To: ShyTorque
A very easy to understand description.
The following is a nit-picking comment and a continuation of your story;
You may wish to slightly modify the following sentence by changing the word 'Gyroscopic' to ' Centripetal'.
>The Aerodynamic forces generated by the blades overcome the Gyroscopic forces tending to hold the original plane of rotation. <.
"Centripetal (center-seeking) force is the constant inward force necessary to maintain circular motion." "Gyroscopic force is the characteristic that causes the gyroscope to react to an applied force at a point 90-degress away from the point of application, in the direction of its rotation."
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To continue your story of the two helicopters;
Assuming that the maximum blade pitch is on the left side of both helicopters, then I believe that the following will take place.
In your first instance, because the rotor is rigidly attached to the helicopter, the mast and helicopter will be pried (rolled) to the right.
In your second instance, because the rotor is teetering, the disk will continue to climb past the left side for another 90-degrees. The tilted disk will then want to change the pitch atitude of the mast and helicopter by dragging them to a new position.
In other words, the first instance has a phase lag of 0-degrees and will roll the helicopter. The second instance has a phase lag of 90-degrees and will pitch the helicopter.
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I think that;
In first instance, the extremely rigid rotor will act like a gyroscope and therefore experience precession. The amount of this gyroscopic precession should be very small though, because;
1/ the rotor has *relatively* little mass,
2/ it must overcome the inertia of the helicopter as well as the rotor, and
3/ no rotor yet (with the possible exception of the V-22) has achieved this high a level of rigidity.
In the second instance, the 'floppy' teetering rotor will not experience any gyroscopic precession.
[ 04 August 2001: Message edited by: Dave Jackson ]