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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mack Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 12:55pm
Originally posted by LordJovian LordJovian wrote:

You're arguing about how a swallow could or could not carry a coconut.



Is that an African or European swallow?   (Sorry, couldn't resist.)

Edit:  On a more serious note; if I understand the major arguments here, then the questions have already been answered in the following link.

This site, and other pages on it, have been referred to before, but after reading it all the way through, I realized it answers the two major questions being asked here.  To try to keep things relatively straight, I will emphasize sections of quoted text in red print and any personal observations specific to the quoted sections in green print.  Now, on to the questions!

1. Does the paintball gain speed from the backspin after leaving the flatline barrel?
  • No.  "Unless acted upon by some external force (push) an object will not change its speed or direction. We already know from experience that paintballs do all sorts of strange things in the air. They drop; they curve. So they must be acted on by other than forces imparted to it by the marker when in the barrel. However, none of these forces will act to increase the speed of the ball in the direction of motion once it leaves the marker. In other words, the paintball is not going to magically pick up speed once it leaves the marker. I know I keep repeating this, but for some reason this is usually where many people seem to go wrong in their thinking."

2. Does the paintball from the flatline maintain speed longer once fired?

  • Yes, but this could be argued.  For the sake of fairness, I will quote all of the relevant sections and explain the conclusion I reached based on the data presented. 
    • First, a laymans definition of the Reynolds number which I found here. "The Reynolds Number is important in analyzing any type of flow when there is substantial velocity gradient -  shear. The Reynolds Number indicates the relative significance of the viscous effect compared to the inertia effect. The Reynolds number is proportional to inertial force divided by viscous force."  The site goes on to list the five factors in the equation as characteristic length, velocity, density, dynamic (absolute) viscosity, and massvelocity.  Note that actual spin (rpm) is not included anywhere in the calculation. 
    • Now, the information from the paintball physics site: " Lets take a closer look at one of the curves; the smooth sphere data by Achenbach is of particular interest to us. The adjacent graph shows just this data and defines some of the terms used to describe the Reynolds number regions. At the critical Reynold number, the drag on the sphere suddenly drops by nearly a factor of five. Referring back to the drag equation, this means that a ball above the critical region will have reduced drag and fly further. Of course, once the velocity drops below the critical Reynolds number, as we will see it must, then the ball will slow down very rapidly, appearing to drop very fast (relative to the horizontal distance traveled)."  Note, that this is exactly what paintballs fired from a flatline appear to do.

      "So where does a paintball fit into this scheme. The Reynolds number of a typical paintball with a velocity of 280 ft/sec is around 9.4 x 104. From the curve, we can see that this clearly falls into the subcritical region. As far as drag force is concerned (and perfectly spherical paintballs), there is no free lunch for well formed paintballs."  Note, that this appears to directly contradict my previous observation.

  • First, let me say that I believe at least part of the reason that shots from a flatline seem to hit harder than shots fired from a normal barrel is psychological.  As Bruce pointed out above, when people get hit (break or not) at ranges where they can't do the same, they tend to conclude that their opponent is firing hot.  The loudness factor of most flatlines also probably helps to create the impression of illegal velocities as well. 
  • Second, I belive that flatlines also seem to hit harder (and have a better chance of breaking paint at longer ranges) because of the angle at which the ball strikes the target.  Remember that the flat trajectory allows for direct hits at ranges where most markers can only get glancing blows due to the arc of the round.  The paintball physics site touched on this subject here while referring to paintball-drop testing.  "It would appear that most paintballs will break at distances somewhere between 6 feet and 10 feet. What are the speeds associated with these heights? Well the trajectory program won't allow a zero velocity, but if we make the number very small and use an angle of 0 degrees, we can obtain the speeds that the paintball will reach just as it hits the ground. From 4 ft, 15.8 ft/s; 6 ft, 19.3 ft/s, 8ft, 22.1 ft/s; 10 ft, 24.6 ft/s. So the speeds are not very high. Remember, we calculated that even a maximum trajectory would have a speed of 60 ft/s as it hit the ground. However, a big factor here is the type of surface it is hitting.

    The above ball breakage data would appear to conflict with a comment in another study - the "Lapco Barrel Challenge" by Richard Allen on barrels. This study was concerned with trying to answer what is the best barrel. In the document, it was mentioned that some balls were bouncing off a plywood target at 150'. I calculated the speed that the balls should have at this distance and found it to be around 110 ft/s. This is quite a bit different than the ~24 ft/s found in the previous results. The difference between hitting a plywood surface and a concrete floor should be only slight, so it is not clear why the large difference. One possibility is that in this study the balls were hitting the target at a glancing angle rather than perpendicular to the surface as in the drop tests."

  • Now for the controversial part.  I concluded that paintballs from a flatline hit harder than those fired from a regular barrel because they do actually lose speed slower than the shots from the regular barrel.  I base this on the following:
    • Drag slows down objects that are moving on inertia only.  This is a given.
    • The data above shows that at a critical Reynolds number, drag on a smooth object is reduced by nearly a factor of five.
    • The data above also indicates that paintballs do not move fast enough to achieve the critical Reynolds number.
    • However, the data also describes perfectly what happens when an object slows below that number; it appears to "slow down very rapidly", which is exactly what happens with paintballs fired from a flatline barrel.
    • I can only conclude that a part of the equation is missing (as I pointed out, the Reynolds equation does not take spin into account) and that if the missing part was included, the Reynolds number would change to match the observed behavior of the shots.


Edited by Mack
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LordJovian Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 1:45pm

^ Ah, my favorite. Humor. I probably would have done the same in your situation.

Or I could pull what everyone is doing to make a point by stating you used incorrect punctuation at the end of your comment.



Edited by LordJovian
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Clark Kent Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 2:20pm
Originally posted by LordJovian LordJovian wrote:

The ball is spinning backwards, creating lift.

True.

Quote In order for the ball to fall to the ground, it must lose its velocity traveling paralell to gravity.

Not true.  Even if the ball maintained perfect horizontal velocity, the rotation would gradually slow/stop due to friction, at which point gravity would overcome the spin-induced lift.  It's the old cannon-ball drop.

Quote Lift allows the ball to "cut" through the air better. Instead of the ball standing still and basically "slamming" into a wall of air, it's spinning like a drill and "swimming" through.

Not true.  Lift has nothing to do with "cutting" through the air - it has to do with the Berboulli-derived Magnus effect, which used friction to change the orientation of the back pressure on the ball, causing a change in direction.  Entirely different.

And a spinning ball does not "drill" through the air.  If anything, the spinning ADDS friction, made the air more of a wall.  The way that rotation adds velocity retention is by reducing back pressure with rotation-induced turbulence.  Entirely different.

This is evidenced, for instance, by the simple aerodynamic fact that a rough rotating sphere retains velocity BETTER than a smooth sphere - witness a golf ball.  The rough surface creates MORE friction, which is a hindrance, but it also creates more turbulence, which is a benefit.  With the correct balance between Reynolds number, rotational velocity, and travel velocity, the dimples on a golf ball help it retain velocity better, despite the increase friction.

Quote You don't need any complex equations to realize this- logic is a beautiful thing. How, HOW, do you explain the increased range?

The increased range is easily attributable to the Magnus effect, which causes lift on a backspinning sphere.  If there is a velocity effect as well (unclear), then such velocity effect has nothing to do with "drilling" - rather the opposite.  In fact, a Flatline user could probably increase range significantly by roughing up his balls a bit, or using specially made dimpled balls.

Quote Instead of throwing mud about drag, why don't one of you explain how it works, or how it doesn't really work at all.

I think drag has been thoroughly dissected in a couple of posts by now.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lightningbolt Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 2:27pm

Clark,

What's your take on top-spin while shooting in windy condition's?

Specifically shooting stright into the wind.

Increased distance over a ball without spin?

Better retained velocity down range over a  ball without spin?

Any thought's?

Sent from a phone booth
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce A. Frank Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 2:32pm
Originally posted by LordJovian LordJovian wrote:

Have no proof?!?! Haven't you read any of these posts?!

The question about proof is not about the mechanism that generates lift and the resultant flater trajectory. It is whether the back-spin of the smooth surface of the paintball actually creates reduced drag allowing the ball to retain greater terminal velocity. (as in "hits harder")

Though the references linked through this topic suggest that such retained velocity is possible, there is nothing that clearly states that forward velocity has a lower delta for the smooth back-spinning ball than it is for the non-spinning ball. So far no one seems to be able to put a definitive conclusion on that part of the question. Consenses is that empirical data is required.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mack Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 2:39pm
Originally posted by LordJovian LordJovian wrote:

^ Ah, my favorite. Humor. I probably would have done the same in your situation.

Or I could pull what everyone is doing to make a point by stating you used incorrect punctuation at the end of your comment.



Punctuation is for sissies!   Actually, it does bother me when I do that.

P.S.  I updated the post above to actually contain data relevant to the discussion.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce A. Frank Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 2:42pm
Originally posted by Lightningbolt Lightningbolt wrote:

Clark,

What's your take on top-spin while shooting in windy condition's?

Specifically shooting stright into the wind.

Increased distance over a ball without spin?

Better retained velocity down range over a  ball without spin?

Any thought's?

First, shooting into a head wind will do two things, slow the forward velocity and the interaction of the lift and the headwind will cause the ball to rise rather than maintain a more flat trajectory.

Similar the the phenomenon of shortened takeoff distance in a head wind or the need to trim more nose down as you increase the speed in an aircraft. Higher relative speed of a lifting body caused greater lift. 



Edited by Bruce A. Frank
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce A. Frank Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 2:58pm

Originally posted by Mack Mack wrote:



Edit:  On a more serious note; if I understand the major arguments here, then the questions have already been answered in the following link.

(SNIP of one of the most informative articles I have ever seen in lay discussion on the Internet)

Mack,

Your effort to put that all together is amazing. I applaud you and thank you for what, I think, IS the conclusive statement on retained velocity.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote A5 dude15 Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 4:57pm
ok so at that site that was posted by mack, it was proven that balls from the flatline maintain speed longer. thats enough right there. that means that the ball from the flatline is decelarating slower than the ball from another barrel. this means that at any given point that the ball from the flatline will hit harder than the normal barrel due to slower decelaration. good job mack
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lightningbolt Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 5:07pm

Bruce I'm referring to topspin like the Apex can achieve.

Any thought's?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Clark Kent Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 5:22pm

Topspin causes, via the Magnus effect, a divebomb.  This has a detrimental effect on range.   :)

As to velocity retention, the direction of rotation should be irrelevant, except for rotation along the axis of travel (like a bullet) - the turbulence effect should be the same regardless.

Of course, if the ball is traveling straight down, gravity comes to its aid, resulting in better velocity retention, perhaps even acceleration.

Did I understand your question correctly?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote LordJovian Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 5:42pm

Clark-

Your first argument didn't make much sense. You said my statement was not true, then you mentioned it was. Friction slowing down the backspin wasn't even included in my statement. I said an object had to lose parallel velocity to the ground (gravity) to drop. That includes friction. I didn't list every single force that would affect it.

"Cutting" in quotes means, in the english language, that it isn't using the straight and defined method of cutting. If I didn't use quotes, yes, tear into it. But I did. I am trying to use a language everything else can read. And a hammer hitting plywood generates (slamming) less friction than a drill (drilling) into plywood.

And my last statement was my error. I wasn't referring to how drag works, I was referring to how the Flatline works. I probably should have re-defined my subject in the latter portion of my statement.

And, without further ado, all it took to pull the solution out was to mention Monty Phyton and the Holy Grail. Not harsh words or insults, humor. Mack, there will be much rejoicing. We shall dine on breakfast cereals, orangutans, and fruit bats. There will be song and dance (routines and chorus scenes) in your honor at Camelot.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mack Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 6:23pm
Originally posted by LordJovian LordJovian wrote:

Mack, there will be much rejoicing. We shall dine on breakfast cereals, orangutans, and fruit bats. There will be song and dance (routines and chorus scenes) in your honor at Camelot.


Cool, but I have a request for the party.  "Bring me a shrubbery!"

Edited Note:  I like that saying, it's going to be my motto for a while.


Edited by Mack
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Clark Kent Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 6:29pm
Originally posted by LordJovian LordJovian wrote:

Your first argument didn't make much sense. You said my statement was not true, then you mentioned it was. Friction slowing down the backspin wasn't even included in my statement. I said an object had to lose parallel velocity to the ground (gravity) to drop. That includes friction. I didn't list every single force that would affect it.

The bolded statement is false, unless you are traveling at orbital velocity or escape velocity.  Or maybe I am just misunderstanding you.

Rotation aside, consider the following physics example:

Take two identical cannon balls on a castle wall.  One ball is loaded into a cannon.  The cannon is fired exactly parallel to the ground.  At the exact time of the cannon fire, the second cannon ball is dropped off the wall, straight down. 

Q:  Which ball will hit the ground first?

A:  Both will hit at the same time.  The gravitational pull is the same on both balls, regardless of their horizontal velocity.  This is independent of air resistance or drag - the same result would occur on the moon.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lightningbolt Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 7:38pm

While topspin may have a negative effect in still condition's I still believe, in windy conditions it will prove to be an asset, with the proper amount of topspin dialed in with the Apex.

I've seen too many golf balls in flight to think otherwise but don't have the means to perform any sort of test until I decide if I'm going to get an Apex.

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KillerOne Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 8:01pm



KillerOne-  Get a clue, or are you too dumb to follow links?  I responded to your NASA bit back in the Marker Gallery section, and I even mentioned it again in the beginning of this thread.  The picture I posted above was on the NASA website (just in case you weren't paying attention again).   I always have maintained that a backspinning paintball flies farther because of the lift it generates so, don't even try to come on this board and try to act like you helped me out.
You're the one who draws the illogical conclusion that if it flies farther, it must hit harder.  Nobody else here is subscribing to that crap.
Neither in your alleged 'email', or in any NASA pages does it say that a smooth spinning projectile gains the benefit of reduced drag.  In fact, the only reference I have seen to this is in the one Monk provided.  If anyone bothers to read the Physics calculator pages, the author references the speeds a smooth spinnning ball needs to be traveling to gain the benefit of reduced drag, and a paintball, at 280-300fps, clearly does not. 
No, just because a paintball goes farther doesn't mean it hits harder.  Why can't you seem to grasp the concept that the paintball goes farther horizontally because the backspin generated lift gives it more time to move horizontally before it hits the ground?
For crying out loud, you said you have a bachelors in physics.  Yet most of the people here with Jr. High, High School, and even 100 level physics can grasp this concept.
Additionally, how can you even place yourself on the same playing field as myself in this discussion?  When all you have done is gave us a link to a NASA center homepage (which I used to provide further proof of the backspin generating lift for you, and the pic I included above), and give us a supposed quote that you obviously misconstrued.  All this after how many references I have provided from .edu, .gov, the internet in general, and further, an interview from the inventor of the flatline?
I for one, do not believe you have a B.S. and I find it highly unlikely that you are a marine, because a marine would not lie about having a degree, and a marine would have paid a higher attention to detail.  Further, you continue to demonstrate your probability of being an immature brat, when you can't even restrain from mud-slinging.  To even go so far as to call my gun a POS, When you've never seen it perform.  I would even go to say that it would outperform your gun, in terms of consistancy and fire rate, as I'm double regged (a Dye fixed output tank, and a palmer fatty stab), I have an E-bolt, and a Qloader.
And this test isn't being done because people have too much to do.  It's a matter of having the right equipment.  Which unless you happen to have it lying around it's very expensive (at least one, actual, old-school shooting chrony, not your radar ones).
[/QUOTE]

   Wow UV HALO - I'm sorry I hurt your feelings, you are right I have never see you or your gun and I shouldn't have said that you have a POS - but from what I am reading about your gun - it looks like you really do. But that is neither here nor there -

   I can't wait to see the results of this test - until then - try to get this through your balding head - you have posted the same trash over and over again - and all you have given us are the formulas and theories- which mean nothing unless you can fix the variables that correspond to what we are talking about;

flatline

your POS

range

PSI

FPS

Lift

 - so sit down and have a donut you 40 year old reject because all that matters are the out come of these "tests" and not what you pull of the net or the "paintball calculator".

   Write back and let me know whats on CNN.

  

  



Edited by KillerOne
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lightningbolt Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 8:08pm

wow.

I've actually caught a ball shot thru a flatline by some guy, showed it to him across the field and put it in my hopper The Ville at HS



Edited by Lightningbolt
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Clark Kent Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 8:10pm
Originally posted by Lightningbolt Lightningbolt wrote:

I've seen too many golf balls in flight to think otherwise but don't have the means to perform any sort of test until I decide if I'm going to get an Apex.

Keep in mind, though, that golf balls mostly have backspin.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambino Quote  Post ReplyReply Direct Link To This Post Posted: 20 October 2005 at 8:15pm

 

KillerOne, UV HALO - you guys both need to chill on the insults.  Don't make me spank you. 

Play nice.

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