pub fn epicyclic_frequencies(
spin_inertia: f64,
transverse_inertia: f64,
spin_rate_rad_s: f64,
stability_factor: f64,
) -> (f64, f64)Expand description
The two epicyclic yaw-arm angular frequencies (rad/s) for a gyroscopically stable projectile: the FAST mode (nutation) and the SLOW mode (precession). Standard linearized aeroballistic result from the spinning-projectile yaw equation: phi_{fast,slow} = (Ix * p / 2 Iy) * [1 ± sqrt(1 - 1/Sg)] where Ix/Iy are the spin/transverse moments of inertia, p the spin rate, Sg the (dimensionless) gyroscopic stability factor. Returns (0, 0) when Sg <= 1 (no real epicyclic motion — the projectile is not gyroscopically stable) or the transverse inertia is zero. (MBA-941: the previous per-frequency formulas were dimensionally inconsistent — rad/m and length — and ad hoc.)