\frac{R_{a}}{R_{v}} = \frac{ρ_{a} \frac{l_{a}}{S_{a}}}{ρ_{v} \frac{l_{v}}{S_{v}}} = \frac{ρ_{a} d_{v} S_{v}^{2}}{ρ_{v} d_{a} S_{a}^{2}} \approx 1, 36

${\dfrac{R_a}{R_v} = \dfrac{\rho_a\dfrac{l_a}{S_a}}{\rho_v\dfrac{l_v}{S_v}} = \dfrac{\rho_ad_vS_v^2}{\rho_vd_aS_a^2} \approx 1,36}$