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23 November 2024 14:58
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Welcome to the gyroscope forum. If you have a question about gyroscopes in general,
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Question |
| Asked by: |
Paul Rossouw |
| Subject: |
Low speed rotation-first turn-precession. |
| Question: |
Gyroscopic effects are also noticeable at very low speed - the last few turns and the final time around, where it really grips. Studying low speed effects - with a horizontal bike wheel and pencils - there is a wild oscillation right at the moment of slow down of rotation. Conversely, precession grips as soon as rotation STARTS. The firt 90, 180, 270, 360 degrees and you have all the forces already present. You can swing a weight on a chain, UP, get the "antigrav" effect of the mass transfer, with only 1 or 2 swings if you use a nice parabolic trajectory. If anyone has more thoughts about this please contact me at shokdee-at-gmail-dot-com, thanks. Paul. |
| Date: |
3 October 2012
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Answers (Ordered by Date)
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| Answer: |
Kysen Palmer - 16/11/2012 21:23:49
| | | Hi Paul,
There a probably a couple of different effects you are seeing with the precession "gripping" as soon as the rotation starts. The precession you are seeing upon acceleration will look different than during deceleration if for no other reason than mathematically the angular acceleration used in the equations is opposite in sign. Now I also think there may be something to the fact that the "wild oscillation" could be a symptom of conservation of angular momentum. Meaning that the energy going into the oscillation is coming directly from the spin energy. This means that it will slow down the spin increasingly the more wild the oscillations are.
In smaller components I also believe that you are changing the contact surface where spin is oriented around the more the precession and nutation grow. Thus when nutation angle is large the base may actually become unstable or there could be an extreme increase in contact area which would cause friction forces to rise dramatically and that causes all sorts of problems as well as a different set of reaction forces that could potentially cause the system to oscillate.
Cheers, and let me know if you want further discussion.
Kysen
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