spin stabilization of projectile--yes or no?

[kilotanker22]

I think where the confusion is coming from here is people confusing a phenomenon that is known to occasionally happen, for fact. Just because it can happen under certain circumstances does not make it the rule. I would suggest that since it only seems to happen erratically and without consistent study, it must be due to some other forces not being accounted for.

Zeke, regardless of the scale, a change in direction is still a change in direction. However, I might like to think that a major part of this is the shooter and rifle system, and mostly within a reasonable expectation of accuracy from one group to the next.

I do not think it is fair to even call this a phenomenon unless this result can be displayed by measuring the dispersion of a group of shots at 100 yards. Then measuring the dispersion of the same five shots down range. Unless some other force acts upon those bullets, the dispersion downrange for the exact same group, will never be smaller than that same group was at 100 yards. This is true without aa change in direction. The only possible way for a change in direction to occur is by the application of force. SO, still not indicative of the bullet or its flight.

This really is not a complex concept

 

[Bart B.]

.....

 

[zeke]

I think where the confusion is coming from here is people confusing a phenomenon that is known to occasionally happen, for fact. Just because it can happen under certain circumstances does not make it the rule. I would suggest that since it only seems to happen erratically and without consistent study, it must be due to some other forces not being accounted for.

Zeke, regardless of the scale, a change in direction is still a change in direction. However, I might like to think that a major part of this is the shooter and rifle system, and mostly within a reasonable expectation of accuracy from one group to the next.

I do not think it is fair to even call this a phenomenon unless this result can be displayed by measuring the dispersion of a group of shots at 100 yards. Then measuring the dispersion of the same five shots down range. Unless some other force acts upon those bullets, the dispersion downrange for the exact same group, will never be smaller than that same group was at 100 yards. This is true without aa change in direction. The only possible way for a change in direction to occur is by the application of force. SO, still not indicative of the bullet or its flight.

This really is not a complex concept

No one ever said it to be "the rule" . And it has been repeatedly referred to as only happening under specific circumstances, aka long for twist bullets. Projectile yaw is a fact, and researched for many decades by the military.

Am sorry, but Metalgod's chart simply does not show a trajectory, or a change in direction, not matter how many times someone says so.

If a bullet is yawing, imo there certainly are more forces acting on the bullet than if a bullet is fully stabilized. This is why a fully destabilized bullet can progress to actually tumbling in mid air, and why rifle shooters choose barrels with the appropriate twist for the bullets they intend to shoot. It is commonly recognized fully stabilized bullets are more accurate, perhaps why so many manufactures pay attention to stabilizing projectiles. I am assuming a bullet in yaw is not as aerodynamically efficient, as a fully stabilized bullet. If you read up on the Army's numerous studies on how yaw affects projectiles, you may take in that all projectiles/bullets yaw in some degree after leaving the barrel, but quickly become stabilized in very short distances. In fact, the army actually manufactured muzzle devises to induce more yaws for some of their tests.

Imo, the matter of conjecture being discussed is whether a bullet that yaws to a further distance out can become stabilized even further out , and have a reduced moa at further distances. Imo, and experience it can. Certainly many others who haven't experienced this disagree, and have differing opinions. But when they misrepresent what others are saying, use commonly defined terms incorrectly and try to make their opinion true through ridiculing's others, their credibility is severely lacking. Again, imo.

And yes i have read about the proposed test you mention. Like all shooting there are a lot of variables involved in shooting through a medium and at varying distances. If they could do this in a controlled atmosphere and electronically record the 100 yd dispersion to further out dispersions using the same rifle/load/bullet combo as those whose opinion is similar to mine, would agree the results would be very informative. But way beyond my means, or inclination.

And thank you for the politely presented opinion.

 

[Metal god]

But when they misrepresent what others are saying, use commonly defined terms incorrectly and try to make their opinion true through ridiculing's others, their credibility is severely lacking. Again, imo.

Not sure if that's directed at me but I think it's VERY important one reads my second signature line before putting any kind of inflection or meaning to my words other then how they read as written .

I find this to be a major issue with todays common communications . I personally had to fight the urge and still do at times to put inflection or tone to written words I never heard or saw the expressions on the face of the person writing it . The only time I wrote anything in this thread where one can infer intent by how it was written was when I said I GIVE UP and that clearly had to do with me and me alone seeing how the word "I" is in there . I write how I think and what I mean , not how tens , hundreds or thousands of others may "think" I meant . Feel free to ask me to clarify but please don't invent hidden intent or meaning where none was intended .

Thoughts are not reality and what one thinks I meant or one thinks what the tone may have been if I said it is just that , a thought .

Thoughts are not reality -Example : I don't "think" one can shoot a smaller moa group at 300yds then the smallest group one can shoot at 100yds .

 

[hounddawg]

now if you really want a headache, read these

https://www.sierrabullets.com/exter...x-degree-of-freedom-effects-on-bullet-flight/

https://www.sierrabullets.com/exter...f-repose-and-resulting-crossrange-deflection/

https://www.sierrabullets.com/exter...follow-a-crosswind-and-resulting-deflections/


https://www.sierrabullets.com/exter...ow-a-vertical-wind-and-resulting-deflections/

 

[zeke]

Good links and appreciated . Found this one to also be very informative, although just started reading it. EXTREMELY INTERESTING, and alot of the info may sound familiar, although they are calling "yawing" something else. Lots of good stuff in the old manuals.

https://www.sierrabullets.com/exter...stic-coefficient-dependence-on-coning-motion/

 

[kilotanker22]

Zeke,

It is clear to me that you understand the ideals we are discussing. My comment about "the rule" was not directed at you. It was directed at the conversation as a whole. I agree that a projectile that yaws may stabilize after a greater distance, and group size at distance may actually improve to that effect. However, I believe that the cause of this phenomenon is relative to each individual set of shots/groups recorded. I was misunderstanding what discussion was actually taking place.

I have one rifle, and specific load that consistently shoots the same sized groups at 300 yards as it does at 100 yards, when I do my part. With this particular load and rifle my best 7 round group at 100 yards is .71". Which equates to a MOA measurement of .678. My best group at 300 yards is .82". This yields a MOA measurement of .261. SO, although the physical size of the groups at 300 yards are larger than those at 100 yards, the MOA measurement of the 100 yard group is 259% larger than the MOA measurement I got at 300 yards. I am aware that this happens and I have never given it any critical thought until reading this thread. However, I am certain, the 300 yard MOA measurement of each group if measured at both 100 yards and 300 yards would show that the 100 yard group in both cases would have been smaller. Like you, I neither have the resources or the place to set up the appropriate test, or the time to perform the test enough times to be statistically significant.

 

[kilotanker22]

It has always been my assumption that this rifle and load are simply more precise than I am capable of. I also assumed that both of these results were well within an acceptable margin. That is the reason I never gave it any real thought. Whenever something works differently than I expect, I generally look at myself as the prime suspect. In the example I gave above, I do not think my bullets are yawing to any discernable degree. Otherwise, my point of aim vs point of impact would certainly show a greater deviation as the bullets travel down range.

 

[zeke]

It has always been my assumption that this rifle and load are simply more precise than I am capable of. I also assumed that both of these results were well within an acceptable margin. That is the reason I never gave it any real thought. Whenever something works differently than I expect, I generally look at myself as the prime suspect. In the example I gave above, I do not think my bullets are yawing to any discernable degree. Otherwise, my point of aim vs point of impact would certainly show a greater deviation as the bullets travel down range.

kilotanker22-you were remarking about a test procedure at increasing distances. Thanks to houndawg providing some links, it appears a very similar test was done before the 4th Sierra rifle reloading edition. Very quick easy read, and it appears alot of knowledge was lost to history, which sadly happens all to often. Yes, Sierra used a different term for yaw(ing) than the Army has used over the years, but the principles may sound eerily similar to some posts on this subject.

https://www.sierrabullets.com/exter...stic-coefficient-dependence-on-coning-motion/

 

[stagpanther]

Because it sounds like a lot of fun--I had my first go at the "Litz Challenge" today to see what I would get.

Turns out, the biggest part of the challenge is getting the targets lined up so that I could record impacts on both. Shooting on a completely flat range with little to no wind is one thing--shooting on a hilly one with a 10 to 15 mph quartering headwind is something else. And to top it off I have a 20 MOA rail on my savage 110 338 lapua magnum. Took me at least an hour just to get the targets at 100 and 235 yds in the same ballpark. I also had to switch powders from my go-to H1000 to ram magnum--but it turned in a credible performance. 5 shot group after a fouler after cleaning the bore.

Clearly, the 100 yd group is tighter than the 235 yd group--but not by a whole lot IMO. A couple of other technicalities that may have affected the accuracy at the further distance: The 100 yd target was a bit like a sail in the wind and moved around some, and since it was the POA I could adjust to its movement--but the 235 yd target remained stationary. The last 100 yds to the further target was also exposed to more turbulent winds, and it's also possible that the bullets passing through the paper and CU target at 100 could have caused a small amount of deflection I would think.

Which means I will need to repeat the exercise (hopefully at longer distance.

 

[zeke]

either way, nice shooting with big gun.

 

[Metal god]

Yeah , great job Stag , what a pain that must have been setting up . Did you use a laser or red dot sight . How did you line it up .

 

[hounddawg]

great work Stag.

Just my way of thinking but the two targets make a lot of sense. If that had been shot on a windless day The 235 would be the exactly like the 100. As myself and Metal have been saying this entire thread Newtons third law held true. Looks the group on the 100 yard pretty much is a exact match for the group on the 300 in regard to POI

A suggestion next time on the 100 put 5 dots vertically one inch apart on the 100 yard target then shoot over a chrono and see if on the 235 the bullet holes line up vertically 5 inches apart. I would give this a try myself except out long range has no 100 yard line plus it is on a downward slope like your range..... something to think about though

anyway good job

edit reread and saw that the second yardage was 235 not 300, I may be able to rig something up and try this myself on the 100/200 range

 

[stagpanther]

either way, nice shooting with big gun.

It's kind of an "insider secret" that savage managed to put this together so it reduces felt recoil to less than that of a 300 win mag--and is relatively lightweight to boot. It doesn't hurt that 338 LM is one of those "inherently accurate" cartridges. It's probably the best savage rifle I've ever purchased--I kept it completely stock (except for the questionable paint job).

 

[stagpanther]

Thanks for the kudos guys--the shooting was the easy part, the setting up of the targets the hard part. Because of the hilliness I don't think I can get any further out than a couple hundred yards--otherwise the 100 yd target would need to be VERY high.

So I figured that there would not be much bullet drop between the two, so I sighted in on the far target, left the rifle in the rest that way, then positioned the 100 yd target and moved it around until I got it relatively centered in the field of view of the scope. Except I forgot about the height of line of sight from the bore and 20 MOA inclination--so the bullets impacted the 235 yd target about 3 inches off the ground. DOH!

edit reread and saw that the second yardage was 235 not 300, I may be able to rig something up and try this myself on the 100/200 range

I suspect that 300 yds is the "acid test" distance for the whole spin stabilization theory. It's kind of interesting to compare the impacts between the two targets, a couple on the 235 yd target were clearly significantly further apart--but a few of them looked like they stayed almost as tight as they are on the 100 yd target.

 

[RC20]

I think this is one of those areas that has nothing to do with Newton or Watt or Ohm etc.

Trying to apply those various laws is astonishing in what is an incredibly dynamic operation.
We might as well bring in string theory and gravity bending.

That said, the best group I ever shot (MOA wise) was at 200 meters (yes meters) and frankly it was a very credible group at 100 yards (yes yards). It came in for 5 rounds at .190.

So does a bullet settle out for less of a orbit around the general line axis (take that) as it gets further out? Maybe.

As for focus more, balderdash. I have a 6-42 power NF target scope that I can see the dot inside the small circle on my targets at 100 yards. I know how fine focus that is and less so at 200 meters (its a range thing, one range is 200/300 meters and the other range is limited to 100 yards.

So, can I prove it? Nope. Do I think there is something there? I am not agin the possibility but I sure am not bringing a physicist into it! There may well be physics involved, but one of us knowing what it is and how to calculate it? I don't think so.

What I do know is some really weird stuff takes place in the realm of the Universe and no one has explained it yet. Einstein got some of it right and then you have dark matter and it all goes off the rails.

 

[Metal god]

Trying to apply those various laws is astonishing in what is an incredibly dynamic operation.
We might as well bring in string theory and gravity bending.

but I sure am not bringing a physicist into it! There may well be physics involved, but one of us knowing what it is and how to calculate it? I don't think so.

LOL that was good . I figure there is some math that would say yes or no as to the possibility . That's where I tried being funny about bringing Sheldon Cooper in to help haha . I thought if there's anyone that can do it , it would be him . I thought about whaliwitz but he only has a masters degree I crack me up

Yep Covid had me watching way to much TV

 

[stagpanther]

There's one big component I see missing from most discussions about bullet flights--especially those concerning wind-drift. Having a background in glider flight--generally-speaking pilots are accustomed to referencing to an object (like an aircraft) as having air speed and ground speed, which, while related, are separate from one another. We as shooters on the ground are only seeing the trajectory of a bullet in terms of our fixed ground-based points of reference. Because of that we see wind as a blowing force that pushes things around like leaves, grass and bullets. But as long as the airspeed of an aircraft exceeds that of the windspeed, it cannot be "pushed" into a turn by the wind. Wind generally is the result of advective movement--the movement of a frontal millibar pressure difference--or convective--the heating of air at the surface so that it rises.

The bodies of air move in mass--in fact can have tremendous weight--and anything within that mass will be "carried along" entrained in that mass. This has consequences for a slow-flying aircraft on approach that might have a following tail wind and adjusts it's airspeed to slow down its groundspeed upon landing--potentially stalling the aircraft resulting in a loss of lift and ending in a crash.

It's useful to think of wind like water flowing in a stream. Only when the surface is unobstructed and uniform in temperature are you ever going to possibly have a uniform "flat" flow of wind, wind across the land surface runs into things like houses, treelines, mountains etc--and like a rock in the stream will turbulate the water's flow. Even in a flat desert, heating can result in lift lines of air masses which can upset wind flow. Objects in the wind's path can also create wind shadows--or pockets of calm air--but adjacent to them you will also usually encounter wind sheers. This would be analogous to the smooth water immediately behind the rock in the stream, but bordered by the swirling eddies just beyond it. This phenomenon also applies to an aircraft moving through the air and is observable as vortices.

 

[Bart B.]

But as long as the airspeed of an aircraft exceeds that of the windspeed, it cannot be "pushed" into a turn by the wind.

Pure, unadulterated balderdash!!!! Virtually all bullets move faster than the wind.

 

[kilotanker22]

There's one big component I see missing from most discussions about bullet flights--especially those concerning wind-drift. Having a background in glider flight--generally-speaking pilots are accustomed to referencing to an object (like an aircraft) as having air speed and ground speed, which, while related, are separate from one another. We as shooters on the ground are only seeing the trajectory of a bullet in terms of our fixed ground-based points of reference. Because of that we see wind as a blowing force that pushes things around like leaves, grass and bullets. But as long as the airspeed of an aircraft exceeds that of the windspeed, it cannot be "pushed" into a turn by the wind. Wind generally is the result of advective movement--the movement of a frontal millibar pressure difference--or convective--the heating of air at the surface so that it rises.

The bodies of air move in mass--in fact can have tremendous weight--and anything within that mass will be "carried along" entrained in that mass. This has consequences for a slow-flying aircraft on approach that might have a following tail wind and adjusts it's airspeed to slow down its groundspeed upon landing--potentially stalling the aircraft resulting in a loss of lift and ending in a crash.

It's useful to think of wind like water flowing in a stream. Only when the surface is unobstructed and uniform in temperature are you ever going to possibly have a uniform "flat" flow of wind, wind across the land surface runs into things like houses, treelines, mountains etc--and like a rock in the stream will turbulate the water's flow. Even in a flat desert, heating can result in lift lines of air masses which can upset wind flow. Objects in the wind's path can also create wind shadows--or pockets of calm air--but adjacent to them you will also usually encounter wind sheers. This would be analogous to the smooth water immediately behind the rock in the stream, but bordered by the swirling eddies just beyond it. This phenomenon also applies to an aircraft moving through the air and is observable as vortices.

You are right on Stag. Your post essentially embodies the reasons I was saying earlier that this couldn't really be tested with definitive results unless tested in more than one set of controlled circumstances. Testing in a vacuum and testing in a controlled atmosphere would be ideal. Otherwise most of he data collected would be moot, relative to this particular discussion.