Use this aerodynamics calculator to calculate the total skin friction drag for your aerodynamics problems.
Formula:
Df = ( 1.328 × qโ × S ) / โ((ฯ × Vโ × L) / ยต)
where,q - Dynamic pressure (N/m2)
S - Wing surface (m2)
ฯ - Air density (kg/m3)
V - Air flow velocity (m/s)
L - Lift (N)
ยต - Absolute viscosity coefficient (For normal air (T = 288K): 1.7894ร10-5kg/(ms))
Df - Total skin friction drag