Ballistics beyond 2000 yds : do we need/trust them?

[Michael Eichele]

The coriolus effect. I only wish I knew the real answer to that. That subject has been hashed out on this board several times as to whether or not it is even measureable from a hand carried rifle and if so, are bullets always pulled to the right in the northern hemishpere and always to the left in the southern half or if it it soley based upon the direction of fire and the relation of the direction to the physical location of the shooter on the earth. I have yet to find any shooters that agree the subject. I have researched it by way of other non shooting sources untill my head hurt. Still, hardly any sources agree or leave any real conclusions as to which case to follow. I know there is some ballistic software out there that takes coriolus into account, but dont know how accurate it is, or even if they are using the right principals.

Personaly I favor the theroy that bullets along with other objects will be pulled to the right in the northern half regardless of direction of fire. Regardless, its effect at 1000 yards is minimal at best.

Here are some good sites to referance:

http://en.wikipedia.org/wiki/Coriolis_effect#Ballistics

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/crls.rxml

http://www.physics.orst.edu/~mcintyre/coriolis/

http://www.physics.ohio-state.edu/~dvandom/Edu/newcor.html

http://www-istp.gsfc.nasa.gov/stargaze/Slatlong.htm

 

[Gustavo]

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At those distances,depending on which direction your shooting,wouldnt you even have to take the earths rotation into account? /ubbthreads/images/graemlins/grin.gif

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At those ranges, the Coriolis effect will account for some errors, almost negligible for small arms.

Of course, in order to make a good computation, the model will need the input of latitude and azimuth to the target.

When the appropriate Coriolis term is added to the equation of motion the predicted path with respect to the rotating coordinate system is curvilinear, corresponding to the actual straight line motion of the projectile.

At extremely long ranges, artillery must fire projectiles along trajectories that are not even approximately straight; they are closer to parabolic, although air resistance affects this.

For the longest-range artillery, the Coriolis force becomes important.

But again, the effect is really small and is overseeded by many other error sources.

 

[Michael Eichele]

Here is another good read:

http://longrangehunting.com/ubbthreads/s...=true#Post29435

By far, one of the funniest things I have read on this site:

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Levity Break:
"East is east, west is west, and never the twain shall meet" - Kipling, NOT talking about coriolis effect.
"east is least, west is best" - student pilots learning about magnetic variation.
"when I shoot bullets vertically and try to catch them in my teeth, I always run to the west." - Max



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[JBM]

[ QUOTE ]
The coriolus effect. I only wish I knew the real answer to that. That subject has been hashed out on this board several times as to whether or not it is even measureable from a hand carried rifle and if so, are bullets always pulled to the right in the northern hemishpere and always to the left in the southern half or if it it soley based upon the direction of fire and the relation of the direction to the physical location of the shooter on the earth. I have yet to find any shooters that agree the subject.

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I certainly wouldn't wait until shooters agree on a subject to believe it. I don't know what kind of books you're looking in, but every one of my Physics textbooks (mechanics) have the coriolis equations. It's not a theory, it happens (due to our rotating reference frame) and is very well defined. The problem is that there are so many other variables in small arms that it would take VERY controlled environment to see it. My modified point mass program calculates coriolis effects -- for what it's worth.

JBM

 

[Michael Eichele]

Thank you Jim,

My only question is not that coriolis in and ofitself is a theory, but which set of circumstances is correct? Is it that all projectiles are pulled to the right for the northern hemishpere, or it the direction of fire that is of concern?