water the drag on the part of the spinning paddle wheel that is in the water is much greater than the part that moves in air. This uneven drag caused by the paddle wheel partially turning in a fluid 600 times heavier than air is reflected in the forward movement of the paddle boat. Now imagine a golf ball spinning in mid air. Drag is reflected in a uniform torque force (enhanced by the dimples) that opposes rotation. Now imagine a golf ball spinning as it moves through the air. The air around the golf ball is now at different stages of compression and decompression. Compressed air is heavier because it has more molecules of air than an equal volume of ambient air. Decompressed air is lighter because it has less molecules of air than an equal volume of ambient air. This uneven drag caused by the golf ball spinning in air of different densities is reflected in a few extra seconds of hang time and a few more feet of distance. As a result of back spin, the golf ball drags the air from in front over the top where it releases in a slightly downward direction. This tends to move the golf ball forward and upward. This is a movement parallel to the flow generated by the rotation of the golf ball. This flow is only dependent on the forward movement of the golf ball to generate areas of high and low pressure around the ball.