Question Regarding the Behavior of a Gyroscope

Matt Watts

Question Regarding the Behavior of a Gyroscope
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It is my understanding of a gyroscope, once spun-up and set into a position, it will tend to remain in that position for as long as the flywheel remains spinning.  This assumes the flywheel itself is not anchored, i.e. has a two-axis gimbal support.

So my question:  With all the fancy pulse motors that have been built over the years, has anyone constructed a balanced powered flywheel motor and mounted it on a two-axis gimbal?  Then have they let this motor run over a 24 hour period?

I ask this question because something occurred to me.  If the Earth rotates one complete revolution in a 24 hour period, wouldn't it make sense that a powered gyroscope also display this same rotation or change in attitude over the same 24 hour period?  Couldn't the angle of the gyroscope as compared to the direction of gravity be used as a clock?

It's my assumption a basic gyroscope doesn't lock into the direction of gravity.  Instead it attempts to hold its vector as an absolute, regardless of what all other objects in space are doing.

If anyone knows some or all of the answers to my questions above, please respond.  To me this is one of those things in life that should be obvious, but when you really dig into it, doesn't seem so obvious anymore.

Here's a little video for reference:


https://www.youtube.com/watch?v=JnKloSdUJLo
Re: Question Regarding the Behavior of a Gyroscope
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And a video questioning basically the same things I'm asking:


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

Cycle

Re: Question Regarding the Behavior of a Gyroscope
« Reply #2,  »Last edited by Cycle
Every aircraft has a laser gyroscope which accounts for the spin of the earth to determine aircraft position. Laser path crosstalk necessitates re-alignment between flights.

They use a ring laser gyroscope to determine Earth's rotational rate, which is how they know how much an earthquake speeds up or slows down rotation:
http://iopscience.iop.org/article/10.1088/1742-6596/723/1/012061/pdf
Quote
The Gross Ring G is a square ring laser gyroscope, built as a monolithic Zerodur structure with 4 m length on all sides. It has demonstrated that a large ring laser provides a sensitivity high enough to measure the rotational rate of the Earth with a high precision of ∆ΩE< 10-8.

G has continuously improved over the years, by more and more accurate control of the environmental conditions, finally achieving a rotational sensitivity of the order of 0.25 p-rad/s over 104 s, which corresponds to resolving the Earth rotation rate to 3 part in 109.
In fact, Gravity Probe B is utilizing gyroscopes to determine the amount of frame-dragging the planet does on space-time as it rotates.
https://einstein.stanford.edu/content/articles/pdf/Discover-Mar97.pdf

And you can even build a device yourself which can sense planetary rotation (although not very accurately):
http://www.pabr.org/copernitron/copernitron.en.html

The problem with the smaller gyroscopes is that bearing drag and air friction introduce far too much uncertainty... to be accurate, you'd need at least a 2 foot diameter, 100 pound gyroscope in a vacuum. The earth spins too slowly for the smaller gyroscopes with higher-drag bearings to be accurate.

I suppose you could create your own ring laser to use the Sagnac Effect (interferometry). Create two loops of fiber optic, each wound in opposite direction to the other. Have a specific-frequency LED pumping visible-frequency light into both fiber optic cables via a beam-splitter (so your light source is exactly the same for both fibers). Basically as the ring laser moves (due to planetary rotation), it moves the nodes and anti-nodes of the two separate fiber optic rings (think in terms of General Relativity here... even a small acceleration (linear or angular) has a frame-dragging effect, even upon light). The constructive or destructive interference between the two beams shows the movement of the ring laser after the beams leave the fiber optic and are projected on a screen through a prism.

"The principle of the constancy of light must be modified for accelerating frames of reference." - A. Einstein

Matt Watts

Re: Question Regarding the Behavior of a Gyroscope
« Reply #3,  »
Okay, so with a mechanical gyroscope, the precision isn't high enough to overcome the bearing drag, hence we cannot see the movement of the earth referenced to the gyroscope.  Fair enough.

Follow-up question then:

Has anyone put one of these small mechanical powered gyroscopes on a 24-hour turntable to ensure they do not have the precision necessary for measuring the Earth's rotation?

How did President Regan put it, "Trust but verify."

Cycle

Re: Question Regarding the Behavior of a Gyroscope
« Reply #4,  »
If I were doing this experiment, I'd rig up a vacuum bell (like the glass dome type we had in high school science class) connected to a refrigeration vacuum pump that can pull down to a low micron vacuum. Atmospheric pressure measures around 760,000 microns. a good pump can pull down to around 20 microns (.026666 millibar). This removes air friction from the equation.

I'd make a floating platform on which everything would be mounted, floating in mineral oil (so it doesn't evaporate in the vacuum), and mount the gyroscope along with a photovoltaic cell or cells to run the motor which keeps the gyroscope spinning. This way you have no drag (as you would have from the wires running from the motor to a stationary battery) except for the small amount from the mineral oil viscosity.

The wires running from the solar cell to the motor will drag on the gyroscope's rotation, but since the whole assembly can rotate in the mineral oil, you'd still see any motion via the rotation of the entire assembly.

I'd shine a bright light into the chamber to keep the motor running, then record the gyroscope's movement, recording the whole time to keep a record.
Re: Question Regarding the Behavior of a Gyroscope
« Reply #5,  »
To test if a gyroscope is capable of detecting Earth's rotation is simple enough... just make a turntable which rotates once per day and set your gyroscope on it... it the gyroscope doesn't move when you've got a platform beneath it which you know is rotating once per day, then it's not going to detect Earth's rotation, either.

Matt Watts

Re: Question Regarding the Behavior of a Gyroscope
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I think Rob Durham's experiment was about as good as I could do, minus the turntable verification.  Twelve degrees per hour is a lot of deflection and any one of us should be able to reproduce this effect.


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

Just so people know, I'm not going down the flat earth rabbit hole--I don't really care one way or another; I except whatever life is.  I just want to know with some certainty the concept of "rigidity in space" is valid.  This knowledge is essential for understanding Joseph Newman's work as extensively investigated by Russ over here.

PeakPositive

Re: Question Regarding the Behavior of a Gyroscope
« Reply #7,  »
Quote from Matt Watts on February 16th, 2018, 06:28 PM
I think Rob Durham's experiment was about as good as I could do, minus the turntable verification.  Twelve degrees per hour is a lot of deflection and any one of us should be able to reproduce this effect.


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

Just so people know, I'm not going down the flat earth rabbit hole--I don't really care one way or another; I except whatever life is.  I just want to know with some certainty the concept of "rigidity in space" is valid.  This knowledge is essential for understanding Joseph Newman's work as extensively investigated by Russ over here.
In the video where he takes the gyro apart he shows a thin wire kind of looking like a paperclip. My guess is this is used to cause friction and keep the dial from spinning around freely.

Depending on how much friction there is slowing it down could explain why no drift is seen after the 15 minuets.

Maybe if he removed that wire and redid the test we might see some drift.

Just a guess.

Matt Watts

Re: Question Regarding the Behavior of a Gyroscope
« Reply #8,  »
All the debunking comments I've read from people that seem to know what they are talking about pretty much come to a consensus bearing friction in the gimbals resist the ever slight force from the gyro.  They go on to say a much larger, faster gyro is necessary with extremely good bearings and an evacuated chamber.  Seems odd someone in the 1800's could devise a crude device that works without all this advancement.

I still think a precision avionic gyro placed on a turntable would put the final nail in the coffin.  May have to dig a bit deeper.

Still my goal is to prove beyond a shadow of a doubt that rigidity in space is a solid concept and is not in any way subjected to the forces of gravity.

~Russ


Matt Watts


~Russ

Re: Question Regarding the Behavior of a Gyroscope
« Reply #11,  »
U finaly found your gyrotron :)
~Russ

Matt Watts

Re: Question Regarding the Behavior of a Gyroscope
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Yeah I did.  An infinitely long rapidly rotating cylinder.  A Gyrotron.

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