Function fin_friction_thickness_factor 

pub fn fin_friction_thickness_factor(
    thickness_m: f64,
    mac_length_m: f64,
) -> Result<f64, AeroError>

Fin friction thickness factor 1 + 2t/c̄, with t the fin thickness and c̄ the mean aerodynamic chord (Niskanen 2009 eq. 3.85).

Errors

AeroError::Domain for a negative thickness or a non-positive chord.