Possible feedback problems of a uni-directional torque

[chazemz]

Hi, I wonder if someone can help with the following problem? We have a sealed box in space and inside the box is an electric motor with the stator attached to the box. The rotor arm is attached to the inner race of a bearing and the outer race of the bearing is also attached to the box.

There is an internal power supply. We know that when the power is applied to the motor, the stator will begin to rotate in the opposite direction to the rotor arm and the outer race will rotate in the opposite direction to the inner race and so will apply a torque to the box in the same direction as the stator.

Will the stator and rotor rotate in balance?

Will the rotor arm rotate faster than the stator so that the outer race will always apply a small torque to the box?

Will the rotor arm slow so that the outer race now starts a reverse effect on the rotor arm?

None of the above.

 

[berkeman]

Is this related to your Reactionless Drive threads here back in 2017?

 

[chazemz]

No

 

[chazemz]

May I add that the stator and outer race will act as described they are well known. What I would like to know is how the rotor and stator interact as the box, stator and outer race all rotate in the opposite direction to the rotor.

 

[Lnewqban]

At least during initial acceleration time, it seems to be a struggle among moments of inertia (of rotor and stator), polar moment of inertia (perpendicular to plane of rotation) and gyroscopic effect.
Any unbalanced mass may cause additional rotational movements in other planes.
If feasible, experimentation seems to be the simplest way to an answer.

 

[berkeman]

May I add that the stator and outer race will act as described they are well known. What I would like to know is how the rotor and stator interact as the box, stator and outer race all rotate in the opposite direction to the rotor.

Can you upload a diagram? That would be a big help.

I'll also move this thread to the ME forum for now...

 

[chazemz]

No problem. I will upload a diagram tomorrow morning.

 

[Dale]

Will the stator and rotor rotate in balance?

Total angular momentum is conserved. So everything together will rotate in balance. Not necessarily the stator and rotor, since there are other parts too.

 

[jrmichler]

That's how they aim orbiting telescopes and other satellites. A reaction wheel turns one way, and the satellite turns the other way. Search terms that lead to good links include satellite angular positioning reaction wheel and satellite angular positioning flywheel. Here's one of a number of good links: https://aerospace.honeywell.com/us/en/about-us/blogs/understanding-reaction-wheels. And a quote from that link: They can be used to control the position and attitude of a satellite without requiring thrusters or any other external applicators of torque. This brings multiple benefits, including a significant reduction in the payload fraction needed for fuel.

 

[berkeman]

And a quote from that link: They can be used to control the position and attitude of a satellite without requiring thrusters or any other external applicators of torque. This brings multiple benefits, including a significant reduction in the payload fraction needed for fuel.

(I fixed that for them)

 

[chazemz]

Diagram attached

 

[Dale]

So the stator, box, and outer race are all rigidly attached to each other, and the rotor and inner race are rigidly attached to each other?

 

[chazemz]

That is correct.

 

[Dale]

Will the stator and rotor rotate in balance?

So the stator + box + outer race will rotate in balance with the rotor + inner race.

 

[chazemz]

The stator of an electric motor is usually attached to an object that does not rotate. In this situation it is easy to say that as long as the rotor spins faster than the object a uni- directional torque will be applied to the object. The physics has no problem with this. By putting the box in space means that the box can counter rotate with regard to the rotor with ease. If the box can counter rotate faster than the rotor, a crossover point should be reached and the bearing will now apply a toque to the rotor not the box. What I am interested in is how this would change the dynamics between the rotor and stator?

 

[Dale]

a uni- directional torque will be applied to the object

Angular momentum is conserved. So there is no uni-directional torque. Any torque is accompanied by an equal and opposite torque. Just like forces with newton’s 3rd law

If the box can counter rotate faster than the rotor, a crossover point should be reached and the bearing will now apply a toque to the rotor not the box.

I don’t think so. I cannot see any physical justification for such a crossover point

 

[chazemz]

The ball bearings between the inner and outer races change the direction of the torque of the rotor. It is impossible for the rotor in the diagram to apply a torque to the box. Even though everything is connected to each other a torque is applied to the box in one direction only. May I also add that the box will spin and therefore interact with its surrounding which will introduce an exterior force. Conservation of angular momentum applies in a closed system.

 

[berkeman]

the box will spin and therefore interact with its surrounding which will introduce an exterior force.

Interact with the vacuum of space?

Is this related to your Reactionless Drive threads here back in 2017?

No

Short leash...