Coriolis & Eötvös Physics

1. The Physics of Rotating Frames

Projectiles in flight travel through a non-inertial reference frame—the rotating Earth. This results in apparent deflections known as the Coriolis and Eötvös effects. While negligible at short ranges, these forces become critical when time-of-flight exceeds transonic thresholds, shifting impact points by several inches at distances beyond 1,000 meters.

2. Horizontal Coriolis Deflection

Horizontal Coriolis deflection is caused by the Earth rotating beneath the bullet during its flight. The magnitude of this shift depends on the Earth's angular velocity (ω), the projectile's horizontal velocity component, and the firing latitude (φ). In the Southern Hemisphere, this deflection is always to the left, regardless of firing azimuth.

Where ω ≈ 7.2921 x 10⁻⁵ rad/s and φ is the precise geographical latitude.

3. The Eötvös Effect (Vertical Correction)

The Eötvös effect is the vertical component of the Coriolis force, resulting from the projectile's velocity relative to the Earth's rotation. Shooting East increases the centrifugal force on the bullet, making it "lighter" and causing it to hit high. Conversely, shooting West increases its relative weight, causing it to hit low.

This vertical shift is maximized when shooting exactly East (90°) or West (270°) and disappears when shooting North or South.

4. Practical Implementation in ONESHOT

ONESHOT Ballistics utilizes your device's internal magnetometer and GPS (when available) to automatically derive azimuth and latitude. The Earth Modeling Physics Core then integrates these variables into the primary trajectory solution in real-time.