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 1 
 on: September 27, 2022, 11:32:06 PM 
Started by Jeremy McCreary - Last post by Jeremy McCreary
Right, its a law of nature, but actually this is just the way to say it in a special set of circumstances, the law in its most general wording is called "Murphy's Law".

The more applicable law in my case is Gumperson's: The least likely contingency will always occur at the most inopportune time.

And there's no way around it per Gumperson's Corollary: All attempts to circumvent Gumperson's Law are themselves subject to Gumperson's Law.

Of course, all these laws are just recognitions of the fundamental perversity of Nature.

 2 
 on: September 27, 2022, 11:24:15 PM 
Started by Jeremy McCreary - Last post by Jeremy McCreary
You know you will later need the stuff you got rid of.  It's a law of nature.

Inescapable. And now that we're starting renovations on our new house, I also need lots of things still in storage 1,100 miles away in Denver.

 3 
 on: September 27, 2022, 05:12:31 PM 
Started by Armando (elprofedeltrompo) - Last post by Armando (elprofedeltrompo)
Hola quisiera abrir un nuevo tema, o por lo menos para mi, no me lo van a creer pero nunca he rodado un trompo con punta de rodamiento, rodalibre, o bueno como se quiera llamar,  mi primer duda es esa, cual es el nombre tecnico de esos trompos cuya punta gira?   que tamaños se manejan?  que tan diferentes son en cuanto a lanzamiento tecnica, etc, son más fáciles de manejar?   en colombia empecé la busqueda para adquirir algunos pero no ha dado frutos,  lo unico es traerlos por ebay desde estados unidos.   bueno,  lo que quieran ir contando sobre este tema seria genial   parto desde ceros con este tipo de trompos.
Saludos a todos desde Bogotá colombia.

 4 
 on: September 27, 2022, 05:05:25 PM 
Started by Turegano - Last post by Armando (elprofedeltrompo)
Really  beautiful 

 5 
 on: September 27, 2022, 04:36:20 PM 
Started by Bill Wells - Last post by Iacopo
You know we will make one of these.  Seems that just a decent fan underneath would suspend a sphere.

I started looking for the materials for making the mine. Even if I don't know yet when I will make it...

 6 
 on: September 27, 2022, 04:12:10 PM 
Started by Bill Wells - Last post by Iacopo
I don't know if I follow your reasoning.
I think the only difference regarding the direction of the rotation of the gyro is that in one case one end of the gyro axis ends up pointing north and in the other case the opposite side.
If there is no gimbal to let the gyro rotate with respect to the boat, it will drag the boat with it.
If it's free to rotate in the horizontal direction, it will rotate with respect to the boat (stationary with respect to the earth) but the rate of rotation will depend on the spin.
In a commercial gyrocompass, it is fully gimballed, but it's maintained horizontally with weights (like a balanced arm scale).

You are right, Ta0, I was misunderstanding how the gyro compass works.
I found a better article about it and now I understand it a bit better;
the gyro compass points north, not because it precesses at the same speed of the rotation of Earth, but because it stops precessing when it points north.

I try again.
The small boat with the flywheel fixed horizontally in it, is a simplest kind of gyro compass.
It works well onlybest at the equator.
In the drawing below, the small boat is at the equator, we see it from North Pole.
The flywheel spins, with its axis oriented east-west, (A), and it tries to maintain its orientation, but Earth rotates and in position B a torque from the small boat wanting to align itself to the sea makes the flywheel to precess, so the boat rotates on the plane of the water.
The boat rotates until the position C, then it stops rotating, and the flywheel remains with its axis oriented north-south.
The reason that the precession stops at this point is that now the flywheel axis is exactly parallel to the rotation axis of Earth, and, from here, the rotation of Earth does not change the situation of parallelism, so there is no more torque, and no more precession.

This works best at the equator because at the other latitudes, especially near the poles, the axis of this flywheel, horizontal, would never be parallel to that of Earth, and the flywheel would tend to continue to precess, the leverage for making the flywheel to precess becomes progressively less efficient, until, at the North Pole, the gyro compass doesn't follow the rotation of Earth anymore.     



Still the experiment with a small boat and a simple horizontal flywheel without gimbals maybe could be worth.
Depending on the direction of spinning and the orientation of the flywheel, before to point north, a clockwise or a counterclockwise rotation of the boat on the water could be seen, showing that Earth rotates.

 7 
 on: September 27, 2022, 01:57:22 PM 
Started by Jeremy McCreary - Last post by ortwin
Downsizing means lots of stuff to dispose of...

You know you will later need the stuff you got rid of.  It's a law of nature.
Right, its a law of nature, but actually this is just the way to say it in a special set of circumstances, the law in its most general wording is called "Murphy's Law".

 8 
 on: September 27, 2022, 01:10:08 PM 
Started by the Earl of Whirl - Last post by ta0
It's a weird feeling to find one's picture on a website one didn't expect. It has happened to me. I guess we are micro (but also "top") celebrities  ;D
But that photo is really nice, snowing included, so I'm not surprised it was used:



Of the 5 spintop related movies listed, I've seen the first 3 and I don't consider the last one to be a top movie. The fourth one, The Secret of Crickley Hall, I would in principle have wanted to watch. But the description is not very appealing:  "One of the heartbreaking moments is when the movie shows an abused orphan spinning a top while he waits to be rescued, though the audience knows the rescue isn’t coming." I might pass on this one.

 9 
 on: September 27, 2022, 01:01:46 PM 
Started by Bill Wells - Last post by ta0
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.

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).
I don't know if I follow your reasoning.
I think the only difference regarding the direction of the rotation of the gyro is that in one case one end of the gyro axis ends up pointing north and in the other case the opposite side.
If there is no gimbal to let the gyro rotate with respect to the boat, it will drag the boat with it.
If it's free to rotate in the horizontal direction, it will rotate with respect to the boat (stationary with respect to the earth) but the rate of rotation will depend on the spin.
In a commercial gyrocompass, it is fully gimballed, but it's maintained horizontally with weights (like a balanced arm scale).

 10 
 on: September 27, 2022, 11:57:07 AM 
Started by Bill Wells - Last post by Bill Wells
I found the patent for an air gyroscope...

You know we will make one of these.  Seems that just a decent fan underneath would suspend a sphere.

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