Talk:Gyrocompass

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im doing an assignment for maths on the gyrocompass. what is the history of this instrument? why was is developed? have there been any similar instruments before or after this one? what is it used for? how do you use the instrument? what are its limitations? what cant it do? what possible errors of measurement can it produce? what are some of the implications of these errors?

if anyone can help me by answering any of these questions id greatly appreciate it! thankyou so much for your time.

krystal.

Contents

[edit] "North Star"

I'm no where close to an expert on gyrocompasses but I'm questioning the article's use of the term "north star" repeatedly. As in "This friction force caused by the fluid results in a torque acting on the axis, causing the axis to turn in a direction orthogonal to the torque (that is, to precess) toward true North (to the North star)." I had always thought that the notion of "true north" being in the general direction of the North star was a coincidence. In a few thousand years true north and the North star will diverge. Shouldn't all of the uses of the "North star" in this article be replaced by something more accurate and less coincidental?

24.159.110.25 23:55, 25 December 2006 (UTC) Brad Dixon

Like North Celestial Pole?

[edit] "Crucial ingredient"

I don't really feel I can change the article itself but I do have a slight issue with the wording of one part. I have done a fair bit of work at university on the gyrocompass, and I think that to cite friction as the "crucial ingredient" is misleading. The actual "crucial ingredient" is the combination of an applied torque and the rotation it causes (it can also be a rotation and a resulting torque, the two are both linked). Friction may be one method of applying this torque but I have not yet come across it.

In its simplest and most effective form, a gyrocompass is a gyroscope in which the gimbals (or mountings) are modified to force the rotor axis to remain horizontal relative to the earth's surface. The components of rotation caused by the spin of the earth mean that the rotor must align itself with the true meridian in order to obey the law of conservation of angular momentum.

Other, more practical gyrocompasses use gravity to keep the rotor horizontal/apply the torque. This is necessary on a pitching and rolling ship, where horizontal is not the same as the floor!

James

Nosrednax 15:54, 28 September 2005 (UTC)

I didn't know anything about gyrocompasses before reading this article, but I've tried anyway to apply James's advice to the article. Feel free to correct me if I've done so incorrectly, and please add sources if you know of any. --Allen 05:59, 9 October 2006 (UTC)

[edit] Forgot to add the reason for my change.

Changed the link of Magnetic North to http://en.wikipedia.org/wiki/Magnetic_North_Pole#North_Geomagnetic_Pole because it was instead linking to an album by Hopefall: http://en.wikipedia.org/wiki/Magnetic_North.--M-w-b 09:39, 20 July 2007 (UTC)

[edit] Satellites and History

It migth also be mentioned the gyrocompass is used is satellite stabilization. In combination with a horizion sensor, this is how early American and Soviet spy satelites maintained 3-axis orientation.

With regard to history, the discussion of Kaempfe vs. Sperry seems to imply that Sperry just stole someone's ideas. Kaempfe was an art major who stumbled on the gyrocompass concept while trying to convince the navy to fund a submarine expedition. Sperry did independant work on gyroscopes, and his engineers dominated the research and development of many gyroscopic-based servomechanisms over a period of years (ship stabilizers, autopilots, etc). What I'm saying is, Kaempfe was first, but Sperry (and Minorsky and others) were really more important, not just someone who stole an idea from someone else. A good book to look at is Bennett's history of control engineering. DonPMitchell (talk) 22:32, 19 May 2008 (UTC)