Abstract: A rotor blade for a driven horizontal rotor of a rotary-wing aircraft comprises an elongated main body which includes a leading edge, a trailing edge, and an upper surface extending between the leading edge and the trailing edge. The rotor blade further comprises at least one flap having a front end and a rear end and mounted to the main body at its front end swiveling about a swiveling axis running in parallel to the radial or spanwise axis of the rotor blade. The flap has a basic position in which it lies flat against the upper surface of the main body. Further, the flap is passively swiveled by aerodynamic forces and inertial forces about its swivel axis to raise above the upper surface of the main body, and a reset force acts upon the flap to reset it into its basic position on the surface of the main body.

Abstract: A rotor blade for a driven horizontal rotor of a rotary-wing aircraft comprises an elongated main body which includes a leading edge, a trailing edge, and an upper surface extending between the leading edge and the trailing edge. The rotor blade further comprises at least one flap having a front end and a rear end and mounted to the main body at its front end swiveling about a swiveling axis running in parallel to the radial or spanwise axis of the rotor blade. The flap has a basic position in which it lies flat against the upper surface of the main body. Further, the flap is passively swiveled by aerodynamic forces and inertial forces about its swivel axis to raise above the upper surface of the main body, and a reset force acts upon the flap to reset it into its basic position on the surface of the main body.