FearNoWind
Well-Known Member
Just plan your shots to run along the longitudinal plane and you don't have to worry about Coriolis force. 
Question on Applied Ballistics App and Coriolis
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DocUSMCRetired
Well-Known Member
No, shot inclination is separate. We don't use the improved rifleman's rule, or rifleman's rule. We use a function of Mach vs. Drag. So that the rate of drop of the bullet at distance is properly accounted for in the formula. We do not just scale the trajectory, we actually take in to account the physical affects of uphill vs downhill. This is covered in Chapter 4, page 53 of Applied Ballistics for Long Range Shooting Third Edition by Bryan Litz.
A lot of this is over thinking. Most shooters will not be able to differentiate the minor horizontal effect of Coriolis vs wind call. This is really only important for shooters who need 1st round accuracy. If you get sighters, it wont affect you.
Large inclination affects time of flight over long distances of bullet flight, per my example showing time of flight and bullet velocity at 1000, 2000, 3000, and 4000yds.
Time of flight affects the magnitude of the horizontal and vertical components of coriolis.
Therefore inclination affects coriolis drift very slightly with very large angles of inclination, over very long distances. Back to my earlier comment, I don't think any of us need to bother with it. This discussion may be pertinent to understanding the principles/theory of coriolis drift, but doesn't have practical application.
My ballistic software obviously does include the minor contribution of inclined/declined shot angle when calculating both horizontal and vertical components of coriolis drift.
Time of flight affects the magnitude of the horizontal and vertical components of coriolis.
Therefore inclination affects coriolis drift very slightly with very large angles of inclination, over very long distances. Back to my earlier comment, I don't think any of us need to bother with it. This discussion may be pertinent to understanding the principles/theory of coriolis drift, but doesn't have practical application.
My ballistic software obviously does include the minor contribution of inclined/declined shot angle when calculating both horizontal and vertical components of coriolis drift.
I agree with all of this but I think the rifleman's rule and inclination effects on trajectory are completely exclusive from horizontal Coriolis deflection. I also agree on the the overthinking.
But my motivation is in fact 1st round accuracy!
At the end of the day, shooting long range is a big math problem that would be impossible without a shooting app... so why not start out with the app providing the most accurate solution possible for the 1st shot?
I also get that I could learn a lot from your 3rd edition Applied Ballistics book. I'll go ahead and buy the book and read up, and maybe it will shed new light to disprove my train of thought.
But maybe there's a small chance that a ballistics novice like myself has found a small hole in a rather insignificant part of the Horizontal Coriolis equation? Maybe run this by Bryan... worst case is you get a good laugh at my expense.
DocUSMCRetired
Well-Known Member
I agree with all of this but I think the rifleman's rule and inclination effects on trajectory are completely exclusive from horizontal Coriolis deflection. I also agree on the the overthinking.
But my motivation is in fact 1st round accuracy!
At the end of the day, shooting long range is a big math problem that would be impossible without a shooting app... so why not start out with the app providing the most accurate solution possible for the 1st shot?
I also get that I could learn a lot from your 3rd edition Applied Ballistics book. I'll go ahead and buy the book and read up, and maybe it will shed new light to disprove my train of thought.
But maybe there's a small chance that a ballistics novice like myself has found a small hole in a rather insignificant part of the Horizontal Coriolis equation? Maybe run this by Bryan... worst case is you get a good laugh at my expense.
These items are separate from each other, and our software calculates them separately. But they are included in the final firing solution. While Coriolis, and inclination are effected by time of flight independently, they are also calculated independently.
I think you are over thinking this. Since they are independently calculated the tof(or distance) are correct for each variable.
But maybe there's a small chance that a ballistics novice like myself has found a small hole in a rather insignificant part of the Horizontal Coriolis equation? Maybe run this by Bryan... worst case is you get a good laugh at my expense.
Been there done that with my ballistic software. I researched coriolis drift to gain an understanding of the concept and its application. In the process, I located and reviewed mathematical equations expressing coriolis drift. Lo and behold, I found an error in my ballistics software. I contacted the author/programmer of the ballistic software and provided him with web links to the articles and the math/equations. He looked it over and agreed with the need to revise his algorithms. Then released an update to the software, correcting the error.
I haven't reviewed the mathematical equations you're currently studying. But having reviewed the theory and the governing mathematical equations several years ago, I believe the concepts DocUSMCRetired and I presented in this thread to be correct.
Well I'm certainly not afraid of being wrong, in fact it would be the easiest solution here. But I approach everything the same way... I argue (friendly debate) my point until I get enough facts to disprove my logic. So far I have not seen enough evidence to prove that I am wrong...
maybe I'll get that evidence when I read the Applied Ballistics 3rd edition. But I do very much appreciate all of your responses/debates/arguments that you guys have brought up. If I follow FearNoWinds advice it doesn't matter who is right... I'll ask the next elk I am about to shoot to line up in just the right spot before I pull the trigger... and even then I won't be shooting long enough for Coriolis to make a difference since I'm not good enough for Coriolis to be the only source of error in my shot, which DocUSMC has pointed out
10-4, thank you for your time answering my questions. I'll give your 3rd edition book a read.
The primary reason I participated in this Thread and ran the ballistic comparisons was to refresh my understanding of coriolis, and to practice using the coriolis related functions on my ballistics program.
It's nice to have a good recollection of the required coriolis data inputs when hurriedly entering the data into my ballistics program to obtain the dope for a long range shot - before the game moves out of sight. Practice makes perfect... sometimes.
It's nice to have a good recollection of the required coriolis data inputs when hurriedly entering the data into my ballistics program to obtain the dope for a long range shot - before the game moves out of sight. Practice makes perfect... sometimes.
I cant imagine a hunting shot where coriolis is critical. Unless you are hunting with artillery.
Funny looking at my logs I cant even determine whether or not turning on spin drift in the apps has any discernible effect on my targets. I think I may have been able to discern it once at 950 yards on a zero wind day when the light was right and the conditions perfect with no mirage. Coriolis? Sure....
Its fun to talk about, but do this test. Have a buddy run your app as a spotter. Give him your wind call, have him call the elevation and wind solution for you. Have him randomly turn on and off the coriolis. Do ten shots with coriolis on, and ten off. See if you see a difference on target.
If you can call wind to 1 mph, then maybe....
Funny looking at my logs I cant even determine whether or not turning on spin drift in the apps has any discernible effect on my targets. I think I may have been able to discern it once at 950 yards on a zero wind day when the light was right and the conditions perfect with no mirage. Coriolis? Sure....
Its fun to talk about, but do this test. Have a buddy run your app as a spotter. Give him your wind call, have him call the elevation and wind solution for you. Have him randomly turn on and off the coriolis. Do ten shots with coriolis on, and ten off. See if you see a difference on target.
If you can call wind to 1 mph, then maybe....
It's a known cause of bullet shift from POA at long ranges. The farther from the equator, the greater the horizontal component. Something that can be determined and compensated for quite accurately. One less unknown in your Kentucky windage correction.
If you can't identify spin drift at 950 yds in windless conditions, you've mismanaged some other number of affecting factors in a way that has magically offset the rightward drift. And if you can't identify spin drift combined with coriolis drift, it's even worse unless you live at the equator, where coriolis causes no rightward drift.
I never bothered with it either while my longest shots were confined to less than 600yds. I don't need to run your suggested test, because the first time I fired two of my rifles at 1000yds, I was immediately seeking an explanation for the 1/2" leftward impacts at 300yds, yet the 9" rightward impacts at 1000yds from both rifles. 10-11" of rightward bullet drift at 1000yds at my latitude due to the known combined affects of spin drift and coriolis drift is 10-11" less fudge factor winged into my dope. I consider it consequential. But that doesn't mean it has to matter to you.
If you can't identify spin drift at 950 yds in windless conditions, you've mismanaged some other number of affecting factors in a way that has magically offset the rightward drift. And if you can't identify spin drift combined with coriolis drift, it's even worse unless you live at the equator, where coriolis causes no rightward drift.
I never bothered with it either while my longest shots were confined to less than 600yds. I don't need to run your suggested test, because the first time I fired two of my rifles at 1000yds, I was immediately seeking an explanation for the 1/2" leftward impacts at 300yds, yet the 9" rightward impacts at 1000yds from both rifles. 10-11" of rightward bullet drift at 1000yds at my latitude due to the known combined affects of spin drift and coriolis drift is 10-11" less fudge factor winged into my dope. I consider it consequential. But that doesn't mean it has to matter to you.
Spin drift with my 7mag load, 180hybrids at 3000, in the example I quoted at 950 yards is 4.5inches according to Shooter. Coincidentally thats is exactly also what 1 mph of wind drift is. You call it mismanagement, but calling wind to 1 mph accuracy is a difficult task even on a flat range with flags. Any fclass shooter will tell you that. You can barely detect a 1 mph wind on your face. In all my years of shooting, that is the only time I remember it being so dead calm that I thought it was possible that it was actually zero wind over a half a mile in the hills I shoot in...and even then, how could I be sure? I can barely detect a 1 mph wind in my own location, much less downrange.
I know it exists. I just leave spin on in the app, because thats easy. But I dont bother with coriolis, and I think that if one ran the test I proposed you wont notice it skewing the results, because it is swallowed up in the inherent accuracy potential of the rifle, shooter, and wind call. Putting in the azimuth data is just an extra step that I skip. I should be seeing misses in the direction of the correction, but I dont, on sub moa distant targets they are evenly distributed left and right as I struggle with discerning wind let offs and pickups. Maybe in Shooter turning spin drift on seems to provide enough correction for both, or something else is going on. I am surprised that an experienced shooter like yourself immediately thought coriolis when you noticed 1/2in left at 300 and 9in right at 1000. Considering the 1/2in of deflection at 300 yards is 1/6 moa, inside of a single scope click, well inside 1 mph, not to mention it takes a better than 1/6 moa shooter for it to have any meaning...well thats why I consider these discussion more academic than practically useful.
It doesnt cost anything To input it, but inexperienced shooters will often misdiagnose misses in the field when in my opinion 99.9% of the time its failure to dope the wind or poor consistency of position on the rifle. Just trying to keep it real. Others may be good enough in the wind to discern it, I dont deny that though I think its rare.
Also, I should probably spring for a better solver. I think the phone type, point solver apps that I use have their limitations. In my opinion they seem to over correct but again, maybe I have an inherent shooting technique that "corrects" for right drift by inducing a left error and I dont even know it.
I know it exists. I just leave spin on in the app, because thats easy. But I dont bother with coriolis, and I think that if one ran the test I proposed you wont notice it skewing the results, because it is swallowed up in the inherent accuracy potential of the rifle, shooter, and wind call. Putting in the azimuth data is just an extra step that I skip. I should be seeing misses in the direction of the correction, but I dont, on sub moa distant targets they are evenly distributed left and right as I struggle with discerning wind let offs and pickups. Maybe in Shooter turning spin drift on seems to provide enough correction for both, or something else is going on. I am surprised that an experienced shooter like yourself immediately thought coriolis when you noticed 1/2in left at 300 and 9in right at 1000. Considering the 1/2in of deflection at 300 yards is 1/6 moa, inside of a single scope click, well inside 1 mph, not to mention it takes a better than 1/6 moa shooter for it to have any meaning...well thats why I consider these discussion more academic than practically useful.
It doesnt cost anything To input it, but inexperienced shooters will often misdiagnose misses in the field when in my opinion 99.9% of the time its failure to dope the wind or poor consistency of position on the rifle. Just trying to keep it real. Others may be good enough in the wind to discern it, I dont deny that though I think its rare.
Also, I should probably spring for a better solver. I think the phone type, point solver apps that I use have their limitations. In my opinion they seem to over correct but again, maybe I have an inherent shooting technique that "corrects" for right drift by inducing a left error and I dont even know it.
I do agree that spin drift and coriolis quickly become noise in the background of significant crosswinds. Completely agree with that.
My comment on coincidental mismanagement of equipment counteracting spin drift and coriolis was then presuming wind free conditions. If a person has windless conditions and doesn't see the combined effects of spin drift and coriolis at 1000yds, then the rifle has been fired in a canted position, the scope isn't mounted parallel to the rifle bore, or some other less than perfect equipment setup or execution has coincidentally (a lark) combined to disguise the left to rightward drift.
I didn't mean to imply I knew the left to right drift I experienced was coriolis and spin drift when I first observed it. I didn't have the explanation. So I asked about it on this forum, and continued to investigate potential causes. It was a windless day. I knew the bullets flight path was initially to the left based on the 300yd target impacts. If anything, I expected even further leftward impacts at 1000yds. I NEVER expected rightward impacts, let alone 8-9 inch rightward impacts. That was 8 years ago and I was a novice @1000yds. Very first times I ever shot at 1000yds, as I recall. What I meant to communicate in my prior post was that the effects of spin drift, combined with coriolis drift, were plainly apparent on targets from two different rifles on my very first engagements of a 1000yd target. Not that I knew the cause for the rightward drift. In fact I didn't know the cause, but the rightward bullet drift was very obvious.
Those initial experiences were the beginning of my spin drift and coriolis education. Here's the Thread I started back in November 2008.
http://www.longrangehunting.com/forums/f17/left-300-yds-right-1000-yds-wth-35255/
It's very clear in that Thread that I didn't have the explanation, but was on a mission to understand how my bullets could strike left at 300yds, and then right at 1000yds, in wind free conditions.
Pretty certain you have a lot more wind than I have where I live, shoot, and hunt. We have some wind, but we also have our share of little to no wind days.
To clarify, 8 years later, when I shoot in wind free conditions now (a few times I've been out when light snow was lazily falling straight down, from muzzle out to the 1000yd target), I expect to see rightward movement of my bullet caused by the combined effects of spin drift/coriolis. If I don't, I know my equipment isn't properly assembled, and/or fired, "plumb" with gravitational force. Left to right drift was so obvious between my 300yd target and 1000yd target, that I couldn't overlook or deny it. I couldn't rest until I identified the cause.
My comment on coincidental mismanagement of equipment counteracting spin drift and coriolis was then presuming wind free conditions. If a person has windless conditions and doesn't see the combined effects of spin drift and coriolis at 1000yds, then the rifle has been fired in a canted position, the scope isn't mounted parallel to the rifle bore, or some other less than perfect equipment setup or execution has coincidentally (a lark) combined to disguise the left to rightward drift.
I didn't mean to imply I knew the left to right drift I experienced was coriolis and spin drift when I first observed it. I didn't have the explanation. So I asked about it on this forum, and continued to investigate potential causes. It was a windless day. I knew the bullets flight path was initially to the left based on the 300yd target impacts. If anything, I expected even further leftward impacts at 1000yds. I NEVER expected rightward impacts, let alone 8-9 inch rightward impacts. That was 8 years ago and I was a novice @1000yds. Very first times I ever shot at 1000yds, as I recall. What I meant to communicate in my prior post was that the effects of spin drift, combined with coriolis drift, were plainly apparent on targets from two different rifles on my very first engagements of a 1000yd target. Not that I knew the cause for the rightward drift. In fact I didn't know the cause, but the rightward bullet drift was very obvious.
Those initial experiences were the beginning of my spin drift and coriolis education. Here's the Thread I started back in November 2008.
http://www.longrangehunting.com/forums/f17/left-300-yds-right-1000-yds-wth-35255/
It's very clear in that Thread that I didn't have the explanation, but was on a mission to understand how my bullets could strike left at 300yds, and then right at 1000yds, in wind free conditions.
Pretty certain you have a lot more wind than I have where I live, shoot, and hunt. We have some wind, but we also have our share of little to no wind days.
To clarify, 8 years later, when I shoot in wind free conditions now (a few times I've been out when light snow was lazily falling straight down, from muzzle out to the 1000yd target), I expect to see rightward movement of my bullet caused by the combined effects of spin drift/coriolis. If I don't, I know my equipment isn't properly assembled, and/or fired, "plumb" with gravitational force. Left to right drift was so obvious between my 300yd target and 1000yd target, that I couldn't overlook or deny it. I couldn't rest until I identified the cause.
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I started this thread for the single reason of figuring out if the Applied Ballistics app accounts for inclination in the Coriolis solver. Based on the equation presented, it does not. The thread wasn't even started to debate the usefulness of Coriolis, although that can still be something very interesting to debate and I welcome all discussion. I was really hoping that somebody could provide some additional insight to the physics of Coriolis as it applies to a shot that has inclination/declination, and only because it is clear that the equations in any of the apps do not account for it.
Up to this point, nobody has discussed the physics of Coriolis with me as to how my logic might be right or wrong. Could my theory be wrong? Sure. But nobody can tell me why based on physics. That is probably my fault, I should have kept Applied Ballistics out of the discussion and been more specific when I started the thread, but the reason I included them is I felt they would be the few guys that would have the best grasp on the physics.
With that said, nobody has the right to tell me what I should or should not account for in my shooting solution. I of course want the solution to be correct, and I think this is one small little aspect where the fundamental physics might wrong. I also really do not buy that I am overthinking this. That's just part of the drive that leads to perfection. Bad personality trait? that's a different discussion.
If somebody does not want to account for Coriolis, that's just fine. turn the little button off on your solver. nothing wrong with that. But it's just not right to turn around and tell me I shouldn't account for it in my shooting solution. At the distances I am shooting it is a full click of adjustment, or more, depending on the distance. I want to account for that click, regardless of my wind call.
Up to this point, nobody has discussed the physics of Coriolis with me as to how my logic might be right or wrong. Could my theory be wrong? Sure. But nobody can tell me why based on physics. That is probably my fault, I should have kept Applied Ballistics out of the discussion and been more specific when I started the thread, but the reason I included them is I felt they would be the few guys that would have the best grasp on the physics.
With that said, nobody has the right to tell me what I should or should not account for in my shooting solution. I of course want the solution to be correct, and I think this is one small little aspect where the fundamental physics might wrong. I also really do not buy that I am overthinking this. That's just part of the drive that leads to perfection. Bad personality trait? that's a different discussion.
If somebody does not want to account for Coriolis, that's just fine. turn the little button off on your solver. nothing wrong with that. But it's just not right to turn around and tell me I shouldn't account for it in my shooting solution. At the distances I am shooting it is a full click of adjustment, or more, depending on the distance. I want to account for that click, regardless of my wind call.
