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    Re: Gyro sextant
    From: David Pike
    Date: 2019 Jan 28, 01:56 -0800

    Geoffrey Kolbe your second attemt to post said:

    Here is an inuatively understandable explanation of gyroscope properties and cross products are not mentioned once!

    https://www.youtube.com/watch?v=n5bKzBZ7XuM

    Oh! And I thought your first attempt to post was complementing my explanation. 

    Never mind, it’s a very nice video.  You could also use the satellite demonstration to explain why you need to apply cyclic pitch to an articulated helicopter rotor 90 degrees sooner than you might expect.  The trouble with all of these explanations, and there must be hundreds on them on the internet with and without vectors, is that they do a very good job of explaining precession, but that’s where they stop.  Very few go on to explain why a spinning top eventually stops precessing and runs vertical for a while.  It has to be some sort of counter precessional feedback (I think I just invented a new phrase). 


    Two things still have to be tested with the side force on the pivot point theory.  First, when it comes to angular momentum changes, we really need to talk about couples or torques.  Looking at the side force on the pivot, where is the distant counter force to make a couple?  Can I simply rely on the gyros inertia acting at its centre of somewhere or other as a fulcrum for the side force to produce a moment about?

    Second, even if I can do this, is the precession produced about the same space axis as the original precession, and if it is, is it counter or additive?  I’m running out of hands and fingers to model this.  Anyone looking through my office window would wonder what was going on. DaveP

       
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