Function interference_factor 

pub fn interference_factor(
    span_m: f64,
    body_radius_m: f64,
) -> Result<f64, AeroError>

Fin–body interference factor K_T(B) = 1 + r_t/(s + r_t) (Barrowman 1966 eq. 77; Niskanen 2009 eq. 3.56), with s the span from the body surface and r_t the body radius at the fins.

Errors

AeroError::Domain for a non-positive span or a negative body radius.