pub fn boattail_factor(
length_m: f64,
fore_diameter_m: f64,
aft_diameter_m: f64,
) -> Result<f64, AeroError>Expand description
The boattail rule’s share of base drag (Niskanen 2009 eq. 3.88), from the length ratio
γ = l/(d₁ − d₂): 1 for γ ≤ 1, (3 − γ)/2 between 1 and 3, and 0 from 3. A boattail’s
pressure drag is this factor times the base drag coefficient on the boattail’s decrease in
area, so a zero-length boattail drags like the base it uncovers.
§Errors
AeroError::Domain for a negative or non-finite length, or diameters that don’t decrease.