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Author Topic: Shop made gyroscope  (Read 1730 times)

Iacopo

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Re: Shop made gyroscope
« Reply #15 on: September 19, 2022, 03:13:37 PM »

Yes, exactly what I will do after my new DC drive motor arrives. I did preliminary trial in this way using the "Super precision gyroscope". Now I am turning larger flywheels on lathe and will have more powerful 12V double shaft motor. The inclined plane will be set at 43 degrees since I am at 47 latitude. And will have a more precise alignment with Polaris. Also better anti-friction bearings.

I saw a couple of videos with the flywheel kept in motion with electric motors, with the set up floating in water, and it seems to me that the magnets of the motor do act like a compass. Maybe a solution could be to use two equal electric motors mounted in opposite positions, trying to neutralize the magnetic field.  I would enclose the spinning flywheel, and maybe even the motor(s), in a cover, for to avoid thrusts due to the air moved by the flywheel.  A second larger cover could be put around the whole floating gyro, for to avoid the possible influence of air currents in the surrounding environment.  There could be currents in the water too, caused by temperature differences, which could be better to try to avoid. The most difficult part is to have a gyro that spins with a stable orientation, without random movements, sufficient for to detect the Earth rotation which is only 1 degree every 4 minutes, twice slower than the rotation of an hour hand in a clock.   
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Bill Wells

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Re: Shop made gyroscope
« Reply #16 on: September 19, 2022, 08:11:47 PM »

... it seems to me that the magnets of the motor do act like a compass.

I also wondered about the magnetic field of the motors.  I asked Jorge, he is an electrical engineer. He now agrees that a cheap DC motor with two magnets (exactly describing my motor) would act as a compass. Not sure what I could do to compensate.

I also watched the YouTube videos where the experimenters had their motor and flywheel in a small "boat" floating in water.  Another video showed the motor and flywheel in a glass jar, suspended from above. None of these experiments were successful. None addressed the issue of alignment regarding latitude.

I will take all of your (and Jorge's) suggestions into consideration. I will also continue experimenting with the "Super Precision" gyroscope.
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Iacopo

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Re: Shop made gyroscope
« Reply #17 on: September 22, 2022, 04:04:12 AM »

DC motor with two magnets (exactly describing my motor) would act as a compass. Not sure what I could do to compensate.

I thought to it in these days.  One possibility could be to make the flywheel to spin by inertia, without motor.
So there would be no problems related to the magnets.
There should be no need for a very long spin duration, after all; even after just 1 minute spinning, Earth rotated by 0.25 degrees, which is an angle easy to detect, using a laser pen and a mirror on the small floating boat, like in the YouTube videos we saw.

The problem of not having a motor is that the deceleration of the flywheel would cause a torque on the small boat;
if the plane of the flywheel is set at 43 degrees, a component of this torque would make the boat to rotate on the water and the stable orientation would be rapidly lost.

This problem can be overcome by setting the rotation axis of the flywheel exactly horizontal;
in this way, the torque from the decelerating flywheel would have no effect on the orientation of the small boat, which would remain stable.
The construction would be not too complicated, because it's a flywheel with two bearings, mounted on the small boat, no gimbals needed.
The horizontality of the rotation axis of the flywheel can be fine tuned by moving some weight in the boat from stern to bow or from bow to stern.

I believe in fact that it is not necessary the plane of the flywheel to be set at 43 degrees.
The Foucault pendulum works even at the intermediate latitudes, even if its plane of oscillation is always vertical; in the same way, the spinning flywheel should be able to follow the rotation of Earth, at the intermediate latitudes, even if the plane of its flywheel is vertical.

As for the problem of the currents, maybe it could be better to use oil instead of water;
water evaporates and this makes its surface to be colder, this certainly causes some currents in the water, with the colder water moving downwards.
The currents can move the small boat and hamper its stable orientation.
We want the liquid to be as steady as possible, so it could be better to use a liquid which does not evaporate, and that has the same temperature of the surrounding environment; also, with a sufficiently steady liquid, it would be not necessary anymore to use a device to maintain the small boat at the center of the pool.     
« Last Edit: September 22, 2022, 06:58:45 AM by Iacopo »
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ta0

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Re: Shop made gyroscope
« Reply #18 on: September 22, 2022, 10:47:47 AM »

Measuring the rotation of an inertial flywheel over a short time/angle is how Foucault did it. Not spectacular but probably the best approach.

If you start the gyro horizontal, it will not be anymore after a while, moving in a plane at [90° - latitude] from the horizontal.
If you constrain it to stay horizontal, you have to apply a torque, and this will make the flywheel precess. What you get is a gyrocompass that will align after a while with the north pole (with the help of friction).
If it's not constrained, the angle measured in the horizontal plane will be the rotation of the earth x sin (latitude), as per the Foucault pendulum (so about 70% for 43 degree latitude).
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Bill Wells

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Re: Shop made gyroscope
« Reply #19 on: September 22, 2022, 12:17:20 PM »

Jorge and Iacopo, thanks for your useful input.
I have several schemes planned for gyro compass experiments.

Presently using the Super Precision gyroscope. Learned something interesting yesterday. I was using the gyro in a configuration suggested in the operating manual. It would precess for a few minutes with the gyroscope getting lower and lower. I wondered why it would not precess for longer time, since spin of the flywheel was still very fast (I can now spin the flywheel up to 15,000 RPM). I suspected friction at the mounting, indicated with red arrow. So I mounting it upside down, suspended with a bearing ball between two magnets. This arrangement has lower friction. Result was much longer precession.






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« Last Edit: September 22, 2022, 12:22:12 PM by Bill Wells »
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Iacopo

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Re: Shop made gyroscope
« Reply #20 on: September 22, 2022, 02:48:16 PM »

If you start the gyro horizontal, it will not be anymore after a while, moving in a plane at [90° - latitude] from the horizontal.
If you constrain it to stay horizontal, you have to apply a torque, and this will make the flywheel precess. What you get is a gyrocompass that will align after a while with the north pole (with the help of friction).
If it's not constrained, the angle measured in the horizontal plane will be the rotation of the earth x sin (latitude), as per the Foucault pendulum (so about 70% for 43 degree latitude).

You seem correct... The simple flywheel with its axis fixed horizontally and without gimbals on the small boat, seems more like a gyrocompass, unable to detect the rotation of Earth. So at least one gimbal should be added..
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Iacopo

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Re: Shop made gyroscope
« Reply #21 on: September 22, 2022, 02:51:58 PM »

I suspected friction at the mounting, indicated with red arrow...

I can confirm it, I could see the same in my gyroscope, I even made a video about this effect, (the first of the three experiments explained here, "Effect of the friction of the bearings of the vertical axis in a gyroscope"):

https://youtu.be/s-wt6m7KDFo
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Bill Wells

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Re: Shop made gyroscope
« Reply #22 on: September 22, 2022, 03:22:22 PM »


(1)   One possibility could be to make the flywheel to spin by inertia, without motor.

(2) ... problem can be overcome by setting the rotation axis of the flywheel exactly horizontal;

(3)  .. it is not necessary the plane of the flywheel to be set at 43 degrees.


Iacopo, I noticed that you sent new reply with videos. Have not yet reviewed the videos.

Regarding comments above:
(1) I am now experimenting with our Super Precision gyro. Now have TWO of them! I can spin them to over 15,000 RPM by increasing voltage. That should give enough spin time.
(2) and (3) Setting angle to 43 degrees increases complexity. My experiments will be with axis horizontal.

Not sure what you meant in your comment: "The simple flywheel with its axis fixed horizontally and without gimbals on the small boat, seems more like a gyrocompass, unable to detect the rotation of Earth. So at least one gimbal should be added..".  Why would a flywheel with its axis fixed horizontally in a small boat not detect rotation of Earth?
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Bill Wells

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Re: Shop made gyroscope
« Reply #23 on: September 22, 2022, 03:32:31 PM »


I can confirm it, I could see the same in my gyroscope, I even made a video about this effect...


YOU MADE THIS GYROSCOPE?
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ortwin

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Re: Shop made gyroscope
« Reply #24 on: September 22, 2022, 03:47:38 PM »

"Why would a flywheel with its axis fixed horizontally in a small boat not detect rotation of Earth?"


I don't think that he really meant that it can not detect rotation, is would act as a north seeking gyro compass and the rotation of the earth is of course the most important thing to make this possible. But with a gyro compass you can not detect directly at what speed the earth is rotating, it just points north.
With Foucault's pendulum you can calculate the rotational speed of the earth directly also with a gyroscope that is free, at least in part, to  keep the orientation of its axis stable in space. In the gyro compass this axis is aligning as well as possible in parallel to the axis of the earth.



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ortwin

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Re: Shop made gyroscope
« Reply #25 on: September 22, 2022, 03:59:51 PM »


I can confirm it, I could see the same in my gyroscope, I even made a video about this effect...


YOU MADE THIS GYROSCOPE?


I don't think Iacopo made himself the so called "Super Precission gyroscope" that is also visible in the video, but the shiny one that he starts with a string I am pretty sure he made all by himself. Really impressive indeed!
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Bill Wells

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Re: Shop made gyroscope
« Reply #26 on: September 23, 2022, 12:20:04 PM »

Really impressive indeed!

 I thought the gyroscope Iacopo was using in his demonstrations was a commercially made one similar to the one you borrowed from a university. Then it dawned on me that he actually made it!

Welcome back, Ortwin.  Among my recent wacky experiments was (accidentally) an example of eddy current torque. I used a Styrofoam boat  to float the spinning Super Precision gyroscopes, with a magnet in the pan to keep the boat centered. Made the boat rotate due to Eddie Current! Reversed spin of gyroscopes and boat rotated in opposite direction.
« Last Edit: September 23, 2022, 12:38:31 PM by Bill Wells »
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Iacopo

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Re: Shop made gyroscope
« Reply #27 on: September 23, 2022, 02:23:02 PM »

Why would a flywheel with its axis fixed horizontally in a small boat not detect rotation of Earth?

Because it would work like a gyro compass, maintaining its orientation relatively to Earth, like a compass, so it couldn't show that Earth rotates.

The reason, to use the words of Jorge, is that, with a flywheel having its axis fixed horizontally on a small boat,
If you start the gyro horizontal, it will not be anymore after a while, moving in a plane at [90° - latitude] from the horizontal.
If you constrain it to stay horizontal, you have to apply a torque, and this will make the flywheel precess. What you get is a gyrocompass that will align after a while with the north pole (with the help of friction).
Practically, if our small boat has its flywheel axis horizontal, and oriented east-west, as Earth rotates a bit, the axis of the flywheel cannot maintain its orientation relatively to the stars because it is constrained to follow the rotation of Earth; the rotation of Earth would cause a torque on the flywheel axis in the direction to make the east side of the axis to sink down and the west side to rise up.  Because of the gyroscopic effect, the movement happens with a 90 degrees delay, this makes the flywheel and the boat to rotate on the plane of the water.  The speed of the rotation of the boat would be the same of the rotation of Earth, so, on Earth, the boat would appear to be steady.

Anyway...

I think that this also depends on the direction of spinning of the flywheel;

if the flywheel axis is horizontal, and oriented east-west, and the flywheel spins with its upper part moving towards south, the gyroscope will rotate in sync with Earth, practically maintaining a stable orientation relatively to Earth.

But, in the same situation, if the flywheel spins in the opposite direction, (its upper part moving towards north), this should make the gyroscope to behave differently. We will see the gyroscope, and the small boat with it, to rotate clockwise on the plane of the water, (at a speed twice that of Earth, i.e. 0.5 degrees per minute).

If my reasoning is correct, the experiment could still be interesting.
The logicality is a bit more complicated than that of a gyroscope maintaining its orientation relatively to the stars, but it still shows, using a flywheel, that Earth rotates.  On the plus side, to make a boat with a flywheel fixed horizontally is relatively simple, there are not gimbals, it is easier to make it work precisely, without random movements. And the speed to detect is doubled, so it is easier to perceive it. 

     

« Last Edit: September 23, 2022, 02:55:43 PM by Iacopo »
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Iacopo

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Re: Shop made gyroscope
« Reply #28 on: September 23, 2022, 03:08:16 PM »

YOU MADE THIS GYROSCOPE?

Yes I did !   ;)





But looking at the your I thought to make another one, with more wood and less metal.  Maybe one day...
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ortwin

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Re: Shop made gyroscope
« Reply #29 on: September 23, 2022, 03:51:56 PM »

...
Welcome back, Ortwin. 
Thank you Bill, but I was never gone! It is true, my posts lately were mainly in the other section of the forum, but I followed this one at least.
The season with worse weather is coming up so I guess I will turn more to endurance tops again for the next few month. I still have goals there that I did not reach yet and some clear ideas how to move forward there. The main improvement I am hoping for will come from an idea you Bill brought here: a balancing method with a vibration app. We will see if it works for me over the course of the next few month.


....Among my recent wacky experiments was (accidentally) an example of eddy current torque. I used a Styrofoam boat  to float the spinning Super Precision gyroscopes, with a magnet in the pan to keep the boat centered. Made the boat rotate due to Eddie Current! Reversed spin of gyroscopes and boat rotated in opposite direction.

Sounds  like a fun effect you observed, but I don't quite get it:
  • where exactly was the magnet?
  • to what was it supposed to get attracted?
  • What was the orientation of the flywheel?
  • what other metal parts were present?
Maybe a little rough sketch would help me understand your setup. My first impulse was to say " that is not eddy currents, it is just the conservation of angular momentum!" But then I realized that because of the opposite spin directions it can't be that.





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