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Does a RB travel with constant rotation, or accelerate?

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TNGhost

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What if you were to fire that ball straight up in the air. Would it still be spinning as it hit the ground coming down?
 

nkbj

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There was a large bore flintlock rifle shown in a post years ago that had a rear sight with four peep holes in it, the longer the range the further off center the holes were. The ball rotation being discussed here is why the holes were offset. If anyone has pictures of that rascal I'd love to see it again.
 

TNGhost

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Can you differentiate between spinning and tumbling ?
Spinning denotes a single central axis, while tumbling is not limited to such.

Can you differentiate between spinning, rotation and tumbling?
 

Carbon 6

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That's right, but can you reverse direction and maintain that axis ?
 

Loyalist Dave

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In summation

The original premise and question question was...,

A 50 cal, 48" barrel, with 1 revolution in 48" twist is fired ..., Does the RB continue rotation of 1 turn every 4', or does it accelerate to a faster rotation?
After several answers, here is one of several that seem to me to hit the "nail on the head"...,

Insofar as the rotation, it will be slowing as well, from friction, and the rate of slowing will be determined by the density of the air. While not as great as the resistance on forward velocity, it is still there.
So the answer is, the ball is not increasing its spin, and is in fact, due to friction, the ball is decreasing its spin.

A follow-up question would then be, Does the decrease of the ball's spin have any meaningful effect on the flight path of the round ball?

The answer to that has also already been given

..., it is my opinion that the amount of slowing before the ball struck the ground would be almost negligible considering it was spinning at something like 20,000 RPM.
So the ball does not increase in spin. The ball decreases in spin as it flies. That decrease is, however, so tiny that in-and-of-itself..., the reduction of the spin does not effect the path of the ball in flight.

LD
 

bisleyjohn

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In summation

The original premise and question question was...,



After several answers, here is one of several that seem to me to hit the "nail on the head"...,



So the answer is, the ball is not increasing its spin, and is in fact, due to friction, the ball is decreasing its spin.

A follow-up question would then be, Does the decrease of the ball's spin have any meaningful effect on the flight path of the round ball?

The answer to that has also already been given



So the ball does not increase in spin. The ball decreases in spin as it flies. That decrease is, however, so tiny that in-and-of-itself..., the reduction of the spin does not effect the path of the ball in flight.

LD
I have read these pages with interest and, I have to say, amusement at the ‘mathematics’ of finding a solution for which there doesn’t seem to be a problem🧐

I’m going to sign off now because my head is spinning!😘
 

Loyalist Dave

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I have read these pages with interest and, I have to say, amusement at the ‘mathematics’ of finding a solution for which there doesn’t seem to be a problem
Oh I like brain teasers, and physics is often a brain teaser..., OK at least for me...., ;)

But I like them in and for themselves. And with a dearth of mental tasks due to teleworking from COVID, a mental problem is good for me to avoid other mental problems..., IF you know what I mean?

Do I worry about such questions when actually using a muzzleloader? NOPE

I load into my rifle W sized powder in X amount, followed by Y sized ball wrapped in Z thickness patching material. I them prime my lock with the same W sized powder and close the pan. When the deer shows up, I align the sights, gently pull the trigger, and BOOM. I reload the rifle an set it aside, and then I smoke my pipe. THEN I go look for and collect the deer. Seems to work fine, and without a lot of tertiary information. 👍

LD
 

FishDFly

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" I reload the rifle an set it aside, and then I smoke my pipe."

Aw, but what are you thinking about during the pipe smoking?

You could be solving one of the brain teasers!
 

MrMackc

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Wow, there are some smart people on this forum!

It seems only logical to me that a ball shot from a barrel with rifling cut at a uniform or consistent rate of twist would not increase its rate of spin after it leaves the muzzle. However, I think all of the responses thus far have assumed the barrel was rifled with a uniform twist. A very few makers now and in the past have offered barrels cut with a gain twist, which has a relatively slow rate of twist at the breech, to get the ball started, but the rate of twist in the rifling gets progressively faster toward the muzzle. So, the ball starts out turning slowly but the rate of rotation increases as it travels toward the muzzle. The old Numrich muzzleloader barrels could be had as either uniform or gain twist, and I think Colerain, Hoyt, and possibly Oregon Barrel Company can make barrels with a gain twist on special order now. Maybe the OP's buddy was thinking of a gain twist barrel.

One thing I don't know is what happens with the spinning roundball after it exits the muzzle of a gain twist barrel. Does it continue to progressively accelerate its spin, even as it loses forward velocity and succumbs to gravity, as the OP's friend suggested, or does it continue spinning at the rate it had when it exited the muzzle? I don't know.

Notchy Bob
Once the ball leaves the barrel all it does traveling thru air or any other median is SLOW DOWN.
 

tenngun

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You can tell by my blank stare when smoking that I’m living proof of the proverb:
A pipe gives a wise man time to think and a fool something to stick in his mouth.
Most of us stay around a hundred yards as max range for a ball in a hunting load. And a hunting loaded ball will cross a hundred yards in about a forth of a second and two thirds of a second should you take a two hundred yard shot
 

Griz44Mag

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On the ballistics table on the back of a Winchester cartridge box it seems to indicate that a .45 colt will leave the muzzle at 750 FPS with 312 pounds of energy. At five yards it’s traveling 747 FPS with 310 pounds of energy and at 25 yard it’s going 735 FPS with 300 ft pounds. This indicates the projectile slows down as it leaves the muzzle With the same rule applying to a muzzle loader.
We are not supposed to do those - so here is a ballistics chart for a PRB
Was shot over a magnetospeed - weather data via weatherflow meter.

2020-08-10T13-44-51.png
 

MrMackc

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You can tell by my blank stare when smoking that I’m living proof of the proverb:
A pipe gives a wise man time to think and a fool something to stick in his mouth.
Most of us stay around a hundred yards as max range for a ball in a hunting load. And a hunting loaded ball will cross a hundred yards in about a forth of a second and two thirds of a second should you take a two hundred yard shot
I'll take your word for it, I never timed a shot, myself, ever.
 

tenngun

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Once the ball leaves the barrel all it does traveling thru air or any other median is SLOW DOWN.
I think the question could be spin rate
Does a ball continue at one turn in four feet ( or 56”60”66”72, or what ever) or does it’s spin rate increase as the ball slows.
I THINK it keeps one/forty eight, but gyroscopic action can suggest an increased rate of spin
Everything slows but how much. Will 24000 RPM out last 1600 fps?
 
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