Understanding the Coriolis Effect: Paris Gun Shells and Deviation Measurements

In summary, the shells of the Paris Gun fired over 120 km landed 1,343 meters to the right of where it would have hit if there were no Coriolis effect. The drift due to the Coriolis effect is non-linear with respect to distance and cannot be scaled down in a linear manner. The impact area of the shell is affected by the Earth's rotation and the speed, direction, and latitude of the shell, making the impact point slightly to the west of "due south" in the northern hemisphere. This deviation is not constant and follows a sine function, making it non-linear.
  • #1
restfull
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According to Wikipedia, the shells of the Paris Gun fired over 120 km landed "1,343 meters (4,406 ft) to the right of where it would have hit if there were no Coriolis effect"...

Is it then correct to say that it would have deviated by 134.3 metres over 12 km, and 13.43 metres over 1.2 km etc etc?

i.e. is it correct that the drift due to the coriolis effect can be scaled down in this way, or is it non linear with respect to distance
 
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  • #2
restfull said:
According to Wikipedia, the shells of the Paris Gun fired over 120 km landed "1,343 meters (4,406 ft) to the right of where it would have hit if there were no Coriolis effect"...

Is it then correct to say that it would have deviated by 134.3 metres over 12 km, and 13.43 metres over 1.2 km etc etc?

No.

i.e. is it correct that the drift due to the coriolis effect can be scaled down in this way, or is it non linear with respect to distance

Only if the Earth is a spinning cone. Of course it's non-linear.
 
  • #3
Ignoring aerodynamic effects on the shell, I would assume it would follow a sub-orbital path and land exactly where it should. It would only land to the "right" if the Earth were treated as flat, and the shell was fired in a certain direction at a certain latitude. Sort of like the difference between rhumb line (consant headin) versus GPS (great circle) navigation.

Another issue would be the speed of the Earth's rotation and the speed, direction, latitude of the shell. Assuming the shell travels at a very high speed, than I assume that the fact the Earth moves while the shell travels through the air isn't going to create that much difference in the flight.

or am I missing the point and there's some other factor in play here?
 
  • #4
Yes, you are missing the point: the "coriolis force" as cited in the original post. The cannon and shell in it have a certain speed eastward because they are attached to the Earth and the Earth is rotating to the east. If the cannon is fired southward, the impact area is also moving eastward but, in the northern hemisphere, faster- thus, the shell hits slightly to the west of "due south" of the cannon. It may not "create that much difference" but enough: 1346 meters in 120 km.

The amount of "rotation" at any latitude is proportional to the circumference and therefore the radius of the great circle around the Earth at that latitude. That itself is radius of the Earth times the sine of the "co-latitude" (angle measured from the north pole). The distance between the cannon and the point of impact is proportional to the difference in co-latitudes and so the rotation involves a sine function and is not linear.
 

1. What is the Coriolis Effect and how does it affect the Paris Gun shells?

The Coriolis Effect is a phenomenon caused by the rotation of the Earth. As the Earth rotates, objects moving on its surface (such as bullets fired from a gun) appear to deviate from their straight path due to the Coriolis force. In the case of the Paris Gun shells, this force caused the shells to deviate from their intended target.

2. How did scientists measure the deviation caused by the Coriolis Effect?

Scientists used a device called a ballistic pendulum to measure the deviation of the Paris Gun shells. The pendulum would swing in the direction of the shell's trajectory and the angle of deflection could be measured to determine the amount of deviation caused by the Coriolis Effect.

3. What factors influence the amount of deviation caused by the Coriolis Effect?

The amount of deviation caused by the Coriolis Effect depends on the latitude (the closer to the poles, the greater the effect), the distance the object travels, and the velocity of the object. In the case of the Paris Gun shells, the high velocity and long distance of the shells contributed to a significant deviation.

4. Can the Coriolis Effect be predicted and accounted for in shooting trajectories?

Yes, the Coriolis Effect can be predicted and accounted for in shooting trajectories. Modern ballistic calculators and software take into account the Earth's rotation and the Coriolis Effect when determining the trajectory of a projectile. This allows for more accurate shooting at long distances.

5. Are there any other examples of the Coriolis Effect in action?

Yes, the Coriolis Effect can be observed in other phenomena such as the rotation of hurricanes in the northern and southern hemispheres, the direction of ocean currents, and the direction of winds in large-scale weather patterns. It is also responsible for the rotation of the Earth's polar vortex.

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