Beyond gravity and drag, long 155mm shells fly far and long enough for the Earth's
rotation to matter: the Coriolis pseudo-force deflects the round sideways depending on
latitude and firing azimuth.
a_drag = -k * v * vec(v)
a_cor = -2 * Ω × v (Ω = Earth's rotation vector, |Ω|=7.29e-5 rad/s)
a = g_vec + a_drag + a_cor
P_peak ≈ c * v0² (simplified internal-ballistics estimate)
- Fire / Clear — launches a shell using the current firing solution, or clears trails.
- Muzzle velocity (charge) — propellant charge sets exit velocity; also drives the estimated peak chamber pressure shown below.
- Elevation angle — barrel angle above horizontal.
- Firing azimuth — compass bearing of the shot, which changes how strongly Coriolis deflects it left or right.
- Latitude — firing position on Earth; Coriolis deflection scales with sin(latitude) and vanishes at the equator.
Real 155mm howitzer fire-control computers apply exactly this Coriolis correction —
at 20+ km range, ignoring it can miss a target by hundreds of metres.