PPRuNe Forums - View Single Post - Helicopter Dynamics: Gyroscopic Precession
Old 10th Mar 2014, 12:01
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awblain
 
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We're not resorting to anything, we're trying to avoid incomplete or misleading statements - like yours about a "puff of wind" and "scaling" which miss the point.

The impression that I get from you is that there is no place for mentioning that the control inputs sculpt much more powerful aerodynamic forces to shift the orientation of rotation of the disk, whether rigid, flexible, flapping or whatever, which is odd, since that's what's happening.

It's a rotating system whose angular momentum is being redirected, so it is precessing. That might not help to illustrate some point about stability, and using the terms "precess" and "gyroscope" probably isn't helpful as it seems to imply rigidity to you, but it is a complementary explanation of how the disk arrives at a new attitude, and it would affect how, and how quickly, stability is lost. You get precession from a torque at an angle that's not 90 degrees away from a rotation axis, it's just different, and more complex, as the motion doesn't stay in a plane.

Where does the differential lift induced by the controlled blade pitch changes point? Which way does it try to twist the disk, and which way does the disk move? That's a question for you, and one which I think you answered correctly on 3rd March.
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