Suppose you have a heavy flywheel rotating about a spindle in thr [latex]X[/latex] axis at a considerable rate of radians/sec.

Now suppose you have another one on the same spindle -- same mass, same diameter, etc, but colocated and rotating in the opposite direction.

What will happen if force is applied to rotate the spindle about the [latex]Z[/latex] axis?  (I'm guessing lots of resistance, leading eventually to catastrophic heat transfer.)

Edited November 6, 20187 yr by THX-1138
Fix notation & typo

2 hours ago, THX-1138 said:

Suppose you have a heavy flywheel rotating about a spindle in thr X axis at a considerable rate of radians/sec.

Now suppose you have another one on the same spindle -- same mass, same diameter, etc, but colocated and rotating in the opposite direction.

What will happen if force is applied to rotate the spindle about the Z axis?  (I'm guessing lots of resistance, leading eventually to catastrophic heat transfer.)

Presumably the 'spindle' is not rotating so what is driving the flywheels?

Irrelevant.  Assume the spindle is turning, and is being suspended in touchless magnetic bearings and driven by magnetic induction motors.  Assume frictionless under normal circumstances.

4 minutes ago, THX-1138 said:

Irrelevant.  Assume the spindle is turning, and is being suspended in touchless magnetic bearings and driven by magnetic induction motors.  Assume frictionless under normal circumstances.

 

Are you being serious or is this thread just a wind up?

 

 

I'm being serious.  I'm wondering about the situation of freedom being restricted in two of the directions of precession.

All right, either the spindles are Klein manifolds or some engineering ingenuity is used to get the wheels, spinning each on its own spindle, as close as possible and welded into a single unit, so precession forces will apply to the entire structure.

Edited November 6, 20187 yr by THX-1138
typo

15 minutes ago, THX-1138 said:

I'm being serious.  I'm wondering about the situation of freedom being restricted in two of the directions of precession.

All right, either the spindles are Klein manifolds or some engineering ingenuity is used to get the wheels, spinning each on its own spindle, as close as possible and welded into a single unit, so precession forces will apply to the entire structure.

 

If they are welded together how can one spin one way and the other spin in the opposite direction?

They're welded into a framework containing them both, not to each other.

8 minutes ago, THX-1138 said:

They're welded into a framework containing them both, not to each other.

So why didn't you think this through in the first place?

There is an arrangement like you are trying to describe, used in some helicopters with contra rotating main rotors to balance the spin torque and avoid the need for tail rotors.

I suggest you look it up.

All right, I will.  I didn't think of that example.

Why are you being so unpleasant?  Were you born knowing everything?  I'm sorry I wasn't.  It's rather a put-off to ask questions here to get slapdowns like the above.

On 11/6/2018 at 12:18 PM, studiot said:

So why didn't you think this through in the first place?

There is an arrangement like you are trying to describe, used in some helicopters with contra rotating main rotors to balance the spin torque and avoid the need for tail rotors.

I suggest you look it up.

I imagine the rotors are designed to have low moments of inertia and use their lift properties to counteract any precession effects caused by tilting the axis.  I'm actually asking about the other end of things; coaxial spinning disks with high (and equal) moments of inertia, and high angular velocities -- what happens if an attempt is made to tilt the axis?