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[ta0]

Found this by chance today:

[Iacopo]

There are persons asserting that, combining some gyroscopes together, it is possible to produce a machine able to lift, and, maybe, even to fly, (UFOs, for believers, could use this "technology").
For example:



I don't believe in UFOs but I was curious about the principles of this theory, I found this other (more serious) video:



I tried spinning one of my tops, in precession, on a scale.  The top, spinning or not, results to have always exactly the same weight, it isn't lighter while spinning in precession.

My question is: in the gyroscope on the scale of the second video, if precession was forced to go faster, by a little electrical engine in the gyroscope, the weight on the scale would be still the same, or not ?
Accelerating the precession would move upwards the flywheel of the gyroscope, but let's suppose that that axis is fixed, so that the flywheel is forced to stay always at the same height. 
Would the weight on the scale be always the same, also if precession is accelerated, (or slowed down) ?

My guess is that, at constant speed, whatever the precession velocity, the weight would be always the same.
And that, consequently, it's impossible to make a machine able to lift, based on this principle.
So it's fake for me.
But I'm not totally sure, so I ask you.
   

[ta0]

I combined it with the old thread.

So it's fake for me.

You are correct, it is all pseudo-science (and interesting psychology).

[Iacopo]

if you speed up the (stable) precession rate it will stand up, while if you slow it down it will sink. But the weight on your hand will remain almost the same (except for the vertical acceleration imparted: it will weigh a little less when it drops and a little more when it rises).

Thank you, Ta0, for combining the threads, it was interesting to read the old one.
And you answered to my question, too.

This other video explains in simple and logical terms how gyroscopes work.
I like it because it is clear enough for dummies like me to understand some basic principles.
It can be seen that the flywheel does not produce a force directed upwards, instead there is rather, simply, a resistance of the spinning flywheel to be tilted.  If sinking implies tilting, like in gyroscopes, the flywheel does not sink, and the tilting resistance transfers the weight of the flywheel to the pivot.
The video contributed to address my thinking in this direction, and this thread has made the issue more clear to me.
   
https://www.youtube.com/watch?v=EJWIl4MYMbw&index=6&list=PLksvI9o_0C0_I_V4M2qxl1JWZAao9ULaB

BTW, I don't think that the wheels of a bycicle acting as gyroscopes contribute much to its stability.
 

[Kirk]

BTW, I don't think that the wheels of a bycicle acting as gyroscopes contribute much to its stability.

In the days before the internet I recall reading a magazine article about creating an un-rideable bicycle.  One of the tests was to mount a contra-rotating wheel to see what would happen if the gyro effect was canceled or even reversed.  Result -- rideable bike
Perhaps this article has been archived on the web.  If I recall correctly it was in American Wheelmen Magazine prior to 1981.

[Iacopo]

In the days before the internet I recall reading a magazine article about creating an un-rideable bicycle.  One of the tests was to mount a contra-rotating wheel to see what would happen if the gyro effect was canceled or even reversed.  Result -- rideable bike

It makes sense to me.  After all, the wheels of a bicycle are not so heavy, do not spin so fast, so their gyroscopic effect can't be that strong.  And we don't have gyroscopes attached to our bodies, but we can walk without any problems, so there are other explanations.

[Iacopo]

The experiment at the end of part 4/7 (8/19), "possibly the most remarkable experiment I have ever done", I find interesting and I need to think about it.  I am not sure if it works like that or if he is faking it.

I looked at that experiment, at first I didn't understand..
Why the axis doesn't stay horizontal, while spinning ?
I looked at it more carefully, until I noticed something...
I laughed.
I am not totally sure, but it seems to me that, when the gyro is not spinning, and he balances the main axis to stay horizontal, the axis of the gyro in the meanwhile is not perfectly vertical as it should be, but it stays slightly tilted outwards. So the balance is apparently correct, but reality is that the side of the main axis with the gyro is lighter than the other one.  Which is what we see when the gyro spins.
I laughed because it is a ... questionable way to show experiments, so to say...
but I don't see other explanations.

[Jeremy McCreary]

In the days before the internet....

Wait, there were days before the internet??

[Jeremy McCreary]

Found this by chance today:

The older professor in this video is Rod Cross, author of one of my favorite articles on top physics (The Rise and Fall of Spinning Tops, American Journal of Physics, v.81, 2013). He also has an interesting top- and gyro-related web site at http://www.physics.usyd.edu.au/~cross/SPINNING%20TOPS.htm.

[Jeremy McCreary]

Found this by chance today:

Couldn't resist whipping up a little LEGO demo along similar lines on seeing this thread this morning...



See the video description for details. Sure wish I had one of those fancy brass gyros.

[ta0]

Nice demo! I liked it!
It looks like you can assemble almost anything with your Legos!

The older professor in this video is Rod Cross, author of one of my favorite articles on top physics (The Rise and Fall of Spinning Tops, American Journal of Physics, v.81, 2013). He also has an interesting top- and gyro-related web site at http://www.physics.usyd.edu.au/~cross/SPINNING%20TOPS.htm.

Thanks! I will check his site!

[Jeremy McCreary]

Nice demo! I liked it!
It looks like you can assemble almost anything with your Legos!

Thanks, ta0! That's not far from the truth -- and quickly, too. The main limitations (scale and material properties) don't take much off the table, and I get to park my car in the garage where the fabrication shop would be.

As I know you know, NASA designs, tests, and builds all of its spacecraft at the Jet Propulsion Laboratory in Pasadena, CA. Engineers there often take brand new ideas to a room called "Left Field". It's full of LEGO. Universities and engineering firms also use it as a prototyping tool. Computer simulations are fine, but gut-level 3D mechanical understanding of a new gizmo usually comes fastest when you turn it and work it with your own 2 hands with eyes and ears wide open. We all know that. LEGO makes it easy.

[Iacopo]

Couldn't resist whipping up a little LEGO demo

Well done, Jeremy.  A clear demo.  I envy your possibility to make tests with that ease. 

[Iacopo]

Look at this experiment of Laithwaite:



I thought that the gyro shouldn't raise up, so I repeated the experiment:



What do you think ?

[ta0]

Great experiment, Iacopo! Thanks for doing it!

Your result is what I would have expected and I am still scratching my head about Laithwaite's demo.

Did you push the wheel in the direction of the precession?