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Are glass batteries a hoax?


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#21 KipIngram

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Posted 18 May 2017 - 12:24 PM

Actually if they are counter-rotating at the same speed then the gyro torques cancel "externally."  Whatever structure is holding them in a parallel configuration will experience stresses, though, so that would have to be a strong enough design hence weight etc.  I actually "experienced" this recently - my wife bought my daughter a couple of those little spinner thingies people use to just play with or spend nervous energy.  I could hold one between my thumb and finger, spin it, and feel the gyro torques.  But if I held two and spun them opposite directions (matching speed as best I could) that effect was much diminished.

 

These gizmos:

 

http://www.asseenont...PxoCI_gQAvD_BwE


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#22 mistermack

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Posted 18 May 2017 - 08:03 PM

Actually if they are counter-rotating at the same speed then the gyro torques cancel "externally." 

I don't really understand what that means. 

From memory, if I held a spinning gyroscope in my hands, it resisted being turned to the left, and to the right, equally.

So I was imagining that two parallel ones would just double the resistance to turning. 


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#23 KipIngram

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Posted 18 May 2017 - 08:17 PM

They would if they are turning in the same direction.  But if they are turning in opposite directions you won't feel that resistance (if they're turning at the same speed and have the same mass distribution).

 

You're right that there's resistance to either direction of turn.  But there's still a cancellation effect when the flywheels are counter-rotating.  I'd probably have to go to a reference to express it mathematically, though.


Edited by KipIngram, 18 May 2017 - 08:18 PM.

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#24 Bender

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Posted 19 May 2017 - 07:21 AM

I can help you out in that respect, since it is quite simple:

L-L=0

With L the angular momentum. Both angular momentums cancel each other out, and the resulting angular momentum is zero. Without angular momentum, no gyroscopic effect.


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#25 mistermack

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Posted 19 May 2017 - 09:54 AM

Ah, are you talking about two gyroscopes rotating on the same connected axis? 

 

I was picturing two parallel. If the two are connected through the axis of rotation I can see how they could cancel each other that way.


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#26 Bender

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Posted 19 May 2017 - 12:06 PM

That makes no difference. They can cancel each other out when parallel as well. Angular momentum doesn't have a position, only an orientation.


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#27 mistermack

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Posted 19 May 2017 - 01:34 PM

Yep, I looked and it's correct. Which seems to negate the objection to flywheels being used to supply power to vehicles.

It makes it more complicated, but it shouldn't wear out your tyres or make you go straight when you turn the wheel.

Nice illustration of it on youtube :

 

https://www.youtube....h?v=vGun5athdfg

 

Edit. I guess that maybe the forces on the bearings might be prohibitive. Although wheel bearings seem to take plenty of force in their lifetimes. 


Edited by mistermack, 19 May 2017 - 01:41 PM.

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#28 KipIngram

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Posted 19 May 2017 - 01:37 PM

Yes, the point I was trying to make is that you have to engineer the system to deal with it (rigidly support the two counter-rotating wheels), and said engineering adds extra weight, cost, and so on.  You're right - it shouldn't wear out your tires; the gyro effects would be "contained" by the supporting structure.

 

Another thing you have to keep in mind is what's going to happen if a flywheel fails; those tend to be rather violent events.  So you'd also need a containment system, and that adds weight and cost as well.  But of course all of these technologies have risks (gasoline can explode too).


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