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A good Idea

Dec 23, 2001
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your grammer makes bad sense of whatever idea you are trying to convey.

the problem with rifeling is that it rely's on the projected body having a centripetal force (rotational) applied to it to maintain accuracy.
heres a simple example as to why that wont work with paint.

Take a container of a liquid, (Water, tea coffee) and turn the container round, or back and forth (makes no differance), you will see that the liquid inside the container doesnt shift.
This is exactly the same with paintballs.

you can get the shell to rotate, but not the paint, and therefore the rotational force has no effect.

End of lesson, now its story time.......
 

QuackingPlums

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Oct 30, 2002
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I'm no physicist, but isn't the ability to rotate with the container dependent on the viscosity of the liquid?

If I open a tin of paint (they type that goes on walls with a brush) and spin that, the paint does in fact rotate with the tin (probably due to molecule sheer factors or something, but as I said, I'm not a physicist... ;) )

Presumably then, the paint in paintballs is also thicker than water, and would gain a bit of rotational momentum if put through some kind of rifling mechanism?

More to the point though, being completely spherical, a paintball wouldn't really gain much from being "spun" because it has no axis as such, and even the smallest deviation will get amplified to the point where the spin would actually make it more unstable (ie, it would tumble, rather than spin towards it's target)?

:D :D :D
 
Dec 23, 2001
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point taken.
But the paint in paintballs is actually quite thin at recball level, the tourney paint is a very differant story.

Instability would actually be caused by rifeling, especially if you think about the shape of the paintball as it is fired.
like when you kick a football, it will first compress then elongate, making rifeling very ineffective. a rugby ball shape will be less stable than a ball when spun

i was just trying to make the point that rifeling a barrel is actually not that advantagious. even if it is a good talking point and physics lesson.
 

QuackingPlums

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Oct 30, 2002
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yes, I probably didn't make it clear under all that guff, that although I think rifling could indeed cause a paintball to spin, I was agreeing to the fact that a spinning paintball wouldn't be any more accurate than a non-spinning one.


Besides, if you look at golf balls, they're actually made to spin on a different (vertical) axis, and they use those little dimples to create a "cushion" of air on which to maintain lift and accuracy.

I don't fancy being hit on the goggles by a golf ball though! :D
 

Rabies

Trogdor!
Jul 1, 2002
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Originally posted by QuackingPlums
If I open a tin of paint (they type that goes on walls with a brush) and spin that, the paint does in fact rotate with the tin (probably due to molecule sheer factors or something, but as I said, I'm not a physicist... ;) )
However, if you suddenly spin the pot of paint very fast, it won't spin, at least for a couple of seconds until the paint gets up to speed. When a paintball is shot, it goes from standstill to full velocity (and full spin speed if the barrel were rifled) in a very short time, then exits the barrel very soon after. In that time, even more viscous paints don't have time to start spinning, so the shell itself would also stop spinning pretty sharpish.

Also, rifling works in real guns because the bullets are not spherical, they are bullet-shaped (well duh) and aerodynamic. The accuracy of a bullet depends on it staying pointy-end forwards -- if the nose veers to one side, the flight path will veer as well. The reason rifling works there is that the gyroscopic force of the spin stops the bullet from tumbling (throw a rugby ball or american football with and without spin and observe the difference.) Round bullets don't have the same aerodynamic effect, and the effect of spin is very different (more like that of a golf ball.) If you did get your ball to spin to the right, say, it would veer right, which is exactly what happens when you slice a golf ball instead of hitting it square.

The only rifling that would have a desirable effect on paintballs would be to induce a backspin to improve range (or "loft" :) ) But, as everyone has said, getting a decent spin on a paintball in the fraction of a second it is travelling down the barrel can't really be done.
 

Morter

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Jul 31, 2002
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after re-reading his post I think he was saying about how possibly using a thicker fill would mean the paint would spin aswell....?:eek: