Function boattail_base_pressure_ratio 

pub fn boattail_base_pressure_ratio(
    mach: f64,
    base_area_ratio: f64,
) -> Result<f64, AeroError>

The base pressure behind a boattail over a cylinder’s, as a ratio of pressure coefficients k = C_p,bt/C_p,cyl that scales the base drag, for a base of area ratio a_b (its area over the boattail’s fore area) and an attached boattail (MIL-HDBK-762 Fig. 5-141, printed p. 5-210):

• From Mach 2.5, p_bt = p_cyl/(0.442 + 0.558 a_b) with the cylinder’s p_cyl/p = 1 + C_p,cyl γM²/2 from Love’s correlation (LOVE_BASE_PRESSURE), and k = (1 − p_bt/p)/(1 − p_cyl/p), not below 0 (no measured base pressure is above the free stream’s).
• From Mach 1 to 2.5, k at Mach 2.5.
• From Mach 0.8 to 1, a straight line from 1 to that value; 1 below.

Errors

AeroError::Domain for a negative or non-finite Mach number, or a_b outside [0, 1].