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19 April 2024 10:22
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Welcome to the gyroscope forum. If you have a question about gyroscopes in general,
want to know how they work, or what they can be used for then you can leave your question here for others to answer.
You may also be able to help others by answering some of the questions on the site.
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Question |
| Asked by: |
Nitro |
| Subject: |
Yet another video by the genius-or genies ass |
| Question: |
Dear all
https://www.youtube.com/watch?v=5GrJ60axymI
This is the link to a video to educate Dr Dave Fisher about MacPhail's pendulum - enjoy.
Kind regards
NM |
| Date: |
1 April 2016
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Answers (Ordered by Date)
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| Answer: |
Glenn Hawkins - 03/04/2016 17:24:18
| | | For anyone on here with a brain left after studying a gyroscope forever
Ignore the red ball. Its pacific intend is to hide the alignment of the motorized gyro inside. The gyro is tied off at the tip-ball of its shaft. The shaft hangs vertically and the wheel spins in the horizontal plane. As the spinning flywheel swings back and forth in pendulum motion, the wheel rises at the end of each swing and dips down to the vertical position between the swings. The motion of its travel back and forth is a dishpan-like concave curve.
Whenever a spinning flywheel's path is curved, the flywheel will attempt to precess at a right angle, notably: precess to the same degree as the degree of the overhead drop curvature. This video example has a very long pendulum arm; hence it produces a very wide curvature in the swing therefore producing only a small deflection sideways to the swinging.
When the gyro is swung forward it deflects in one direction. When the gyro swings rearward it deflects in the opposite direction.
You can comprehend this easily. Note that while you watched a precessing gyroscope a thousand times, it precessed forward on one side of the pedestal, then precessed rearward on the other side of the pedestal. One direction of precession curves one direction, and then the curve is in the other direction. It is quite simple. The mystery ball does the same repeatedly with each swing. There is nothing new or unexpected here.
Glenn,
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| Answer: |
dave!!! - 07/04/2016 23:19:52
| | | Nitro;
gibble, gobble, gooble, gabble; or in other words;
"up is down except when it's sideways", or "black is white except when it;s sideways" and so says the Jabberwocky. We're so lucky to have one here.
The action of your pendulum has little to do with precession and everything to do with centrifugal force. The principle on which it works was demonstrated by Eric Laithwaite's talk on gyroscopes in 1974 as shown in the youtube video
https://www.youtube.com/watch?v=g60ZCcquCl8&nohtml5=False
Starting at 7:37 of the storyboard he demonstrates a gyro hung by a long string and spinning at right angle to the suspension string by a pivot point offset from it's "center of gravity"(COG); the gyro translates some of it's primary angular momentum(PAM) into a secondary angular momentum(SAM) about the pivot point in a horizontal plane. It is said at this point that the offset gyro does not form any noticeable barycentre angle with the suspension string when spinning at high RPM when it's weight is initially taken by the support string.
In the demonstration, the gyro proceeded to spiral out from it's center of suspension increasing the barycentre angle from zero to a maximum determined by it's initial PAM and the offset from it's COG.It is said at this point that the barycentre is a negative value as is true for all offset orbiting masses constrained in a gravity field; Centrifugal and Centripetal are in play.
It is also shown that the height of the COG relative to the vertical remains relatively constant as it spirals out to it's max. It is also shown that the angle of the gyro changes in relation to the barycentre angle of the support string. From the video and Laithwaite's comments it is apparent that the gyro, during the spiral out and final orbit, is orientated such that it's axis of spin is at right angle to it's direction of motion in it's spiral and orbit and that, if "the string is burned through" at any point in the orbit, the gyro will speed off at whatever tangent it has at the time.
Set up the apparatus as Laithwaite did, but have it over a large table with the gyro suspended just a few millimeters above the table. Have the gyro cage fitted with a very light tricycle landing gear and have a pinpoint butane or propane torch (Nitro inspired that) positioned so that the support string, as it spirals out with the gyro, will intersect with the torch flame.
When the gyro drops with it's axis orientated at right angle to it's tangent, it should speed off somewhere ,as any object that is subject to a centrifugal force is wont to do.
The question is not; "will this work", but, is the effect due to precession or an unknown translation mechanism; whichever, the result is a translation of PAM to SAM and a resulting centrifugal force. A further question is, if the effect is not entirely to do with precession, then what is the unknown mechanism. We need at least six or more dimensions to answer that question.
As to Nitro's pendulum, I DOUBT if the progressive march of the oscilation plane is due in any small part, if any at all, to do with precession. There may be observable precessional effects but the swing of the gyro would produce alternating torques that would tend to cancel out. When we analyse the operation of the device, we find that it begins life in a positive potential energy state, elevated above any potential lowest point, with the gyro slanted at the same angle of the negative barycentre angle of the string.
When the gyro is released from it's restraint, it will be ass-backward from Laithwaite's device. Laithwaite's original device can be engineered so that with a specific PAM and specific COG and specific suspension string length, the final orbit of the device would have the angle of the rotating gyro congruant with the negative barycentre angle of the support string.
The difference between the two; Laithwaite's has centrifugal force at the corresponding point while Nitro's has only centripetal.
Examining the motions of Nitro's device after release; it becomes apparent that the first swings of the pendulum gyro has only minor polar rotation and that the rate of change increases as the amplitude decreases and that the device is translating from an oscillation to "an inward spiral" towards a stable orbit. Nitro gives no data on mass and RPM of the gyro or the barycentre angle and corresponding gyro angle, so we can only go from eyeballing; however Laithwaite also neglected such information.
Sandy; these beasts are far stranger than even you have imagined.
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| Answer: |
Glenn Hawkins - 08/04/2016 08:21:36
| | | Everything a gyroscope dose is a reaction to precession. Precession is very complicated, but realizing how it applies in different set-ups is very simple. Accept precession, and from there you can trace the mechanical causes behind every odd thing you have ever seen. All the mysteries vanish.
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