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Skittle
05-19-2002, 06:44 PM
Ok, well I heard that the dimples in golf balls reduce turbulance. So what if someone could make paintballs like that? WOuld that like make them super accurate as long as u could evenly place dimples and keep the painball in a perfect circle shape? Like a mini golf ball...I mean, if it could work it would be the most awesome thing because they could be the most accurate paint. Do you guys think this is possible?


Hey, I better not see these on the shelf in like 2 years and still be as broke as i am now.

BlackVCG
05-19-2002, 08:15 PM
It doesn't work with paintballs. In order to create the turbulent boundary layer, the object must be spinning at a high RPM. Paintballs don't see much spin, so it's not beneficial.

It can be explained by the Magnus Effect. There's a region of turbulence downstream from the ball. When the ball is spinning, it becomes asymmetric. Basically the area behind the ball experiences greater pressure and therefore a force is applied to the ball. There's a bit more to it dealing with Bernoulli's Principle, but that's the general idea.

Skittle
05-19-2002, 08:22 PM
well, lets say u use the paint in something like a flatline barrel where the whole purpouse of the barrel is to create a spin, would this make a diffrence? (the flatline)

Mav D MagMan
05-19-2002, 08:29 PM
But what would be the cost - performance relation to manufacture such paintballs? It really doesn't seem to me that they would be very cost effective.

Skittle
05-19-2002, 08:40 PM
well, you see i dont think i can be that hard to make, but there could be potential to make alot of money. if u can prove the paint is awesome, even people with tippmanns and flatline cockers would love the paint and it would go like hot cakes, if it worked. even if it was a fad, you can make lots of money in the month or 2 it sells.

BlackVCG
05-19-2002, 08:53 PM
Right once I started typing my reply, I thought - I wonder how a dimpled paintball would shoot out of a Flatline barrel. AGD has made nylon paintballs with dimples drilled in them to do testing with and saw no benefits in a regular setup. It would be interesting to see how it behaves out of a Flatline. I'm thinking that the air blast might have an effect on it and not let it work the same as with a golf ball.

Skittle
05-19-2002, 08:56 PM
I think it would be really intresting to see how it did perform w/ a flatline, espically a flatline cocker.... and even though the chances are it wouldnt be a signifigant positive change there are chances it would be awesome...

Mav D MagMan
05-19-2002, 08:56 PM
But who's going to pay the costs to produce it? Nobody wants to buy 100 + dollar paint if they can get something else. Even with the benefits.

Skittle
05-19-2002, 09:01 PM
well the paint dosent nessicarily have to be 100+ bucks, all u need is the right mold (im guessing) and then it could work. and if ti did work, like i previously said fads make tons of money, remember giga pets? little 5$ production cost peices of junk that sold for 30 bucks? if u can do something like that it would all be worth it

Mav D MagMan
05-19-2002, 09:04 PM
Are you familiar with how paintballs are made? If so I shall not go into detail.

But after they are sealed they are swollen above their normals size and left to cool and shrink down. During this time they would lose any tiny features put into them by a special mold.

Skittle
05-19-2002, 09:07 PM
well how about the rps advantage shell? how is it so hard like that? mabye if u can make the paintball like that it could have potential

Mav D MagMan
05-19-2002, 09:10 PM
I don't get your reference towards how hard Advantage is? Please explain.

But that paintball was derived from a new process. The likes of which I'm not sure but the design does have it's positive side but also a negative side as well.

What bothers me about the idea is the probability that the dimples will never be consistant enough to make a quality paint worth buying.

How paintballs are made (http://www.rps-paintball.com/index_frames.html) The link to it's on the picture of the slamballs.

Skittle
05-19-2002, 09:33 PM
i meant that if u use the same process that mabye it would be possible to make paintballs like than and make the dimples consistant. because the advantage shess is made diffrently

P8ntballerAK
05-20-2002, 03:56 AM
OK, I went over this one with one of my friends who is a physics major. First of all a golf ball does not have to have a spin to launch like it does, hit one with a baseball bat and see. Second, a paintball with dimples would cause gaps between the barrel and the paintball which would let the air flow past the paintball and cause effeciency drop and would cause turbulance. And third, have you ever wondered why paintball are round instead of a bulletshape or anyother more aerodynamic shape? I will tell you why. If you have a sphere and apply pressure to one side the sphere will expand at all point equally untill resistans(the barrel) stops the side from expanding further. this keeps the pressure on a paintball equalized as much as possible. if you change the shape of the sphere lets say make it fimpled or make it like a bullet, you change the structural integrity of the entire object. if you try putting that much pressure on a bullet shaped object with the same size shell as on a paintball, it would explode. you could give it a thicker shell but that starts becoming more painful and dangerous. If put many dimples in a ball it will lose strength on the entire object so putting pressure on it would push the dimples out and then the ball would explode.

anyways
my .02$

BlackVCG
05-20-2002, 07:28 AM
Actually the more determining factor as to why paintballs are round is because round provides the easiest shape to load in the gun. With all other shapes, you'd need a gravity fed stacked column or some kind of pressure fed magazine. Much easier to load round objects than bullet shaped or anything else for that matter.

ShooterJM
05-20-2002, 10:36 AM
The air blast would ideally be spread evenly across the impact point on the paintball, but depending on design I don't know of if dimples would greatly change the structural integrity of a paintball. the more I research this the more I think that "dimples" aren't the answer. It has consistancy problems, extreme manufacturing issues, and cost effectiveness is highly doubtfull. Some step would have to be insterted after manufacturing and before the drying process I think.


EDIT: Was just thinking about this....perhaps instead of dimples a raised latticework? Could be applied in the rolling/drying process using modified driers.

BlackVCG -

I realize that this might be propriatary, but would there be a way to post the data of the nylon ball experiment on the data thread?

Xerces
05-21-2002, 07:02 PM
well, dimples on a golf ball have to be in a certain geometric pattern to get the best lift, or whatever you call it. after looking at how rps makes theirs, it looks like they would have to make a completely different type of machine to make them, and to mass produce them with efficiency would drive the price up pretty well id imagine.

ShooterJM
05-22-2002, 09:41 AM
Eh, working on that. Been in discussions with a manufacturer rep to see if the capabilities can be altered slightly. Gonna take some serious capital to set it up though, if it does work. That's why I'm really interested in AGD's test results. I need hard data, not theoretical calculations. Heck, just a source for nylon paintballs would be awesome!

FatMan
05-23-2002, 08:35 AM
Originally posted by P8ntballerAK
OK, I went over this one with one of my friends who is a physics major. First of all a golf ball does not have to have a spin to launch like it does, hit one with a baseball bat and see. Second, a paintball with dimples would cause gaps between the barrel and the paintball which would let the air flow past the paintball and cause effeciency drop and would cause turbulance. And third, have you ever wondered why paintball are round instead of a bulletshape or anyother more aerodynamic shape? I will tell you why. If you have a sphere and apply pressure to one side the sphere will expand at all point equally untill resistans(the barrel) stops the side from expanding further. this keeps the pressure on a paintball equalized as much as possible. if you change the shape of the sphere lets say make it fimpled or make it like a bullet, you change the structural integrity of the entire object. if you try putting that much pressure on a bullet shaped object with the same size shell as on a paintball, it would explode. you could give it a thicker shell but that starts becoming more painful and dangerous. If put many dimples in a ball it will lose strength on the entire object so putting pressure on it would push the dimples out and then the ball would explode.

anyways
my .02$

Actually, empirical tests has shown that most of this lore is myth. Most paintballs already have a gap between them and the barrel - and the don't normally expand to fit the barrel. The round shape is to emable loading (as has already been stated). dimples probably wouldn't affect any of this. The issues probably come down to manufacturability versus actual performance gain.

FatMan

mag-nanamus
06-12-2002, 12:08 AM
I had the same idea a couple years back. the golf ball paintball idea is even patented by someone. it would be interesting to talk with him to find out why he hasn't gone forward with this project.

ShooterJM
06-13-2002, 04:17 PM
Originally posted by mag-nanamus
I had the same idea a couple years back. the golf ball paintball idea is even patented by someone. it would be interesting to talk with him to find out why he hasn't gone forward with this project.

The patent has expired. I called and checked. Yeah, I'm guessing the manufacturing expense Vs performance gain is what killed the idea from going into production.

Miscue
06-16-2002, 03:51 PM
Problems:

Paintballs are only 3 grams = you need tons of spin.

Paintballs are filled with paint = viscocity of paint resists spin.

Paintballs are gelatin = hard to spin, hard to spin consistently, they have a hard enough time as it is keeping them round let alone round with dimples.

Paintballs already cost a lot of money... $1.00/paintball isn't gonna fly. :)

It won't be backspin if you tilt your gun.

Even if you could get them, I don't think they would help you.

hostage
06-27-2002, 03:32 PM
Are these just theories? See i think it is a good idea it helps with golf balls, actually a golf ball was banned from the PGA, it had dimples on the outside and it had a ring going down the middle that was just flat. They put some putty around it then rapped a seranwrap around the ball and put it next to a heater to dry. Hey the ball preformed so well that they banned it from the PGA. BTW pleas make factual statements and just dont hypothize.
-Hostage

aut911
07-07-2002, 11:53 PM
ok, if im not mistaken, an idea similar to the golf ball idea was thought of a while back during the initial testing of the flatline barrel. paintballs with tracks on them, the problem was that the tracks rarely lined up with the barrel the right way, so thats why (i believe) the flat line barrels bore is actually mottled. but my point is,a paintball will not fly farther or straighter due to its dimples set in a pattern, i think it will make a paintball less accurate and slow down faster, i might be totally wrong but i dont think so. the main thing paintball manufacturers should be worried about is consistency of paint size and shape than dimples.

no im not bashing anybodys ideas, im just giving my opinion, in a 16 year olds fashion.

thanks for reading

aut911

ShooterJM
07-08-2002, 09:18 AM
I think we're combining two different issues. Spin and Dimpling. They're not neccesarily related.

aut911
07-08-2002, 10:09 AM
the reason i put in the spin part is because of the way a golf club sends a golf ball flying, giving it backspin when it hits it, to give it a longer range, and the dimples are there to keep the ball from veering off into the bushes and staying on target. the problem with a paintball is that it is too light to carry spin for very long at all, thats partially why we see a flatline barrel have that really drastic drop in altitude, because alot of its energy was spent on that flat line trajectory. but for the coolness factor of the flat-line shootting paint without any arc is amazing.


aut911

i have no idea if this post makes any sense, i just woke up.

ShooterJM
07-08-2002, 10:25 AM
Originally posted by aut911
the dimples are there to keep the ball from veering off into the bushes and staying on target. the problem with a paintball is that it is too light to carry spin for very long at al

well, dimples themselves, as far as my limted understanding goes, are only used to delay boundry layer seperation from the surface of the object in flight (in this case a golfball). By delaying the seperation the vacuum behind the object is greatly decreased allowing the object to fly further. As to the direction of the flight, as long as the dimpling is consistant the direction won't change. That's why if you have old paint that has a few dimples on it it tends to fly out of your barrel like a hummingbird on heroin.:D It's not uniform so the airflow changes.

The big question is would dimpling alone (sans any spin) cause enough effective distance gain to be worth the manufacturing costs?:confused:

nerobro
07-08-2002, 11:43 AM
Dimples on a golf ball are about making the boundry layer stick to the ball longer. for a ball without spin you want the boundry layer to seperate as soon as it reaches the middle of the ball. But round objects cling to the boundry layer and wrap it around the back of the ball. That's what causes the buzzing you hear when a paintball flys by you. it's the boundry layer tearling off the paintball at different points and causing a wiggle in the paintballs path. (think the air behind a semi, but on a much smaller scale) Dimples will only cause this problem to worsen.

Dimples will cause a ball shot from a flatline to climb.. a LOT. But that's not the point of the flatline, the point of the flatline was to keep the ball level..... golf balls are much more dense items than paintballs can need all the lift they can get. Being such light items paintballs are difficult to compensate properly with lift. And at least from testing it looks like it's best to leave them NOT spinning at all, and smooth.

CTG
07-09-2002, 09:14 PM
It's not the spin of the ball. Dimples on a paintball would be helpful, but not at speeds below 300fps.

Skunk_werkes
07-10-2002, 10:24 AM
Originally posted by ShooterJM


well, dimples themselves, as far as my limited understanding goes, are only used to delay boundary layer separation from the surface of the object in flight (in this case a golf ball). By delaying the separation the vacuum behind the object is greatly decreased allowing the object to fly further. As to the direction of the flight, as long as the dimpling is consistent the direction won't change. That's why if you have old paint that has a few dimples on it it tends to fly out of your barrel like a hummingbird on heroin.:D It's not uniform so the airflow changes.

The big question is would dimpling alone (sans any spin) cause enough effective distance gain to be worth the manufacturing costs?:confused:

Your bang on :) , The purpose of dimples is thus: to create a very fine layer of turbulent air along the surface of the golf ball, the turbulent air actually has more friction then non-turbulent air and as such tends to 'stick' to the ball longer this delays the boundary layer separation and reduces the area of turbulent lower pressure air behind the ball. The main outcome of this is to reduce the pressure differential (well actually force differential... F=p*A) between the area in front and behind the ball. Quite simply; we know that the air in front of the ball is at a higher then atmospheric pressure, normally (without dimples) the boundary layer would separate just past middle and as a result you would have a large area at a lower pressure (relative to the air in front of the ball). I think everyone can figure out what happens with a high pressure in front and a lower pressure behind. The resultant force is acting opposite to the direction of travel, (it would slow the ball down). The dimples delay the boundary layer separation, reducing the area of low(er) pressure behind the ball, thus reducing the resultant force.
It's interesting to note that the slight increase in friction caused by the dimples is greatly outweighed by the benefits of increased boundary layer adhesion. A similar method can be seen in Formula 1 racing, the bulge (when viewed from the top) in the middle of the car is designed to prevent boundary layer separation. If done properly if yields a greater improvement then the negative effects of increasing cross sectional area.


Originally posted by nerobro

Dimples on a golf ball are about making the boundry layer stick to the ball longer. for a ball without spin you want the boundry layer to seperate as soon as it reaches the middle of the ball. But round objects cling to the boundry layer and wrap it around the back of the ball. That's what causes the buzzing you hear when a paintball flys by you. it's the boundry layer tearling off the paintball at different points and causing a wiggle in the paintballs path. (think the air behind a semi, but on a much smaller scale) Dimples will only cause this problem to worsen.

Actually under no circumstances (spinning or not) in this application do you want premature boundary layer separation. Also the boundary layer on smooth sphere’s usually separates a tad past the middle, you have to induce them to ‘cling’ to it (it’s not the norm).

Allow me to apologize for the length of this post (my first), I didn’t have time to write a shorter one. I’ll drop back later and post some diagrams to clarify what I’m talking about, as well as applying this to paintball.

Cheers,
Shaun Martin.

nerobro
07-10-2002, 12:58 PM
given the shape of a sphere, you want to release the boundry layer smoothly and as soon as possiable. Remember tha in flight a paintball's boundry layer can wrap all the way to the back of the ball before it rips off and hte other side swings in. the point I was trying to make was to have something there to kick the boundry layer off and provide a smooth seperation of flow. This is the same reason that the new corvette has a sharp edge around the back of the car. And why the VW bug is getting a wing.

aut911
07-10-2002, 01:34 PM
that the dimples basically make the golf ball, more aerodynamic? meaning a golf ball with dimples will fly a little bit farther than one without?

aut911

nerobro
07-10-2002, 01:41 PM
The dimples KEEP hold the slipstream to the ball. So when it's spinning it changes the lift charecteristics of the ball. Golf balls are dense, and they can use whatever lift they can get. More lift means more range with a golf ball. that isn't true with a paintball.

the ball isn't more aerodynamic, it just makes more lift ;-)

Skunk_werkes
07-10-2002, 05:23 PM
nerobro: I think I might be mis-understanding you, but... Concerning conventional paintballs, the boundary layer separation is just a lil bit past the mid point, the boundary layer does not adhere all the way to the back. Your quite right when you say that the dimples also aid in the creation of lift, but there are aerodynamic advantages to having a dimpled non-spinnig golf ball.
If you'd like to discuss automotive aerodynamics, we could do so in greater detail, but please email me (shaun@cardesignnews.com), I've actually written a paper on it (automotive aerodynamics), and attended a few lectures by Aiolos (one of the Worlds largest makers of aerodynamic/acoustic/and hydrodynamic test chambers) so I'm always up to a good discussion.

aut911: Yes, that's right. A golf ball actually has a lower Aerodynamic coefficient of friction then does a similar smooth ball. I'll look up the numbers for a conventional golf ball, but off the top of my head I remeber that the Cd of a sphere is 1.2

I'll work on those diagrams tomorrow, along with some math on dimpled paintballs.

Cheers,
Shaun Martin.

BlackVCG
07-10-2002, 08:08 PM
In order to find the Cd (Drag Coefficient) of a sphere, you first need to find the Reynolds number of your sphere.

This is acheived by taking the velocity of the object multiplied by the diameter of the sphere and that quantity divided by the kinematic viscosity of the substance your sphere is moving through. In the case of a golf ball or paintball, it would be air.

So...

Nr = (vD)/y

Where v = velocity of sphere
D = Diameter of sphere
y = kinematic viscosity of substance sphere is traveling through

From this you can find the Cd based on a Cd vs. Nr graph.

From there, you can find the drag force by using this equation...

Fd = (ACd)(pv^2/2)

Where A = Reference area, which is the Cross sectional area of the sphere in the middle
p = Density of substance
v = Velocity
Cd = Drag Coefficient

Your Cd is different based on the Reynolds number of your sphere. In the end a sphere with a rough surface usually has about half of the drag force as a smooth sphere.

Testarosa
07-10-2002, 11:39 PM
Small bore, Large bore, Dimples, No Dimples,- In my oppinion, paintballs go were they want.:cool:

BlackVCG
08-02-2002, 03:01 AM
skunk_werkes-

What happened to the charts and math?

AGD
08-03-2002, 02:33 PM
Boundary layers, Reynolds numbers AHH it makes my heart sing! Only on AO would you get such a worthy discussion.

If I remember right the dimples on the golf balls INCREASE the size of the boundary layer which without any other effects increases the CD. BUT spongier boundary layers allow the laminar flow to stay attached longer past the mid point of the ball so the overall CD goes down. The other effect of this is the spin on the ball gets its lift from the percentage of laminiar flow sticking to the top of the ball. bigger BL->stickier LF -> more LF area -> more lift.

Love this stuff,

AGD

sniper1rfa
08-03-2002, 08:53 PM
not size, thickness. thats what i learned anyway, could be (probably is) wrong.
i also bet you get little eddies in the dimples acting almost like bearings. that would be nifty.