coriolis effect?

[Boxcar77]

Coriolis makes the bullet drift because it is spinning. You will get on opposite drift whether the bullet spins clockwise or counter clockwise.

What you're referring too is "Spin drift" not Coriolis.

I don't hold for Coriolis but I shoot 1k and under. If I was shooting ELR I might account for it.

 

[Alex Wheeler]

Everything is relative. The earth does not catch up to an air plane because the plane is traveling 600 mph relative to to the surface of earth. Depending on direction of fire the bullet is either chasing the target or the bullet and target and headed towards each other. Turn north or south and the target will move out of the bullets path either left or right. Once the bullet is in the air it is in a free fall. Einstein says object in free fall have all the same properties as an object in space. So the bullet is not effected by the spin of the earth.
Spin of the bullet causes spin drift and also a vertical component I cant remember the name of. Magnus effect I think.

 

[NealC]

Thank you for correcting my mistake. I was talking about the gyroscopic drift, not coriolis.

Besides aerodynamics (including Magnus effects, winds), there are 2 other kinematic items that will affect your trajectory.

1) Gyroscopic Drift
2) Coriolis

 

[NealC]

Here is a good explanation of the effects. It also includes Coriolis.

http://www.appliedballisticsllc.com/spindrift.html

 

[people]

How many folks just let a ballistic calculation app do the math?


Ray

This is what I do.


Plug in all the information you can and your shot will be more on target. Hunting long range I would say it is needed. Paper not so much unless you do not get sighters.

 

[Mozella]

How many of you 1000 yard shooters have honestly experienced coriolis effect ? I'm wondering how the earths rotation can effect a bullets impact by ten inches if you were to shoot East or turned and shot West? ......... snip ......

Ray:
I think you've mixed a couple of things together. The Coriolis effect is pretty easy to grasp when you consider someone shooting north or south over the surface of a rotating earth. One can see, with a little thought, that the bullet will be deflected to the right in the northern hemisphere. That deflection is roughly two and a half or three inches in North America when shooting at 1000 yards using a typical long range target rifle.

What's more difficult to conceptualize is the fact that the exact same Coriolis deflection to the right (northern hemisphere) happens no matter what direction you shoot; i.e. Coriolis is independent of direction of fire. The reason gets a bit technical, but you can find the answer using Google if you wish. Or you can just take it as fact.

The effect you seem to be talking about is known as the Eötvös effect. This IS dependent on direction of fire with bullets fired East impacting high and vice versa. The Eötvös effect is similar in magnitude to the Coriolis effect. At 1000 yards it will change the POI about 3 inches, more or less.

Neither of these effects have anything to do with aerodynamics; however, there are several important aerodynamic forces acting on a bullet too, some of which are significantly greater than the Eötvös effect or the Coriolis effect.

And yes, aircraft react to the Coriolis effect; however, in all my years of flying as an airline captain, I never heard it mentioned simply because the effect is tiny compared to even the lightest winds. Shooting is the same.

So to answer the question: Yes, each and every 1000 yard shooter has experienced the Coriolis effect, and the effect is sufficient to make a real difference in POI. But, the effect is so tiny compared with wind, powder temperature, caffeine twitch, whiskey shakes, and brain farts that it goes unnoticed except by your smart phone ballistics calculator app.

 

[wwbrown]

Coriolis makes the bullet drift because it is spinning. You will get on opposite drift whether the bullet spins clockwise or counter clockwise.

What you describe is called by many/most shooters as spin drift which is very different thing from coriolis effect. The best way to think about the coriolis force is to think about the earth under the bullet as it goes from the muzzle to the target. The earth moves under the bullet whether the bullet is or not.

I hope this does not further cloud the issue, the best way to clear the clouds away is to read Bryan Litz's book as referenced earlier.

 

[fredo]

The earth moves under the bullet whether the bullet is or not.

I hope this does not further cloud the issue, the best way to clear the clouds away is to read Bryan Litz's book as referenced earlier.

The kicker is that the Earth's atmosphere is being dragged along with the Earth as it rotates. Therefore, the net affect Coriolis has on a bullet arcing within 30feet of the Earth's surface is negligible, at best.
Coriolis can be quantified, but realizing the net difference on a target just don't happen in reality. Other factors mask actually being able to see the effect, not the least of which are wind, mirage, shooter error, velocity spread, etc. So for all intents & purposes related to centerfire rifle shooting at distance, SKIP IT...

 

[savagedasher]

Where I shoot Mid Florida close to the Equator . The test and tune range shoots South. The gun range shoots North. Should I see a difference in Tune? ;D Larry

 

[fourpower]

this used to drive me crazy but I got a new app for phone that takes that all stuff into account! it list every bullet and every scope into account and you enter gun info! put gun on target and lay phone on gun barrel and it tells angle-spindrift-coriolis. you enter temp barometric pressure and wind speed then with finger draw a line on phone for way wind is blowing. this is mind blowing how accurate you will now be shooting! we shoot 5in plates at 1000yds and if we don't hit it is so close that it is still fun as hell!!

 

[JDMock]

Although I don't shoot 1000 yd, I do shoot a 600 yd match once a month. It seems to me that many shooters are TOO busy worrying about Coriolis than they are about the wind. The Coriolis will be constant at a given range, but the wind will NOT. I believe the secret to winning at 600 or 1000 yards is to get a good set of wind flags and learn to use them. Also, if one has good equipment (both rifle and ammo), he/she must trust that equipment and what the sighter shots show. When the conditions are the same as when he shot the sighters, he should shoot the string w/ confidence. If the conditions change during the string, one must hold off based on what his experience dictates. Practice is the key to learning how much to hold. Good shooting....James Mock

 

[savagedasher]

Although I don't shoot 1000 yd, I do shoot a 600 yd match once a month. It seems to me that many shooters are TOO busy worrying about Coriolis than they are about the wind. The Coriolis will be constant at a given range, but the wind will NOT. I believe the secret to winning at 600 or 1000 yards is to get a good set of wind flags and learn to use them. Also, if one has good equipment (both rifle and ammo), he/she must trust that equipment and what the sighter shots show. When the conditions are the same as when he shot the sighters, he should shoot the string w/ confidence. If the conditions change during the string, one must hold off based on what his experience dictates. Practice is the key to learning how much to hold. Good shooting....James Mock

Wind flags where we shoot don't help much. The range is flat to 500yds then on the right side we have a huge tailing pile from the mining . from 600 yds on to 1000 . The range from 600 to 1000 is a cut .Wind flags on the ground don't tell you much the bullet is 28' high . The flags on the left berm can be going three different direction with certain wind directions. Tails at 1000 yds the wind is i going up in different directions. With a smoke balm the cross wind the wind stacks on the back berm and is going out the cut 180 from the back berm. We have conditions that not many ranges have. 50 plus inches of rain and 90 plus temp don't help.
I feel any shooter that shoots at Manatee and wins can be competitive at all other ranges. Larry

 

[Keith Glasscock]

I agree with Mozella. In the flying of an airplane, the most consideration we give the Coriolis effect is in the weather. The same forces that cause your bullet to impact to the right in the northern hemisphere causes low and high pressure zones to rotate.

The reason airplanes don't compare well is the fact that they are a piloted vehicle. Course corrections to make the airplane track a course across the surface of the earth is what navigation is all about.

 

[Raythemanroe]

I would assume most feel it isn't significant enough to dig into more then entering your load/rifle info into the ballistic app? I was hoping for a grid or chart that may give a straight up estimate for fast mental entries..


Ray

 

[CharlieNC]

Ray the advice I was given to simplify correction for coriolis and spin drift is once you have zeroed at 100, then dial in one click to move to the left to account for all of this; set the turret at zero. This is from a guy who teaches long range shooting. The wind is certainly the main factor to fight, and the apps/calcs that I have used do not account for the effect on vertical which I have experienced. Wind from left will drive bullet low, while from the right will drive it up (right twist barrels). You need to shoot in variable wind to work out the correct factor for your bullet.

 

[people]

Unfortunately there is no truly quick and easy way of having that number. If you are shooting due north or south pretty straight forward. When do you ever shot N E S W? Let's say you want to take a shot at 38deg at 863yds. Then your next shot is 277deg at 1,029yds. That is why I just let the application take care of it. Now the more you shoot the better you will get if you look at the numbers.

What the PRS guys do who knows. I have shot a few and wind was what I was thinking about most.

 

[savagedasher]

Working with tuners I have found a tune that is Vertical Right and Horizontal Up has the biggest tune sweet spot.
Is it because of spin drift or coriolis effect?
But I can say a tune vertical up and right has a wider sweet spot. Larry

 

[Ringostar]

Hey, now I have a new excuse when I throw an 8! It couldn't possibly be the nut behind the trigger!

 

[LHSmith]

Wind flags on the ground don't tell you much the bullet is 28' high . The flags on the left berm can be going three different direction with certain wind directions. Tails at 1000 yds the wind is i going up in different directions.

[/quote]
Perhaps you are not aware that the range terrain problem has been addressed years ago by short range BR shooters using flag poles capable of adjusting to 20' high and secured with guy wires. Flags going in every direction is not exclusive to your range. It is a given occurrence during a typical short range agg here in the Northeast and oftentimes the conditions seen through the entire match.

 

[boater]

I would think the coriolis effect would only be an issue if the earth stopped rotating part way thru the match...