A crosswind at the muzzle produces a deterministic aerodynamic jump (change in trajectory). (This is not modelled in the existing code, but it would be a nice feature. I think Hornady's "4DOF" calculator includes this.)
McCoy Equation 12.57 gives the complete functional form, but it requires coefficients that are not readily found for small calibers.
Litz Equation 5.4 is a useful small-caliber approximation that gives (vertical deflection, in MOA)/(crosswind, in MPH): Y = 0.01 * SG - 0.0024 * L + 0.032 where:
- SG is the Miller Gyroscopic Stability term from
TrajectoryCalc.calc_stability_coefficient()
- L is bullet length in calibers
- For RH-twist barrels: crosswind sign is positive for wind from the right, negative for wind from left.
So, for example, for a RH-twist barrel the aerodynamic jump for a 10MPH crosswind component from the left is -10 * Y MOA.
A crosswind at the muzzle produces a deterministic aerodynamic jump (change in trajectory). (This is not modelled in the existing code, but it would be a nice feature. I think Hornady's "4DOF" calculator includes this.)
McCoy Equation 12.57 gives the complete functional form, but it requires coefficients that are not readily found for small calibers.
Litz Equation 5.4 is a useful small-caliber approximation that gives
(vertical deflection, in MOA)/(crosswind, in MPH): Y = 0.01 * SG - 0.0024 * L + 0.032where:TrajectoryCalc.calc_stability_coefficient()So, for example, for a RH-twist barrel the aerodynamic jump for a 10MPH crosswind component from the left is
-10 * YMOA.