[tyronejk]

What would happen if you shot paintballs through a spinning barrel? If you used good paint, it'd probably break, depending on how fast the barrel's spinning, but what about Monsterballs or Reballs? If the control bore was long enough, and underbored, and spun just slow enough not to break the Monsterballs (ie really really fast), would the liquid paint inside be spinning fast enough to give you a rifling effect? It'd probably be easier with Reballs, though. What are your thoughts on this?

[dustyshouri]

The problem is paintballs aren't filled all the way, so it creates a wobbling effect. I think it was Mike who did the best analogy of throwing a half-filled water bottle. Probably the best candidate for increasing accuracy with rifling/spin would be first-strike rounds, but they also have fins, and apparently rifling damages the fins, which does more harm than good.

(I'm just parroting what I have heard/read, I'm not speaking from experience).

This post has been edited by dustyshouri: 16 January 2013 - 11:09 PM

[andrewthewookie]

I wouldn't just assume that all paintballs aren't filled all the way.

I seem to recall someone actually trying this way back in the day, don't remember if I'm just imagining things or what though.

[tyronejk]

Even if they aren't filled completely, they could still spin fairly straight. Like if you filled a water balloon and left a little air and twisted the end, when you release it, it would still spin straight and the air would just move to the axis of rotation.

[dustyshouri]

Hmm... maybe we need dimpled paintballs!

[andrewthewookie]

That's been tried with the Rap4 "golf balls" paintballs, and the way they were manufactured made the depth of the dimples very inconsistent over the whole; basically, they shot like utter shit. They were pressed powder, like smarties are. Also, IIRC, Tom Kaye took nylon balls and drilled dimples in the surface to test, and that didn't yield any better results either.

This post has been edited by andrewthewookie: 17 January 2013 - 12:19 AM

[dustyshouri]

andrewthewookie, on 17 January 2013 - 12:17 AM, said:

That's been tried with the Rap4 "golf balls" paintballs, and the way they were manufactured made the depth of the dimples very inconsistent over the whole; basically, they shot like utter shit. They were pressed powder, like smarties are. Also, IIRC, Tom Kaye took nylon balls and drilled dimples in the surface to test, and that didn't yield any better results either.

Aye, I was reading about those just now, and saw you had posted Seems like the Rap4's just suffered from poor manufacturing. Dimples aren't going to work if they aren't done right, I guess. Also they were like a chalk.... why?

Anyways... I guess if you want hard numbers and explanations about the physics of paintballs and what rifling can and can not do, http://www.forums.xkcd.com/ would be a good place to go(unless there are some guys around here who are into physics). I guess the biggest problem trying to accomplish any of these things(rifling, dimples) is consistency. It seems like a very fickle thing to mess with, and when you're manufacturing hundreds of thousands of paintballs, it's hard to maintain that degree of consistency.

This post has been edited by dustyshouri: 17 January 2013 - 12:42 AM

[brycelarson]

http://www.punkworks...x.php?p=7&id=35

[cockerpunk]

andrewthewookie, on 16 January 2013 - 11:33 PM, said:

I seem to recall someone actually trying this way back in the day, don't remember if I'm just imagining things or what though.

tom kaye did. he actually tested it as a rifling alternative.

[UV Halo]

I suspect that there are a few things going on here.

Paintballs are capable of spinning just fine. For evidence, look to the apex barrel. Or, you could do this experiment on your own:
Using your fingers, spin a paintball like a top as you drop it (from about 1") onto a smooth surface (i.e. glass table). If you give it enough RPM, it will spin for much longer than even the longest paintball shots.

With rifled barrel designs, it's difficult to impart a consistent spin to a paintball due to the need to grip the shell tightly enough without damaging the shell. Tom Kaye's solution to see if spinning even made a difference was to use a spining barrel. In his tests, he found no benefit. What I don't know is if he tried applying rifling or, spinning the barrel with his Perfect Circle paintballs.

With all that being said, there are two major obstacles for a spun paintball to overcome before there is any benefit to accuracy:

Lopsided shape- This is like applying spin to an out of round tire, or an unbalanced laundry load- it will push the round off of it's intended trajectory.

Vortex shedding- Being such a lightweight round projectile, they are vulnerable to vortex shedding which tends to push the projectile from it's intended course.

The First Strike round ignores all of these features: they're self-spinning in flight. The skirts are slightly lopsided but, the diameter of the body (the widest part of the round) is next to perfectly circular. The skirts reduce the drag of the rounds.

The things I suspect but, I'm unsure of:

• The finned skirt may reduce the laminar flow that leads to vortex shedding.
  
• The hollow skirt might induce a low pressure zone that may increase drag. It's obviously not enough to negate the reduction in drag gained from the skirt.
  
• The fill can separate in storage (an oily fluid and a thicker paste). This may lead to rounds being out of balance until centrifigal forces remix The fill. If so, would pre-spinning within the confines of the barrel help these rounds stabilize quicker?
  
• Since the rounds rely on drag to start spinning, would pre-spinning them reduce the drag enough to make a difference in range?

[Cookybiscuit]

Wouldn't work.

The barrel would unscrew and fall off.

[tyronejk]

Cookybiscuit, on 17 January 2013 - 04:00 PM, said:

Wouldn't work.

The barrel would unscrew and fall off.

Lol, you troll.

[mr.satire]

UV Halo, on 17 January 2013 - 12:13 PM, said:

I suspect that there are a few things going on here.

Paintballs are capable of spinning just fine. For evidence, look to the apex barrel. Or, you could do this experiment on your own:
Using your fingers, spin a paintball like a top as you drop it (from about 1") onto a smooth surface (i.e. glass table). If you give it enough RPM, it will spin for much longer than even the longest paintball shots.

With rifled barrel designs, it's difficult to impart a consistent spin to a paintball due to the need to grip the shell tightly enough without damaging the shell. Tom Kaye's solution to see if spinning even made a difference was to use a spining barrel. In his tests, he found no benefit. What I don't know is if he tried applying rifling or, spinning the barrel with his Perfect Circle paintballs.

With all that being said, there are two major obstacles for a spun paintball to overcome before there is any benefit to accuracy:

Lopsided shape- This is like applying spin to an out of round tire, or an unbalanced laundry load- it will push the round off of it's intended trajectory.

Vortex shedding- Being such a lightweight round projectile, they are vulnerable to vortex shedding which tends to push the projectile from it's intended course.

The First Strike round ignores all of these features: they're self-spinning in flight. The skirts are slightly lopsided but, the diameter of the body (the widest part of the round) is next to perfectly circular. The skirts reduce the drag of the rounds.

The things I suspect but, I'm unsure of:

• The finned skirt may reduce the laminar flow that leads to vortex shedding.
• The hollow skirt might induce a low pressure zone that may increase drag. It's obviously not enough to negate the reduction in drag gained from the skirt.
• The fill can separate in storage (an oily fluid and a thicker paste). This may lead to rounds being out of balance until centrifigal forces remix The fill. If so, would pre-spinning within the confines of the barrel help these rounds stabilize quicker?
• Since the rounds rely on drag to start spinning, would pre-spinning them reduce the drag enough to make a difference in range?

I would be curious to see if the skirt could be formed in to a cone shape a the end in an attempt to reduce the low pressure zone behind the round, and if that would give more range.

I know it is very impractical to manufacture a first strike this way but it would be interesting to see none the less

[UV Halo]

mr.satire, on 18 January 2013 - 11:52 AM, said:

I would be curious to see if the skirt could be formed in to a cone shape a the end in an attempt to reduce the low pressure zone behind the round, and if that would give more range.

I know it is very impractical to manufacture a first strike this way but it would be interesting to see none the less

Well, there is the SniperBall, that's the primary method they rely upon. Unfortunately, they don't use spin stabilization and, it adds mass to a normal paintball.

I'd be interested in a projectile that had a more conical tail and, spin stabilization but, kept the same paintball weight and a greater fill volume than an FS round. I don't expect to see this round mainly because as you increase the mass of the shell, you must decrease the mass of the payload.