1.32 ~= (3)**(1/4)
The figure derives from an
incompressible flow analysis where it can be demonstrated for max range the parasite drag is equal to three times the induced drag. This contrasts the case where at minimum drag, the two contributions are equivalent.
For a constant total lift, C_L is proportional to (1/V**2), V_mr can be shown to be equal to 3**(1/4)*V_md.
But its only an approximation good perhaps for M<=0.3.
