Function cone_pressure_drag_coefficient 

pub fn cone_pressure_drag_coefficient(
    fineness_ratio: f64,
    mach: f64,
) -> Result<f64, AeroError>

The pressure drag of a cone nose of fineness ratio f (length over base diameter) at any Mach number, on its base area (Niskanen 2009 eq. 3.86–3.87 and B.3–B.6):

• below Mach 1, eq. 3.87 from 0.8 sin² ε at rest to the transonic method at Mach 1;
• sin ε at Mach 1 (eq. B.6), with slope 4/(γ + 1) (1 − sin ε/2) (eq. B.5);
• between Mach 1 and 1.3, the cubic that meets both ends’ values and slopes;
• from Mach 1.3, 2.1 sin² ε + 0.5 sin ε/√(M² − 1) (eq. B.4),

with the half-angle ε from tan ε = 1/(2f) (eq. B.3). The joint angle of a cone meeting its tube is ε, so its value at rest is eq. 3.86’s 0.8 sin² ε. A 3:1 cone: 0.0216 at rest, 0.1644 at Mach 1, 0.1557 at Mach 1.3, 0.1042 at Mach 2.

Below fineness 1 the closed form passes a flat face’s drag as the cone flattens, so there hpr scales between a flat face at fineness 0 and this curve at fineness 1, as eq. B.9 does, from Mach 0.8 (PressureDragCurve::new): a cone of fineness 0.5 gets 0.647 at Mach 1, not sin ε = 0.707.

Errors

AeroError::Domain for a non-positive or non-finite fineness ratio, or a negative or non-finite Mach number.