Microlight » Gyroplane Technical Knowledge » Rotor Flap
On take-off there is a danger of ROTOR FLAP.
It is a case of the gyrocopters forward speed being too fast for a relatively slow Rotor RPM, resulting in the rotor blades flapping, over-flexing and making contact with the propeller, tail or the ground.
At a relatively slow RRPM, for example 60 RRPM, the blades don’t have centrifugal rigidity and are still quite flexible.
Due to Dissymmetry of lift, the advancing blade flaps up and flexes up, then becomes the retreating blade, flaps down and flexes down as well.