Paintball Spin Physics - Getting to the final Answer

[mysteryfish]

Cheers guys, for both replies.

I think I missed a bit of reading in the middle of this thread. I'll go back and do a bit more reading before I hit the post button any more.

[AGD]

Well the rabbit hole is the problem, once you have seen how deep it goes, you come to understand why people making random statements about "what they have seen" is pretty pointless.

But like fad diets and ancient treasure maps people will always want to believe the simple story.

AGD

[jackwood]

So Tom, where does this go from here? Does the rabbit hole hold no secrets for you any more? Did this thread reach the same and full conclusions that you found back in the 90's or has your research on this subject continued?

Jack

P.S. I can't see any of the data on the data thread, which is a shame.

[hitech]

The data is here:

http://www.automags.org/forums/showthread.php?t=34429

The begining is graphs for recharge rates and after that is Tom's paintball ballistics testing.

[Beemer]

The data is here:

http://www.automags.org/forums/showthread.php?t=34429

The begining is graphs for recharge rates and after that is Tom's paintball ballistics testing.

Ya but all the pics are dead. Do they work for you?

___________

[jackwood]

Hitech, same as Beemer for me. All the pics/links are dead. Just shows a blue border with " attached images" above it.

Am I doing something wrong?

Jack

[hitech]

links don't work for me either. I don't know if I have them archived or not. I've only found one so far. I'll look. Maybe Tom will read this and republish them...

[UTDragun]

when AO went through some cleaning a while back, all images hosted on AO went bye bye

[sparktroop]

This may just be redundancy but anytime you try to change the trajectory of a round ball you are going to run into issues like the aforementioned. The only real way to change the trajectory and ballistic behaviors of a projectile would be to change the trailing edge. Like in actual ballistic science. If one were to change the leading edge of a bullet you would find that very little effect is achieved as far as trajectory is concerned. You could cut an "X" or drill a hole into the front of the bullet but not much would happen to distance traveled, drop ratio, or flight pattern.

Altering the aft end of the bullet however has drastic effect! An "X" or dove tailed bullet would be completely erratic in flight pattern and very dangerous. Just imagine a brass slug traveling at 2500 fps and behaving like a Super Swirl out of a Tippmann Flatline!! I dont think I would want to be anywere near it!! Basicaly the point being made here has two factors.

1st - The reason spin from a riffled barrel on a paintball doesn't work too well is because there is no sence of a trailing edge for the trajectory to set a base for flight and maintain that base.

Some may say that certain civil war era muskets used round balls and rifled bores. BUT, soon after, they found that it didn't help too much and developed what we view as a bullet today. It was just loaded like a muzzleloader.

2nd - Unless you change the trailing edge of a paintball, thereby changing the entire manufacturing process thereof you will never achive great success with rifled bores in paintball.

[spooky]

for because?

Tom, could you elaborate on the ball exploding pictures?

Thanks.

Moving on...

So if we do have spin, to have any effect on accuracy it must be on an axis differing from it's path.

Whether or not the seams affect flight is what we're after. However, Glenn found differing velocity due to seams. Seams have different effects before and after barrel?

Good discussion!

back spin is cool, but not quite as consistant as we would like. the problem with making the paint spin in the shell is the duration of time required to get the paint moving up to a suitable revolution per minute to stabalize the ball, without deteremental effect. i am a gunsmith not an airsmith or balistican(did i spell that right), but i know that there are differemt rates of spin required for the same projectiles at different speeds. as an example my .300 winchester magnum can use 220 grain bullets with a one twist in 10 inches barrel and will lob them out at about 2600-2800 feet per second depending on my load, but the same bullet cannot be stabilized at all out of my .300/221fireball barrel with the same twist as it only goes 920 or so feet per second to do that at a slower speed with the same bullet i need a faster spin or a one in eight twist. as far as nino_fs vortices question i think you might look in a book named "rifle accuracy facts" i would give you more specifics but my cohort has my copy.

Merry Christmas

spooky

[spooky]

this info i can use

Here are some measurements I made. Min of 20 balls were weighed for each paint type. Yes, I know, 0.1 mg resolution is overkill. I also have some seam and pole crush load data around here somewhere.

the more weight per ball, the more momentum= staying faster for a longertime. a higher sectional density, even marginally higher will make a difference when you have such a small ammount of play in velocity.
thank you

spooky

p.s. i will make an attempt to make a spinning barrel marker and post the findings of various lots of paint.

[spooky]

paintballs made to spin?

i have an idea, does anyone have any way to make a paintball with more flash from the casting on the i.d. of the ball so that the required duration of spin required to stabalize the paint in the ball would be lessened due to more friction on the balls interior?

later

spooky

[spooky]

out of phase sound vs. out of phase air

Playing a sound 180* out of phase with the sound created by the shedding vortices would indeed cancel it out. The "it", however, is the sound. Trying to pulse air, in the correct direction and at the correct time to "cancel" the shedding of a vortex seems like a monumental task, if not impossible with today's technology.

look up the reflex style supressor "silencer" at http://www.reflexsuppressors.co.uk/

sound cannot move without air

spooky

[Pneumagger]

Spooky, tell me you did not register an account to reply to several posts made literally year(s) ago?

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Paintballs are not bullets. Bullets spin about the axis of travel to prevent significant yawing and tumbling. Sort of how a round may be stable out to certain ranges and then start tumbling because it's constantly loosing spin rate (Like shooting heavy 5.56 rounds out of a slow twist AR15 barrel - stable, but only for a short flight distance). The spin keeps the bullet point-forward and the ballistic coefficient good... which means accuracy. It's easy to spin a bullet because it can be dug into by the rifling without breaking (like a paintball).

People try to spin paintballs consistently simply so they all act in a consistent manner. It, has nothing (or little) to do with "stabilization" in a physics sense of the word. It's a sphere, it doesn't and cant be "stabilized"... it already is. Most paintballs shoot with random or no spin, causing either random deviations or unpredictable knuckleball deviations, respectively.

Now you'll say "some old muskets that fired balls were rifled and accuracy was greatly aided." True, this is to get rid of the "knuckleball" and random oriented spin effects and create consistent spin (and thus flight) patterns. It was not to "stabilize" the ball. Once again, it is a ball and has no geometric orientation more stable than other orientations.

The most important reason why spinning a paintball is hard is plain simple inertia. A paintball is not solid like a bullet, as you mentioned. It cannot be forced to spin to a precise twist rate consistently in just a few milliseconds. The shell spins, inertia makes the paint stay stationary. There is no way to effectively spin paintballs to a consistent spin rate on the field of play. Tom Kay actually did tests with rotating barrels in the past. Finally, in the end when all is said and done... they are paintballs. They have seams and dimples and internal liquid. It would be foolish to assume that even paintballs flying with exact speed and rotation would still hit the same point of impact.

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*I realize that a rotating sphere will have a gyroscopic stabilized relative coordinate system, but the accuracy effects from that are nearly negligible compared to the magnus effects. A consistent magnus effect will produce consistent ballistic path deviation... and thus increased accuracy.

[spooky]

i was thinking of letting the barrel itself, do the spinning at say 10.000rpm or so and allowing the ball to sit in the spinning barrel untill the fill is also spinning. it's a paintball the effect of a light projectile constantly losing speed when allready starting out slow is a moot point as the shell would have to be tougher to deal with the higher rpm and velocity, again not safe. i'm just wondering if anyone has tried getting the barrel and the balls fill to spin then while spinning shoot. just trying to envoke more thought

i think that consistant velocity and sorting the paint by weight and size would be the most important for practical accuracy, but i'm the type who has to hotrod every thing i own

later
spooky