Naked Science Forum
On the Lighter Side => New Theories => Topic started by: Momentus on 23/08/2020 13:51:44
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https://www.thenakedscientists.com/forum/index.php?action=dlattach;topic=80399.0;attach=31024;image
I made a complex, and hence a useful model many years ago. It was designed as an automotive transmission. This is a much simplified version, to demonstrate a new form of motion.
The experiment goes like this:
1. Run the gyroscope motor to bring the gyroscope rotors up to a modest speed. As the rotors are are touching, they counter rotate. Equal and opposite. Now let the motor freewheel.
2. Run the reaction motor. This rotates the Gyroscopes about their precession axis, accompanied by equal and opposite torque orthogonal to the spin axis. There can be no torque exerted by the reaction motor along a precession axis, therefore no substantial movement of the reaction flywheel.
3. Increase the speed of precession until the precession axis changes to the spin axis. When this happens the reaction motor will meet resistance as it tries to increase the spin speed of the system and there will be movement of the reaction flywheel to counter this. At this point let the reaction motor freewheel.
4. As the spin axis of the gyroscopes is now aligned with the Reaction motor, precession has changed to what was the spin axis and the gyroscope motor can be used to brake the precession to a halt.
6. Both gyroscope rotors are now rotating about the reaction motor axis.
I called have this manipulation of momentum, Dark Motion. I have made other devices that demonstrate equal and opposite reactions as in the above with similar outcomes.
I am going to post this without further explanation at this point, to see what develops.
Ideally some model maker with an interest in science will duplicate the device. Or a mathematician may be able to model it. Or a computer program could be written. I do not have the skill set to do that.
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I made a complex, and hence a useful model
Complex does not mean correct.
The geocentric model of the Solar System was quite complex, with epicycles upon epicycles - but it wasn't really useful as it kept giving wrong predictions about the motion of the planets.
If you are trying to design something at a comparable level of mystery to Dark Energy and Dark Matter, we have a special section of the forum called New Theories.
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I did not say the model I posted is complex. If you read the post again you will see that the drawing refers to a simple model.
When manipulated as per instructions the model will create Angular Momentum. I do not claim this as a novel theory. It is a machine built for a specific purpose. I do not have your experience or status on this forum. I thought that a machine would best fit in Technology. If that is incorrect then perhaps it should be moved to a more acceptable place.
Moving it does not change its validity, or purpose.
It is not new science. The analysis of the machine can be carried out using the bog standard formulae from any good gyrodynamics textbook.
I am not trying to design something, I have designed and built something that works. I expressed the hope that this design could be built by others, or analysed by a Forum King.
The link that I see is that of anomalous motion, a better description for the actual observations of the phenomena of dark energy/matter.
Your observations on the complexity of medieval science are relevant to the current situation with Dark Matter and Dark energy.
I have posted the design of a simple device which will create Angular Momentum, It is the device and its operation I want to have analysed, preferably from an informed source.
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I did not say the model I posted is complex. If you read the post again you will see that the drawing refers to a simple model.
I don’t think @evan_au was specifically referring to your simple model.
The link that I see is that of anomalous motion.....
What do you see as being anomalous about the motion.
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Colin2B
The rotation of certain Galaxies is too fast when calculated using the observed matter and Conservation of Momentum. To explain this anomalous motion, Dark Matter was invented.
The universe is expanding too fast, to explain this anomalous motion, Dark Energy was invented.
As you can see when you analyse the motion of my model, I trust that you have done that, Momentum is created. That is also anomalous motion. I call it Dark Motion.
I notice that you have not commented on the Model itself. Is this because you have not understood how it works?
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I notice that you have not commented on the Model itself. Is this because you have not understood how it works?
I was less interested in how it works as why you consider the motion anomalous.
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I was less interested in how it works as why you consider the motion anomalous.
At least You have shown some interest, but no understanding. How is creating momentum anything other than anomalous?
I really need some help with this, some feedback.
This post has been treated like a challenge to intelligent Design. Conservation of Momentum is ordained and should not, make that cannot, be questioned. There is no evidence that will convince otherwise. To suggest it can be otherwise is Heretical.
Best way to treat a toxic post like mine is to ignore or trivialise. I got both.
The fact remains, the model works and I need help with Dark Motion.
It may be that I have underestimated the difficulty, the complexity of the model. That which I see as a very simple model may not appear so to others.
I did not go to university, I do not have a degree, I do not speak mathematics. I hesitate to give simplistic explanations for fear of being ridiculed.
So here is a simplistic explanation of this Dark Motion Model. Feel free to mock.
Take two pencils. Equal in length and weight, but opposite in colour. I will use red/blue. Place them side by side. Pointing in equal and opposite directions. Next, rotate each pencil through 90 degrees, rotate the red pencil clockwise, rotate the blue pencil widershins, that is do it in equal and opposite directions. They now both point in the same direction.
Spin and momentum are vector quantities. The pencils can be said to represent the spin/momentum of the gyroscopes in the Dark Motion model. It is trite but true that the counter-intuitive behaviour of a gyroscope is easily explained by saying “changing the vector of its momentum.”
The direction of the virtual vector sum of the precession spin and the gyroscope rotor spin is moved through 90 degrees by the sequential operation of the motors.
There is nothing about the construction or operation of the Dark Motion model that cannot be calculated by a competent design engineer. It is not some weird new exploitation of hitherto unknown and mysterious properties.
No new forces. Just a new understanding of the existing ones. Sir Isaac made a trivial error in framing the wording of “to every action”
May I finish with a further plea for help?
I have not mastered the art of inserting a picture. If there is mathematical member lurking out there who can translate my pencil example into proper physics diagrams with symbols, it would be much appreciated.
This is far to big and important for me to carry on with on my own. Please help. If you can see that I am mistaken tell me how the Dark Motion model will behave differently.
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1. Run the gyroscope motor to bring the gyroscope rotors up to a modest speed. As the rotors are are touching, they counter rotate. Equal and opposite. Now let the motor freewheel.
You've created a system with rotating parts but zero net angular momentum. Viewed as a black box, it will behave like a rock with the same mass. Net angular momentum is zero. It disturbs me to see those axle clamps in the picture, which allows external torque to be applied if the apparatus at any point would have otherwise twisted to the side. Better to consider the thing in space.
2. Run the reaction motor. This rotates the Gyroscopes about their precession axis, accompanied by equal and opposite torque orthogonal to the spin axis. There can be no torque exerted by the reaction motor along a precession axis, therefore no substantial movement of the reaction flywheel.
It is not labeled, but I presume the reaction motor is that grey thing that spins up the red wheel. Also not labeled is whatever you consider the precession axis. There is the one main axle in the whole setup which is the rotation axis of the red wheel. There is no precession axis
since there's only the motor producing spin and counterspin. So the red wheel spins one way, and the contraption to the left spins the other way. Still zero net angular momentum.
3. Increase the speed of precession until the precession axis changes to the spin axis.
You seem to think there is a precession axis that is different than the spin axis. There is only the latter. The contraption to the left acts as a whole as a rock, and thus does not precess. Internally, sure it does, but the precession forces produced by the wheels inside exactly cancel each other, putting significant internal stress on the bars and bearings and such, but exactly cancelling and so having no external effect. In other words, if you put a shroud around the yellow wheels and the thing was quiet enough, you'd not be able to tell by just holding it if the wheels were spinning or not. They won't resist any external change in orientation.
When this happens the reaction motor will meet resistance
The contraption to the left has a certain moment of inertia which is the same whether the yellow wheels are spinning or not. That moment serves as the reaction mass that counters the torque on the red wheel. If the red wheel has the same moment as the contraption, then the two will spin at equal and opposite rates, at any speed, whether or not the gyros inside are spinning.
If you spin it fast enough and the gyros have sufficient angular momentum, the internal stresses on the contraption will make it fly apart, but until then, the contraption as a whole acts like a rock.
4. As the spin axis of the gyroscopes is now aligned with the Reaction motor
The spin axis of the gyroscopes is always perpendicular to the spin of the reaction wheel. It is drawn that way and you're provided no mechanism where that can change without deformation of the parts. Unless we're all missing something and the picture just doesn't convey some hidden secrets or something.
I see no point in going on. You seem to be basing conclusions on the existence of a separate 'precession axis' which is allowed to change. There is no such axis, and the picture doesn't show one.
Both gyroscope rotors are now rotating about the reaction motor axis.
That they are, in equal and opposite directions. Net angular momentum is still zero. No anomaly. Class dismissed.
I am going to post this without further explanation at this point, to see what develops.
You're essentially planning not to answer questions is what you mean. Your replies have been really hostile towards requests for clarifications.
I'm watching your posts in David's topic and you seemingly have much to learn about angular momentum. There are direct replies pointing out your trivial errors, but you deny them, and then wonder why your mathematics comes up with supposed anomalies. It doesn't if you do it correctly.
For instance, you say "For angular momentum to be conserved the tangential velocity [of a ball on a string] must remain constant. " which is just wrong. If radius is shortened (such as the skater pulling her limbs in), the tangential velocity must go up to maintain constant angular momentum. L=rmv, making it a function of radius, not just speed. This was pointed out in the first reply to your post there, and you ignored it. You don't seem to want the help that you ask for.
Ideally some model maker with an interest in science will duplicate the device.
Why? It is uninteresting. Ideally, you will realize that a conclusion of angular momentum being created in a closed system implies that you've made an error somewhere. Be open to that possibility.
You have shown some interest, but no understanding. How is creating momentum anything other than anomalous?
It would be anomalous. Your device doesn't do that. Only your assertions do.
I really need some help with this, some feedback.
You seem to be ignoring the help in the other thread. Are you going to listen to it here?
This post has been treated like a challenge to intelligent Design. Conservation of Momentum is ordained and should not, make that cannot, be questioned. There is no evidence that will convince otherwise. To suggest it can be otherwise is Heretical.
All the trolls say that. But the math does not bear out your description.
The fact remains, the model works and I need help with Dark Motion.
Angular momentum is conserved with your model. I don't see any computations, so I don't see how you figure it works, but you describe a precession axis which just plain doesn't exist. The left part does not precess at all since it has no net angular momentum.
I did not go to university, I do not have a degree, I do not speak mathematics.
And yet when you make a mistake, you assume it is with the people who do have the degree and speak mathematics. Consider the possibility that this thing which you've not actually built behaves differently than what you imagine it does.
I hesitate to give simplistic explanations for fear of being ridiculed.
You're not being ridiculed, except possibly for being completely closed to the feedback you asked for.
Take two pencils. Equal in length and weight, but opposite in colour. I will use red/blue. Place them side by side. Pointing in equal and opposite directions. Next, rotate each pencil through 90 degrees, rotate the red pencil clockwise, rotate the blue pencil widershins, that is do it in equal and opposite directions. They now both point in the same direction.
I learned a new word today. Thanks!
Spin and momentum are vector quantities.
Angular momentum in this case. Both momentum and angular momentum are vector quantities, yes, but they're different things and separately conserved.
The pencils can be said to represent the spin/momentum of the gyroscopes in the Dark Motion model. It is trite but true that the counter-intuitive behaviour of a gyroscope is easily explained by saying “changing the vector of its momentum.”
But add the vectors of the two pencils. They add up to zero, so the system has zero angular momentum.
The direction of the virtual vector sum of the precession spin and the gyroscope rotor spin is moved through 90 degrees by the sequential operation of the motors.
An object with zero angular momentum doesn't have a direction to it, so it cannot be rotated or precessed meaningfully.
Just a new understanding of the existing ones. Sir Isaac made a trivial error in framing the wording of “to every action”
More likely a misunderstanding of the existing ones by you. When I consider a model and find some violation of a conservation law, my first reaction is to assume I've made a mistake, and not a mistake with a law that has withstood centuries of verification.
If you can see that I am mistaken tell me how the Dark Motion model will behave differently.
I did above. No momentum is created if the forces are kept internal. When you brake all the wheels, there will be no remaining net rotation of the thing. There is no 'dark motion'.
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I learned a new word today. Thanks!
Ah, widdershins. Obsolete, but very useful for taking the lefthand way around a bonfire, or stirring a concoction on Walpurgisnacht.
You have shown some interest, but no understanding. How is creating momentum anything other than anomalous?
It would be anomalous. Your device doesn't do that. Only your assertions do.
When I was assessed as having no understanding, I realised nothing I could say would be heard, so dropped out.
Like you I saw the anomalies in the ‘precession axis’ and in the overall description of the so called anomalous motion, but as you say, neither of those are correct.i
Will you be listened to??
A video of the device would be good.
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Halc
Thank you for your detailed analysis of my Tandem Rotor device.
It does sound much more complicated than I had assumed it to be.
My big problem is that I have a device which works. I thought that I had figured out how it works, which is why I posted.
You've created a system with rotating parts but zero net angular momentum
So far so good, we are in agreement. The “Axle clamps” are in fact pillow block bearings It is OK to “consider the thing in space.”
There is no precession axis
A gyroscope has 3 orthogonal axes. They are the spin axis, at right angles to this is the torque axis and orthogonal to both is the precession axis.
To translate this to the model the spin axis is the left to right axis, the torque axis is the vertical axis the precession axis is the one that is left, the one main axle in the whole setup which is the rotation axis of the red wheel.
So that is the set up. Two contra rotating gyroscopes, producing equal and opposite torques and precessing about the main axis of the red wheel.
Precession/torque in a gyroscope is instantaneous. Applying precession to a gyroscope along an axis at right angles to the spin axis the same thing as applying torque at the other, orthogonal axis. Its counter intuitive, but that is what a gyroscope does.
So with the model, there is no torque present to be reacted by the red Flywheel. The rotation of “the contraption” is driven by the gyroscope torque reacted within the frame.
Since this description varies radically from the one that you propose and leads to a different outcome. I ask for your comment before continuing.
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It does sound much more complicated than I had assumed it to be.
It's actually more simple than you assume it to be. The yellow wheels have no net angular momentum so they’re effectively just mass, making it a trivial system.
My big problem is that I have a device which works. I thought that I had figured out how it works, which is why I posted.
Maybe then a short video clip of the device in action.
Those pillow block bearings are not frictionless, so they’ll contribute external torque to the entire device. But I take it you claim that the device behaves differently with the yellow wheels spinning than if not.
A gyroscope has 3 orthogonal axes. They are the spin axis, at right angles to this is the torque axis and orthogonal to both is the precession axis.
To translate this to the model the spin axis is the left to right axis, the torque axis is the vertical axis the precession axis is the one that is left
Left to right is the spin axis of the red wheel, the main rod held by the bearings. The torque axis of that wheel is the same axis, and so the precession axis is as well. All three are the same, so it shouldn't precess since there is no orthogonal torque applied to it.
The spin axis of the yellow wheel is not fixed since you intend to spin the device. Most of the torque applied to each yellow wheel will come from the other.
Your description here of these three fixed-direction axes contradicts your OP where you imply that the precession axis slowly changes as the red wheel speeds up. That makes no sense to me, so not sure what you mean by those words.
So that is the set up. Two contra rotating gyroscopes, producing equal and opposite torques and precessing about the main axis of the red wheel.
If they produce equal and opposite torques, they don’t precess at all. That was my point. No net torque, so no precession.
Similarly, a classic wheel spinning at the end of a rod will precess and not fall, but two wheels spinning in opposite directions on the end of the rod will fall like they’re not spinning at all. The first case would violate a-m conservation if it fell, but the latter does not.
So with the model, there is no torque present to be reacted by the red Flywheel.
Yes there is. The device on the left has a moment of inertia, wheels inside spinning or not. It is that moment of inertia that takes the reaction torque from the red wheel spinning up. If the rest of the device had zero moment, the red wheel could not spin at all, having nothing against which it can apply torque.
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Those pillow block bearings are not frictionless, so they’ll contribute external torque to the entire device.
As @Halc says these are not frictionless. Friction is a major problem with gyroscope models as the theory assumes zero friction. Your ball races with cages and lubricants is enough to provide external torque so not behaving as free space. Most toy gyros have cone/cup bearings to reduce friction, but these are unlikely to be able to take the load you are creating, ceramic unlubricated, or graphite composite bearings might give less friction.
A gyroscope has 3 orthogonal axes. They are the spin axis, at right angles to this is the torque axis and orthogonal to both is the precession axis.
To translate this to the model the spin axis is the left to right axis, the torque axis is the vertical axis the precession axis is the one that is left
Left to right is the spin axis of the red wheel, the main rod held by the bearings. The torque axis of that wheel is the same axis, and so the precession axis is as well. All three are the same, so it shouldn't precess since there is no orthogonal torque applied to it.
The spin axis of the yellow wheel is not fixed since you intend to spin the device. Most of the torque applied to each yellow wheel will come from the other.
Your description here of these three fixed-direction axes contradicts your OP where you imply that the precession axis slowly changes as the red wheel speeds up. That makes no sense to me, so not sure what you mean by those words.
To add to what @Halc says
If the yellow wheels are fixed flywheels, and assuming only one exists, then turning the reaction motor axis would cause the yellow wheel to try to precess perpendicular to both the gyro axis and the reaction axis. This is the only precession axis in the model and it is not the reaction motor axis. Again, if the other yellow gyroscope were the only yellow wheel it would try to precess in the opposite direction. As @Halc says the two together produce considerable stress on the frame.
So your comment “So that is the set up. Two contra rotating gyroscopes, producing equal and opposite torques and precessing about the main axis of the red wheel” is incorrect as they would not try to precess around the reaction axis (main axis of the red wheel).
The assembly of the reaction motor and reaction flywheel is unclear. I had assumed the motor frame is fixed to the flywheel and the rotor shaft to the gyro frame. Have you measured the moments of inertia of the flywheel and the gyro frame? If the gyro frame is less than the flywheel it will turn with only small movement of the flywheel until at higher speed the flywheel will begin to turn.
I have to ask again, why do you think the motion of this assembly is anomalous.
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The assembly of the reaction motor and reaction flywheel is unclear. I had assumed the motor frame is fixed to the flywheel and the rotor shaft to the gyro frame.
Does it matter? All that seems to matter is the moment of the part that turns one way vs the moment of the part that turns the other way, and even then it doesn't matter since we're not comparing the number of revolutions of each.
Related: Most prop airplanes put the propeller on the engine shaft, but the Sopwith Camel used a rotary engine with the shaft mounted to the chassis, giving considerable angular momentum to it, resulting in gyroscopic effects that made it difficult to steer.
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Does it matter?
Just helps with my lack of understanding ;)
As an aside, I wonder what techniques the OP has used to measure all the angular momenta and all the energy inputs/outputs.
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Tooth abscess, very painful, has kept me quiet for a few days. Thanks to modern antibiotics I am functioning again.
I find myself not where I want to be. The postings are “I'm right, no I'm right”. Repeating the same thing, louder. That does not work in real life, not going to work here either.
But this is not a political debate where the most skilful orator would prevail. No alternative facts.
It is a machine.
There is a point at which the views diverge. I will try to find that point.
Starting with a tower gyroscope, children's toy. Set it in motion and it does not tumble over, it rotates, defying gravity hooray.
I can use it to illustrate some points which are relevant to how I think the machine works.
The orthogonal axes are internally referenced, as the spin axis revolves about the tower, so does torque and precession, always orthogonal
Gyroscope Spin has a vector, precession spin has a vector. The vector sum is is a resultant spin axis between the spin axis and the precession axis.
The model has twin rotors so we need to modify the toy to have two gyroscopes, hinged either side of a central pole. This demonstrates that with equal and opposite gravity torque and gyroscope spin direction both precess in the same direction.
The rotors in the model are constrained by the frame so that they only have two freedoms of movement. Locking the hinges of the toy gives the same result.
When a torque is applied to the vertical axis of the toy, the gyroscopes respond by precessing at right angles to the applied torque. This motion is prevented by the locked hinges. A reaction torque results which precesses the twin gyroscopes about the vertical axis. This is an instantaneous reaction.
This appears to remove the inertia of the gyroscopes. As any attempt to apply a torque about the vertical axis is instantaneously reacted by the gyroscopes as precession about the vertical axis. Counter intuitive, which is the source of false claims that “gyroscopes become weightless”
I think that I will pause my explanation at this point, because this may well be where Halc’s view is different.
So the red wheel spins one way, and the contraption to the left spins the other way. Still zero net angular momentum.
To relate the toy to the model, the axis of the red wheel corresponds to the vertical axis of the toy. The motor shaft is attempting to apply torque to the frame to turn the spinning gyroscopes. The toy demonstrates that there cannot be a torque along that axis. Therefore no reaction torque, no movement of the red reaction flywheel.
In the real world, there is some rotation of the red wheel. Bearing rolling resistance must be overcome just for a start and the frame has inertia.
More in my next post.
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Tooth abscess, very painful, has kept me quiet for a few days.
Well that bites. Good to hear you are functional again.
The orthogonal axes are internally referenced, as the spin axis revolves about the tower, so does torque and precession, always orthogonal
We already diverge, because those axes are not always orthogonal. I spin up a dreidel and it is close to vertical on my table, but not quite. The spin axis and precession axis are only 14° different. OK, the torque axis is perpendicular to the precession axis in this case, but not to the spin axis.
I will acknowledge from your drawing that you've set up a device where these forces are orthogonal. I'm just saying that it need not be built that way, so this blanket statement implying that they must be orthogonal simply isn't true.
Gyroscope Spin has a vector, precession spin has a vector. The vector sum is is a resultant spin axis between the spin axis and the precession axis.
They're different things, so not sure why you'd want to add those two vectors, but OK. Your device (as a whole or as a half) lacks angular momentum and thus does not precess, so there is no precession axis or precession vector. The child's gyroscope and the dreidel both do have angular momentum and thus do precess due to the torque exerted by gravity.
The model has twin rotors so we need to modify the toy to have two gyroscopes, hinged either side of a central pole. This demonstrates that with equal and opposite gravity torque and gyroscope spin direction both precess in the same direction.
Good example of a system with zero angular momentum that nevertheless precesses. But change it to one common axle (instead of two independent gyros whose axles coincidentally line up) and the thing will not precess. Do you see the difference?
Closer to your device: Picture two independent gyros on opposite sides of the same tower, but with identical spin vectors this time. Left alone, they precess in opposite directions, but we instead constrain that motion via a barrier connected to the tower. Each gyro now exerts precession pressure on that barrier, but cannot move. Nothing precesses. This adds stress to the barrier, but no net force or net torque, and thus no motion. The wheels spin without any precession. That's closer to what's going on in your device, where the precession is constrained by having both ends of the yellow spin axles constrained, resulting in equal and opposites stresses that cancel any precession.
The rotors in the model are constrained by the frame so that they only have two freedoms of movement.
Locking the hinges of the toy gives the same result.
Not sure what your toy looks like. I picture a top leaning to the side of a tower upon which it rests, or just a top on a table.
When a torque is applied to the vertical axis of the toy, the gyroscopes respond by precessing at right angles to the applied torque.
You mean the gyro moves up and down? I've not seen many toys that work with torque being applied vertically like that. Usually the torque is supplied by gravity, which can only result in torque along a horizonal axis, resulting in precession along the vertical axis. Maybe a link showing such a toy would help me visualize what you have in mind. Unclear where the hinges are and what motion is allowed/prevented when locked and not locked. Don't say vertical. Say up or down, since that tells me which way the torque vector points.
This appears to remove the inertia of the gyroscopes. As any attempt to apply a torque about the vertical axis is instantaneously reacted by the gyroscopes as precession about the vertical axis.
You're contradicting yourself now. You said the torque and precession axes are orthogonal, but here you have them both vertical, which is parallel. A vertical torque cannot produce vertical precession, only a change to vertical angular momentum.
Counter intuitive, which is the source of false claims that “gyroscopes become weightless”
Of course that's wrong and not even intuitive. I've seen heavy ones, and they're definitely not weightless when spinning. If it weighs 100 newtons stationary, it weighs 100 newtons while spinning. If the weight changed, you could get cargo into space easier by spinning it first.
I think that I will pause my explanation at this point, because this may well be where Halc’s view is different.
You haven't really said much with which I disagree except the reaction to vertical torque.
Your model depicted in the OP runs on these bearings which have friction in real life, so torque is applied through these bearings and you cannot expect the device to retain its angular momentum of zero. That's why I envisioned the device in space with no external forces possible. It can have all the internal friction it wants up there, and it isn't going to gain any momentum from it.
To relate the toy to the model, the axis of the red wheel corresponds to the vertical axis of the toy.
OK, so you are putting the equivalent of vertical torque on it, but the yellow wheels to not precess in the same direction as the torque like you assert. One is spinning east and the other west and they are constrained from precession, so there is no precession of the yellow wheels. The two wheels attempt to precess, but the frame holding them prevents it, and those forces are equal and opposite, so there is no effect: no resistance other than the same regular angular moment that it had when nothing was spinning.
I don't know what your toy looks like, but if precession is constrained, then there will be no precession, just spin without resistance.
The motor shaft is attempting to apply torque to the frame to turn the spinning gyroscopes. The toy demonstrates that there cannot be a torque along that axis.
You can apply torque along any axis you like, so not sure what you mean by this statement.
Therefore no reaction torque, no movement of the red reaction flywheel.
You're saying the red wheel stays stationary when you turn on its motor? That can't be right. It would violate angular momentum conservation to spin one side and not the other in an equal and opposite way.
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Hi Halc
For me today's new thing is Dreidel. But I am familiar with spinning tops, so I can see your point clearly. The precession axis and the spin axis of a nearly vertical spinning top are not orthogonal. I have no explanation for this. Spinning tops are complex beasts and usually have several chapters devoted to their behaviours in most text books.
The orthogonal nature of the gyroscope is the orthodox view. It is not my idea. When you work from first principles using the laws of motion, you get orthogonal spin precession and torque.
Your example is however quite compelling, so I checked. It has not changed. My memory is not at fault, although it is a long time since I first looked at Professor Leonard Maunder’s 400 page tome on Gyrodynamics. I do not know how to reconcile your example with the standard view of gyroscope behaviuor.
so this blanket statement implying that they must be orthogonal simply isn't true.
No
orthogonal rules!!!
May I suggest you check your own gyro-dynamics reference work?
Good example of a system with zero angular momentum that nevertheless precesses. But change it to one common axle (instead of two independent gyros whose axles coincidentally line up) and the thing will not precess. Do you see the difference?
Zero angular momentum describes a system where the wheels are not spinning. No net angular momentum describes a system where the wheels are contra rotating. I see that as the difference. There is kinetic energy stored as as angular momentum in a gyroscope, two contra rotating gyroscopes would store twice the energy. So must have twice something that the static, zero momentum system does not have. A spinning wheel reacts torque in a different way.
One common axle is an accurate portrayal of the “toy” and it will sit with contra spinning rotors without precessing. Now you intervene to change that state. You turn the vertical shaft, and note the effort required to turn it.
When you turn the vertical axis, the motion that results is precession, by definition of what a gyroscope is, also it is accompanied by an instantaneous torque, again because it is a gyroscope.
Nothing happens until you try to turn it, then it reacts as a gyroscope must, it produces orthogonal torque and precession. From the direction you turn it, the torque will try to bend the bar either up or down. The faster you turn it, the greater the orthogonal torque, the greater the speed of precession.
Your intervention does not apply torque to the vertical shaft. It precesses the twin gyroscopes.
Your subsequent points in your post are all affected by this. I shall refrain from detailed analysis as I shall only be repeating myself.
The motor shaft is attempting to apply torque to the frame to turn the spinning gyroscopes. The toy demonstrates that there cannot be a torque along that axis.
You can apply torque along any axis you like, so not sure what you mean by this statement.
Torque can only be applied where there is an equal and opposite torque to react the torque you are determined to apply. The stubborn nut gives way suddenly and you bark your knuckles. You tried to apply a torque along an axis you liked. In the example I gave there is no reaction torque along the red axis. It is the absolute nature of a gyroscope that it reacts torque at right angles to the precession axis.
You're saying the red wheel stays stationary when you turn on its motor? That can't be right. It would violate angular momentum conservation to spin one side and not the other in an equal and opposite way.
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I am saying that if you do this, then that is what happens. I give my reasons, couched as best I can using orthodox, standard, accepted, laws of motion.
Yes the Frame is spinning and the red wheel is not, but if you try to harvest the stored momentum by reversing the red wheel motor, you will simply stop the precession of the rotors in the frame. And return to two rotors contra-rotating, all as before.
You need to progress on to the two pencil vector part of my post to see how the angular momentum can be harvested.
Which if you have followed so far I will repeat in my next post.
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Zero angular momentum describes a system where the wheels are not spinning. No net angular momentum describes a system where the wheels are contra rotating. I see that as the difference.
OK then, you have that system with two opposite spinning wheels like you describe. Your toy apparently has this. How much angular momentum does the system have? Because I don’t see that as a difference. This seems to be the root of your problem: that you cannot add.
There is kinetic energy stored as as angular momentum in a gyroscope
Momentum is not energy, so this cannot be correct. There is kinetic energy in the gyroscope, but it isn’t stored as momentum, angular or otherwise. This continued equivocation of the two is causing you to make all sorts of nonsense statements like this.
So must have twice something that the static, zero momentum system does not have.
Both have zero momentum. It the spinning one doesn’t have just twice the kinetic energy, because the other one has zero kinetic energy, and nonzero is more than twice zero.
One common axle is an accurate portrayal of the “toy” and it will sit with contra spinning rotors without precessing. Now you intervene to change that state. You turn the vertical shaft, and note the effort required to turn it.
This description violates conservation of angular momentum.
When I was assessed as having no understanding, I realised nothing I could say would be heard, so dropped out.
Considering it. Trying to pare down the text to the critical mistakes.
Will you be listened to??
Nope. Not unexpected actually.
He seems to be in it for the view count, not for learning anything.
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To add to what @Halc says
If the yellow wheels are fixed flywheels, and assuming only one exists, then turning the reaction motor axis would cause the yellow wheel to try to precess perpendicular to both the gyro axis and the reaction axis. This is the only precession axis in the model and it is not the reaction motor axis. Again, if the other yellow gyroscope were the only yellow wheel it would try to precess in the opposite direction. As @Halc says the two together produce considerable stress on the frame.
So your comment “So that is the set up. Two contra rotating gyroscopes, producing equal and opposite torques and precessing about the main axis of the red wheel” is incorrect as they would not try to precess around the reaction axis (main axis of the red wheel).
The stress in the frame is due to equal and opposite gyroscope couples, orthogonal to precession. The reaction motor axis becomes the precession axis. The spin axis and couple axis maintain their orthogonal relationship as the device rotates.
When the reaction motor is switched on, the device rotates about the reaction motor axis. As you would expect. It is what happens. Out there in the real world.
A gyroscope that is rotating about one orthogonal axis produces a couple at the other axis.
@Halc
Thank you for keeping this thread alive. 800+ views, there was always the chance that someone who has an understanding of gyroscope behaviour was looking in.
Both have zero momentum. It the spinning one doesn’t have just twice the kinetic energy, because the other one has zero kinetic energy, and nonzero is more than twice zero.
Difficult to argue with that!!!!
One common axle is an accurate portrayal of the “toy” and it will sit with contra spinning rotors without precessing. Now you intervene to change that state. You turn the vertical shaft, and note the effort required to turn it.
This description violates conservation of angular momentum.
Even more difficult to see !
Mod edit: Fixed embedded quote
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If a gyroscope is rotating about any axis, other than the spin axis, then that is precession and Orthogonal to that axis is the couple.
For clarity, let the red axis be along the red flywheel axis, The yellow axis is the gyro axis and the blue axis is orthogonal to these. In the model the red axis does not move, the yellow and the blue axes move but remain orthogonal to red.
In the model we have forced precession along the red axis, with equal and opposite torque about the blue axis and spin about the yellow axis. This is the starting condition.
The spinning gyroscope rotor is forced to precess about the red axis as that is the only axis that permits rotation orthogonal to the yellow, gyroscope spin axis. This simultaneously induces a torque about the other orthogonal axis, the Blue axis.
When the frame containing the spinning gyroscopes is rotated by the red motor, That rotation induces an orthogonal couple at the blue axis. As the spin of the gyroscopes are equal and opposite, these torques, induced by the precession about the red axis are equal and opposite.
This is the condition you describe in your early experiments with bicycle wheels. The two torques were still there in your manipulation of the counter rotating bicycle wheels, but as they were balanced, they had no external effect. The torque did not disappear. No external torque does not mean the same thing as a balanced internal torque. Because you could not longer feel the torque generated by the wheels does not mean it was not present.
I will bang on about this some more. Take a bicycle, with the frame securely clamped to hold it off the ground. With the front wheel not spinning move the handle bars. There will be some slight resistance due to the inertia of the wheel about the vertical axis, but not very much.
Now as you have already guessed, spin the wheel and do it again, move the handlebars. It feels much the same. However you know, from previous experience that is not the same, there is a torque being reacted by the forks supporting the front wheel. If your clamps are loose, the frame will move.
My conclusion.
The conditions for the flywheels to act as gyroscopes are fulfilled. A spin axis of the rotor, Yellow, A torque axis, Blue and a precession axis, Red.
Momentus
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This is a machine. It is indisputable that by judicious manipulation of the two motors the gyroscopes can be spun up to speed about the yellow axis and set freewheeling and the frame can be rotated about the red axis.
Now take one of the gyroscopes, it is rotating about two separate axes. The yellow axis, and the red axis at the same time. The angular velocity diagram shows these two simultaneous rotations.
A similar diagram is drawn for the other contra rotating gyroscope.
Assuming a spherical gyroscope rotor the polar moment of inertia will be the same for spin about OxA, OxC, OxD and OxB as they all pass through the centre of the sphere.
If Ω is the spin speed of the gyroscope at the start, then the angular momentum is I Ω
Precessing a gyroscope does not change the magnitude of its angular momentum. The torque is reacted by the changing direction of the angular momentum.
The direction of the angular momentum is the vector sum of the two rotations. The magnitude has not been altered by the application of the torque at the blue axis, only the direction.
Thus in the diagram OxC shows the angular momentum as the frame precesses about the red axis at low speed.
OxD is the point at which speed of precession is equal to spin sped and is the limit where increasing the precession speed will change the direction of the resultant angular momentum.
OxE shows the angular momentum as the frame precesses about the yellow axis at low speed.
Diagram of Angular momentum
By manipulating the speed of the two motors, the direction of the angular momentum can be moved through 90 degrees.
The vector sum of the initial angular momentum of the system is null.
The vector sum of the final angular momentum of the system is positive.
Further posting will follow. I am off now to watch a recording of the Northampton Saints Rugby match. Come on you Saints.
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If a gyroscope is rotating about any axis, other than the spin axis, then that is precession and Orthogonal to that axis is the couple.
I'm fine with those terms. The term couple is not always used, but yes, it seems always orthogonal to the precession axis. It is also orthogonal to the spin axis in your model, but that is just because you set it up that way. It need not be at all.
For clarity, let the red axis be along the red flywheel axis, The yellow axis is the gyro axis and the blue axis is orthogonal to these. In the model the red axis does not move, the yellow and the blue axes move but remain orthogonal to red.
These differ from the picture in the OP, but I like these better.
The description is incomplete. Which way is positive for each? A coordinate system is less useful if no designation is made as to which way is positive.
I'll choose if you don't mind: Red is positive to the right where the flywheel is. Yellow is positive to the upper-right (as per OP picture). The yellow gyro near to the flywheel (which I will call gN) has positive spin, and the far gyro (gF) has negative spin. As for the couple, positive is up when the spin is oriented as per the picture. Yes, both these two precess around, so not permanently in any one direction.
In the model we have forced precession along the red axis, with equal and opposite torque about the blue axis and spin about the yellow axis. This is the starting condition.
You need to identify the components so we can talk about them clearly. Each yellow wheel is a gyro, designated gF and gN respectively. The device is in two halves which consists of the assembly A and the red flywheel R, both of which spin along the red axis, with say R having positive spin and A having negative spin. Finally there is the entire system S which is A and R combined. S is suspended in a 3-gimbal that allows free rotation in any axis, and thus prevents any external torque from being applied to S though the bearings that hold the main shaft. The angular momentum of S thus always remains zero, and the device stays put.
Part of the problem with this post is the absence of identification of component being discussed.
The spinning gyroscope rotor is forced to precess about the red axis as that is the only axis that permits rotation
Each gyro gF and gN is now free to precesss any way physics says it will. I've purposely freed the system from any restraints that prevent motion in directions other than the red axis. So if it doesn't rotate, then it is because nothing is attempting to rotate on the other axes, not because of any restraints. The scenario hasn't changed since I assert that no such motion will occur. If a gryo precesses, then there must be a torque being applied to it along the couple, which is not the red axis since that's the precession axis.
This simultaneously induces a torque about the other orthogonal axis, the Blue axis.
Yes, that's the only torque, the reaction torque to the torque being applied to each gyro. Blue is the couple.
When the frame containing the spinning gyroscopes is rotated by the red motor,
This is what I'm calling assembly 'A'. The red motor only serves to change the angular momentum of A from zero to nonzero. We can assume that the moment of A is the same as the moment of R (whether the gyros are spinning or not), and thus they spin at equal but opposite directions, all without help of the motor which is only used to change the spin, not to maintain it. So in steady state, there is no torque exerted along the red axis.
That rotation induces an orthogonal couple at the blue axis.
It induces an orthogonal couple on gN and gF, but not on A. This is what I mean by you switching objects without identifying them. Label your objects, or your statement becomes meaningless. The spin on A along the red axis does not induce an orthogonal couple on A because there is no torque on the red axis and thus no precession of A. Your statement seems to imply there is one, but lacking precise language, it is simply ambiguous.
As the spin of the gyroscopes are equal and opposite, these torques, induced by the precession about the red axis are equal and opposite.
Fine. This statement identifies the gyros gN and gF, and not the frame A. I agree with this.
My conclusion.
The conditions for the flywheels to act as gyroscopes are fulfilled. A spin axis of the rotor, Yellow, A torque axis, Blue and a precession axis, Red.
We're all still wondering what 'anomalous motion' is being asserted on top of this description, with which I do not disagree. The thread is entitled 'dark motion', yet no dark motion has been identified.
This is a machine. It is indisputable that by judicious manipulation of the two motors the gyroscopes can be spun up to speed about the yellow axis and set freewheeling and the frame can be rotated about the red axis.
With the frame also set freewheeling, yes. In a frictionless environment, all motors serve only to change the spin rates, not to maintain them.
Now take one of the gyroscopes, it is rotating about two separate axes. The yellow axis, and the red axis at the same time.
No, it is rotating only about yellow axis. Precession is not rotation. The former is the product of the angular momentum of the gyro. The latter is the product of a change in angular momentum, and that requires continuous external application of torque.
The angular velocity diagram shows these two simultaneous rotations.
A spin vector and a precession vector are thus different units and cannot be directly added or compared as you are doing in your diagram. The black vectors are meaningless. Your diagram also shows a dotted circle of constant magnitude which seems to imply that the magnitude of the precession angular velocity must be identical to the spin angular velocity, which is untrue. The precession angular velocity is purely a function (in this case) of how much spin the red motor happens to put on A, which you describe below as 'low speed', contradicting your diagram.
If Ω is the spin speed of the gyroscope at the start, then the angular momentum is I Ω
Ah good. A number. If gN has an angular momentum of I Ω, then gF has an angular momentum of -I Ω. Let's say the frame assembly A has an angular moment of 3 (two for the pair of spheres, and 1 more for the frame mechanism), and the red flywheel thus also has a moment of 3. We've not designated a symbol for the angular velocity of R or A.
The direction of the angular momentum is the vector sum of the two rotations.
The direction the angular momentum is by definition that of the one spin rotation, so this statement is wrong. You cannot add a momentum vector to a torque/precession vector any more than it is meaningful to add velocity to acceleration. Different units.
The rest of your post seems to depend on this invalid mathematics, and is thus wrong.
The vector sum of the initial angular momentum of the system is null.
There is only one system, and its angular momentum is always zero, and there are no other vectors to add to it. It would be more correct to say that the vector sum of the angular momentum of the various components of the system S is null. The components definitely do have angular momentum, but since S is an isolated system, the angular moment of S cannot change from zero.
The vector sum of the final angular momentum of the system is positive.
Well, given all the invalid addition of vectors of different units, perhaps you came to that conclusion. If so, positive in which direction, and you need to show this without the invalid mathematics. Only add vectors of the same units.
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Dear Halc,
Could you please further elaborate on your statement below:
Precession is not rotation.
I would say, precession is a process, that manifests itself as a rotation. Vaguely formulated.
At the end one will see a rotation about an axis different than the axis of spin.
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With a light frame and heavy spherical gyroscopes spinning in equal and opposite directions
Scenario 1) Viewed as a black box, it will behave like a rock with the same mass. Net angular momentum is zero.
Start the motor on the red axis. . So the red wheel spins one way, and the contraption to the left spins the other way. Still zero net angular momentum.
Nope. At the end, one will see a continuous change in the axis of spin, which is mandated by the change in the angular momentum resulting from the continuous applied torque. But the gyro always has only one axis of spin, and one rate at which it is spinning on that axis. If at any point in time the torque is removed, it will remain spinning only about that one axis.
So let us do just that. Remove the torque. Stop the rotation of the yellow mass about the red axis.
The Red flywheel continues to rotate. The contraption does not.
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Scenario 2
1. Run the gyroscope motor to bring the gyroscope rotors up to a modest speed. As the rotors are are touching, they counter rotate. Equal and opposite. Now let the motor freewheel.
2. Run the reaction motor. This rotates the Gyroscopes about their precession axis, accompanied by equal and opposite torque orthogonal to the spin axis. There can be no torque exerted by the reaction motor along a precession axis, therefore no substantial movement of the reaction flywheel.
Remove the Torque. Gyroscopes stop precessing. Back to square one.
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So let us do just that. Remove the torque. Stop the rotation of the yellow mass about the red axis.
The Red flywheel continues to rotate. The contraption does not.
This comment shows a complete lack of understanding of rotation and momentum.
If assembly A (what you're calling the yellow mass) is spinning about the red axis, then its angular momentum vector is along said red axis, and with any external torque removed, it must continue to spin, not stop (in complete violation of conservation laws). Your assertion otherwise shows said lack of understanding. Its angular momentum cannot just vanish. It's a conserved quantity. It has to go somewhere.
It would require external torque on it to stop it, and of course this would also stop the red wheel, which always has equal and opposite angular momentum of assembly A.
Scenario 2
1. Run the gyroscope motor to bring the gyroscope rotors up to a modest speed. As the rotors are are touching, they counter rotate. Equal and opposite. Now let the motor freewheel.
2. Run the reaction motor. This rotates the Gyroscopes about their precession axis, accompanied by equal and opposite torque orthogonal to the spin axis. There can be no torque exerted by the reaction motor along a precession axis, therefore no substantial movement of the reaction flywheel.
Remove the Torque. Gyroscopes stop precessing.
Unclear description. Remove what torque? The torque from the reaction motor isn't attached to any gyroscope, it is attached to assembly A and the wheel R, so it gives those two things equal and opposite angular momentum, and thus both must spin, contradicting your assertion above which is in direct violation of Newton's 3rd law.
That motor applies no torque to either gyroscope gN and gF, as evidenced by the fact that neither precesses around an axis perpendicular to the torque along the red axis. The reaction motor thus exerts torque only against the identical (arbitrary designation) moments of the wheel R and assembly A, which is the same whether the gyros within are spinning or not since the angular momentum of A is unaffected by the gyros spinning or not.
Yes, there is torque exerted on each gyro, but not along the red axis, so the reaction motor does not contribute to it.
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Forced Precession. Or Induced torque.
Tb=JΩyΩr
Tb is the torque at the blue axis in Nm
Ωy is the angular velocity about the yellow axis in rad/sec Gyroscope spin
Ωr is the angular velocity about the red axis in rad/sec Precession
Consider one gyroscope spinning about the yellow axis. Apply a torque at the blue axis, it will rotate about the red axis in a clockwise direction.
Consider the other gyroscope spinning about the yellow axis in the opposite direction. Apply a torque at the blue axis, again in the opposite direction, it will rotate about the red axis in a clockwise direction.
Put the gyroscopes in a frame and repeat the exercise, applying torque at the blue axis etc. They will rotate about the red axis in perfect harmony, precessed by the blue opposite torques. The Red flywheel plays no part, remains unmoved. The net angular momentum has not changed, it is still null
Everybody happy? Take a video. Go to lunch
Next spin gyroscopes as before and rotate them about the red axis, using the Red Reaction flywheel, at exactly the same precession speed as before. The net angular momentum has not changed, it is still null. Take a video. You already had lunch.
What is the physical difference in the speed and torque between the two cases? What motion or force is there in the first case that is not identical in the second case?
There is no difference. The speeds of the gyroscopes are the same, the torques are the same and the precession speed is the same.
Shown the video, how to tell the difference? So what did the red flywheel do? There is no difference in the net angular momentum of the system in either case, so it did the same thing in both cases, nothing.
Run the reaction motor. This rotates the Gyroscopes about their precession axis, accompanied by equal and opposite torque orthogonal to the spin axis. There can be no torque exerted by the reaction motor along a precession axis, therefore no substantial movement of the reaction flywheel.
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is comment shows a complete lack of understanding of rotation and momentum.
If assembly A (what you're calling the yellow mass) is spinning about the red axis, then its angular momentum vector is along said red axis, and with any external torque removed, it must continue to spin, not stop (in complete violation of conservation laws). Your assertion otherwise shows said lack of understanding. Its angular momentum cannot just vanish. It's a conserved quantity. It has to go somewhere.
I am pointing out the inconsistency I see in your definition of precession as being a different form of rotation.
Quoting Conservancy laws. You have missed the entire point of my thread.
If I may try to see what you are saying. I observe the contraption rotating about the red axis, it is either spinning or precessing and these are different.
If it is precessing that is because I am exerting equal and opposite torques about the blue axis. It is rotating about the red axis and that is precession.
If it is spinning, that is because the equal and opposite torques are being generated by rotating it about the red axis with an external torque. It is rotating about the red axis and that is spinning.
No I have got that wrong. There cannot be an external torque spinning it, that would increase the spin speed over time. Inertia?
To calculate Gyroscope torque There is a formula. The angular velocity of the Gyroscope is given as rads/sec. The precession is also given in rads/sec. Same units? Can multiply spin by precession? Maybe even vector sum angular velocity when expressed as rads/sec?
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Dear Halc,
for me, rotation is a kinematic quantity, it is defined without forces and torques. Let’s say, that rotation is a transformation, or a series of transformations. It doesn’t matter, whether it is a steady or constantly changing rotation, both could be described as a series of successive rotations about some steady or instantaneous axis.
The precessional motion of a gyro can be quite steady. In this case it looks like steady rotation, and it is a rotation, it has angular velocity and a moment of inertia, therefore it has angular momentum too. Although it can be quite small in some cases.
You use in your definition for rotation the notion “external torque”. I assume, that you do not consider gyroscopic moments as external. And to some degree I would agree.
But if one considers the equation of motion of a precessing (and maybe nutating) gyroscope, one will find some terms called inertia quadratic velocities. If one starts with the Lagrangian, then these terms are derived from the kinetic energy. They are torque-like quantities (gyroscopic moments), in case of rotations as generalized coordinates. To be able to solve the equations of motion, they should be moved to the right hand side along with the generalized external forces. They are not external, but they act on the system, as they were.
The distinction of let's say "standard" rotation and "precessional" rotation is somewhat exotic to me. Could you give me some literature references, where this is discussed in detail?
Thanks, and sorry about being off topic so long.
Best regards,
Miklos
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Forced Precession. Or Induced torque.
Tb=JΩyΩr
Tb is the torque at the blue axis in Nm
Ωy is the angular velocity about the yellow axis in rad/sec Gyroscope spin
Ωr is the angular velocity about the red axis in rad/sec Precession
Exactly so. This is what I was talking about here:
Yes, there is torque exerted on each gyro, but not along the red axis
Yes, Tb on one gyro (gN say) is significant, probably much larger magnitude than what either motor is putting out, especially in the steady state where neither motor is exerting any torque at all. Where is the reaction for that torque? Our assembly A doesn’t start rotating about any blue axis even though it is free to.
Consider one gyroscope spinning about the yellow axis. Apply a torque at the blue axis, it will rotate about the red axis in a clockwise direction.
Clockwise isn’t a direction without specification of a PoV. Your statement lacks directions for all three vectors. Be precise.
Anyway, yes, there is a torque about the blue axis and thus it precesses (or rotates, if you ask Miklos) about the red axis, exactly as we observe.
Consider the other gyroscope spinning about the yellow axis in the opposite direction. Apply a torque at the blue axis, again in the opposite direction, it will rotate about the red axis in a clockwise direction.
Very good. Equal and opposite torque about the couple, so no net torque on assembly A. This is why it has no more resistance to rotation with the gyros spinning or not. You’d not be able to tell from holding it if they gyros were spinning. Listening would be your best bet.
Put the gyroscopes in a frame and repeat the exercise, applying torque at the blue axis etc. They will rotate about the red axis in perfect harmony, precessed by the blue opposite torques. The Red flywheel plays no part, remains unmoved.
The red wheel doesn’t remain unmoved because something had to get assembly A spinning in the first place. Without that, there’s no precession of the gyros and no blue torque. But such motion is real rotation, which continues once torque is removed. Precession doesn’t do that, so assembly A spins and has angular momentum about the red axis, and the red wheel has equal and opposite angular momentum about the same axis.
The net angular momentum has not changed, it is still null
You’re describing a system with nonzero angular momentum. This cannot be since no torque has exerted from outside the system.
Next spin gyroscopes as before and rotate them about the red axis, using the Red Reaction flywheel, at exactly the same precession speed as before. The net angular momentum has not changed, it is still null.
This time I agree that the net angular momentum is null, as it always has been.
What is the physical difference in the speed and torque between the two cases? What motion or force is there in the first case that is not identical in the second case?
The first case has external angular momentum used to spin assembly A, but not spin wheel R. Since external momentum was introduced, it has nonzero system angular momentum. That’s the difference.
There is no difference. The speeds of the gyroscopes are the same, the torques are the same and the precession speed is the same.
The system angular momentum is not the same.
Shown the video, how to tell the difference?
One has the red wheel spinning, the other not. Not sure why a video is suddenly needed. You seem to have no such actual device built, although it seems simple enough to make one.
So what did the red flywheel do? There is no difference in the net angular momentum of the system in either case, so it did the same thing in both cases, nothing.
If you think two systems, that are identical except for the red wheel spinning in one and not the other, have the same angular momentum, then you’re just lying to yourself. Surely the red wheel contributes to angular momentum of the system of which it is a part.
I am pointing out the inconsistency I see in your definition of precession as being a different form of rotation.
If I may try to see what you are saying. I observe the contraption rotating about the red axis, it is either spinning or precessing and these are different.
The ‘contraption’ I think is what I call assembly A. Yes, I consider assembly A to be rotating (spinning) about the red axis, all without torque required to maintain that spin. The gyros on the other hand are precessing since their spins are about the yellow axis, and require continuous torque to maintain that precession. You seem to describe all that pretty well in the above post, yet somewhere you get lost with what goes on along the red axis.
If it is precessing that is because I am exerting equal and opposite torques about the blue axis.
There is no torque on A, so no, I don’t consider A to be precessing. Torque is only needed to get it spinning from a stop, and opposite torque can be used to stop it again. The red wheel always has equal and opposite angular momentum to A.
If it is spinning, that is because the equal and opposite torques are being generated by rotating it about the red axis with an external torque.
No external torque is needed for A to continue spinning any more than the red wheel needs continuous torque to continue spinning.
No I have got that wrong. There cannot be an external torque spinning it, that would increase the spin speed over time. Inertia?
Assembly A has a moment (which I specified as 3, same as the red wheel), so yes, continued torque along the red axis would make it spin ever faster. Earth’s spin is continuously slowing because there is always external torque on it. The day used to be like a 3rd of what is now.
To calculate Gyroscope torque There is a formula. The angular velocity of the Gyroscope is given as rads/sec. The precession is also given in rads/sec. Same units?
Both are rads per second if you look at it like that, but adding them does not give a single vector that describes the motion of the thing. One is an angular velocity vector, and the other the angular velocity of the angular velocity vector, essentially the rate of direction change of the first vector. One is the derivative of the other. No, they’re not the same units.
You also had that funny curved dotted line, which is not how vector addition works if the vectors actually had been the same units.
Can multiply spin by precession?
Multiply, yes. It was adding apples to oranges that doesn’t work. Your formula at the top of this post multiplies them, yielding torque.
for me, rotation is a kinematic quantity, it is defined without forces and torques. Let’s say, that rotation is a transformation, or a series of transformations. It doesn’t matter, whether it is a steady or constantly changing rotation, both could be described as a series of successive rotations about some steady or instantaneous axis.
Fine, you have different definitions. I admit I’m not speaking on any authority for the terms. I’m just trying to distinguish the one kind of motion from the other.
Your definition violates Newtons first law of rotational motion: "1) a rotating body will continue to turn about its axis of rotation with constant angular momentum, unless an external couple or eccentric force is exerted upon it" https://www.asu.edu/courses/kin335/documents/Angular%20Kinetics%20and%20Angular%20Momentum.pdf
Precession about an axis will cease in the absence of external forces, so you calling this rotation seems contrary to the prevailing definition.
I found the law on http://www.4physics.com/phy_demo/newton/newton_rot2.htm as well, but it is clearly wrong: "The rotational principle of inertia: In the absence of a net applied torque, the angular velocity remains unchanged." That says that the skater will not spin faster when she pulls in her arms since no net torque is being applied. So just because it's out there doesn't mean it's correct.
The precessional motion of a gyro can be quite steady. In this case it looks like steady rotation, and it is a rotation, it has angular velocity and a moment of inertia, therefore it has angular momentum too.
That angular momentum isn’t going to maintain the precession in the absence of continuous torque, so I balk at using such terms. Our assembly A on the other hand has angular momentum, and it rotates slow or fast at our choosing, and will continue to rotate without external torque, so that’s spin. Assembly A does not precess.
The distinction of let's say "standard" rotation and "precessional" rotation is somewhat exotic to me. Could you give me some literature references, where this is discussed in detail?
Sorry. I’m not working off any literature, just the mathematics of simple situations and conservation laws.
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Quote from: Momentus on Yesterday at 15:25:18
Forced Precession. Or Induced torque.
Tb=JΩyΩr
Tb is the torque at the blue axis in Nm
Ωy is the angular velocity about the yellow axis in rad/sec Gyroscope spin
Ωr is the angular velocity about the red axis in rad/sec Precession
Exactly so. This is what I was talking about here:
Quote from: Halc
Yes, there is torque exerted on each gyro, but not along the red axis
Yes, Tb on one gyro (gN say) is significant, probably much larger magnitude than what either motor is putting out, especially in the steady state where neither motor is exerting any torque at all. Where is the reaction for that torque? Our assembly A doesn’t start rotating about any blue axis even though it is free to.
You ask where is the reaction to the torque applied at the blue axis of the gyroscope which is spinning about the yellow axis. You ask because you do not know?
Then you say it does not start rotating about any blue axis. It is a gyroscope. Why do you say that a gyroscope does not rotate about its torque axis? Did you expect it to?
You do not say how the torque is reacted. Again is that because you do not know?
We should be told. The nation demands an answer, How is the torque reacted?
Clockwise isn’t a direction without specification of a PoV. Your statement lacks directions for all three vectors. Be precise.
Anyway, yes, there is a torque about the blue axis and thus it precesses (or rotates, if you ask Miklos) about the red axis, exactly as we observe.
I stand corrected. But pleased that you managed to solve the difficult question of POV without my help.
You also understand that there is clockwise movement around the red axis. You accept that the second gyroscope also moves in the same way, about the same axis. Do follow my logic, that if you have two gyroscopes moving in the same direction you would see them moving in the same direction?
Very good. Equal and opposite torque about the couple, so no net torque on assembly A. This is why it has no more resistance to rotation with the gyros spinning or not. You’d not be able to tell from holding it if they gyros were spinning. Listening would be your best bet.
And that because they are moving in the same direction, you would not need to listen, you would see the difference?
The red wheel doesn’t remain unmoved because something had to get assembly A spinning in the first place. Without that, there’s no precession of the gyros and no blue torque. But such motion is real rotation, which continues once torque is removed. Precession doesn’t do that, so assembly A spins and has angular momentum about the red axis, and the red wheel has equal and opposite angular momentum about the same axis.
You defined assembly A. The device is in two halves which consists of the assembly A and the red flywheel R, both of which spin along the red axis, with say R having positive spin and A having negative spin.
With a light frame and heavy spherical gyroscopes spinning in equal and opposite directions
That is component A.
The two gyroscope are both moving in the same direction, reacting the equal and opposite torques applied at the blue axis. You have agreed that this is the case. The light frame is attached to the gyroscopes and thus rotates with them all driven by the torque applied at the blue axis. It is an applied torque. It is reacted by orthogonal rotation.
So it has been established and you have agreed that something has got A moving. That observed motion is the reaction to the applied torque. Applied torque, equal and opposite applied torque. Applied at the blue axis, precessing about the red axis.
The red wheel is not needed, it has nothing to add.
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The distinction of let's say "standard" rotation and "precessional" rotation is somewhat exotic to me. Could you give me some literature references, where this is discussed in detail?
I think halc is a little busy on a number of threads and we are getting a lot of spam which takes up our time.
I’m not aware of any detailed discussion in the literature, most I’ve seen on definitions tends to be in passing. For gyroscopes spin is defined, but precession is often defined as a change in inclination of the spin axis which probably covers most situations. Generally, precession of a gyroscope is taken to mean the response to an input rotation or a torque/couple/moment, but the OP is using it here to refer to the input (rather than the gyroscopic precession) without qualifying the term eg input precession. This is leading to some confusing statements and lack of clear thinking.
To explain more, what halc has designated assembly A is surprisingly representative of a model of a boat antiroll system I helped build many years ago as a lab demo. The workshop team built a model ship’s hull so it could be used in a wave tank, but I’ll describe it relative to assembly A to make it clear what I mean about the precession confusion.
If you consider the assembly A with its 2 yellow flywheels as the side view of a boat (I’ll leave you to imagine pointy end) with the yellow flywheel axles vertical, we have an illustration of a real life gyro stabiliser used in luxury yachts to reduce rolling at anchor (rolling is a nauseating motion far worse than pitching). Usually there is just one flywheel, but 2 can be used, and in this application the flywheel is on a gimble and allowed to pitch forwards and backwards around the blue axis.
In this system the red axis plays the part of the rolling motion, waves broadside will rotate the (yellow) flywheel axle around the red axis (ok, input precession) and the flywheel will respond by trying to pitch - gyroscopic precession- around the blue axis in either direction depending on the direction of rotation, thus the precession axis is across the boat - side to side (perpendicular to the plane of the frame in assembly A, blue axis). Of course in the OP’s model the blue axis is locked to the frame and cannot pitch, although it tries to with the frame taking the strain. In the real world system the precession axis is provided with a brake, if the brake is fully released the flywheel will pitch (precess) freely and there is a resulting torque that directly opposes the rolling motion (red axis), however it is almost instantaneous and of such force that is can damage the bearings and gyro mountings. If the brake is locked the flywheel cannot precess and there is no roll-opposing torque. So in the real world system the brake is set to provide controlled precession by applying a negative torque to the precession axis, usually under electronic control to allow adjustment. In the model I built there was no electronic control, just a friction brake to demonstrate the ability to control the roll-opposing torque and the effect of locking the precession axis to prevent any counter torque. In theory you could also apply a positive torque to the gyroscopic precession axis in order to increase speed up the precession and increase the roll-opposing torque.
Although you can use 2 flywheels, in the OP’s model the axles of both of these are locked to the frame and unable to precess, so no roll-opposing torque on the red axis results. Because the gyroscopic precession axis is locked it doesn't matter whether the flywheels are spinning or not, whether there is 1 or 2, or whether they are co-rotating or counterrotating.
The OP claims anomalous motion, but it is not clear what this is. He has not provided videos or even photos, so there is some doubt that the model exists other than as a drawing.
If it does, item 4 of the opening post is telling:
“ 4. As the spin axis of the gyroscopes is now aligned with the Reaction motor, precession has changed to what was the spin axis and the gyroscope motor can be used to brake the precession to a halt.”
I wonder if he is thinking that stopping the yellow gyroscopes is stopping what he has now defined as the precession axis, even though nothing has changed in reality. In other words, this is all in the mind and a question of definitions rather than a physical change.
To be honest, I’m surprised the yellow flywheels do much freewheeling as the rolling friction, drivebelt friction and motor friction (including magnet effect) must be quite large.
I did ask (no reply) how the reaction motor is connected to the reaction flywheel as this probably acts as an automatic transmission due to friction and magnetic effects. This is why in most lab demos the spinup motors are external to the system and can be disconnected rather than influence the experiment.
I gather that you are generally skeptical, but hopeful ;)
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For gyroscopes spin is defined, but precession is often defined as a change in inclination of the spin axis which probably covers most situations.
This change in inclination can be seen in my velocity diagram as the vector OC of the gyroscope when it is precessing, displaced from the vector OY when the gyroscope is not precessing.
Generally, precession of a gyroscope is taken to mean the response to an input rotation or a torque/couple/moment,
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There is no input rotation at the torque axis, only a couple, torque, or moment. It is not possible to rotate a gyroscope about the torque axis. Rotation of a gyroscope, (other than spin) is precession of the gyroscope. The rotation is orthogonal. There is no other mode of rotation.
My assumption was that these facts were general knowledge, as such any reference made to rotation (other than about the spin axis) is a reference to precession and vice versa.
Bear in mind that the OP is a novice and was labouring under the delusion that a forum god would know the basics.
but the OP is using it here to refer to the input (rather than the gyroscopic precession) without qualifying the term eg input precession. This is leading to some confusing statements and lack of clear thinking.
Gyroscope basics.
A gyroscope reacts a torque with orthogonal motion.
A gyroscope reacts motion with an orthogonal torque.
My use of the word precession is motion orthogonal to torque and spin.
Your work on gyroscope stabilization of boats has Victorian precedents https://en.wikipedia.org/wiki/Anti-rolling
In this system the red axis plays the part of the rolling motion, waves broadside will rotate the (yellow) flywheel axle around the red axis (ok, input precession) and the flywheel will respond by trying to pitch - gyroscopic precession- around the blue axis in either direction depending on the direction of rotation, thus the precession axis is across the boat - side to side (perpendicular to the plane of the frame in assembly A, blue axis).
The waves do not rotate the boat about the red axis. They may well try to do so, but the gyroscope will not allow the motion. The waves apply a torque.
In the real world system the precession axis is provided with a brake, if the brake is fully released the flywheel will pitch (precess) freely and there is a resulting torque that directly opposes the rolling motion (red axis), however it is almost instantaneous and of such force that is can damage the bearings and gyro mountings. If the brake is locked the flywheel cannot precess and there is no roll-opposing torque. So in the real world system the brake is set to provide controlled precession by applying a negative torque to the precession axis,
The your “negative torque at the blue axis” means that the system is subjected to two torques. The original roll torque from wave action and the brake torque. These are vector quantities, and can be summed to produce a resultant torque vector. This torque precesses the gyroscope orthogonally. This resultant precession vector can in turn be expressed as vectors around the red and blue axis. There is rotation about the red and blue axes.
Although you can use 2 flywheels, in the OP’s model the axles of both of these are locked to the frame and unable to precess,
That should read “unable to precess about the blue axis”. For clarity.
It is free to precess about the red axis. When it is precessing about the red axis there is a torque reacting that motion about the blue axis. May I repeat that for emphasis? Reacted by a torque at the blue axis. The gyroscope reacts the torque orthogonally.
If the flywheels ARE Spinning about the yellow axis
The rotation about the red axis is gyroscopic precession, and it is reacted by an orthogonal torque at the blue axis.
If the flywheels ARE NOT spinning about the yellow axis, the reaction to the rotation of the red axis is torque about the red axis. Or as Newton might have said had he been asked “along the line of action”
With the wheels spinning force is changing the momentum vector’s direction You called that “inclining the spin angle“. Precession, orthogonal.
When there are different conditions, when the wheels are not spinning. Then the magnitude of the momentum is changed, along the right line, in the direction of the angular velocity.
Although you can use 2 flywheels, in the OP’s model the axles of both of these are locked to the frame and unable to precess, so no roll-opposing torque on the red axis results. Because the gyroscopic precession axis is locked it doesn't matter whether the flywheels are spinning or not, whether there is 1 or 2, or whether they are co-rotating or counterrotating.
It does matter.
Static Flywheels
The inertia, the momentum change, of the static flywheels must be overcome by a torque along the line of action of the resultant rotation. The angular velocity vector is extended in length.
Spinning flywheels
The inertia, the momentum change, of the spinning flywheels must be overcome by a torque orthogonal to the line of action of the resultant rotation. The angular velocity vector is changed in direction.
There is a difference, the difference matters.
The OP claims anomalous motion, but it is not clear what this is. He has not provided videos or even photos, so there is some doubt that the model exists other than as a drawing.
The model as drawn does not exist. I felt that it gave enough information for any interested party to construct one. I asked that some one might do so.
The model I did make and patented back in the day was designed as an automotive transmission. It is an order of magnitude more complicated. Photos and Videos would further confuse a complicated subject.
You wrote your post in response to @Miklos
Quote from: Miklos on 15/09/2020 18:16:23
The distinction of let's say "standard" rotation and "precessional" rotation is somewhat exotic to me. Could you give me some literature references, where this is discussed in detail?
Whilst your post was both interesting and instructive, I don't see how it addressed "standard" rotation and "precessional" rotation, The question asked by @Miklos
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Now to consider the vectors
A particle of mass dm has velocity V relative to point O
A continuous force Fc is exerted at a right angles to the direction of travel (centripetal force) and the path of dm is changed to orbit around the point O with an angular velocity of Ωdm . If this force is removed then dm will move in a straight line, at the same speed as it had before. Force at right angles to the direction of travel changes momentum by changing direction, not by changing magnitude.
An orthogonal torque is applied, which exerts a variable force Ft with a max value as dm passes the north and south poles of its orbit and zero at the equator.
The resultant vector sum of Fc & Ft is Fx and is also orthogonal and determines the path followed by dm. If Fx is removed then dm will move in a straight line, at the same speed as it had before.
Rotation has angular momentum to it, and obeys the angular version of Newton's first law: A rotating object will continue rotating in the absence of an external force. This isn't true of precession, which ceases upon removal of external force (torque). Hence my saying that precession is not rotation. It is far more akin to acceleration since it is a process resulting from a force (torque).
The particle dm is part of a rigid mass. The mathematical determination of the path of dm whilst acted upon by Fx is complex and can be found in a gyro – dynamics text if you wish to know more.
Suffice to say that it resolves to the formula
Tb=JΩdmΩr
The actual path of the particle dm can be traced by observing a wheel that is rotating about the axes y and r. I did this by using the stop motion technique. I used a polystyrene ball and a felt marker pen to make a dot on the surface of the sphere, moved it through a small arc in one direction Sr, then a larger arc in the other Sy and made a second mark and so on tracing a curving path on the surface of the ball.
Sy is the displacement about the yellow axis. Sr is the displacement about the red axis
Their vector sum, the arc Sdm can be resolved to the tangential speed of the Gyroscope, and hence to the speed of rotation, Ωdm This value does not change as it is derived from the constant instantaneous speed of dm, acted upon by Fx.
Sy can be resolved to an angular velocity Ωy. Sr can be resolved to an angular velocity Ωr
The interaction of the angular velocity of Ωy and the angular velocity of Ωr are shown in Angular momentum diagram 2
As the gyroscope rotor under consideration is a sphere, the polar moment of inertia is the same for any plane intersecting the sphere. As such Diagram 2. can be interpreted as a momentum diagram.
The equal and opposite momentum generated by the contra rotation of the gyroscopes is turned through 90 degrees in reaction to equal and opposite torque, resulting in the positive momentum at the red axis, the vector sum of the original momentum about the yellow axis.
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There is always the other way to operate the device.
In the OP the process started by contra-rotating the two gyroscopes about their yellow axis.
This time, do something different, start the motor attached to the red reaction flywheel which rotates the flywheel about the red axis and counter rotates the two gyroscopes, also about the red axis. The gyroscopes are both spinning in the same direction. The sum of their angular momentum is equal and opposite to that of the flywheel. This generates momentum in equal and opposite quantities. You could if you wanted to, detach the flywheel, take it away and use the momentum that has been generated to tighten a bolt.
Equal and opposite momentum does not mean no momentum. But to be clear do not do that yet. Leave it where it is.
Now for the difficult to understand part.
Uncouple the red flywheel. The two heavy gyroscopes and the light frame will continue to spin about the red axis. The flywheel will continue to spin.
Start the yellow gyroscope motor to counter rotate the rotors about the yellow axis.
This movement, the physical rotation by the drive belt of the spherical rotors about the yellow axis is orthogonal to the spin of the gyroscopes which is about the red axis.
Yes very difficult to visualise. But possible if you try.
The two gyroscope rotors are spinning about the red axis and therefore the orthogonal rotation about the yellow axis is, by definition precession.
The dynamics of a gyroscope dictate that there is a torque present at the blue axis, again by definition. Each of the rotors will generate a torque. The torques will be equal and opposite..
When a rotor spinning about an axis(red) is subjected to a torque about an orthogonal axis (blue) there is precession about the other orthogonal axis (yellow)
Remember, the red wheel is disconnected, it has no influence.
The condition as described above is best represented by the angular velocity vectors in angular momentum diagram 2
OB is the Spin axis
OA is the precession axis.
OE is the vector sum of the actual physical rotation of the rotor about the yellow axis and the actual in the real world physical rotation of the rotors about the red axis.
The original spin vector OB is displaced by the orthogonal force exerted by the torque at the blue axis This changes only the direction of the vector, it does not change the magnitude. The length of the line representing the vector does not change. Hence the dotted curved line which Halc queried.
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Bear in mind that the OP is a novice and was labouring under the delusion that a forum god would know the basics.
The OP may then stand corrected in this delusion. The rank is assigned by the site software and is purely due to the number of posts (10000 in this case) and nothing else. There are some here who easily have posted more than that and are 'forum god's and know little of said basics. Colin is not one of those.
There are better clues as to which posters are likely to know what they're talking about. Think about it.
You seem to be posting for our educational benefit, and have asserted no more of this 'anomalous dark motion', so I've pretty much been leaving it alone. But I've accumulated a few comments:
A particle of mass dm has velocity V relative to point O
Relative to frame F, which defines a spatial point O.
A continuous force Fc is exerted at a right angles to the direction of travel (centripetal force) and the path of dm is changed to orbit around the point O with an angular velocity of Ωdm
This makes a lot of assumptions, primarily that Fc is not continuous but actually changing over time. A continuous force on a particle actually causes a more or less parabolic trajectory.
The statement makes the assumption that the particle is in the vicinity of point O. That point could be on the other side of the galaxy, and a force Fc exerted at right angles to its motion (in frame F) is hardly going to put it in orbit about O.
Just pointing out that you're missing a lot of assumptions in that statement. Try to be precise.
Force at right angles to the direction of travel changes momentum by changing direction, not by changing magnitude.
This is a frame dependent observation. The very same force on the same particle relative to a different inertial frame will change the magnitude of its momentum vector in that frame. Velocity and momentum are frame dependent, but angular velocity and momentum are not (sort of).
An orthogonal torque is applied, which exerts a variable force Ft with a max value as dm passes the north and south poles of its orbit and zero at the equator.
And I cannot make sense of this statement, which seems to imply that no force is exerted on an orbiting thing if it is over the equator at the time. I don't think you meant that, but I cannot figure out what you're actually trying to convey there. An orbiting thing doesn't pass its own poles. Those poles define its axis of orbital motion.
The particle dm is part of a rigid mass.
Then it's not in orbit. Not sure why you're bringing up orbital mechanics to describe the precession of a rigid object. The physics is different.
Yes, your description of the precessing path of a particle over a ball seems accurate enough, and is not unlike the path traced over Earth by a satellite with a polar orbit. But that satellite orbit isn't precession, it's just the Earth rotating underneath it in that case.
The equal and opposite momentum generated by the contra rotation of the gyroscopes is turned through 90 degrees in reaction to equal and opposite torque, resulting in the positive momentum at the red axis, the vector sum of the original momentum about the yellow axis.
Your diagram 2 (reinterpreted as momentum instead of velocity as labeled) doesn't do its vector addition correctly. It seems to imply (via the dotted line) that all vectors have the same magnitude, but if I add OA to OB, I get OD except with √2 greater magnitude. This becomes more apparent if vectors OA and OB have significantly different magnitude, as is typical.
There is always the other way to operate the device.
In the OP the process started by contra-rotating the two gyroscopes about their yellow axis.
This time, do something different, start the motor attached to the red reaction flywheel which rotates the flywheel about the red axis and counter rotates the two gyroscopes, also about the red axis. The gyroscopes are both spinning in the same direction. The sum of their angular momentum is equal and opposite to that of the flywheel. This generates momentum in equal and opposite quantities. You could if you wanted to, detach the flywheel, take it away and use the momentum that has been generated to tighten a bolt.
Yes, this is the angular momentum of 'assembly A' of which I spoke. It includes the precession momentum if the gyros are running. Precession does have momentum, and it needs to go somewhere when external torque is removed. It isn't often discussed in the typical youtube videos.
Uncouple the red flywheel. The two heavy gyroscopes and the light frame will continue to spin about the red axis. The flywheel will continue to spin.
Start the yellow gyroscope motor to counter rotate the rotors about the yellow axis.
This movement, the physical rotation by the drive belt of the spherical rotors about the yellow axis is orthogonal to the spin of the gyroscopes which is about the red axis.
The two gyroscope rotors are spinning about the red axis and therefore the orthogonal rotation about the yellow axis is, by definition precession.
Um, no. The red axis is fixed, and the yellow axis is changing at the rate of rotation of the red axis. That makes the yellow axis the spin and the red the precession. It's all about which axis changes, and not which one spins up first. So even if the yellow motor gives very low RPM to the yellow axis and the red one is spinning like crazy, that's just very fast precession of of a low-speed gyro. Yes, the angular momentum of the ball at any moment is nearly aligned with the red axis in this case. If you suddenly severed one yellow ball from the system, the ball would be rotating along some axis that is close to but not quite aligned with red.
The dynamics of a gyroscope dictate that there is a torque present at the blue axis, again by definition. Each of the rotors will generate a torque. The torques will be equal and opposite.
Yes.
When a rotor spinning about an axis(red) is subjected to a torque about an orthogonal axis (blue) there is precession about the other orthogonal axis (yellow)
But red does not precess about the yellow axis in this case, so this is wrong. The assembly A, spinning with the red wheel detached, will continue to spin at an unaltered rate when the yellow motor spins up the two gyros. It will not precess at all about the yellow axis, only the red. Doing otherwise would violate conservation of angular momentum.
OE is the vector sum of the actual physical rotation of the rotor about the yellow axis and the actual in the real world physical rotation of the rotors about the red axis.
Except as I pointed out before, you did that addition incorrectly. The light dotted square you drew does not meet points B and A like it should. Look up vector addition on the web.
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I posted a drawing of a device that creates momentum. I thought that there was sufficient detail in the drawing for it to be replicated, as a physical or as a virtual machine.
I also thought that there would be some interest in the fact that it creates momentum, this is a science forum and the ramifications are profound. It should have been, could have been exciting.
I did try to explain how the device does work. Please note works. Did anyone try to follow my explanation?
@Halc It is evident from your posts that you do not know very much about gyro-dynamics.
It is not labeled, but I presume the reaction motor is that grey thing that spins up the red wheel. Also not labeled is whatever you consider the precession axis. There is the one main axle in the whole setup which is the rotation axis of the red wheel. There is no precession axis
Spin axis Yellow
torque axis blue
precession axis red
There is a precession axis. The Red axis is the precession axis. Which is an essential part of the way the device works. You did not grasp that at the start of this thread, simple basic gyroscope theory and you do not understand it. Not then and not now.
I does seem that I am posting for your educational benefit, so much of your stuff is alternative facts. I would have enjoyed discussing Anomalous Dark Motion, not having to endlessly repeat basic gyroscope theory.
This makes a lot of assumptions, primarily that Fc is not continuous but actually changing over time. A continuous force on a particle actually causes a more or less parabolic trajectory.
The statement makes the assumption that the particle is in the vicinity of point O. That point could be on the other side of the galaxy, and a force Fc exerted at right angles to its motion (in frame F) is hardly going to put it in orbit about O.
Everything in this statement is wrong, part of your fantasy alternative facts world.
“This makes a lot of assumptions,” It is not my assumption “primarily that Fc is not continuous” It is your very own very strange idea that centripetal force (Fc) changes over time. And that “A continuous force on a particle actually causes a more or less parabolic trajectory.”
“on the other side of the galaxy, and a force Fc exerted at right angles to its motion (in frame F) is hardly going to put it in orbit about O.” I will bear this point in mind when I design a device which requires a force that spans the galaxy.
Um, no. The red axis is fixed, and the yellow axis is changing at the rate of rotation of the red axis. That makes the yellow axis the spin and the red the precession. It's all about which axis changes, and not which one spins up first. So even if the yellow motor gives very low RPM to the yellow axis and the red one is spinning like crazy, that's just very fast precession of of a low-speed gyro. Yes, the angular momentum of the ball at any moment is nearly aligned with the red axis in this case. If you suddenly severed one yellow ball from the system, the ball would be rotating along some axis that is close to but not quite aligned with red.
This is just gabble and there is no one reading your rubbish who cares enough to correct you.
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Not much point in posting on this thread. However the subject is of such a fundamental nature that I feel I should try
The current state of American politics shows the power of belief The Dunning-Kruger Effect. I like to think that I don't do that. I do not “believe” the current paradigm, only that it gives theories that are the best explanations.
If it disagrees with experiment, it's wrong. In that simple statement is the key to science. Richard Feynman.
The three people who posted on this thread “believe” that momentum is conserved. I guess that is the same for everyone else who has read the thread.
The twin rotors device can be given the grand title of experiment. It works in a universe governed by Newton’s laws, it obeys those laws. Therefore it can be analysed by the laws.
As @Halc demonstrated with considerable effort, if you wish to prove that it does not work then you must also change Newtons laws. (Multiply, yes. It was adding apples to oranges that doesn’t work )
So to continue.
First a reprise of the basics.
A gyroscope’s Spin, torque and precession are orthogonal.
Torque results in orthogonal motion
Motion results in orthogonal torque.
Precession does not change the magnitude of angular momentum only the direction.
(Force must move mass along the line of action to do work).
Now on to my vector drawing.
There are two axes, red and yellow. The red axis could be said to represent, for example the flow of a river, the yellow axis could be the speed of a ferry boat. As the boat crosses the river, its actual path can be plotted.
It could represent a trackball, controlling the cursor of a computer. As the ball is moved it rotates sensors placed at right angles. If only the yellow sensor is rotated, a horizontal line is drawn. If only the red sensor is rotated, a vertical line is drawn. To draw a curve, both are rotated.
I choose my vector drawing to represent the physical motion of the twin rotors experiment. The red axis represents the rotation, the angular velocity about the red axis, the yellow axis represents the rotation, the angular velocity about the yellow axis. No more than that and certainly no less.
So I can ask the question what happens if I rotate it first about the yellow axis with a magnitude of OA then rotate it about the red axis with a much smaller magnitude of AC?
Obviously the vector is changed in direction to OC. Less obvious is the fact that, in the real world model which the diagram represents, the magnitude of the yellow vector is reduced.
Furthermore I can ask the question what happens if I rotate it first about the red axis with a magnitude of OB then rotate it about the yellow axis with a much smaller magnitude of BE?
Obviously the vector is changed in direction to OE. Less obvious is the fact that, in the real world model which the diagram represents, the magnitude of the red vector is reduced.
This becomes clear when the magnitude of of both rotations is changed to give the resultant OD.
The changes in magnitude in the red and yellow vectors are governed by the fact that the resultant spin speed must remain constant. (precession does not change the magnitude).
The vector drawing shows that starting with rotation(spin) about either axis and then adding rotation about the orthogonal axis, (precessing) will move the resultant spin axis to the OD vector. Returning this rotation (precession) back to zero will return to the original vector condition. As one would expect.
The vector drawing also shows how the angular velocities must be manipulated to change the spin vector all the way from OA to OB and vice versa, whilst maintaining a constant magnitude of spin.
To conclude:
Equal and opposite forces are used to generate equal and opposite changes in momentum in accordance with Newton’s axioms.
The resultant vector sum gives a positive value. Momentum is created
That is the anomaly which I call Dark Motion.
It manifests in the Newtonian Universe as Dark Matter and as Dark Energy.
Build your own model, that is the only proof you will need.
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So where did I go wrong?
2. Run the reaction motor. This rotates the Gyroscopes about their precession axis, accompanied by equal and opposite torque orthogonal to the spin axis. There can be no torque exerted by the reaction motor along a precession axis, therefore no substantial movement of the reaction flywheel.
It is not labeled, but I presume the reaction motor is that grey thing that spins up the red wheel. Also not labeled is whatever you consider the precession axis. There is the one main axle in the whole setup which is the rotation axis of the red wheel. There is no precession axis
since there's only the motor producing spin and counterspin. So the red wheel spins one way, and the contraption to the left spins the other way. Still zero net angular momentum.
I assumed @Halc was being serious. He was actually taking the piss. Wind up the Newbie and watch him struggle to explain.
I hope you all enjoyed the Newbie roasting.