Correct option is (b) Ratio of aerodynamic and inertial force
The best explanation: The rotor blade’s lock number is given as the ratio of the aerodynamic and inertial force. The formula is:
γ=\(\frac {\rho acR^4}{I_b}\)
Where, γ is the blade lock number
a is blade section two-dimensional lift curve slope
c is the chord length
R is the radial location to the blade tip
Ib is the moment of inertia of the blade