1. farther shots

2. harded shots.

Just like a baseball."

"Thanks to the laws of Physics - When you put a backspin on a ball (just like the flatline does) the result is acceleration and distance; increasing the Maximum Effective Range of my A-5 and anyone else using a flatline."

Personally, I find this to be garbage.  Everything I have seen in websites,  discussions on the topic, High School, and College level physics (granted only 100 level) leads me to believe that the backspin on a paintball gives the paintball lift which temporarily reduces the effect of gravity, allowing it to fly further down range before it hits the earth.  I've even found two calculators that show the effect of backspin on a ball.  The first http://home.comcast.net/%7Edyrgcmn/pball/trajectory.html - here , and another through a link he even replied with, http://www.grc.nasa.gov/WWW/K-12/airplane/beach.html - here .
 Everything I have seen through the use of my flatline (and being shot by a flatline) tends to agree with the first calculator (the second isn't designed specifically for a paintball but, explains the same theory).  The shots fired from a flatline fly farther but do not hit with more force than a non-backspinning ball.

What do you all think?  I would prefer to keep this intelligent, and it would help if you could site your sources.  Feel free to include your personal observations just be sure to identify them as such.

UV Halo...You observations and research are correct.  There is no velocity change on a ball once a gun is chronoed.  If you chrono a flatline and a stock barrel and both are set at 285fps, then they are both at 285fps...exact same velocity.  There is no way the velocity will increase unless you reset the velocity screw or have "hot" CO2 issues.  (As a side, most field chronos are nothing more than a radar gun, which detects doppler shift, so generally the ball speed is measured after about 10 feet from the barrel.)  You are also right about the backspin creating lift to keep the ball up longer.  The backspin basically creates a low pressure (might be high pressure, I forget), that allows the ball to stay up longer.  Much like the vortex effect from an airplane wing....As far as it hurting more, or making the ball break easier, I can only guess that this too has to do with the backspin.  If the ball hits with a spin, it is more likely that the shell will "rip" and break, versus a "knuckle ball" with no spin.  Try to throw a water balloon at a sheet hanging from a clothesline.  If you are successful enough to get a spin on the balloon, I guaruntee it'll break on the sheet.  If you knuckle ball the balloon, it might very well just hit the sheet and fall to the ground.  Now as far as what "You Won't See Me" said.  That's correct too.  The backspin will allow gravity to be defeated a bit longer, thus at a given distance, the velocity might be maintained longer.  However, it is impossible to "gain" velocity from a backspin.

SO, your thoughts and opinions are absolutely correct.

UV HALO has sandenginyitus -

 So I went back and reviewed my previous posts – 

   I still maintain that a paintball fired from a flatline hits harder thanks to the backspin.

Lift allows paintball to travel further – because of this lift (backspin) a shot fired from a flatline will maintain its velocity better than a paintball fired from a regular barrel – so that when you are hit by one – it is a harder hit.

Both from on field observations and http://www.grc.nasa.gov/ - www.grc.nasa.gov .

One other thing:

"

   Same thing with a Backspin -

When I am not hanging out here I participate in a homebuilt aircraft group. Knowing a little bit about air flow over a high lift wing (blunt and rounded)  I am going to postulate that the back spin, while generating lift from the low pressure generated on the top side of the ball and the deflection of air downward, also reduces the drag on the ball allowing it to retain a higher velocity down range.

That is to say that a non-spinning ball has the air wrapping around all side equally causing a low pressure area directly behind the ball. With back-spin, I see the low pressure area being pushed to one side effecting less of the surface area of the ball. While at the same time causing the low pressure area to be smaller.

Now I am going to have to pull out my old firearm chronograph to check down range velocity. Hope it will actually go as low as the paintball velocity.

UV Halo wrote: Over in the Markers Gallery, KillerOne made the following statements: "Tried multiple barrels - preferred A-5 Flatline due to ruggedness and increase range, shots hit harder." "...expecially the way i've got it - it put a spin on the ball which does two things: 1. farther shots 2. harded shots. Just like a baseball." "Thanks to the laws of Physics - When you put a backspin on a ball (just like the flatline does) the result is acceleration and distance; increasing the Maximum Effective Range of my A-5 and anyone else using a flatline." Personally, I find this to be garbage.  Everything I have seen in websites,  discussions on the topic, High School, and College level physics (granted only 100 level) leads me to believe that the backspin on a paintball gives the paintball lift which temporarily reduces the effect of gravity, allowing it to fly further down range before it hits the earth.  I've even found two calculators that show the effect of backspin on a ball.  The first http://home.comcast.net/%7Edyrgcmn/pball/trajectory.html - here , and another through a link he even replied with, http://www.grc.nasa.gov/WWW/K-12/airplane/beach.html - here .  Everything I have seen through the use of my flatline (and being shot by a flatline) tends to agree with the first calculator (the second isn't designed specifically for a paintball but, explains the same theory).  The shots fired from a flatline fly farther but do not hit with more force than a non-backspinning ball. What do you all think?  I would prefer to keep this intelligent, and it would help if you could site your sources.  Feel free to include your personal observations just be sure to identify them as such.

Yep...wow, you guys should come to work for the gubmint...you know more physics than some of the guys I work with and we're all electrical engineers......BTW, Bruce, I imagine your old firearm chrono should go down to paintball speeds.  My buddy's chrony goes down to something like 100fps.  If you have the diffuser type, it should work.  It just measures the time the ballistic takes to go between a fixed distance.  I'm sure you know that though.  I'm actually making my own with a PIC as a timer, and some photocells for detectors.

BTW, Bruce, thanks for all the great insight you give on this forum.  I've learned alot about paintball from your posts.

"Ok – I’m going try help you out - so dig this:

Thanks to the laws of Physics - When you put a backspin on a ball (just like the flatline does) the result is acceleration and distance; increasing the Maximum Effective Range of my A-5 and anyone else using a flatline."

Sargent Duck wrote: I doubt if Tippmann's Tech dept is able to give a good answer. They just fix the things, they don't look at the theory of why these things work. You'd be better off contacting Tippmann Research and Development (if such a dept. existed).

I'll bet you that if you could contact Ben Tippmann he would be able to discuss the theory of round ball flight. Certainly he has accomplished development of a unique product that many "experts" said could not be done. Heck, I know some players who say that the Flatline really doesn't work. I guess they think it's an optical illusion...like the curve ball pitch in baseball. (years of controversy over whether a curve baseball really curved)

A5 dude15 wrote: ok for some reason it wont let me copy paste my post that i made but i posted it in this argument in the marker gallery and i think it might pretty much end the argument.  i presented my argument backed up with facts...everyone should go read it.

You know, it doesn't exactly help your scientific cred when you can't figure out cut 'n paste...

But as it turns out, I did go and read your post.  You assume your conclusion, and fail to properly account for the variability of air resistance (among other problems).  So I am not persuaded.

I return to my previous point - somebody with a couple of chronos should do an experiment.

Nice Aristotleian physics there, duck...   :)

When the ball leaves the barrel there are two significant forces acting on the ball, yes - but the force that fired the ball is NOT one of them.  That force stops acting on the ball as soon as it leaves the barrel (or very shortly thereafter).

Gravity acts on the ball, and air resistance (friction) acts on the ball.  Gravity is (more or less) constant, air resistance is anything but constant.  It depends on the surface of the ball, the rotation of the ball, the velocity of the ball, the wind, atmospheric conditions, and a zillion other little things.  From one second to the next, however, the velocity and rotation of the projectile are the factors that will vary most significantly.

But - I do hope somebody does a proper experiment.  It would be tricky to design, however, since it might be difficult to compare apples and apples.  Since the Flatline has a flat trajectory and other barrels do not, the ball shot from the straight barrel travels further to get to the same horizontal point.  This makes it harder to determine exactly what we are measuring.  There is also the matter of "velocity" - are we talking horizontal velocity only, or vector-directional velocity?  Gravity is increasing the downward velocity of the straight-barrel ball, but not the Flatline ball, which would skew the results.

In addition to the normal confounding variables, we are adding a layer of complexity by measuring and comparing two entirely different trajectories.  In order for a study to be meaningful, the methodology would have to be carefully designed and justified.

UV Hallo - Heelo - Halo:

12 years in the navy huh - WOW. Corps-men are good to go - i've even met a couple of seals that weren't pricks - most seaman i've met are overpayed and over weight - you know what I mean? 12 years. WOW.

Anyway - I shot an e-mail down to some guys at NASA - the real NASA you know rockets - space. I have below my question and I used a Baseball as I'm sure they didn't have a Paintball Calculator handy like you did - and this is what they said( and by they I mean he).  

"Would a spinning fastball pitched at a batter have an increased acceleration because of the spinning?"

Actually .. yes. But it is a little tricky. Acceleration, like a lot of other physical things, has two parts to it .. a magnitude (size) and a direction.

 And both are important. If you accelerate a 1 pound ball with 500 pounds of force to the north .. the ball accelerates to the north. If you apply the 500 pounds of force to the east .. the result is very different .. the ball goes east. Obviously if apply a force of only 200 pounds to the north, the ball goes north, but it doesn't accelerate as fast .. the result is different again. So acceleration has two parts .. size and direction.

  If you throw a ball with some spin on it .. you have a couple of different forces at work. Obviously, there is the force in your arm which accelerates the ball in the direction set by your release. But the ball is travelling through the air, and the second your release it, an aerodynamic force begins to slow it down .. it decelerates because of aerodynamic drag. If you put a spin on it, you get an additional aerodynamic "lift" which is at right angles to the direction of travel and to the spin axis. So the ball is accelerated at right angles to the direction of travel. This makes the ball curve."

Curve? Yep Curve - up - down - left - right - the dircetion of the spin in relation to the y and x axis will determind that - Backspin? Lift? Acceleration?  What do all these things have in common- BT Flatline barrel 15% Farther - Harder.

Oranges, Apples  - symantics.  

How's CNN?

   Special thanks to NASA.

UV HALO -

KILLERONE- 

  BE ADVISED, TRAFFIC UNDERSTOOD -

  FLINELINE HITS HARDER _ GOES FARTHER,

  KILLERONE ACTUAL, REQUESTS TO SEE YOUR GOGGLE CALCULATOR -

  HOW COPY, OVER  

  HALO want everyone to assume he's an engineer - that e-mail is from NASA and We can All talk to the CDC too if you like - either way - This is all for fun and at the end of they day I've seen my flatline and the flatline of my buddys at work - it hits harder and goes farther.

I've been reading more of your posts - and wrote that if you dropped a paintball and then fired one at the same time from the same distance they would both hit the ground at the same time - thats about as good as the other stuff you have posted -

"Gravity accelerates all objects downwards at a rate of 9.8m/s  So, if you dropped and fired a paintball from 4.9m up, they would both hit the ground at the same time, of 1 sec (not accounting for drag)."

                         --- UV HALO, TIPPMANN FORUM, MARKER GALLERY.

Killer, if you actually emailed people at NASA, you should at least have asked the correct question.

"Would a spinning fastball pitched at a batter have an increased acceleration because of the spinning?"

Technically, of course, deceleration is simply negative acceleration, but your question implies (as did one of your posts in the other thread) that the Flatline balls actually accelerate (move FASTER) after leaving the barrel, and that is of course patently false.  All the acceleration occurs inside the barrel.  Afterwards, it's all negative acceleration (gravity aside for the moment).

The correct question to ask would be "would velocity change of a travelling spherical object due to air resistance be affected by rotation of the object?"  - or some version of that.

I will continue my theoretical inquiries on this subject as well (no conclusive response yet), but I really do hope somebody does a proper study.

Sargent Duck wrote: Heh, Clark Kent, now that you mention it, I do see the error in my ways.

I figured you just slipped...   :)

You actually posted a description almost exactly the way Aristotle would have explained motion, before the world had the benefit of Newton's genius.  So you might say that you are as smart as Aristotle.

An airplane wing functions on the Bernoulli principle.  Almost by definition, the Bernoulli principle cannot apply to a travelling sphere.

The Flatline functions on the Magnus effect, which (as noted) is the same reason curveballs curve.

The question is a matter of semantics - the answer I got was the correct one - if my earlier posts implied that the paintball gains acceleration because of the spinning than I just failed to explain myself – the real issue here is weather or not a flatline shots farther and harder – I still say Yes. What say you?

 By the way – anyone can e-mail any government agency – most of the time they don’t mind talking to you – just remember that you need to have a legitimate question to ask.  If you catch the right person they will talk your ear off, as long as you want to listen.  

I say that I have been unable to reach consensus as to whether or how, as a theoretical matter, air resistance would be affected by the rotation of a sphere in flight.  I have some more people I want to ask, but I don't expect to get a clear answer.

At a minimum, I find that this is a very difficult question.  I have not looked in the literature, and nor do I plan to.

KillerOne wrote: UV Hallo - Heelo - Halo: 12 years in the navy huh - WOW. Corps-men are good to go - i've even met a couple of seals that weren't pricks - most seaman i've met are overpayed and over weight - you know what I mean? 12 years. WOW. Anyway - I shot an e-mail down to some guys at NASA - the real NASA you know rockets - space. I have below my question and I used a Baseball as I'm sure they didn't have a Paintball Calculator handy like you did - and this is what they said( and by they I mean he).   "Would a spinning fastball pitched at a batter have an increased acceleration because of the spinning?" Actually .. yes. But it is a little tricky. Acceleration, like a lot of other physical things, has two parts to it .. a magnitude (size) and a direction.  And both are important. If you accelerate a 1 pound ball with 500 pounds of force to the north .. the ball accelerates to the north. If you apply the 500 pounds of force to the east .. the result is very different .. the ball goes east. Obviously if apply a force of only 200 pounds to the north, the ball goes north, but it doesn't accelerate as fast .. the result is different again. So acceleration has two parts .. size and direction.   If you throw a ball with some spin on it .. you have a couple of different forces at work. Obviously, there is the force in your arm which accelerates the ball in the direction set by your release. But the ball is travelling through the air, and the second your release it, an aerodynamic force begins to slow it down .. it decelerates because of aerodynamic drag. If you put a spin on it, you get an additional aerodynamic "lift" which is at right angles to the direction of travel and to the spin axis. So the ball is accelerated at right angles to the direction of travel. This makes the ball curve." Curve? Yep Curve - up - down - left - right - the dircetion of the spin in relation to the y and x axis will determind that - Backspin? Lift? Acceleration?  What do all these things have in common- BT Flatline barrel 15% Farther - Harder. Oranges, Apples  - symantics.   How's CNN?    Special thanks to NASA.

Hmmm? I think your conclusions from their information could be an exercise in semantics. How could there be any acceleration after the ball (or paintball) leaves the pitcher's hand (or the muzzle of the marker)?

Spin is imparted to the ball in the same energy transfer that accelerates the ball to the release. No further energy can be imparted to the ball after it leaves the hand or a marker muzzle. The imparted spin is not an increase in energy state. It is part of the energy state  at release. You cannot have acceleration without energy input. After release there is no further energy input.

The spin of the ball causes it to move, in the air, in a direction related to the axis of the spin, because of its interaction with the air. If spin imparted acceleration then the spinning ball would curve even in a vacuum, which it will not do.

UV Halo wrote: KillerOne wrote:     HALO want everyone to assume he's an engineer - that e-mail is from NASA and We can All talk to the CDC too if you like - either way - This is all for fun and at the end of they day I've seen my flatline and the flatline of my buddys at work - it hits harder and goes farther. I've been reading more of your posts - and wrote that if you dropped a paintball and then fired one at the same time from the same distance they would both hit the ground at the same time - thats about as good as the other stuff you have posted - "Gravity accelerates all objects downwards at a rate of 9.8m/s  So, if you dropped and fired a paintball from 4.9m up, they would both hit the ground at the same time, of 1 sec (not accounting for drag)."                     & ;nbs p;    --- UV HALO, TIPPMANN FORUM, MARKER GALLERY. First off KillerOne, I never said I was an engineer.  I found and linked refereces, which to date, you have not provided.  Sorry but, the homepage of a NASA research center is not the same as the link to the page on the NASA website that describes the phenomena.  You seem to be intent on passing yourself off as a Marine with a B.S. in physics.  You even explicitly said so in the marker gallery: KillerOne wrote: You talk from ZERO intel.  First. I am a marine. Second. I have a BS. in physics.  This is Fun.   Second, do you doubt that the following equation is true: Distance traveled = 1/2 (acceleration * time * time) If you had a B.S. in physics you would certainly remember that.  I certainly remembered it from my Physics 100 level class.  Oh, and just to make sure I got my bases covered, the formula is on pg 23 of the Conceptual Physical Science, Second Edition, Hewitt, Suchocki, Hewitt. Therefore, 4.9m = 1/2 (9.8 *1*1). Third, do you doubt that if you drop, or fire an object horizontally, it accelerates downward at a rate of 9.8m/s in the absence of an atmosphere, (unless you give it some lifting force)? This is illustrated and explained in section 4.4 Projectile Motion on pgs 86-87 of the above referenced publication.  Here is a question and answer from pg 87. Q: "At the instant a horizontally held rifle is fired over a level range, a bullet held at the side of the rifle is released and dropped to the ground.  Which bullet, the fired downrange, or the one dropped from rest, strikes the ground first? A: "Both bullets fall the same vertical distance with the same acceleration g due to gravity and therefore strike the ground at the same time." This was also found http://hyperphysics.phy-astr.gsu.edu/hbase/grav.html - here (an EDU site for you): " A dropped bullet will hit the ground before one which is fired from a gun. As shown in the illustration of a horizontal launch, gravity acts the same way on both bullets, giving them the same downward acceleration and making them strike the ground at the same time if the bullet is fired horizontally over level ground."

  So now we are fireing a round horizontally and dropping one from same height at the same time  - in that case, point taken. Though you didn't say anything about a horizontal variable the first time you posted.  Now you are good - I guess it is a matter of semantics. 

Monk wrote: http://www.warpig.com/paintball/technical/zbody/index.shtml - http://www.warpig.com/paintball/technical/zbody/index.shtml Bam, even from a paintball related website.

Most of the article isn't that helpful (a discussion of the old Z-Body), but it does have this sentence tucked away in the middle:

WARPIG wrote: One consequence of moving the low pressure out from the center behind the ball is that the pressure difference between the front and back is decreased, so the ball will not decelerate as quickly from drag.

Unfortunately, no reasoning or explanation is provided - just another claim/statement.

UV Halo wrote: True but, never has anyone, pointed out a reference that says a backspinning ball has less air resistance.  The only context of a ball somehow gaining lowered resistance in it's flight by it's design or path, is a golf ball, and specifically, it's the dimples on the ball that allow for this.   Additionally, don't you think that backspin would be a concern for the ASTM, Tippmann, or even the goggle manufacturers, if the paintballs somehow hit harder?

Take a look at the article for which Monk provided a link:

http://www.warpig.com/paintball/technical/zbody/index.shtml - http://www.warpig.com/paintball/technical/zbody/index.shtml

Though the purpose of the article is to review the GS Z-Body, it prefaces the review with a fairly decent condensation of what happens to drag when a ball is spun.

Even this article does not give a quantitative analysis of velocity retained, but is reinforces my earlier postulation on the effects of reduced aerodynamic drag of a spinning ball.

A5 dude15 wrote: this is pointless...everytime someone says something or presents any facts that benefits their argument the other side is too stubborn to just except that the other side made a good point.

It isn't pointless. It is not an argument with a winner and a looser. It is a discussion with presentation of facts and thesis on what may or may not be happening in the physics of the flight of a ball. It is a learning process with comments that enlighten some and spark others to do more research. Beats the heck out of the same old, "i ghot sum muny, wat shood i by?"

I read the article you linked, and didn't see the points made that you describe (granted I read it pretty fast).  Can you point to a section?

(And, BTW, UV, I believe the Reverse Magnus Effect means that the ball curves the other way - not that it slows down less)

Ah, the last sentence.  Yes, the reverse Magnus does imply that under some conditions "regular" drag could be reduced for some projectiles.  That is interesting and helpful.  Although more details (including some type of quantitative scale) would have been nice...

But does that also mean that, since we do NOT see the reverse Magnus with paintballs (either due to conditions or nature of the ball), that this drag-reduction will not be seen with paintballs?

Hmm.

I tossed out some golf ball theory a couple of years back.  Mainly my top-spin theory in windy conditions. 

Still looking for feedback on the Apex in dive bomb mode in windy conditions.

I may try this while doing yard work this weekend-

-Take a sphere of some type and drill a hole thru the center of it

-run a long rubber band or string thru the hole and attach the string/band to 2 stakes which are driven into the ground making the string/ band tight.

-charge up the air compressor and blow air over the ball while it is both static and with the string wound up making the ball spin and take some pics.

The only thing is that i need something to make the air flow visible.

Any suggestions?

anyone else is welcome to try this too.

Ok.

I heard back from one of my rocket scientists, and he wasn't sure.

I also had a chat with another friend of mine, however.  Not a rocket scientist, but one of the smartest people I know.  This is all off the top of his head from aerodynamics class a zillion years ago.  This all assumes subsonic travel - supersonic aerodynamics are different.

Drag has two parts - friction and back pressure. 

Friction is ... friction between the traveling body and air molecules. 

A traveling body creates a small vacuum pocket (or at least pocket of thinner air) behind itself, in the space it just vacated.  This vacuum pocket sucks on the body to creates backwards pressure.  This is called back pressure.

As velocity increases, so does friction, and the vacuum pocket gets bigger, so back pressure also increases.

Now - we rotate the sphere.  Rotation along the axis of travel (like a bullet) gives a different result, so we will ignore that case.

Rotation increases friction.  On one side of the sphere (the side that it rotating into the wind, so to speak) friction will increase, and on the other side it will decrease.  The increase is greater than the decrease, however, due to inefficiencies introduced at the point of separation.  So overall, friction is increased with rotation.  As the rotation increases in speed, so does the friction.  More rotation = more friction.  This will reduce velocity faster.

Rotation also increases turbulence - it moves the air around.  Some of this moved air will land in the vacuum pocket behind the sphere.  This will reduce the back pressure.  So initially rotation reduces back pressure.  This allows velocity to be retained longer.  More rotation = greater reduction in back pressure.

But - once the vacuum pocket has been fully filled by turbulence, this effect stops.  The back pressure can only be reduced to zero.  Faster rotation beyond this point will yield no further benefits on drag.

For most bodies, the drag reduction benefit from back pressure reduction far outweighs the drag increase cost from friction increase.  Therefore, rotation tend to have a net reducing effect on drag.

However, when rotation is more than fast enough to max out the back pressure reduction, friction continues to increase, and at some point the friction increase exceeds the back pressure benefit, which leads to a net increase of drag.

Therefore, the short answer is:  Depends.

For a given body, traveling at a given velocity, rotation will reduce drag, unless the body is rotating very fast, in which case it will increase drag.

The intercept - the point at which rotation increases drag - is lower for bodies that create turbulence on their own, like rough bodies.  So a smooth body will gain more from rotation than a rough body.

The intercept is higher for bodies traveling at higher velocities, since the higher velocity creates a larger air pocket and more back pressure.

To get an exact answer to our question, we would have to determine the Reynolds number of a paintball, and use that to determine a drag coefficient.  We would also have to determine the exact rotations per second of a Flatline paintball.

The answer could be faster, slower, or both.  For instance, it might be that a ball leaving a Flatline initially has high enough velocity to take max advantage of the rotation effect on back pressure (allowing it to retain velocity better), but as velocity drops the rotation is causing a net increase in drag, causing faster velocity dropoff. 

Or the rotation could be a benefit the whole time, or a detriment the whole time.  Impossible to determine without knowing more about the aerodynamic qualities of a paintball.

There.

• Perpendicular to the air flow- yes but, certainly not as much as a rough ball.
• In line with the flow (horizontally, or vertically) not much, if at all.
• Any other angles, who knows??
• To compound all this, the seam varies from brand to brand, batch to batch, ball to ball.
  

Clark Kent wrote: Did you read the various points about back pressure?  Nobody is arguing, I don't believe, that friction is reduced.  It's just that friction is not the only force acting on a body traveling through a fluid.

I do believe i recall something being mentioned about back pressure...think it was said that as a spherical object travels through a fluid at any velocity, there is a low pressure area created directly opposite the path of travel on the trailing edge of the sphere....seems to me that when there is a low pressure area behind something, it would tend to slow down at an even greater rate.  Am i way off base with that idea?  Look at Bernoulli's theorem and the way a wing works.  Lower pressure on top of the wing, atmospheric pressure on bottom of wing....wing goes up>>>into the area of lower pressure.

I was referring to my own post half-way up this page, where I discuss back pressure at some length.  Essentially, rotation causes turbulence, which in some circumstances relieves the back pressure, which in turn reduced overall drag.

Bernoulli's principle is of limited utility when applied to a sphere - it's principal implication here is through it's nephew the Magnus effect, which changes the trajectory of a rotating sphere.

Incidentally, I just heard back from another friend, who works in the aerospace division of Honeywell.  He also did not have a specific answer.  The one I posted above is the best I have been able to uncover.  UV's link also provides lots of great information.

Spinning will create lift, yes.  As to reducing drag, it depends on the velocity of the ball, the drag coefficient of the paintball, and the speed of rotation.

Rotation could either reduce or increase drag, depending on those variables.

im sorry but the flatline
OWNS

nuff said

Monk wrote: Is 300fps fast enough to cause a spinning ball to decrease drag?

I don't think we know enough about the aerodynamic qualities of a paintball to know that.  We would also have to know the rotational speed.

And, of course, we have the further problem that velocity is constantly reducing - so even if 300fps is fast enough for spin to help, 200 fps might not be (which would be the velocity after a short while).

Ugh - complicated.  The flight calculator that UV posted is impressive, but I'm not man enough to know how accurate it is.

We definitely need some science.  If somebody develops a data set, I would be happy to crunch the numbers.  (I could also help with experimental design, I just don't have the wherewithall to perform the actual study).

Come to think of it, if we did a proper study with a good write-up, I bet we could get it published someplace...  (Most likely WARPIG, but hey - published is published)

Any formula is based on theory, and theory is what we are trying to test.

The only way to conclusively determine the answer to our question is to run a couple of experiment.

I have method in mind that would involve a gun bench w/clamps, an A-5 with a Flatline and other smoothbore barrel, two chronographs, and a couple hundred paintballs.

The resulting statistical analysis won't be that complicated.  I can handle that, as can a number of folks here, I suspect.

All we need is some volunteers.

Wow. You guys need to go back and read this. It's pretty much the same statements repeated over and over again.

It is relatively easy to explain-

1. Distance- apparently everyone has accepted this, because it's true.

2. Ball hitting harder- I'm guessing this is the main arguement here? Hard to tell since every post is the same. Basically, this comment is too broad. What does "hitting harder" mean? Did the ball dry up and harden into a rock? Is it gaining speed? Does it break different?

Easy answer here- the ball is slowing down (decelerating) slower than a normal ball- so yes, it "feels" like it's hitting harder compared to a ball without backspin. BUT, at longer range here's the tricky part. Most players that have been playing a while know a ball that doesn't break hits harder and hurts more than one that does. Why? When it breaks, the paint and shell is shot off in different directions. The force of your skin pushing back has reached a point to push the ball into pieces. We'll give this a number- say it takes 10 "hit force" from your body to break a normal ball at normal speed (say 130 fps). If the ball slows down more than 130 fps, it would drop. However, the flatline keeps shots up in the air that shouldn't be up in the air. So, if a ball from the Flatline hits you at 95 fps, we'll say the ball won't break until 25 "hit force" from your body. Unfortunately, your body reaches only 20 "hit force" and doesn't break the ball, and sends it bouncing. 20 HF is twice as much as 10, so it hurt twice as much, thus making it seem it "hit harder."

Simple.

Not so simple, Jovian, if I am understanding your post correctly.

Most of us read "harder" to mean "retains velocity better".  And whether a rotating sphere retains velocity better or worse than a non-rotating sphere traveling through a fluid is not simple at all.  As discussed, there are a number of variables that impact this issue.

Now, you do raise a good point about perceived "hard-ness" based on whether the ball breaks or not, but that is really not what this discussion has been about.

Last weekend I actually started to rig up an experiment to try and make proof of something but my sprayer wasn't working right and I couldn't produce enough water mist mixed with the air to make the air flow visible.

The most valuable thing is that backspin creates lift which we all know is true so...

KillerOne is back again I had to go work for awhile -

 at any rate I've been catching up on what’s been going on and I'm glad to see that HALO finally read the NASA page - I'm sure glad that it helped you out there buddy boy -

So far we got back spin = reduced drag, and lift.

  Thus farther shots right - So have we agreed that because its goes Farther it also Hits harder or are we still working on that one?

   This is taking along time to figure it out – but wouldn’t it stand to reason that if I have two barrels a Flatline like mine and a wonderful POS like UV HALO uses  – and if both of these barrels were shooting at the same PSI/FPS – wouldn’t it stand up in court that because of the Back Spin the Flatline would go Farther and Hit harder?

Understanding of course that Backspin = lift, reduced drag.

What say you ?   

the longer it can maintian a higher vel. then the harder it will hit- the farther it will go.

• The theory of backspin helping at higher speeds and hindering once the ball slows down correlates with my observations.  The shots from my flatline seem to fly reasonably straight/level out beyond ranges capable with normal barrels, then they just kind of "flutter" and drop.
• I keep my flatline chronoed in the low 270s.  Through experience I've found I get the best results at exactly 272 fps with my marker and barrel set up.
• Faster than that will get me additional range but really decreases the accuracy.
• Slower (down to about 260 fps) doesn't affect accuracy or range appreciably.
• Below 260 fps is where I really start to notice decreased range.
• With this in mind, I always try to chrono in at 265-270 fps so that the velocity doesn't jump to much as the CO2 heats up during the game.
• Now, with all that said above, I still get accused of shooting "hot" at medium and long ranges; but, when I checked, it has never been above 280 fps.
• Is it possible that the spin makes it hurt more?
• Could a flatline projectile actually be moving faster at the longer range because it traveled less distance to get to that point?  (Since the shortest distance between two points is a straight line.)
  
• If the flatline shot was faster in such a case, would the shot from a normal barrel gain back sufficient momentum from gravity on the "downhill" side of the arc to compare favorably?
• Finally, and this is unsupported personal opinion; I believe that while the flatline may provide a small velocity advantage at certain ranges, the main reason it seems to hit harder is because of the angle the ball strikes the target at.  The flatline provides the capability to hit targets at longer ranges at a near 90 degree angle while shots being "lobbed-in" from normal barrels tend to strike at much less severe angles.  Longer range flatline shots hurt more because they are direct hits rather than glancing blows.
  

Nobody read my post?

Killerone- you're right and wrong at the same time.

At closer range- yes it "hits harder" (you need to use a term that isn't so elementary).

At long range- no, it doesn't hit harder. It has slowed down too much, and the lift is causing a ball that shouldn't be in the air anymore to stay in the air.

Mack wrote: (SNIP) Now, with all that said above, I still get accused of shooting "hot" at medium and long ranges; but, when I checked, it has never been above 280 fps. (SNIP)

I think it is likely that you are getting accused of shooting hot because you are making long range contact with your target. Many competitors are not fully aware that the flat trajectory is caused by back-spin rather than higher velocity.

When I was using the Flatline all the time there were several calls per session for the Ref to chrono my marker. The ref knows me and knows the barrel , but since there was a call for a check he had to comply. Also the down range loudness of the Flatline made many on the opposite side suspicious of high velocity.

Calls for chrono got worse when I switched to the Hammerhead Pro for a while. The way it is ported makes for a strange echo crack with each shot. Funny, now that I am using the Apex, which in my evaluation is louder than both the Flatline and the Hammerhead, no one has called for a spot chrono yet.

LordJovian wrote: Nobody read my post? Killerone- you're right and wrong at the same time. At closer range- yes it "hits harder" (you need to use a term that isn't so elementary). At long range- no, it doesn't hit harder. It has slowed down too much, and the lift is causing a ball that shouldn't be in the air anymore to stay in the air.

Ladies and Gentlemen we use elementary terms so that all can understand -

Bruce A Frank - I often get the same attention because of my flatline.

Range

Lift

Drag

All of these are relevant to the initial velocity (FPS/PSI) – so far all we have is speculation biased on formulas and theories – but none of this is relevant to a flatline or a POS because they will present their own set of variables, to say nothing of paintballs used – so what we really need is for some one to walk there happy self out-side and try this out.

Get a Chronometer – a cardboard box – a Tippmann a-5 , a flatline and then an assortment of other barrels. Fire a few rounds through each barrel at the cardboard box at different ranges. Record the results. Ie. what effect did each round have on the box, we are looking for Penetration, Denting ect... 

Then come back and let everyone see the results – I can’t be the one to test this and neither can UV HALO since we started this mess and would likely be accused of some sort of impropriety.

So someone who has nothing else to do and who will do it right get out and run some tests –  

well, i just got my A5 kit in the mail today, and it has a flatline with it.  I didnt order the flatline, but now i have it.  SO, the dilemna is should i just sell the dang thing, or take it out and shoot it first.  You can surely understand the risk of shooting it, then not liking it, and having to sell it for a used value.  If i do end up shooting it, then i wil do the experiment that KillerOne suggested with the Flatline, J&J Ceramic, and the stock barrel.  Only problem is that i dont have a chrono.

KillerOne wrote: So far we got back spin = reduced drag, and lift.

No.

So far we have lift, and reduced drag UNDER SOME CIRCUMSTANCES, and INCREASED drag under other circumstances.

What we DON'T have is a precise calculation to determine which of these circumstances apply, or an empirical study to determine the actual result.

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

The ball DOES travel farther than a normal barrel. It's been proven time after time since the 98C Flatline has been out. No, I don't know a link to a wensite to that tells you how it works, but you're sitting on a website that tells you it does work.

The ball is spinning backwards, creating lift. In order for the ball to fall to the ground, it must lose its velocity traveling paralell to gravity. This is a gradual drop. 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. You don't need any complex equations to realize this- logic is a beautiful thing. How, HOW, do you explain the increased range?

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.

Why does everyone have to appear smarter than the other guy? You guys look like children explaining the biological difference in ATP production on why your dad can beat up his dad. You're arguing about how a swallow could or could not carry a coconut.