The twist distribution of torsionally-flexible rotor blades is adjusted by exploiting centrifugal effect on inertial torquers affixed at one or more stations along the blade span. Twist is thereby made to vary passively as a function of rotor speed and hub incidence angle. With inertias of appropriate size and location, the twist variation is such that high rotor efficiency is maintained over a wide range of operating conditions. Satisfactory dynamic behavior of the blade, including cyclic-pitch response and flutter resistance, is simultaneously achieved.