Rotor Flap

During take-off, there is a danger of rotor flap if the gyroplane's forward airspeed becomes too high for its relatively low rotor RPM.

At low rotor RPM, for example 60 RRPM, the blades have insufficient centrifugal rigidity and remain relatively flexible.

Due to Dissymmetry of Lift, the advancing blade produces more lift and flaps upwards. As it rotates around to become the retreating blade, it experiences less lift and flaps downwards.

If the forward airspeed is excessive for the rotor RPM, this flapping becomes exaggerated, causing the blades to strike the teeter stops.

The repeated impacts can cause the blades to flex and bend excessively. In extreme cases, a blade may strike the propeller, tail or ground, resulting in serious damage to the gyroplane.

Recognising Rotor Flap

The pilot will initially notice a knocking or shaking sensation through the control stick.

If allowed to continue, this can rapidly develop into violent side-to-side stick movements, potentially becoming so severe that the pilot is unable to maintain control of the stick.