Left @ 300 yds - Right @ 1000 yds? WTH?

[royinidaho]

Thanks again phorwath,

I tune/sight/etc all of my rifles for a broad side shot at a yote. I've learned that if I can hit from the point of the shoulder to just behind the ribs its pretty much DRT. My practice targets of choice are paper for record keeping. For practice at unknown distances rocks are the targets. At known distances out to 1130, 1 liter pop bottles placed horizontally are used due to their being similar to an extended yote vital zone with a proper bullet.

 

[Eaglet]

phorwath,

Nice postings! You surely have done your homework and things are looking good for you. LoadBase does work amazinly well! Good Buy!

Thanks for sharing!

 

[4xforfun]

Phorwath......I gotta call you on this one.

You will get horizontal coriolis when firing N to S or S to N, but they will be in oppisate directions. Also, the amount will be greatest when firing due N or S, and reduce to ZERO horizontal effect when firing due E - W or W-E. Due E-W or W-E will give you VERTICAL coriolis, wither high or low, depending on the direction you are shooting, and NO horizontal coriolis will exist. The more you adjust your fire logitudanaly, the less vertical you will get, untill you get to due N-S, where you will get ZERO vetical.

Anything other than strait N-S or E-W shooting will get you a COMBINATION of windage and vertcal coriolis effect!!!

My guess is you either have a glitch in the software, the software was written wrong in the first place, OR.........................I AM WRONG........AGAIN

My brother and I talked about this once not long ago, and he is one of those fighter pilot physics geeks who is into this kind of stuff. And , it makes sence (to me).

I am sure I will here about it if I am wrong!!

 

[royinidaho]

Anyone make a compass that mounts on the scope same as and ACI and level?

Oh, and, who makes the longest scope tube?

 

[Pdvdh]

4xforfun,

What you said is what I would expect. I was hoping someone would correct me on the Coriolis drift if I was wrong. However your post doesn't sound any more confident than I am. Maybe one of the "experts" can chime in here and settle this Coriolis drift once and for all.

I reported what my software produced on Coriolis drift. Both the desktop and PPC LoadBase 2.0 software provided the same results. I kid you not, it reports only right drift no matter what Azimuth (direction of fire) I input. I'll read more on it tonight and see if there's any additional clarification in the Users Manual.

Course..., you could always research it and let us know what you determine?

I'd like to know which of us is blowing hot air...

UPDATE:

4xforfun,

Two different sources of information from the internet:

1) "There are three components to the Coriolis Effect which accounts for the apparent shift in the target position while a projectile is in flight. For rifle shooters we only need two components because we are not shooting directly away from the earth for great distances as would a missile for example. The horizontal component of this rotation results in a shift of impact point to the right (compared to line of sight) in the Northern hemisphere and to the left in the Southern hemisphere. There is also a vertical component which is caused as the target rises while it follows the arc of rotation. A due North (or South) will not have a vertical component but all other directions will have at least some Coriolis vertical component."

2) This force tends to curve an object to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. An observable example would be that the air moving outward from a high becomes clockwise wind and air moving into a low becomes counterclockwise wind.

Finally, read and research more on this LRH Thread >> http://www.longrangehunting.com/forums/f19/coriolis-effect-4124/

In conclusion, I believe your post was hot air. It looks like Coriolis drift is always to the right in the northern hemisphere, and always to the left south of the equator, no matter the Azimuth of fire. But please let us know if you find references that suggest otherwise?

 

[Michael Eichele]

Phorwath......I gotta call you on this one.

You will get horizontal coriolis when firing N to S or S to N, but they will be in oppisate directions. Also, the amount will be greatest when firing due N or S, and reduce to ZERO horizontal effect when firing due E - W or W-E. Due E-W or W-E will give you VERTICAL coriolis, wither high or low, depending on the direction you are shooting, and NO horizontal coriolis will exist. The more you adjust your fire logitudanaly, the less vertical you will get, untill you get to due N-S, where you will get ZERO vetical.

Anything other than strait N-S or E-W shooting will get you a COMBINATION of windage and vertcal coriolis effect!!!

My guess is you either have a glitch in the software, the software was written wrong in the first place, OR.........................I AM WRONG........AGAIN

My brother and I talked about this once not long ago, and he is one of those fighter pilot physics geeks who is into this kind of stuff. And , it makes sence (to me).

I am sure I will here about it if I am wrong!!

Coriolus is one of the most missunderstood subjects among long range shooters.

Most would naturally think that direction of fire would have a bigger impact than the alternative. This isnt the case.

Actually objects in the northern hemisphere are drawn to the right while in the southern portion they are drawn to the left. Ever notice how hurricanes and tornadoes always twist to the right in the NH and left in the SH regardless of their direction of travel?

How far from the equator one is and how far something is launched, the greater the effects of it. Coriolus can affect nearly anything including bullets, bowling balls, golf balls, baseballs ect...however minor the effects, they are still there.

 

[jwp475]

 

[Eaglet]

Gents,
here are my two cents worth.

This is how I understand it:

Coriolis effect has two components, X and Y. X is a horizontal component and Y is a vertical component.

The X component or Horizontal component has to do with your Latitude, meaning how far you are above or below the equator. Right at the equator the horizontal effect is zero. At the poles you obtain the max. values. It goes from zero to max, from equator to a pole.

The horizontal component has nothing to do with the direction you shoot.

The Y Component or Vertical Component has to do with the direcction you shoot or the Azimuth of the target as well as where you are on the earth. In the northern hemisphere when shooting easward you'll hit high and when shooting westward you'll hit low.

Here how it looks in LoadBase:

Here we are only concerned with Azimuth = 90° and Latitude 45° N. Now let's go to our shooting tab.

This screen does not show any corrections for Coriolis because the Coriolis box is off. When we turn it on, we will automatically see the numbers change for both, elevation and windage.

Because shooting east you hit high, the program corroborates that by showing a lower come up when corrected.

On this last screen-shot, it'll show you in inches the correction needed for x and y at 1200 yards.

Thanks for reading!

 

[Ballistic64]

 

[4xforfun]

I think our problem is the term "right". Who's right are we talking about....the guy facing north( who's "right" is east), or the guy facing south ( who's right is west). Their "right's " will be oppiset!!. I would think that the proper discription would be...."it's always to the east in the northern hemisphere, and west in the southern hemisphere". (Or visa-versa)

Could this be the case, and would this make sence???

Again......let me have it!!

I know that there is a "poindexter" type out there with funny glasses and a pocket protector with the proper credentials who can clear this whole thing up. I, you see, don't NEED glasses!!


EDIT........I just re-read EAGLET'S post....................Sir.......do you have a pocket protetor??................That looks like a FANTASTIC program!!!........Is it somthing us mear mortals can run, or do you need to be caled "Dr" to run it?

 

[Michael Eichele]

Again......let me have it!!

I know that there is a "poindexter" type out there with funny glasses and a pocket protector with the proper credentials who can clear this whole thing up. I, you see, don't NEED glasses!!

The poindexter type in the white coat with 20 years of college and funny glasses couldnt hit a box car at 1K with 10 tries.

Stick to the boys here who dont have white coats and funny glasses without 20 years of college who ACTUALLY could hit a MUCH smaller target at 1K with one bullet. This is where you will learn the real effects of gravity, air density, spin drift AND coriolus. Are they qualified? Do they have credentials? Yeah its in the results. Not the glasses.

 

[Pdvdh]

Eaglet,

My understanding of Coriolis matches yours. Since miechele didn't jump in to correct either of us, I consider that a vote of confidence as I'm of the impression that he's got this Coriolis stuff down pat.

And jwp475 - I'm not certain... but I suspect he thinks we're looney toons or aliens.

 

[jwp475]

According to Gerald Perry (Designer od ExBall) the reason that Exball does not include Corrolis Effect is because that maximum effect for the 308 Milltary Sniper round (with the 175 SMK) is less than a scopes adjustment at 1000 yards. In other words less than 1/4 MOA. Coriolis is important to Artillery and Mortor rounds because thry are in the air for a long period of time. Also Corriolis effct is definately direction oriented shooting East and West has no Corriolis Effect. Thie approach works for me out to as far As I have practiced and that's all that I can go by. I have not seen anywhere near the "spin drift" that is being claimed here. On days that I have no percieved wind I do not find that I am consistently shooting to one side of my POA. Yes Spin Drift does exist, but with the bullets that I shoot it is nowhere near the amount that is being claimed by some of these programs with the bullets that are fired from my rifles.


http://www.meyersix.org/the_mysterious_coriolis_effect.htm

 

[Eaglet]

Eaglet,

My understanding of Coriolis matches yours. Since miechele didn't jump in to correct either of us, I consider that a vote of confidence as I'm of the impression that he's got this Coriolis stuff down pat.

And jwp475 - I'm not certain... but I suspect he thinks we're looney toons or aliens.

Phorwath, you really had me cracking up. LOL
If jwp475 thinks we're looney, I'm not offended by that, he's alright. Just wait for my next post... LOL