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Thread: Spinning Paintballs Tech Tip #3

  1. #1
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    Post Spinning Paintballs Tech Tip #3

    Spinning Paintballs Tech Tip #3

    It was asked in another post what effect do riffled barrels have on spinning a paintball, not drilled holes, actual rifling like in real guns. This is a good question and one that was explored by our research team.

    In theory spinning a projectile on the axis of flight adds gyroscopic stability as well as averages out any imperfections in the surface air flow. Paintballs leave a bad turbulence wake behind them that "walks around" the back of the ball as it flies through the air. This is the main cause of a paintballs inaccuracy as the turbulence tail drags the ball around sideways in flight. Spinning the ball should create a tornado like vortex in the back of the ball thereby evening out all the turbulence so the ball is not pulled any particular way.

    So great you say lets do it and get more accuracy!! Well if it was possible it would already have been done. The problem is the liquid fill, when you rotate the shell, the liquid tends to stay where it is. The best example of this is a glass of water with ice floating in it, when you rotate the glass the ice stays in the same place (you have all seen it). So if you can grab the ball hard enough to go from 0 to about 10,000 RPM's in 5 thousands of a second (remember TechTip #1?) Yes the shell is spinning but the fill is not. When the ball leaves the barrel the viscosity of the fill slows the shell down but the fill's rotation is speeding up from the shell too, so you get an almost instant reduction of the RPM's out of the barrel. The balls rotation does not come to a complete stop because the shell does impart some spin to the fill.

    In order to test this properly we actually developed a gun that spun the barrel, with the ball in it, up to 30,000 RPM's and then shot the ball out. In this way we knew the ball and the fill were completely up to speed when it left the barrel. We had visions of a spinning barrel paintgun that would make that high speed turbo wine! Unfortunately this didn't improve the accuracy because the ball is still too light.

    As a final test we developed a barrel that had three razor edged knife blades running down the length of the bore. Using our plastic paintballs they wedged in the blades perfectly and we spun up the barrel and fired more test rounds. Because the knives would cut the ball we could examine them after the fact to see if they were rotating in the barrel etc. Again unfortunately we saw no improvement in accuracy and gave up.

    Based on this data we believe round paintballs are too light and have lousy aerodynamics to expect any more accuracy than what we are currently getting. When the military came to us and wanted a more accurate non lethal system we made a bullet shaped, spin stabilized paintball that far outperformed any equal weight round projectile. Accuracy by volume has been, and will remain, the best way to score eliminations.

    Just the facts from,

    AGD


  2. #2
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    So much for those 1-shot 1-kill thumpers...

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    30,000 RPM? geeez... crazy AGD people ;D

    Hey, can I get some of those bullet shaped paintpellets? hehe

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    Dude, that is so wierd...you notice how i said part 1??? Well i was planning on making part 2 my idea for a PB marker were it would spin the barrel. I based my spechs off the Tippman M98 though

    I thought this up, and even made a few design specs (although i left most of the math/physics out ) about 3 years ago in my physics class.

    Hey, i could be an AGD tech, great minds think alike


    thank you for answering my questions.

    [This message has been edited by thecavemankevin (edited 07-13-2001).]

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    Look Look Look! Even Mr. Kaye says, "Accuracy by volume has been, and will remain, the best way to score eliminations." Haha, I was just reading an article on accuracy or volume? The two markers to prove the article was an Angel and an Autococker. Sooo, following Mr. Kaye's advice, I'm gonna bring TWO cases of paint to dump on people next time.(Just funnin' ya )

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    "Alright, no one look until I get my cork back in!"- Ham, Toy Story 2, one of the greatest movies ever made

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    hmmmm..... interesting. *blows in bubble pipe*

  7. #7
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    What would happen if you placed divots in the paintball shell to reduce the "walkaround" effect of air behind the paintball? Rounded divots, or a more aggressive Hard cornered hexagonal shaped divot would allow the air to flow closer to the ball surface, reducing the turbulent wake that the ball leaves behind.

    Just like Golf ball aerodynamics... for paintball?

    Maybe a 4:1 rifling twist rate to impart as much spin on the ball and fill as possible, or 10:1 with the divots as they will pull a little more paint into the spin with them?

    And if all else fails, stick them in a backspin barrel to see how straight they fly.

    Sounds good in theory... what are your thoughts?

    ------------------
    "...it's a conspiracy of our relative reality at frequency!" -me

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    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by AGD:
    Accuracy by volume has been, and will remain, the best way to score eliminations.</font>
    dont mean to disagree or anything, but i wanted to see if i shot more paint throughout the day if i would get more eliminations. well i bought a case and a half for the day (i usualy go through half a case). i had my mini mag and i would rain paint in from the break, when i seen a guy, when guys were running and everything. i kept track of how many poeple i eliminated and i got an average of 2 or 3 a game (with teams of 7 or 8 people). that is around the same i usualy get using only a half a case throughout the entire day. it might help some people, but not me.

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    As usual Bill points out some pertinent facts. Yes the fill is thicker than water but the incredible acceleration rate of the RPM's when rifling a barrel makes the difference less obvious. Think of dropping a marble into a glass of honey, it takes a while to sink to the bottom. Now fire that marble into the honey at 500 fps and it goes to the bottom without hesitation.

    Maybe I was not clear but in my post I wanted to make the point that as the ball leaves the barrel the fill slows the rotation of the shell down but the same force also speeds the fill up. So in effect the ball's RPM "meets in the middle" somewhere and yes the ball is spinning as if flies down range. What we do see in the data that tells us the fill is not up to speed is the deceleration of the RPM's out of the barrel. We determined this by putting marks on the ball that showed us how fast it was spinning.

    SO curving paintballs as well as the Flatline Barrel do spin the balls but must over spin them in order to have enough residual spin to make them curve in flight. My overriding point in this is that there was not a dramatic increase in accuracy when doing this.

    AGD


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    Bill and Tom, I sit and watch in amazment at you two. Facinating stuff! Makes me think. You guys are my Hero's. Love it! Love it! Keep it up. Now this is what AO can realy do for us Guys. I am gettin smarter all the time.

    Phil

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    CPhilip, your back! I found someone with more posts than you, Pyro, 1200 some...I did try the extra paint deal one day too, I just wound up with leftover paint but i was more confident on the field not having to worry about running out, I still got about the same amount of eliminations with the extra paint.

    ------------------
    "Alright, no one look until I get my cork back in!"- Ham, Toy Story 2, one of the greatest movies ever made

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    I feel smart

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    Heat has more than me also. And there are some others too. And we all lost a bunch in the crash. However their posts are much better quality than mine...So they have many more quality points! And Yipes posts ought to count as at least 10 each.

    Yep! back!! only been gone a couple days...Good stuff happening here today though huh?

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    Wow... Nice explanation!

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    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by squall:
    What would happen if you placed divots in the paintball shell to reduce the "walkaround" effect of air behind the paintball? Rounded divots, or a more aggressive Hard cornered hexagonal shaped divot would allow the air to flow closer to the ball surface, reducing the turbulent wake that the ball leaves behind.

    Just like Golf ball aerodynamics... for paintball?

    Maybe a 4:1 rifling twist rate to impart as much spin on the ball and fill as possible, or 10:1 with the divots as they will pull a little more paint into the spin with them?

    And if all else fails, stick them in a backspin barrel to see how straight they fly.

    Sounds good in theory... what are your thoughts?

    </font>
    AGD produced a machined nylon ball with dimples in it that looked like a miniature golf ball in .68 caliber. The end result was that it shot worse than a regular paintball.

  16. #16
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    Another note on this topic is that the new Worr paint from Worr games claims to have a patent on their paint because the fill will not separate from the shell. I wold like to know if anyone has shot this paint in a armson or any barrel for that matter and whether it shoots any different.

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    My hats of to AGD as one of the few (if not the only) paintball manufacturers to undertake serious scientific study of paintball when designing their products.

    I agree, we've probably hit a wall as far as how accurate we can make our current paintballs under our current velocity restraints.

    The comments about the fill of the ball spinning separately from the shell however, disagree with my experiences and I'm interested to know how you tracked movement of the fill vs. movement of the shell.

    The ice/water corollary is often used to describe a paintball, as is the corollary of spinning a hard boiled egg or a raw egg (the hardboiled will still spin, because the center spins with the shell, while the raw stops spinning fast.) Good illustrations, but we don't shoot eggs or glasses of icewater, we shoot paintballs.

    The fill in paintballs is relatively thick (practically paste compared to icewater) and I've always been under the impression that it is thick enough, that it spins along with whatever the direction the shell spins (or tumbles) in flight. There are two situations I've observed that lead me to this conclusion.

    Back when I was in college, and paint was much more expensive, and had clear shells (I recently learned from a paint distributor that the main reason clear shells aren't made anymore is because you can see pigment that has settled, so you would be less likely to buy it if it didn't look good, even if it flew just as straight) I had about a quarter case of Nelson bright lime green (it looked like big snowpeas) that had settled a bit. Each ball had an air bubble about 0.5mm in diameter, and the pigment had settled, leaving a clear crescent shaped area in the top of each ball. The fill of the paint was so thick, that if I turned a ball over, the air bubble would take a good minute and a half to get to the other side of the ball.

    I had this idea - if the pigment was rebalanced, the ball would balance. I built a small motorized gyroscope with the goal of using inertia to move the settled pigment into a donut like ring around the equator of the ball (relative to the spin axis). This turned out to be rather impractical, as the thickness of the fill impeded movement, and the difference in density between the pigment and fluid was great enough that a single ball had to spin for days to get "balanced." Though all of this experimentation, including rapid starts and stops of the spinning ball, not once did the fill move fast enough relative to the shell to be visible. Moreover, if the fill could move with any speed relative to the shell that could have an impact during the second or two of a ball's flight, the pigment should settle in a ball in a fraction of a second, not over weeks or months - just as the ice bobs quickly to the top of the aforementioned glass of ice.

    The other situation which makes me doubt the spin of the fill separate to the shell, is the Tippmann Flatline. By putting a rapid spin on the ball, the Tippmann Flatline ball dramatically changes the flight charactaristics of the paintball - and that difference is apparent through the majority of the ball's flight, which would not be so if the shell were slowed quickly and dramatically by friction with the non spinning liquid center.

    And to those following up on this post, please keep in mind it's not meant as "I'm right, you're wrong" kind of thing, but rather for an open discussions of ideas, concepts, and supporting observations and data about the dynamics of a paintball in flight.

    See you on the field,
    -Bill Mills

    ------------------
    Computer / Paintball geek
    Technical Editor, World And Regional Paintball Information Guide - http://www.WARPIG.com
    Producer, Paintball Television - http://www.PigTV.net

  18. #18

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    My experience with an armson barrel is that it shoots no better and no worse than any other high quality barrel with one exception. It shoots remarkably well with old and poor quality paint. In part this is due to its huge bore but its good enough to hit a hopper with 6 mo. old paint.

    Keep in mind that this information is not based on a scientific test. It is based only on my impressions at the field.

  19. #19

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    Black I though of that a while back and like TOm was reading my mind mensioned it.... kinda funny cause those dimples make a golf ball better and NASA uses that stuff on some of their space junk but paintballs don't work... very strange.

    Anyhow... cphilip you're being too modest... AGAIN!

  20. #20
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    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by squall:
    What would happen if you placed divots in the paintball shell to reduce the "walkaround" effect of air behind the paintball? Rounded divots, or a more aggressive Hard cornered hexagonal shaped divot would allow the air to flow closer to the ball surface, reducing the turbulent wake that the ball leaves behind.

    Just like Golf ball aerodynamics... for paintball?

    Maybe a 4:1 rifling twist rate to impart as much spin on the ball and fill as possible, or 10:1 with the divots as they will pull a little more paint into the spin with them?

    And if all else fails, stick them in a backspin barrel to see how straight they fly.

    Sounds good in theory... what are your thoughts?

    </font>
    My brother came back from a tourney with a bag some paint like this, it wasn't proper dimples rather than a sort of matt effect all over the ball. It shot fine through my stock tippmann but broke almost every shot in my bro's angel.

    Flouresent(sp?) yellow it was.


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    I would like to mention that in the last 2 tips the barel tip and the spinning tip it comes down to one thing. We cannot get more accuracy than we currently have. If these experiments were to have been done in a vaccum, I believe more or an effect might have been seen. The fact of the matter is, other factors combined are so much greater. I am still amazed everytime I shot a paintball of the accuracy I am acheiving with this little ball. It is light, it is liquid filled, it is round, it over 1/2 an inch, it is effected by moisture and temperature, we are trying to excellerate it at 50,000 ft/sec/sec, using air as a propellant, and we are shooting through moving air. We should be glad we can hit the broad side of a barn at 50ft. Instead we goggle someone 50-100ft out.
    I am glad AGD is looking into whys to improve paintball Brainstorming and figuring out what works and what doesn't is important. I repeat though, what are we looking for in accuracy? I guess if I never had a fly away ball I would be happier but with all of the veriables I am not holding my breath enless we change the size, shape or wt of the projectile.
    Hitmanng

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    "I would rather hit once than miss 140 times."

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    tk,

    i have to disagree on the accuracy by volume statement. you guys might be paintball gun experts but i am a paintball playing expert in my own mind anyway.

    in a paintball game if you shoot alot then every player on the other team will know where you are and you are exposed, not good.

    if you do not shoot until you have studied the game as it develops you will know when and where to shoot so you have a kill for sure.

    paintball is a game of cat and mouse. if you go still in a game like a stalking cat and do not shoot your gun then the mouse will forget about you when it scurries across the field then you can pounce on it and save alot of money in paint cost.

    many people and new kids the most think the faster you shoot your gun the more kills you get. i disagree take the time to aim and you will shoot less but eliminate more. paintball is still a thinking persons game.

  23. #23
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    'Accuracy by Volume' is not a moral statement or a way to play your game. It's a 'scientific description' of how to hit something using a paintgun.

    Accuracy by volume is a bit of a contradiction since accuracy is actually
    the ability of an event to be consistently reproduced, and since we need volume to reproduce the event... we aren't being accurate... but anyway I digress...

    Taking out all the emotion from the situation, if you have a 2" target at 100ft, you cannot say with any consistency that one paintball shot will hit it.

    I could with my Air rifle, every time, but not my paintguns, so to ensure I hit it I will invariably have to take more shots. So I am using more volume of shots to ensure a hit target. That's the nature of paintball. It's a case of any shot you take at distance.

    It's a case of statistics not ethics of playing the game.

    manike


  24. #24
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    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by BlackVCG:
    AGD produced a machined nylon ball with dimples in it that looked like a miniature golf ball in .68 caliber. The end result was that it shot worse than a regular paintball.</font>
    Don't the dimples help grip the club head better? The lesson from this experiment was that either the shape & weight of the paintball or the liquid fill with the lessing of the M? factor are the reasons that rifling doesn't work with paintballs.


    If AGD is still interested in research, I have a couple of ideas. I'm guessing that accuracy has reached its peak performance. You can't change the velocity or the paintball itself so you are limited. One more idea is an eliptical barrel. I saw it a Palmer's website and I thought it was an interesting idea. Also, I think the 2 stage barrel dynamics isn't fully understood. I have a pet peeve. Why doesn't someone make an barrel adapter so Automags can use Angel or Autococker barrels?


    The Automag design is so compact with very little moving parts which is its strong points. You could probably improve gas efficiency but I have no idea. I think the bolt is worth researching. What about a paintball shaped indent like the Autococker bolts? I hear that there is a new bolt coming out with changes in the length and weight. Can't wait to try it out. I would also look into an anti-chop detector. Electro-guns are the future and all the hype. It is obvious that AGD has some excellent paintball engineering accomplishments. I would take marketing more seriously. Many times the better product doesn't win because of marketing. I'm not talking about advertising but how the public sees the product. Is it cool or awesome? The whole Automag design is a valve assembly at the end of a pipe and a trigger. It is interchangable and upgradable but the aesthetic improvement is limited. Autocockers and Angels win in the ability to improve the looks dramatically. The warp feed is a great idea but I don't understand why not make combine the warp and the loader. The Angel user doesn't mind expense but the cool factor or aesthetics is #1. I think that is why Warp feeds have penetrated that market. I'm just rambling but I like a company that listens to its customers.

    [This message has been edited by chaoticorigin (edited 07-18-2001).]

    [This message has been edited by chaoticorigin (edited 07-18-2001).]

  25. #25
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    I use my Stock barrel more that the Flatline on my tippy, flatline isnt that great.

  26. #26

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    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by daklown33:
    I use my Stock barrel more that the Flatline on my tippy, flatline isnt that great.</font>
    Then you aren't using it right. I have two 98's, both with the Flatline. Every time I go to the field with my bro we end up beig the bunker breakers from the back end of the field. The one thing I most about the Flatline is that in a wooded filed it allows for huge distance with a flat trajectory. All things being equal: air speed, humidity, muzzle velocity, everything. A Flatline will simply outperform any other marker outthere because it has the reach. The only possible exception to this is the Flatline Cocker.

  27. #27

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    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by daklown33:
    I use my Stock barrel more that the Flatline on my tippy, flatline isnt that great.</font>
    Then you aren't using it right. I have two 98's, both with the Flatline. Every time I go to the field with my bro we end up beig the bunker breakers from the back end of the field. The one thing I most about the Flatline is that in a wooded filed it allows for huge distance with a flat trajectory. All things being equal: air speed, humidity, muzzle velocity, everything. A Flatline will simply outperform any other marker outthere because it has the reach. The only possible exception to this is the Flatline Cocker.

  28. #28
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    Anybody remember the J&J Straight rifled barrels? I am a little bit confused by them because under the right circumstances they are more "accurate" than almost all other barrels I have shot, counting a smart parts freak system. Am I wrong to assume that the "rails" down the barrel create an almost porting like affect on the paintball, because the paintball is not touching the actual sides of the barrel only the three or four "rails." Which i turn allows air to pass around the ball while the rails keep the ball on a straight line. I could be really off with that but I would like some opinions.

    And yes i understand that a straight rifled barrel is not there to impart spin on a ball.

    Nice analogy about the 500 fps marble Tom

    Johnny Mo PFB

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    Mags Phantoms and Angels OH MY!

    [This message has been edited by TrevorSkoal (edited 07-18-2001).]

  29. #29
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    Question

    what if the paintball wasnt filled with paint, but powder. would that not spin with the shell. and it would still mark your opponent, maybe even be a bit harder to get off with out being perminent. (might even help out with whiping) i realize this is a drastic change in the name of the game(no pun intended) but it would be an interesting experament.

    any thoughts???

    RT

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    Spheres aren't really aerodynamic. At the St. Louis Science Center they have this huge display on airplanes and aerodynamics. One display that they have is a liquid tunnel (like a wind tunnel except with wind) with three shapes inside. They had an airfoil, a sphere, and a cube. When the water moved over the shapes you could see where the drag was. At the back of the circle there is circular movement. The drag on the circle would be enough to cause inaccuracy, but with the inconsistent surface of a paintball it would be worse. The drag wouldn't be moving all in the same direction. This would cause worse accuracy.

    Then there is the spinning aspect. The liquid wouldn't spin at the same rate as the shell, as stated previously. The higher the viscosity the better it would maintain the speed of the shell. But the liquid wouldn't be evenly distributed throughout the shell due to the massive amounts of G's exerted upon the ball. When the ball starts to accelerate in fractions of seconds, the gravitational forces are being exerted, and then when the ball spins that would give it a little bit of a lopsided spin, defeating whatever purpose that you applied the spin in the first place.

    I can't say for sure if that is 100 percent right, because I don't have time to do the math/physics and I don't know enough of math/physics to be confident of my claims. And of course, I'm not a professional that gets paid to do that, or even paintball related aerodynamics.

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