pub fn fin_pressure_drag_coefficient(
cross_section: FinCrossSection,
leading_edge_sweep_rad: f64,
mach: f64,
) -> Result<f64, AeroError>Expand description
Pressure drag of a fin set on its frontal area N t s (Niskanen 2009 eq. 3.89–3.93): the
leading edge’s (C_D•)_LE⊥ cos² Γ_L plus the trailing edge’s share of base drag.
| cross-section | leading edge, (C_D•)_LE⊥ | trailing edge |
|---|---|---|
| square | blunt face, stagnation_drag_coefficient (eq. 3.90) | base drag (eq. 3.92) |
| rounded | cylinder in crossflow (eq. 3.89) | half the base drag |
| airfoil | cylinder in crossflow (eq. 3.89) | none |
with eq. 3.89 (after Barrowman 1967 eq. 4-17–4-19): (1 − M²)^−0.417 − 1 below Mach 0.9,
1 − 1.785 (M − 0.9) to Mach 1, and 1.214 − 0.502/M² + 0.1095/M⁴ above. Γ_L is the
leading-edge sweep, averaged over the span for curved edges (eq. 3.91).
§Errors
AeroError::Domain for a negative or non-finite Mach number or a
sweep outside (−π/2, π/2), and AeroError::Unsupported for a cross-section this model
doesn’t know.