I know that the rotor blades flap, and that the amplitude of that flapping is a function of the rotor angular speed and of the airspeed of the gyro itself. Now –provided I've got these things right– the periodic flapping of a blade, as observed from the rotorhead axis, can be seen, when observed from the real, blade-tip path plane axis, as a periodic variation of the AoA of the same frequency. My question is: in what form are flapping amplitude and AoA variation related? In other words, if I know the amplitude of the flapping at a given moment, how can I calculate the corresponding variation of the AoA?

For two extreme cases, the variation of AoA is clearly zero for a flapping amplitude of 0º and (it seems to me, intuitively…) it may perhaps reach 90º for a flapping amplitude of 90º, but I doubt that there is a linear correlation between these two extremes that would allow me to say, for example, that for a total flapping of 10º, I would get get a total variation of AoA also of 10º…

Any comment will be welcome...

For two extreme cases, the variation of AoA is clearly zero for a flapping amplitude of 0º and (it seems to me, intuitively…) it may perhaps reach 90º for a flapping amplitude of 90º, but I doubt that there is a linear correlation between these two extremes that would allow me to say, for example, that for a total flapping of 10º, I would get get a total variation of AoA also of 10º…

Any comment will be welcome...

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