Originally Posted by
Jhieminga
I beg to differ. Any rotating mass is a gyroscope with its accompanying effects. A spinning (fixed wing) airframe can also show the effects of gyroscopic precession. You don't need a fixed axle to identify as a gyroscope, just mass and a rotational speed.
Yes but that is not a rotor disc. The spinning fixed wing exhibits precession because external forces are chaning the axis about which the spinning mass is spinning.
With a rotor disc, the disc is not forced to do anything. It flies where it wants to go. The confusion arises from the 90 degree thing because the pitch rods are at a maximum (or minimum) pitch at roughly 90 degrees to the highest point of the blades. But that is because at that (90 degrees "offset") point, the vertical speed of the blades is at a maximum. As the blade approaches its maximum height the pitch reduces until it is flat at the highest point - otherwise the blade would continue to fly up! Ditto when the blade is at its lowest point. So the 90 degrees arises from the difference between blade vertical speed, and blade height. It is nothing to do with gyro precession.