Talk:Gyroscope

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I have just completed Eric Laithwaite who was obviously just plain wrong. However, when I read accounts from experts about the nature of his mistake I'm none the wiser. They talk about fast tops and slow tops and are obviously refering to a body of knowledge that I've never managed to find. Can we have some more content here? An account of where Eric Laithwaite went wrong would be really useful Cutler 12:24, 11 Feb 2004 (UTC)

I've been adding stuff to the Eric Laithwaite article today. One of the external links may help. DFH 21:56:00, 2005-09-08 (UTC)

Contents

[edit] Are flywheels gyroscopes?

This article claims that momentum wheels and flywheels are gyroscopes. Is this true? The definitions I have read state that gyroscopes are devices designed to resist rotation of the spin axis, which is not the purpose of the devices I just mentioned. Obviously, they have this property as a side-effect, but this is not enough to make them gyroscopes. -- Heron 21:29, 25 Jul 2004 (UTC)


[edit] image accuracy

I'm not an expert at this, but I do believe that the image stating that aerobic bicycle is possible due to gyroscopes is incorrect as the wheels really aren't spinning fast enough to really provide any resistance that would aid in the balancing.

[edit] Confused

I don't understand much of this entry. Can someone write an easy to understand version? Gyroscopes explained so a kid can understand?

How about the following introductory paragraph?
A gyroscope is a wheel spinning on an axle, mounted in a frame which allows the axle to be pointed in different directions. When the wheel spins, its rotating mass causes the axle to point in a fixed direction, and to resist any attempts to change its direction. This makes it useful for navigation, balancing of machinery, and demonstrations in physics classes.
Please tell me if this is detailed enough, or too simple. --Heron 08:23, 7 Sep 2004 (UTC)
I like it. That will make a good intro. StuRat 02:19, 28 October 2005 (UTC)

Would it be possible to pick an image with a lighter background to display? It's rather hard to read the names of the parts of the gyroscope with the current green-backed image. -- Guest, 23 Apr, 2005

[edit] Inertia

Moved to talk:inertia


[edit] Proposal for change

I propose that the heading History be changed to Properties. Really, only the first sentence is actually about the history of the gyroscope. The rest is a very good description of how a gyroscope behaves, complete with a correct description of how a gyroscope can hang off the end of a table (the description matches the one given in "Feynman Lectures on Physics.").

[edit] what reference frame for rigidity?

With respect to what reference frame does a gyroscope have a tendency to remain rigid in space? I.e. In what reference frame does the plane of the gyroscope remain constant? The surface of the earth? A celestial reference frame?

Gyroscopic rigidity and precession affect the attitude indicator and heading indicator of an aircraft, but there are 2 different gyroscopes for these 2 instruments. It may be necessary periodically to reset these gyroscopes because they can drift, usually due to to friction in the mechanism or other physics in the construction of the gyroscope that makes it deviate from it's theoretical ideal performance.

But one flight instructor told me that the heading indicator in particular drifts at a certain pace in a certain direction (and generally needs to be reset every 15-30 minutes or so) because the earth is rotating and the gyroscope, being rigid in space, is then not rigid w.r.t. the earth's surface. This theory is consistent with my experience as a pilot, but I can't say with certainty that this is what's happening.

Thus far, I have not found a satisfactory answer to this question. 142.103.14.11 22:56, 7 March 2006 (UTC)

[edit] Gyroscopic inertia

In the intro it says "this is also known as gyroscopic inertia or rigidity in space."

Thats very ambiguous, it sounds as if its saying gyroscipic inertia is another name for gyroscope. More reasonably it would mean that its a synonym to angular momentum. If thats the case, it should NOT link to this page, it should NOT be bolded on this page, and it should be much less ambiguous. Please someone either change it, or answer me so *I* can change it. Thanks. Fresheneesz 22:21, 15 March 2006 (UTC)

[edit] I still don't understand why......

a gyroscope spins faster when force is applied. I think it's due to the conservation of energy law, i.e. that the energy i apply to overcome the resistance to spin must show itself somewhere, but I have tried and tried to think how, using Newtonian laws of motion, the result is an increase in the spin speed. How is the force transferred in this direction, when the only direct physical connection between me and the gyro is my hand on the housing which hold the gyro's axle? I wonder if there is something non-Newtonian going on, but that seems a bit far fetched to me. I'd be very grateful for an answer. -142.103.14.11 14:52, 28 April 2006

I'm not sure I know exactly what applied force you mean, but in case you are refering to something like the Dynabee, the answer, as posted there, is a lot less mysterious than you theorize above:
"The axis of the gyroscope in the gyro powerball is fixed to the spinning mass and it rests in a little groove inside the wrist exerciser device, which almost completely covers the gyroscope inside it, except for a small round opening on top of it, which is where you can manually start the gyroscope. Once the gyro is spinning, tipping the device will cause the gyroscope to start precessing, with its axis slipping around in the groove in a circular fashion. The groove inside the device, is a little wider than the axis, and the gyroscope's evasive action towards the externally applied force will cause one end of the axis to push against the upper rim of the groove, while the other end of the axis pushes against the lower rim of the groove. While the axis is slipping around inside the groove, the friction between the axis and the groove rims will accelerate or brake the spinning gyroscope, with a maximum effect when the axis starts "rolling" inside the groove. Since this friction force is essential for the device's operation, the groove must not be lubricated. The acceleration of the gyroscope is best when the precession of the gyroscope is supported and amplified by wrist motion."
-AndrewDressel 19:12, 12 October 2006 (UTC)

[edit] Right-hand rule

Added reference to right-hand rule and brief description of how it applies. AndrewDressel 12:13, 16 May 2006 (UTC)

[edit] Motorcycles

"Examples of some free-output-gimbal devices ... the front wheel of a motorcycle. Countersteering is how motorcycles turn corners using the gyroscopic roll reaction of the spinning front wheel."

Any references for this claim that have actually done the experiement or the math? My understanding from reading the liturature (Jones, David E. H. (1970). "The stability of the bicycle" (PDF). Physics Today 23 (4): 34–40.  and Gromer, Cliff. "STEER GEAR So how do you actually turn a motorcycle?", Popular Mechanics, February 1, 2001. Retrieved on 2006-08-07. , etc.) is that countersteering is simply a technique for causing a motorcycle to lean and that gyroscopic effects are not necessary. -AndrewDressel 02:27, 15 August 2006 (UTC)

None found, so I've taken it out. -AndrewDressel 14:32, 15 August 2006 (UTC)

[edit] New images and diagrams

Well, I made a few new images for the article, including an animation showing how the gyroscope wheel works. They were originally made with a left-handed spin, so I flipped them horizontally to fix it. ☢ Ҡi∊ff⌇↯ 20:00, 4 October 2006 (UTC)

 Switching the left hand spin seems to have switched the input and output axes.  A quick check of (input) cross (spin) = (output) shows correct orientation.  Dan  —Preceding unsigned comment added by 128.253.139.199 (talk) 14:00, 1 November 2007 (UTC)

[edit] Is my hard drive defying physics?

I'm really confused about how a hard disk can be a gyroscope and still work when it's being moved around. See my entry on the hard disk talk page here. Twilight Realm 19:19, 29 October 2006 (UTC)

If your hard drive is spinning on a vertical axis, you can lift your computer vertically no problem, and you can slide it around the floor no problem either. But if you tilt the computer, the hard disc will "try" very hard to tilt in a plane at 90* to the axis of your tilt. It will be restrained by its bearings, but will stress the bearings, so best not to wobble it about too much.

I think.

So do computers aboard ship tend to wear their bearings out?

Richard

[edit] Still Not Quite Understanding...

I guess I'm just an idiot, but I'm having a hard time understanding the whole bicycle wheel/rotating stool thing. Could someone explain it for me please? --SuperCow 05:37, 21 February 2007 (UTC)

Never mind, I've figured it out. I am an idiot. --SuperCow 14:47, 6 March 2007 (UTC)

[edit] Serson 0 - Laplace 1

I just added John Serson to the History section, then deleted him again, then added Laplace. I ought to explain.

At first, I saw Serson on gyroscopes.org and thought that he had a prior claim to Bohnenberger, so I added Serson to this article. I also created an article on Serson. I then found that Serson's design was merely a spinning top and didn't really deserve to be called a gyroscope, so I removed him again. I then found the article at the Institute of Navigation that explained the link from Bohnenberger via Laplace to Foucault, which I thought was much more interesting, so I added that the the article. Now we have an accurate history, and a new article on John Serson, so everybody wins, I hope. --Heron 14:53, 2 June 2007 (UTC)

[edit] Gyroscopes in Fiction

Needs expanding so as to provide a brief description of where gyroscopes appear in these fictional texts 124.182.230.53 11:50, 29 July 2007 (UTC)

Agreed, this section is completely useless as it is now. Either this section should be expanded to include the way in which gyroscopes are used in those fictional texts or it should be removed. However even an extended section would IMO not make much sense here. A gyroscope is not by itself something fictionary nor does it play a major part in any of these fictional texts. So I don't really see why it is relevant to have this section in this article. Hadoriel 11:06, 13 August 2007 (UTC)

[edit] Gyroscopes in modern technology

Today gyroscopes are used in dozens of different technological machines from the International Space Station to modern aircrafts and even in underwater torpedos. However there is virtually no mention of this in the article. I think a paragraph about this should be added as this is the main use of gyroscopes today. Hadoriel 11:11, 13 August 2007 (UTC)

[edit] opening sentence is inaccurate

I'm new to wikipedia, so forgive me if I'm speaking out of turn. I work with, and lecture on, all sorts of things to do with gyroscopes and I am pretty comfortable with them. I've created lots of videos on things to do with spin (see http://www2.eng.cam.ac.uk/~hemh/movies.htm ) and I've got a page devoted to gyroscopes and boomerangs ( http://www2.eng.cam.ac.uk/~hemh/gyroscopes.htm ). We've also set out to reproduce all of Laithwaites experiments - see http://www2.eng.cam.ac.uk/~hemh/gyroscopes/htmlgyroscopes.html . I'd be happy to help out with the gyro page and if appropriate it may be thought appropriate to include links to our work.

But my main reason for writing gere is to say that the opening sentence of the Wiki Gyroscope page is not correct. It reads:

"A gyroscope is a device for measuring or maintaining orientation, based on the principle of conservation of angular momentum."

But a gyroscope would be useless if angular momentum were to be conserved. The whole point is that a gyro exhibits precession and this requires the imposition of an external couple, thereby changing the direction of its angular momentum - being a vector quantity. Is there any chance of changing this sentence to read:

"A gyroscope is a device for measuring or maintaining orientation, based on the principles angular momentum."

Hughhunt 19:52, 23 September 2007 (UTC)

I agree. The phrase "tends to resist changes to its orientation" should also be changed. Perhaps something like "moves in a direction perpendicular to the applied torques and at a rate inversely proportional to its rate of spin" would work. -AndrewDressel 13:39, 25 September 2007 (UTC)
I'm not sure I see the problem. Angular momentum IS conserved--if the external torque is zero, the angular momentum doesn't change. The usefulness of a gyroscope for measuring orientation derives from the fact that in practice, even with gimbals it is impossible to eliminate torque entirely--if it weren't, you could put a stationary carton of milk (or whatever) in gimbals, and it would maintain its orientation. The orientation of the axis of a gyroscope changes less in response to a given torque than does the "axis" of a stationary carton of milk with the same moment of inertia. The gimbals minimize the torque, and the spin of the gyroscope minimizes the change in orientation produced by whatever torque manages to get through. So I certainly wouldn't go so far as to say the opening sentence is incorrect. On the other hand, it would probably be good to point out that, aside from precession, there is no such thing as "gyroscopic stability" a misconception many people seem to hold. Rracecarr 13:59, 25 September 2007 (UTC)
Surely if the external torque is zero (and hence angular momentum is conserved) then a gyroscope can no longer be used for "measuring or maintaining orientation"? To actually make a measurement you need that torque. --The Great Apple 15:18, 16 November 2007 (UTC)

Thanks for modifying the opening sentence, but the opening paragraph still describes a GYROSTAT not a GYROSCOPE (eg with the words "its orientation remains nearly fixed"). Is this the intention? Besides this there is a lot more that could do with fixing on the page. I'm happy to help if you're interested. Many of my students here in Cambridge are now aware of the shortcomings of the article and I've set them an exercise to produce improvements. When they're ready I will put them on my own web pages ( http://www2.eng.cam.ac.uk/~hemh/gyroscopes.htm ) -- Hughhunt (talk) 21:30, 16 November 2007 (UTC)

I note with dismay that the opening paragraph has gone back to the very-much-incorrect "A gyroscope is a device for measuring or maintaining orientation, based on the principle of conservation of angular momentum." As noted above this is incorrect and misleading and entirely inappropriate for a reputable article in Wikipedia. A "rate gyro" is a perfect example of a gyroscope whose orientation changes in normal operation. It is the most common device used to measure angular motion. And its orientation changes therefore angular momentum is NOT conserved. Also I would appreciate if those commenting above would identify their credentials. It appears to me that Rracecarr, for instance, does not understand gyroscopes by saying such unscientific things as "The gimbals minimize the torque, and the spin of the gyroscope minimizes the change in orientation produced by whatever torque manages to get through." many thanks Hugh Hunt, Cambridge University Hughhunt (talk) 21:59, 15 January 2008 (UTC)