[piranha]

I was watching mythbusters and their topic was testing if a dimpled golf ball would go farther than a smooth one. They proved that the dimpling ball went astronimicallt farther because the drag was reduced by the dimples.

WOULD THIS WORK WITH PAINTBALLLS!!!!!!????? just wondering

The Dimples

Why, then, does a golf ball have dimples? The answer to this question can be found by looking at the aerodynamic drag on a sphere. There are two types of drag experienced by a sphere. The first is the obvious drag due to friction. This only accounts for a small part of the drag experienced by a ball. The majority of the drag comes from the separation of the flow behind the ball and is known as pressure drag due to separation. For laminar flow past a sphere, the flow separates very early as shown in Figure 1. However, for a turbulent flow, separation is delayed as can be seen in Figure 2. Notice the difference in the size of the separation region behind the spheres. The separation region in the turbulent case is much smaller than in the laminar case. The larger separation region of the laminar case implies a larger pressure drag on the sphere. This is why the professor experienced a longer drive with the marked ball. The surface roughness caused the flow to transition from laminar to turbulent. The turbulent flow has more energy than the laminar flow and thus, the flow stays attached longer.


Figure 1: Laminar Flow
Over a Sphere. http://wings.avkids....ges/golf_01.gif <-----link to laminar flow pic

Figure 2: Turbulent Flow
Over a Sphere. http://wings.avkids....ges/golf_02.gif <----link to turbulent flow pic


So, why dimples? Why not use another method to achieve the same affect? The critical Reynolds number, Recr, holds the answer to this question. As you recall, Recr is the Reynolds number at which the flow transitions from a laminar to a turbulent state. For a smooth sphere, Recr is much larger than the average Reynolds number experienced by a golf ball. For a sand roughened golf ball, the reduction in drag at Recr is greater than that of the dimpled golf ball. However, as the Reyn olds number continues to increase, the drag increases. The dimpled ball, on the other hand, has a lower Recr, and the drag is fairly constant for Reynolds numbers greater than Recr.

Therefore, the dimples cause Recr to decrease which implies that the flow becomes turbulent at a lower velocity than on a smooth sphere. This in turn causes the flow to remain attached longer on a dimpled golf ball which implies a reduction in drag. As the speed of the dimpled golf ball is increased, the drag doesn't change much. This is a good property in a sport like golf.

Although round dimples were accepted as the standard, a variety of other shapes were experimented with as well. Among these were squares, rectangles, and hexagons. The hexagons actually result in a lower drag than the round dimples. Perhaps in the future we will see golf balls with hexagonal dimples.

[andrewthewookie]

It's been tried with the Rap4 golf balls, but they perform like shit. We assume that's because of the way they were manufactured, where the depth of the holes are different across the ball.

http://www.techpb.co...showtopic=75403

http://www.techpb.co...showtopic=77606

This post has been edited by andrewthewookie: 11 July 2012 - 12:14 AM

[NotaSniper]

There's also the boundary layer effect.

[invictus]

even if they did work, they would cost much more, because they would be much more difficult to make.

[THE EXTREMIST]

I think that is a good consept but the dimples in the ball might allow air to escape when there being pushed out of the marker

[TK-421]

THE EXTREMIST, on 11 July 2012 - 12:05 AM, said:

I think that is a good consept but the dimples in the ball might allow air to escape when there being pushed out of the marker

That already happens in an overbore situation, doesn't mean anything bad.

[cockerpunk]

NotaSniper, on 24 June 2012 - 11:31 PM, said:

There's also the boundary layer effect.

bundry layer effects is how dimples work

[Filmer_jake]

I feel like for it to work, the shell would have to be a lot thicker than it is to allow the dimples to actually happen. Thus making it too thick to be safe?

[THE EXTREMIST]

would it make the paintball a little bit lighter and so there will not be as much momentum to keep the ball moving through the air .But on the other hand the dimples in the ball reduce drag causing it to go farther. So it might work or it might not.

[TK-421]

THE EXTREMIST, on 12 July 2012 - 01:55 AM, said:

would it make the paintball a little bit lighter and so there will not be as much momentum to keep the ball moving through the air .But on the other hand the dimples in the ball reduce drag causing it to go farther. So it might work or it might not.

That really depends on what material you make the paintball out of, because you can't make it out of gelatin, the way paintballs are made now, the dimples wouldn't stay when the paintball shrinks as it dries. It's entirely possible that the paintball will end up being heavier than a regular paintball, depending on what you make it out of.

[Woodyballer29]

I think even if we did somehow get a paintball dimpled like a golf ball the accuracy would be worse than a non-dimpled paintball. Does a golf ball compress and change shape when it gets hit by a club? Correct me if I'm wrong but I don't think it does. But a paintball on the other hand does compress and change shape. If the ball was dimpled the dimples will either, not stay because of compression, or the ball will change shape and cause the dimples to be ineffective because the shape of the ball is perfectly round. I don't think accurate dimpled paintballs are humanely possible.

This post has been edited by Woodyballer29: 12 July 2012 - 08:31 AM

[Troy]

Woodyballer29, on 12 July 2012 - 08:31 AM, said:

I think even if we did somehow get a paintball dimpled like a golf ball the accuracy would be worse than a non-dimpled paintball. Does a golf ball compress and change shape when it gets hit by a club? Correct me if I'm wrong but I don't think it does. But a paintball on the other hand does compress and change shape. If the ball was dimpled the dimples will either, not stay because of compression, or the ball will change shape and cause the dimples to be ineffective because the shape of the ball is perfectly round. I don't think accurate dimpled paintballs are humanely possible.

A golf ball, absolutely, changes shape when hit by a club. That's one of the reasons they bounce so much.

[Woodyballer29]

Troy, on 12 July 2012 - 10:00 AM, said:

A golf ball, absolutely, changes shape when hit by a club. That's one of the reasons they bounce so much.

It does but look how quickly it retains it's shape. I can't seem to find any on paintballs but I bet they compress way more than golf balls.

[Egomaniacal]

Woodyballer29, on 12 July 2012 - 10:32 AM, said:

Troy, on 12 July 2012 - 10:00 AM, said:

A golf ball, absolutely, changes shape when hit by a club. That's one of the reasons they bounce so much.

It does but look how quickly it retains it's shape. http://www.youtube.c...h?v=2Y57pw_iWlk I can't seem to find any on paintballs but I bet they compress way more than golf balls.

I doubt it. With a golf club you're acting on nearly a point, with a single plane. With a paintball the force is being applied relatively uniformly across nearly a hemisphere of the ball, in a direction normal to the surface of the ball.

I would be surprised if there was much deformation at all.

[andrewthewookie]

Paintballs barely change shape when shot.

http://youtu.be/WXM6MpEsalA?t=4m48s

[Troy]

Egomaniacal, on 12 July 2012 - 12:18 PM, said:

Woodyballer29, on 12 July 2012 - 10:32 AM, said:

Troy, on 12 July 2012 - 10:00 AM, said:

A golf ball, absolutely, changes shape when hit by a club. That's one of the reasons they bounce so much.

It does but look how quickly it retains it's shape. http://www.youtube.c...h?v=2Y57pw_iWlk I can't seem to find any on paintballs but I bet they compress way more than golf balls.

I doubt it. With a golf club you're acting on nearly a point, with a single plane. With a paintball the force is being applied relatively uniformly across nearly a hemisphere of the ball, in a direction normal to the surface of the ball.

I would be surprised if there was much deformation at all.

Even if they do deform, what would fly better, an oblong more aerodynamic object, or an oblong less aerodynamic object....? hmmmm....

[Woodyballer29]

andrewthewookie, on 12 July 2012 - 01:54 PM, said:

Paintballs barely change shape when shot.

http://youtu.be/WXM6MpEsalA?t=4m48s

I can see that the paintball doesn't change shape very much at all but the only reason why is that the barrel is "grabbing" the ball so that it remains round.

[Woodyballer29]

Troy, on 12 July 2012 - 04:14 PM, said:

Even if they do deform, what would fly better, an oblong more aerodynamic object, or an oblong less aerodynamic object....? hmmmm....

I don't know, I'm no scientist or anything close but I just go off of what makes sense not everything in this world makes sense but it is true. Perhaps a dimpled paintball would fly extremely straight and have improved range but at the average Joe's standpoint. Who would want to buy paint that is dimpled everywhere when I have a case at home that has fewer dimples and shoots like crap?

[andrewthewookie]

Woodyballer29, on 15 July 2012 - 12:34 PM, said:

I can see that the paintball doesn't change shape very much at all but the only reason why is that the barrel is "grabbing" the ball so that it remains round.

Can you show us where you saw that paintballs deform in the first place, or is all this coming from your assumptions?

This post has been edited by andrewthewookie: 15 July 2012 - 02:05 PM

[Woodyballer29]

andrewthewookie, on 15 July 2012 - 02:04 PM, said:

Woodyballer29, on 15 July 2012 - 12:34 PM, said:

I can see that the paintball doesn't change shape very much at all but the only reason why is that the barrel is "grabbing" the ball so that it remains round.

Can you show us where you saw that paintballs deform in the first place, or is all this coming from your assumptions?

No I cannot I have tried but I can't find anything. So I guess you could say it is my assumption. But I think it's more common sense. If a gelatin capsule is flying at 280 fps wouldn't that air have an effect on it?