Coriolis Drift of Discrete Objects

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Discussion Overview

The discussion revolves around the Coriolis Drift of discrete objects, specifically bullets, and the mathematical modeling of their trajectories considering various factors such as latitude, direction, and elevation. Participants explore the equations for calculating horizontal and vertical drift and seek modifications to account for shooting at different elevations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant presents equations for calculating Coriolis Drift based on latitude, direction, and other parameters, seeking modifications to include elevation effects.
  • Another participant mentions using iterative simulations for tracking trajectories, expressing uncertainty about the existence of closed-form solutions for the proposed problem.
  • A later reply discusses re-modeling the problem using Great Circle/Spherical geometry, posing questions about determining latitude and direction for a point on a sphere based on angular distance rather than linear distance.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the best approach to model the Coriolis Drift and the applicability of different mathematical methods.

Contextual Notes

Limitations include the complexity of spherical geometry and the potential challenges in finding a closed-form solution for the trajectory calculations. The discussion also reflects varying levels of mathematical understanding among participants.

Sooty
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I am writing a program aimed at 'gun nuts' designed to display Coriolis Drift of bullets (ie, 'discrete objects in free-fall', and not large fluid masses). Using the 2 equations below, I am able to calculate and display the values of Coriolis Drift (in terms of X & Y (vertical and horizontal)) as seen from a Horizontal Plane on the Earth's surface for all cases of Latitude and Direction, (the second 2 essential input terms).
These are my 2 equations:-

X:= T *Range * Sin(Lat) * Omega

Y:= Sin(Dir) * T * Range * Cos(Lat) * Omega;

Where:-
X = Horizontal Drift
Y = Vertical Drift
T = Time to Target
Range = Distance from gun to Target
Dir = Direction/Azimuth of fire in 'compass degrees' - 0 to 360
Lat = Latitude in degrees - from North (+90degrees) to South(-90degrees)
Omega = a Constant for Earth's Rotational Velocity

Now, I am attempting to extend my Coriolis Drift equations to address the same question for all values of Latitude and Direction beyond a Horizontal Plane (as above), to include Elevation above and below the Horizontal (ie, shooting uphill and downhill, +90deg/-90deg).

In short, what I am looking for is the necessary modifications/additions to the above equations (in a form that can easily be implemented in a Pascal program, hopefully using no more exotic math than basic Trig functions!) necessary to take the 7 terms above, plus:-

Elevation of fire from Vertically Up(+90degs) to Vertically Down(-90degs)

and return X and Y (Horizontal and Vertical relative to the Earth at the point in question) values for Drift, as seen by a viewer looking through a scope mounted on a rifle delivering the shot as described.

Thank you!
 
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I have always tracked trajectories by simulating the motion in very small steps. But those simulations had so much going on during the flight that it was completely different from a ballistic trajectory. I do not know if there are usable closed-form solution for your problem.
 
FactChecker said:
I have always tracked trajectories by simulating the motion in very small steps. But those simulations had so much going on during the flight that it was completely different from a ballistic trajectory. I do not know if there are usable closed-form solution for your problem.

'Very small steps'... yes, an 'iterative approach'... that is how I have done it in terms of getting figures for complete ballistic trajectories... literally 'finite element' calculations, a metre/meter at a time, and it gives excellent results. My current problem is really 'nit-picking on top of what is already close to being nit-picking'... so I may just have to accept that although there must be a solution possible, (hey, it's 'only geometry'!) I'm not going to find it!

Tnx for your input.
 
Reviewing my previous question, I believe I can 're-model' it in a way that is 'mathematically equivalent' and will so will allow me to continue with my project.
It addresses the question in terms of Great Circle/Spherical geometry, which although I can find relevant articles on the internet, they present their maths in ways that are waaay beyond my understanding.
So, instead of referring to anything about Coriolis, consider this:

So. Knowing point A on a sphere,
where the position of A is defined solely by Lat, where Lat = Latitude in degrees (as before)

And point B, whose distance from point A is defined (not by actual distance travelled) by the angle Asector, Where Asector = Angle of the sector of a Great Circle path that runs between them.

Now, the direction of point B relative to point A is Dir, where Dir = Direction/Azimuth in 'compass degrees' - 0 to 360 (as measured at point A) along the Great Circle path.

Questions:-
what is the value of Lat of point B?
what is the value of Dir at point A relative to point B on the great Circle path?
- - -
Hopefully, to clarify, if it's not already clear...
2 points on a Great Circle... Lat and Dir for each, obviously different... for my scenario, the distance between the 2 points is defined by the 'included angle' of the 'earth sector' covered, and not by the distance between them on the Earth's surface...
0
 
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