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Author Topic: Gyros & Tops in space  (Read 7561 times)

ta0

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Gyros & Tops in space
« on: October 16, 2013, 05:28:31 PM »

Here is Chinese astronaut (or taikonaut) Wang Yaping demonstrating the gyroscope effect last June.

Wang Yaping demonstrates gyroscopic motion in space

I wouldn't mind getting lost in space with her  :D

By the way, I saw (in 3D) the recently released movie Gravity and it is very good.  There are no actual spinning tops but there is lots of spinning.  It is in fact a lesson on angular momentum.  I would have just changed one scene: when the two main (~ only) characters are separated.  It is physically wrong (most of the movie gets the physics right) and I have a solution that would have worked even better for the drama.  Anyways, I highly recommend it.
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ta0

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Re: Gyros & Tops in space
« Reply #1 on: October 16, 2013, 11:08:52 PM »

And here an American astronaut (Petit ?) showing gyroscopic stabilization using CD players:

Gyroscope behavior in low gravity.
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ta0

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Re: Gyros & Tops in space
« Reply #2 on: October 17, 2013, 11:33:53 AM »

Something hit me this morning when I was still in bed.  On the last video the astronaut seems to not understand what happens when you add more that one gyroscope ! :o What is much more surprising is that nobody in NASA told him!  :o  ???  Perhaps he designed the demonstration without outside vetting and this was broadcasted live so now it lives in youtube and NASA cannot take it back  :-\ 

If you add two gyroscopes at 90 degrees to each other, it is equivalent to a single gyroscope aligned along the middle (bisector, if they are spinning in the "same" sense).  The thing would still be able to rotate around this axis and the stabilization would be less than stacking the two CD players on top of each other.  The reason is that along the perpendicular axis the rotation of the two CD players cancel each other (like two gyros spinning in opposite directions cancel each other).

When he added the 3 CDs at 90 degrees to each other he just got the equivalent to one aligned with the axis going through the center of the corner angle.  But he would get just 1.7 times the angular moment of one CD instead of the 3 times if he had stacked them all together.

By the way, somewhere there must be video of the demonstrations Nasa did with tops and described in this book:



From the Papyrus section: "Nasa´s Toys in Space program flew several tops in two Shuttle flights. The tops included a pump top, a tippy top, a rattleback, gravitrons and gyroscope. Other spinning toys included a yo-yo and a magnetic wheel. "
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ta0

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Re: Gyros & Tops in space
« Reply #3 on: October 17, 2013, 11:33:00 PM »

Found the video showing the experiments with the Gravitron (an enclosed gyro top) by astronaut McMonagle on the Endeavour (ST-54.) The same experiment with three gyros is done but this time the (dubbed) explanation is correct, what is not surprising as the effect is much more obvious, explosive actually!  >:D

NASA - Toys in Space - Gravitron
« Last Edit: October 17, 2013, 11:35:23 PM by ta0 »
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Ketzaltlipoka

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Pioneer = Trompo
« Reply #4 on: October 19, 2013, 07:16:21 PM »

Many, many years ago, I saw on tv a documental about Space exploration and there they showed the drawing that was sent to space, giving information about Earth and mankind.
In that then, I was not affected by this sickness of relationing Trompos with everything. But in that then I was already playing with trompos.
In the drawing appears something ( that according with this text,
http://en.wikipedia.org/wiki/Pioneer_plaque
it seems to be the Pioneer) that in the first time I saw it, I clearly said to myself:
"that´s got the form of a trompo".



« Last Edit: October 20, 2013, 10:56:38 PM by ta0 »
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cecil

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Re: Gyros & Tops in space
« Reply #5 on: January 08, 2014, 01:23:24 AM »

Over hand fighting. I love it.
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johnm

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Toys In SPACE
« Reply #6 on: February 10, 2014, 07:37:21 PM »

many more fun "toys in space" videos on youtube now.

International Toys in Space: Spinning Top

Yo-Yo Classics: Toys in Space

A 23 minute movie of the Toys in Space program here:  STAR FLIX - TOYS IN SPACE: Just for FUN
« Last Edit: February 11, 2014, 11:03:15 AM by ta0 »
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ta0

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Re: Gyros & Tops in space
« Reply #7 on: February 11, 2014, 11:18:22 AM »

I agree with you Cecil, it looks like the man just threw a little top on the ground. When aliens find the Pioneer plaque they may well think it is a description of a spinning top game (played in the nude)   :P

On the first video I was surprised (as was the astronaut) that the top did not have more wobble when she added the weights to the rim.  I think the reason is that the stem has very little mass, so the new proper axis of rotation is still perpendicular to the disc and parallel to the stem. It would have shifted away from the center, but as the stem stays parallel to itself and does not describe a cone the wobble would not be very noticeable.  By the way, a top in micro-gravity will not do the normal precession, which is due to the pull of gravity.  But it can still do a precession-like movement if it is started spinning in a direction that does not coincide with a proper (principal) axis of rotation.
« Last Edit: February 11, 2014, 11:20:29 AM by ta0 »
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Larry D.

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Re: Gyros & Tops in space
« Reply #8 on: February 11, 2014, 03:55:10 PM »

Love the action with those Gravitrons!  :)
 
$9 buck including a holder, not bad.  Anyone know the cost of a Space Flight these days?
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Kirk

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Re: Gyros & Tops in space
« Reply #9 on: February 12, 2014, 07:12:04 PM »

Anyone know the cost of a Space Flight these days?
All seats to fly to space are US$250,000 and deposits are refundable.
http://www.virgingalactic.com/booking/
So far over 600 have been sold.
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Daveid

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« Last Edit: August 24, 2015, 12:57:51 AM by ta0 »
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like I always say:dead monkeys don't fly on sticks.

the Earl of Whirl

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Re: space is fun
« Reply #11 on: August 22, 2015, 07:56:20 AM »

Very interesting!!!
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Happiness runs in a circular motion!!!

ta0

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Re: space is fun
« Reply #12 on: August 24, 2015, 01:23:50 AM »

Very interesting indeed, and I would say related to spintop science so I am moving it out of NSTR  :)

This video is pretty amazing. It gives the impression of the handle flipping between two different stable spinning directions (bi-stable), what is not the usual description for this type of rotations.

Notice that with respect to the space station the rotation is always in the same direction (counter-clockwise looking towards the panel), as conservation of momentum requires. But from the T-handle's point of view (e.g., looking from the handles down to the key) the direction flips from counter-clockwise to clockwise.

Because the T-handle is symmetrical, the initial rotation must correspond to one of the principal axis of inertia. But it is unstable, so it has to be the one with intermediate amount of inertia as the other two axes are stable. This surprised me at first, but after thinking about it I realized that because the handles are more massive than the key shaft this is possible. I think the principal axis of maximum inertia must be perpendicular to the handles (and the shaft); the principal axis with minimum inertia must be in the plane of the handles (and perpendicular to the shaft). And I think the center of mass has to be pretty close to the handles for the other axis to be intermediate.
« Last Edit: August 24, 2015, 10:38:23 AM by ta0 »
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dazzlingdave

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Re: space is fun
« Reply #13 on: August 28, 2015, 04:49:38 PM »

The rotation switch is so cool!

That seems to be the same principle of the tippy top that when it flips it changes directions.

Speaking of that, I have been meaning to make a tippy top on my lathe......Maybe I should get to work!

Dave
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ta0

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Re: space is fun
« Reply #14 on: August 28, 2015, 10:45:37 PM »

The rotation switch is so cool!
That seems to be the same principle of the tippy top that when it flips it changes directions.
It is super cool and surprising, indeed!

The common explanation with the tippy top is that the friction from the table gives it the torque to flip. But perhaps you are right and some of this effect is helping the tippy top start the flip.

After thinking for a while about the video I have a tentative semi-intuitive explanation.
The most stable axis of rotation for an object is the one with largest (moment of) inertia. Although the axis with lowest inertia is also stable, if there is energy loss (e.g. air drag) it will eventually end up rotating along the maximum inertia axis. Imagine an object that is spinning unbalanced: the highest mass will tend to "fly out", thus aligning the rotation of the body with the axis perpendicular. 

The handle is spinning unstable and pulled towards spinning with the T paralllel to the wall, what correspond to the maximum moment of inertia. As it does this it has to slow down to maintain the momentum of rotation. But, as there is little friction the flipping overshoots like a pendulum that reaches the bottom and starts to climb up. The handle retraces its rotation in opposite direction, speeding up as the lower moment axis realigns itself with the momentum. And the same as the pendulum, when it reaches the same position on the other side, it will then "swing" back.

I guess that eventually air friction would settle it down into spinning slowly counter-clockwise with the T in a plane parallel to the wall.

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