Artillery flightpath... Accurate!

[wossname]

Does anyone know how to calculate the trajectory of something like an artillery shell, preferably over long distances?

Given: shell mass, gun elevation muzzle velocity, altitude etc...

Or know anyone who does?

Formulas would be ok because I can translate them into C++ myself. Something accurate, with aerodynamic drag, wind and humidity adjustments would be my ultimate goal but I am happy to build up to that later.

Something like the calculations that the early computers like EDVAC and COLOSSUS had to perform would be super cool.

A prize to the most helpful idea

[chako]

type "projectile trajectory" in google
look at the first result ...some k12 link..

not that hard is it ????

[Darkwraith]

If you neglect air resistance, it should follow 2-dimensional projectile motion.

[DiGiTaIErRoR]

Uh... why are you double posting?

[jim mcnamara]

What you want is called a ballistic trajectory - what happens to a projectile after it leaves the muzzle.

It's, um, interesting.

There are a series of formulas. Here is an overview:

http://hyperphysics.phy-astr.gsu.edu/hbase/traj.html

Then when you get cross-eyed with that, then do a google on
ballistic coefficient which is also equally interesting.

[Darkwraith]

Uh... why are you double posting?

What was that in reference to?

[DiGiTaIErRoR]

Originally posted by Darkwraith
What was that in reference to?

Uh...

http://www.vbforums.com/showthread.p...hreadid=264804

[Darkwraith]

Well, he could ask for the code....

[McCain]

I had a very simular question a while back...
http://www.vbforums.com/showthread.p...hreadid=263262

There you have code to draw the path of the projectile with no windresitance

[CornedBee]

In simulations, you don't need the complicated formulas. They mostly are for calculating the target given some parameters.

In simulations, you calculate it step by step. Each step takes the forces that act on the projectile, calculates a new speed for the projectile and moves it according to the elapsed time.

So what you need is:
speed vector SV (initially calculated from gun elevation and muzzle velocity, updated during flight)
air movement vector AMV (= wind speed and direction)
relative air movement vector RAMV (the airflow past the projectile, = SV - AMV)
medium interaction factor MIF (how much the relative air movement vector affects the projectile, calculated from medium density, projectile mass and shape, for very accurate calculations you should take into account that one shape might have different medium resistance values based on the relative air movement vector)
lift L (only for extermly accurate calculations, or for large medium densities like underwater shots, calculated from projectile mass, projectile volume and medium density)
gravity acceleration G

Based on these values you can then calculate a new speed vector for every step.
Basic physics. Every step the projectile is accelerated downwards by G, upwards by L. It is accelerated by -(RAMV² * MIF).
Finally, update the position vector by the newly calculated SV * Delta, with Delta being the elapsed time since the last calculation.