Compass in a submarine?!
MC
submarine when it is entirely encased in steel? I guess I 've seen one to
many WWII movies?
M
Steve
They use a gyro compass not magmetic. The same for most all commercial and
navy ships.
Surface ships have magnetic compasses for back up in case the gyro goes out.
Steve
s/v Good Intentions
Steven Shelikoff
I'm just guessing, but if they want to use a magnetic compass and not a
gyro compass for some reason, they can always mount the sensor outside
the hull and use a repeater of some sort to drive the readout. Still
guessing that they probably did that before gyrocompasses were invented.
Steve
Bertie the Bunyip
>
>They use a gyro compass not magmetic. The same for most all commercial and
>navy ships.
>
>Surface ships have magnetic compasses for back up in case the gyro goes out.
Subs have magnetic compasses. The gyro compass is merely a
stabilisation system for a mag compass. they have a flux gate (the
sensor component of a magnetic compass) mounted outside and corrected
for the lump of metal it's attached to (the hull)
Bertie
Steve
A flux gate is a magnetic compass that utilizes electronics to detect the
earths magnetic flux fields. A traditional magnetic compass uses a magnetic
compass needle to detect and align with the earths magnetic flux fields.
A gyro compass has nothing what so ever to do with the magnetic flux fields
of the earth. The gyro aligns with the earths rotating axis, True north and
True south.
There is seldom if ever any connection between the magnetic compass and the
gyro, wheather it be flux gate or traditional magnetic compass.
--
My opinion and experience. FWIW
Steve
S/V Good Intentions
Rich Johnson
> "Steve" wowed me with :
Wrong, marine gyro's are completly independant of the earth's magnetic
field and use a gyroscope precession to orientate to true north.
--
Rich
Enfield NS
Canada
JAXAshby
actually, they take into account precession, but are oriented before starting
out (and reoriented as is available)
Bertie the Bunyip
>
>A flux gate is a magnetic compass that utilizes electronics to detect the
>earths magnetic flux fields. A traditional magnetic compass uses a magnetic
>compass needle to detect and align with the earths magnetic flux fields.
>
>A gyro compass has nothing what so ever to do with the magnetic flux fields
>of the earth. The gyro aligns with the earths rotating axis, True north and
>True south.
>
>There is seldom if ever any connection between the magnetic compass and the
>gyro, wheather it be flux gate or traditional magnetic compass.
Actually, they're frequently linked together. The Gyro compass being
updated or "slaved" to the flux gate compass.
Bertie
Bertie the Bunyip
Gyroscopic precession to orient the compass?
Bwawhahwhahwha!
Prithee doo tell how this miracle occurs.
Bertie
Bertie the Bunyip
>>and use a gyroscope precession to orientate to true north.
>
>actually, they take into account precession, but are oriented before starting
>out (and reoriented as is available)
And how do they take into account precession, Jaxhole?
Wouldn't be with a latitude nut would it?
And what, do tell, is the primary cause of the precession?
Would it be apparent drift? Real drift? Friction?
Which of thes would give the most trouble there, Jaxhole?
Bertie
Rick
Those old submarines you saw in the movies had a master gyro compass and
a handful of repeaters located remotely. They did not use magnetic
compasses or flux gate compasses.
The gyro compasses were "north seeking" and had built-in compensation
for all the errors to which gyros are susceptible. Those boats even had
a dead reckoning computer which received inputs from the speed log and
the gyro and displayed lat and long and some even drove a pencil plotter
which traced the boat's track on a chart.
Rick
wf...@ptnospam.com
<harry...@hotmail.com> wrote:
>What about the flux capacitor? What role does that play in navigation?
>
that's where they put the empty beer cans...not that you'd ever have
any of those on a naval vessel...
---------------------------
check my blog at:
http://www.bobview.blogspot.com/
updated 12/30
Eisboch
"Bertie the Bunyip" <B...@vesuviius.com> wrote in message
news:3e11336...@news.alt.net...
Old technology now I am sure, but the last I knew. modern Navy subs used a
system called "SINS" or something like that. I think it was an acronym for
Submarine Inertial Navigation System. The heart of the system was a Ring
Laser Gyro complement that measured multi-axis motion plus acceleration and
deceleration. The data was all fed to a computer that calculated position
based on the collective and additive inputs of the RLGs.
No true compass is required, as position is determined by what movements the
sub made since submerging. The system was calibrated as required by
conventional and electronic checks.
Eisboch
Rick
>"Prithee doo tell how this miracle occurs."
Jax knew this and since, as his dingleberry, you are so close to him in
so many ways it is difficult to believe you haven't benefited through
"trickle down" of sorts.
The north seeking gyros used on those boats used what was called a
pendulous mount and by introducing a small tilt angle to the rotor axis
the westward precession thus induced matched and countered the rate of
easterly movement caused by the earth's rotation. So there you have it,
precession was used to "orient" or more accurately, correct the compass,
not some external signal from other non existent devices.
If you don't know what you are talking about it is probably best to just
keep off the keyboard rather than show yourself a posturing fool ...
even Jax knows when to keep quiet. You have much to learn from him.
Rick
Bertie the Bunyip
Yep, that's right, they do use that. So does just about every modern
long range aricraft flying now. And you're right, no true compass is
required.
They still have one, though. And it works through a flux gate slave.
Bertie
Bertie the Bunyip
Well, actually, the eway they are initialised is to set them to align
while you are more or less stationary. The N/S potentiometer seeks no
movement and the E/W one looks for max. The rate sensed by the E/w one
will help to initialise lattitude, but the operator must insert a
precise Lat Long in for the whole thing to work properly.
I use 'em every day I go to work, ya see...
Bertie
Bertie the Bunyip
>What about the flux capacitor? What role does that play in navigation?
Beats the fuck outa me. I just use 'em.
The flux gate, shich is waht they call it in my manuals, is a three
legged contraption which senses orientation to mag north by the amount
of the earth's mag field passing into and out of each leg according to
it;'s alignment.
So, if two tips are more or less in alignment as I've illustrate in
the attached as 1 and 2, they are going to carry the lions share of
the signal and the system deduces where north is from that.
Kay?
Bertie
Rick
Apples and oranges ... a north seeking gyro could care less about
longitude. You must be referring to an inertial navigation system that
uses a gyro for initial alignment, not just a gyrocompass. What is the
unit you use? An older Carousel?
Rick
JAXAshby
comprehend.
JAXAshby
JAXAshby
there is no such thing as a north ------> seeking <------ gyro.
that's not how gyro's work.
Rick
I seem to have been proven wrong.
To paraphrase P.T.Barnum, it is impossible to underestimate Jax's
intelligence or to overestimate his ability to shoot himself in the foot.
Rick
Rick
Yeah, Ok Jax, you got me on that one ... silly me for thinking I could
sneak one like that past your razor sharp technical mind.
Thank you for saving the world from the misanthropic attempts of the
world's gyro manufacturers to delude so many generations of navigators
since Elmer Sperry claimed to have invented just such a device in 1911.
Sperry .. h'mmm now that sounds familiar for some reason. Ever heard of
a company by that name, Jax? Maybe you can call them and let them know
there is no such thing as a north seeking gyro. I am sure you will share
that conversation with us, won't you?
Rick
JAXAshby
claim to have at least one training class.
too bad they didn't "train" enough to know what inertia is.
JAXAshby
ricky, ricky, ricky it seems you don't understand English. A *magnetic*
compass ---> seeks <--- north while a gyro compass points north.
a gyro is totally incapable of ---> seeking <--- anything. that's not how
gyros work.
the rest below is to help enlighten you (if that is possible) for the utter
lack of education you received during your "training" (that's the word you
used) course.
seek ( P ) Pronunciation Key (sk)
v. sought, (sôt) seek·ing, seeks
v. tr.
To try to locate or discover; search for.
To endeavor to obtain or reach: seek a college education.
To go to or toward: Water seeks its own level.
To inquire for; request: seek directions from a police officer.
To try; endeavor: seek to do good.
Obsolete. To explore.
v. intr.
To make a search or investigation: Seek and you will find.
--------------------------------------------------------------------------
------
[Middle English sechen, seken, from Old English scan. See sg- in Indo-European
Roots.]
seeking
Seek \Seek\, v. t. [imp. & p. p. Sought; p. pr. & vb. n. Seeking.] [OE, seken,
AS. s?can, s?cean; akin to OS. s?kian, LG. s["o]ken, D. zoeken, OHG. suohhan,
G. suchen, Icel. s?kja, Sw. s["o]ka, Dan. s["o]ge, Goth. s?kjan, and E. sake.
Cf. Beseech, Ransack, Sagacious, Sake, Soc.] 1. To go in search of; to look
for; to search for; to try to find.
The man saked him, saying, What seekest thou? And he said, I seek my brethren.
--Gen. xxxvii. 15,16.
2. To inquire for; to ask for; to solicit; to bessech.
Others, tempting him, sought of him a sign. --Luke xi. 16.
3. To try to acquire or gain; to strive after; to aim at; as, to seek wealth or
fame; to seek one's life.
4. To try to reach or come to; to go to; to resort to.
Seek not Bethel, nor enter into Gilgal. --Amos v. 5.
Since great Ulysses sought the Phrygian plains. --Pope.
Seeking
adj : trying to obtain: "profit-seeking producers"; "people seeking happiness"
n 1: the act of searching for something; "a quest for diamonds" [syn: quest] 2:
an attempt to acquire or gain something
Bertie the Bunyip
>it's also impossible to underestimate ricky's education level, though he does
>claim to have at least one training class.
>
>too bad they didn't "train" enough to know what inertia is.
Bwawhahwhahwhhahwhahwhahhw!
But you just said he knew what he was etalking about , Jaxhole.
Make up your (alleged) mind, please.
Bertie
Bertie the Bunyip
>bb/lb, give it up. rick pulled your leg and you had no clew at all.
I have quite a large clue as to how Gyros, INS, flux gates and so on
work, Jaxhole.
Do you?
Bertie
Bertie the Bunyip
>>a north seeking gyro
>
>there is no such thing as a north ------> seeking <------ gyro.
>
>that's not how gyro's work.
Realy? Do tell.
Bertie
Bertie the Bunyip
> >"... the operator must insert a precise Lat Long ..."
Well, initially, I was referring to a just a plain Gyrocompass, but
the thread went INS....
You're right, the compass itself couldn't care less about long for
it's north ref, but if it doesn't know where it is, it has problems
with apparent drift, so it has to be updated as to long, time and so
forth, which brings it back to it's INS computer, unless,of course, it
has some other way of referencing, like a flux gate, f'rinstance?
Bertie
Bertie the Bunyip
> >"... even Jax knows when to keep quiet ..."
Well, I have to agree with you there.
Bertie
Bertie the Bunyip
>rick, you pulled bb/lb's leg in a fashion he'll never have a chance to
>comprehend.
Bwawhahwhahwhahhwhahwhahhw!
Yeah, Jaxxy. Maybe you can dis Einstein on this one too!
Bwawahwhhahwhahwhhahwhahwhahhwhahwhahhwhahwhahhwhahwhahhwhah!
Bertie
Bertie the Bunyip
>> >"there is no such thing as a north ------> seeking <------ gyro."
>>
>>Yeah, Ok Jax, you got me on that one ... silly me for thinking I could
>>sneak one like that past your razor sharp technical mind.
>>
>>Thank you for saving the world from the misanthropic attempts of the
>>world's gyro manufacturers to delude so many generations of navigators
>>since Elmer Sperry claimed to have invented just such a device in 1911.
>>
>>Sperry .. h'mmm now that sounds familiar for some reason. Ever heard of
>>a company by that name, Jax? Maybe you can call them and let them know
>>there is no such thing as a north seeking gyro. I am sure you will share
>>that conversation with us, won't you?
>>
>>
>>Rick
>
>
>ricky, ricky, ricky it seems you don't understand English. A *magnetic*
>compass ---> seeks <--- north while a gyro compass points north.
So, do tell us how a sub gyro works, Jaxholio.
Bertie
SaladinoJA
>From: B...@vesuviius.com (Bertie the Bunyip)
>Date: 12/30/2002 9:59 PM Eastern Standard Time
>Message-id: <3e1176d6...@news.alt.net>
>Harry Krause <harry...@hotmail.com> wowed me with :
What about the flux capacitor? What role does that play in navigation?
Bunyip says
>Beats the fuck outa me. I just use 'em.
I'm guessing, you missed those movies?
John
Steven Shelikoff
Excellent! Add that to the list of stupid things jox has said.
Steve
Steven Shelikoff
>> >"there is no such thing as a north ------> seeking <------ gyro."
>>
>>Yeah, Ok Jax, you got me on that one ... silly me for thinking I could
>>sneak one like that past your razor sharp technical mind.
>>
>>Thank you for saving the world from the misanthropic attempts of the
>>world's gyro manufacturers to delude so many generations of navigators
>>since Elmer Sperry claimed to have invented just such a device in 1911.
>>
>>Sperry .. h'mmm now that sounds familiar for some reason. Ever heard of
>>a company by that name, Jax? Maybe you can call them and let them know
>>there is no such thing as a north seeking gyro. I am sure you will share
>>that conversation with us, won't you?
>>
>>
>>Rick
>
>
>ricky, ricky, ricky it seems you don't understand English. A *magnetic*
>compass ---> seeks <--- north while a gyro compass points north.
>
>a gyro is totally incapable of ---> seeking <--- anything. that's not how
>gyros work.
>
>the rest below is to help enlighten you (if that is possible) for the utter
>lack of education you received during your "training" (that's the word you
>used) course.
[definitions of seek snipped]
Good jox, so you know what seek means. The only thing you don't know is
that a north seeking gyro does exactly that, seeks north from any
position and settles there once it finds it.
Just because you haven't heard of something doesn't mean it doesn't
exist. In this case, they've existed for over 90 years.
Steve
Bertie the Bunyip
Rich Johnson
> >and use a gyroscope precession to orientate to true north.
>
>
> actually, they take into account precession, but are oriented before
> starting
> out (and reoriented as is available)
Read slowly: marine gyros are turned on, given enough time to settle and
then except for speed/latitude compensation are ignored. The
speed/latitude compensation may be automatic such as the Anchutz(now
raytheon marine) or it may be manual such as the old Sperry MK37 system.
For a short non technical explination see:
http://makeashorterlink.com/?Z2A263CE2
--
Rich
Enfield NS
Canada
SaladinoJA
>From: B...@vesuviius.com (Bertie the Bunyip)
>Message-id: <3e1214b2...@news.alt.net>
The flux capacitor, was the power source, in the Back To The Future movies. (I
have no idea if there is a real life flux cap... Harry?)
John
JAXAshby
it certainly doesn't appear you do, otherwise you're just being a turd, again.
shall we guess?
JAXAshby
but a gyro can't.
Rich Johnson
> >"Gyroscopic precession to orient the compass?"
>
> >"Prithee doo tell how this miracle occurs."
>
> Jax knew this and since, as his dingleberry, you are so close to him in
> so many ways it is difficult to believe you haven't benefited through
> "trickle down" of sorts.
>
> The north seeking gyros used on those boats used what was called a
> pendulous mount and by introducing a small tilt angle to the rotor axis
> the westward precession thus induced matched and countered the rate of
> easterly movement caused by the earth's rotation. So there you have it,
> precession was used to "orient" or more accurately, correct the compass,
> not some external signal from other non existent devices.
>
> If you don't know what you are talking about it is probably best to just
> keep off the keyboard rather than show yourself a posturing fool ...
> even Jax knows when to keep quiet. You have much to learn from him.
>
> Rick
>
Thanks for the succint explination, saves me from having to remember how
they work
Rich Johnson
>
> Well, actually, the eway they are initialised is to set them to align
> while you are more or less stationary. The N/S potentiometer seeks no
> movement and the E/W one looks for max. The rate sensed by the E/w one
> will help to initialise lattitude, but the operator must insert a
> precise Lat Long in for the whole thing to work properly.
> I use 'em every day I go to work, ya see...
>
> Bertie
I'll type slowly, not the marine ones. We turned them on at the start of
the season, some were shut down half way throughthe season for
maintenance (raytehon marine ones) while the sperry's would be turned
off at the end of the season. No further input required
JAXAshby
since then that gyro compasses in no way use "precession to orient to true
north".
try thinking of "precession" as an error (it's not but try thinking of it as
such) and maybe things will become clearer.
JAXAshby
good explanation, even though it's not right.
good enough for a deckhand, though.
Bertie the Bunyip
OK, I can buy most of this, but I still can't understand how they can
operate on a moving platform (i.e. your boat) without accumulative
error thorughout the journey. Unless of course, you're adding in some
outside nav input either manually or through GPS. In any case, it'd
have to be pretty accurate info to make such a contraption worth
having in the first place. You do updaye somehow other than just the
tables you speak of, right?
Bertie
Bertie the Bunyip
>>Subject: Re: Compass in a submarine?! - flux.jpg (0/1)
>>From: B...@vesuviius.com (Bertie the Bunyip)
>>Date: 12/31/2002 9:03 AM Eastern Standard Time
>>Message-id: <3e1214b2...@news.alt.net>
>>
>>salad...@aol.com (SaladinoJA) wowed me with :
>>
>>>>Subject: Re: Compass in a submarine?! - flux.jpg (0/1)
>>>>From: B...@vesuviius.com (Bertie the Bunyip)
>>>>Date: 12/30/2002 9:59 PM Eastern Standard Time
>>>>Message-id: <3e1176d6...@news.alt.net>
>>>
>>>>Harry Krause <harry...@hotmail.com> wowed me with :
>>>What about the flux capacitor? What role does that play in navigation?
>>>
>>>Bunyip says
>>>
>>>>Beats the fuck outa me. I just use 'em.
>>>
>>>I'm guessing, you missed those movies?
>>
>>
>>And what movies are those?
>>
>>
>>Bertie
>>
>>
>I think you're putting me on, but I'll bite.
>The flux capacitor, was the power source, in the Back To The Future movies. (I
>have no idea if there is a real life flux cap... Harry?)
I said flux gate, not capacitor, and they're real..
every airliner on the planet has one in each wingtip!
Honest.
Bertie
Bertie the Bunyip
>Sure there is. Karen of Oz holds the patent; it is the summation of her
>life's work...a gadget that looks like a blender and doesn't actually work.
>
Mmm, then the NOAA are wasting their time with this, then..
Bertie the Bunyip
Bertie the Bunyip
>Sure there is. Karen of Oz holds the patent; it is the summation of her
>life's work...a gadget that looks like a blender and doesn't actually work.
>
Sure install an awful lot of them round the world for purely
decorative value, then.
http://www.outfittersparadise.com/r/Raymarine/Raymarine_Flux_Compass_S
ensor_703191.htm
Bertie the Bunyip
>I have understood that, rich, since the days of Nautilus. I also understood
>since then that gyro compasses in no way use "precession to orient to true
>north".
>
>try thinking of "precession" as an error (it's not but try thinking of it as
>such) and maybe things will become clearer.
Well, actually, it's not an error, it just is.
Bertie
Bertie the Bunyip
>stveei, have you ANY idea what the English word "seeking" means?
>
Let me see. I'll try definition with an example:
"Jax seeks abuse with his every post"
That about it?
Bertie
SaladinoJA
>From: B...@vesuviius.com (Bertie the Bunyip)
>Message-id: <3e123326...@news.alt.net>
HARRY WROTE
>What about the flux capacitor?
YOU WROTE
>Beats the fuck outa me. I just use 'em.
I WROTE
>I'm guessing, you missed those movies?
>The flux capacitor, was the power source, in the Back To The Future movies.
>(I
>>> have no idea if there is a real life flux cap... Harry?)
>>> John
Bunyip it was a joke, flux capacitor not flux gate.
Rich Johnson
> Rich Johnson wowed me with :
I'm guessing that your gyro experience is avation based, not marine
based and afaik they are 2 different critters. the avation based ones
are, I believe, just an electrically driven gyro which is set at a known
bearing such as a runway and then perodically realligned from another
known bearing . Marine Gyros are a little more complicted, as they line
up North/South using gyroscopic precession, as Rick explained quite
well. Once aligned they stay alligned but must be corrected for
speed/latitude errors, which are really quite small unless one is moving
quite fast (Airplanes for example). A marine gyro may tumble, which
happens when the ship bounces around in heavy seas, but that is quite rare.
Bertie the Bunyip
>>Subject: Re: Compass in a submarine?! - flux.jpg (0/1)
Yes, I go that, but assumed from the various responses you didn't know
what a flux gate was either!
Anyhow, I called my old nav prof up. Unbeleivably, he's still alive.
and he did indeed know about north seeking gyros. Still can't
understand how they work properly at anything but zero latitude, but I
take it the axis is aligned with the earth's at all time, right?
Pretty much explains why they would be fairly useless to me.
But is there not a probelm with them at very high lattitudes where
centrifugal force and earth's rotation are getting on to similar sorts
of levels? Are they restricted in latitude?
Bertie
Jeff Morris
http://pollux.nss.nima.mil/NAV_PUBS/APN/Chapt-06.pdf
My question for Rich is: how long does it take for the gyro to align itself?
Does it take the pendulum cycle of 84 minutes, or several cycles, or do you
manually correct to speed up the process?
--
-jeff
"The sea was angry that day, my friend. Like an old man trying to send back soup
at the deli."
"Rich Johnson" <rw...@gosympatico.ca> wrote in message
news:tQjQ9.1904$Hs3.2...@ursa-nb00s0.nbnet.nb.ca...
SaladinoJA
>From: B...@vesuviius.com (Bertie the Bunyip)
>Message-id: <3e123abc...@news.alt.net>
>>Bunyip it was a joke, flux capacitor not flux gate.
>
>Yes, I go that, but assumed from the various responses you didn't know
>what a flux gate was either!
Actually I did know, (I only look stupid).
John
Ps. "Yes, I go that"...????
Bertie the Bunyip
Yeh, you're right. I'm a pilot.
Actually, Av gyros are like you described, but onyl in simple light
planes. Even many light aircraft have the flux gate gyros I described
earlier nowadays. Way it works is that the gyro slaves to the
electronic compass. Airliners use a more complicarted system, which is
also ultimately reliant upon the flux compass, but the gyros are
integrated into an inertial navigation system. These gyros would be
aligned with North before departure, but not for the benefit of the
gyro, only that of the pendulums which are the heart of the inertial
nav unit. Nowadays, they're further integrated with GPS which updates
the whole mess. Our gyrocompasses are not oriented to the center of
the earth except by accident, That is they are only right side up as
long as the airplane is, if you like. And because of this are subject
to a nuber of errors caused by the aircraft's motion, the rotation of
the earth, mechanical friction and so forth. I gather that this marine
compass is oriented in space so as to mimic the earth's rotation
therby giving true north always. Still cant understand how it stays
that way over extended periods without fairly frequent updates. Seems
to me they could skew quite badly if the ship were to steam in the
same direction for extended periods of time, as ships are prone
towards!
But fuzzy on this, I know, and I'm sure it's just my previous ass'n
with aviation gyros that's keeping me from understanding this fully,
but surely there has to be some other input to keep one of these units
accurate? I understand they are quite old, as well. WW1? The
mechanical limitations of that time would have been even more of a
problem, so how did they keep error at bay?
Bertie
Rick
>operate on a moving platform (i.e. your boat)
Because a marine north seeking gyrocompass are built with a second
driven element that serves as a "phantom." The errors induced by ships
motions are out of phase and the phantom supplies a correction. These
gyros also use a "ballistic" damping system that corrects for deflection
errors when the ship is on a north/south course.
Speed input from the speedlog is also applied. Remember, a ship at the
equator is moving east at 900 knots when it is dead in the water so any
easting or westing will add or subtract from that speed as will changes
in latitude.
All these features on a marine gyrocompass make it a "hands off" unit
that requires no outside adjustment. Marine gyros could be built
heavily, float on mercury, and be mounted near the CG to reduce motion,
which enabled them to far exceed the capability of aeronautical
gyrocompasses until the development of strapdown systems and electronic
error correction. There is a world of difference between aeronautical
gyros and marine units.
Rick
Bertie the Bunyip
>Bowditch has a section on this in the latest edition:
>
>http://pollux.nss.nima.mil/NAV_PUBS/APN/Chapt-06.pdf
Thanks very much.
Good stuff.
Bertie
Rick
OK, provide the correct explanation for us, Jax.
Somehow I believe we will all have fusion powered dinghys before Jax
provides that bit of information ...
Rick
Bertie the Bunyip
>>Subject: Re: Compass in a submarine?! - flux.jpg (0/1)
Kay, looked at the site that Jeff Morris posted and I think I got it
now. Little fuzzy on some thngs still A few pics would help!
Was a bit surprised to see it slaved to gravity, but that would
eliminate a few probs I thoughtof, but seems to introduce a host of
others. I suspect the early ones were pigs, somehow!
Bertie
Bertie the Bunyip
> >"but I still can't understand how they can
> >operate on a moving platform (i.e. your boat)
> >without accumulative error ..."
>
>Because a marine north seeking gyrocompass are built with a second
>driven element that serves as a "phantom." The errors induced by ships
>motions are out of phase and the phantom supplies a correction. These
>gyros also use a "ballistic" damping system that corrects for deflection
>errors when the ship is on a north/south course.
>
>Speed input from the speedlog is also applied. Remember, a ship at the
>equator is moving east at 900 knots when it is dead in the water so any
>easting or westing will add or subtract from that speed as will changes
>in latitude.
OK, that answers that question. Must also be a nav input to compensate
for latitude, I presume. And according to the doc Jeff posted and to
waht someone mentioned before, there seems to be a NS error as well.
I'm taking that as coriolis?
Bertie the Bunyip
> >"... good explanation, even though it's not right."
Yeah, I knew I was going down a blind alley when Jaxhole started
agreeing with me.
It was scary, let me tell you.
Bertie
Rick
>Does it take the pendulum cycle of 84 minutes, or several
>cycles, or do you manually correct to speed up the process?"
The older ones required about 2 1/2 cycles and were fired up at least 4
hours before sailing. You can speed up the process by manually tilting
the platform to precess faster but its not considered good form.
Rick
Rick
>compensate for latitude, I presume. And according to the doc
>Jeff posted and to waht someone mentioned before, there seems
>to be a NS error as well. I'm taking that as coriolis? "
No nav input for latitude. There is a latitude "knob" that is initially
set at startup. That sets the gyro axis at the meridian angle and the
north seeking feature of the gyro mount automatically corrects the axis
as latitude changes.
The NS error is called a "ballistic error." Imagine yourself standing on
the equator facing north. You toss a ball toward the pole. The ball will
travel in a straight line, a ballistic path. The earth is rotating
beneath the ball at 900 knots when the ball leaves your hand. If the
ball left a smoke trail it would appear to curve westward relative to
the surface of the earth. That is "ballistic error." A north seeking
gyro is built (the old ones used little oil tanks) so that a slight bias
on the gyro axis will utilize precession to supply a force to the east
equivalent to the effect of the earths rotation and counteract the
westerly error.
Latitude changes the amount of force and the degree of correction
required, that is why aero gyros needed constant latitude input. Marine
gyros do not since the axis of the gyro has time to align itself with
the meridian due to the lower speed of a ship.
There is much more to the art of this than I have described. I am not a
gyro technician and my comprehension of the art is bound to be flawed so
we must await Jax's inevitable reaction so that we may all learn how
they really work ...
Rick
JAXAshby
Pacfic under the polar ice cap.
they've gotten better since then, even if they are *still* incapable of
"seeking" anything, let alone North.
JAXAshby
[check the meaning of the word before responding]
>>try thinking of "precession" as an error (it's not but try thinking of it as
>>such) and maybe things will become clearer.
>
>Well, actually, it's not an error, it just is.
>
>
>ertie
JAXAshby
good-enough-for-a-deckhand explanation.
Rick
I see we must add marine gyrocompasses to the lengthy and growing list
of technologies foreign to or totally misunderstood by you, Jax.
After watching you post the most outrageous assaults on reality,
technology, and practice for too long now I am still amazed at your
ability to exceed your former worst efforts ... the depth and breadth of
your ignorance is astounding.
Rick
JAXAshby
deckhands are below average.
the fact that you don't understand something, ricky, in no way means it doesn't
exist.
SaladinoJA
>Date: 12/31/2002 2:35 PM Eastern Standard Time
>Message-id: <20021231143515...@mb-mr.aol.com>
>half of the world is below average. more than half (probably 97+%) of
>deckhands are below average.
jaxy, I read a post (rec. somewhere) about you ragging some guy about a seagull
motor,and him looking up your address, and wanting to drive over and knock the
snot out of you (ring a bell?). Your friend bobspirt replied, that you say
things here, just to break shoes, and in no way is that really you. Truth... or
does bobspirt owe you money?
Ps. I thought you didn't hang out with powerboat guys.
Rich Johnson
> Bowditch has a section on this in the latest edition:
>
> http://pollux.nss.nima.mil/NAV_PUBS/APN/Chapt-06.pdf
>
> My question for Rich is: how long does it take for the gyro to align
> itself?
> Does it take the pendulum cycle of 84 minutes, or several cycles, or
> do you
> manually correct to speed up the process?
>
It varies from gyro to gyro, but 4 hours seems to be it. Some units can
be manually leveled, Robinson I believe made one that one coud speed up
the process. One of the old sperrys could be forced to level as well if
you knew how.
Rich Johnson
> >"OK, that answers that question. Must also be a nav input to
> >compensate for latitude, I presume. And according to the doc
> >Jeff posted and to waht someone mentioned before, there seems
> >to be a NS error as well. I'm taking that as coriolis? "
>
> No nav input for latitude. There is a latitude "knob" that is initially
> set at startup. That sets the gyro axis at the meridian angle and the
> north seeking feature of the gyro mount automatically corrects the axis
> as latitude changes.
>
> Latitude changes the amount of force and the degree of correction
> required, that is why aero gyros needed constant latitude input. Marine
> gyros do not since the axis of the gyro has time to align itself with
> the meridian due to the lower speed of a ship.
Most marine gyros do make some adjustment for latitude, but from memory
the correction is quite small, and the amount of correction required
depends on both speed and latitude. Having said that I don't recall ever
seeing a mate adgust the latitude knob travelling from Haliax to Rankin
Inlet Nunavut.
Heck Rick you know a lot for a guy who isn't a gyro tech, I was one for
8 years and I'm impressed by your knowlidge
Steven Shelikoff
>a *gyro* can't do that, stveie. yup, a magnetic compass can and does "seek"
>but a gyro can't.
You're too funny! I know you won't admit you're wrong when you finally
realize that a gyro *does* "seek" north. That's ok, you're silence will
be more than good enough.
Steve
>>>> >"there is no such thing as a north ------> seeking <------ gyro."
>>>>
>>>>Yeah, Ok Jax, you got me on that one ... silly me for thinking I could
>>>>sneak one like that past your razor sharp technical mind.
>>>>
>>>>Thank you for saving the world from the misanthropic attempts of the
>>>>world's gyro manufacturers to delude so many generations of navigators
>>>>since Elmer Sperry claimed to have invented just such a device in 1911.
>>>>
>>>>Sperry .. h'mmm now that sounds familiar for some reason. Ever heard of
>>>>a company by that name, Jax? Maybe you can call them and let them know
>>>>there is no such thing as a north seeking gyro. I am sure you will share
>>>>that conversation with us, won't you?
>>>>
>>>>
>>>>Rick
>>>
>>>
>>>ricky, ricky, ricky it seems you don't understand English. A *magnetic*
>>>compass ---> seeks <--- north while a gyro compass points north.
>>>
>>>a gyro is totally incapable of ---> seeking <--- anything. that's not how
>>>gyros work.
>>>
>>>the rest below is to help enlighten you (if that is possible) for the utter
>>>lack of education you received during your "training" (that's the word you
>>>used) course.
>>
>>[definitions of seek snipped]
>>
>>Good jox, so you know what seek means. The only thing you don't know is
>>that a north seeking gyro does exactly that, seeks north from any
>>position and settles there once it finds it.
>>
>>Just because you haven't heard of something doesn't mean it doesn't
>>exist. In this case, they've existed for over 90 years.
>>
>>Steve
>>
>>
>>
>>
>>
>>
>
>
Ian Malcolm
>
>
> jaxy, I read a post (rec. somewhere) about you ragging some guy about a seagull
> motor,and him looking up your address, and wanting to drive over and knock the
> snot out of you (ring a bell?). Your friend bobspirt replied, that you say
> things here, just to break shoes, and in no way is that really you. Truth... or
> does bobspirt owe you money?
>
> Ps. I thought you didn't hang out with powerboat guys.
Google him and see the whole sorry saga.
( http://groups.google.com/ [seagull outboard author:JAXAshby] )
The poster showed amazing restraint and didn't physically threaten Jax.
'Tis a pity, an appeal here would have got him plenty of bail money if
he'd broken all of Jaxies fingers.
The saddest bit was seeing the amount Jax's (onscreen) personality has
deteriorated since 1999.
The funniest bit was this joke:
(diplo...@worldnet.att.net)
Subject: Re: Dinghy Outboard
Newsgroups: rec.boats.cruising
Date: 1999/12/06
Which reminds me of the old English joke: new YC member comes to the
bar, where there is a glassed display case showing all the Club items
(scarves, mugs, ties etc.) and asks the bar steward: "I'd want to buy a
Club tie, but I see you have two types, silk and polyester. Which one
would you recommend ?" Replies the bar steward: "It depends on the
occasion, Sir. For a dress evening at the Club, silk is definitely the
thing, but for an emergency start of the Seagull, polyester can't be
beat..."
john
And before Jax points it out, a similar search on me will now find 53
posts on the subject, and I haven't been threatened by anyone either!
--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.
'Stingo' Albacore #1554 - 15' Uffa Fox designed,
All varnished hot moulded wooden racing dinghy circa. 1961
Auxiliary power by British Seagull - "The best Outboard Motor for the
World"
(http://www.math.toronto.edu/almgren/fun/seagull.gif)
Picture now up thanks to Lee Yeaton at his great site
The boats of rec.boats at http://www.thebayguide.com/rec.boats
Lee's The Chesapeake Bay Guide at http://www.thebayguide.com
Rick
The way I understand it the pendulous mount of a north seeking gyro
(sorry Jax) allows the axis of the rotor to tilt relative to the earth
and thereby automatically compensates for changes in latitude with no
need for no Bahama Momma - apologies to Jimmy Buffet. Once the latitude
(read rotor axis tilt angle at that latitude) is manually set at startup
the tilt angle will self adjust due to the pendulous mount with no
further input needed by the jolly tars.
It is the pendulous mount that actually makes the unit north seeking
(sorry Jax) and the speed compensation, ballistic error correction, and
phantom just add to the accuracy and independence of the system.
Jax's rather primitive conception of a gyro is based on a string powered
unit firmly mounted between cast potmetal gimbals and which lacks all of
the features we who actually use or have seen a marine gyrocompass are
familiar.
Thanks for the nice compliment. My exposure is limited to startup and a
bit of last resort troubleshooting ... it had to be last resort for
anyone to let me near it. <G>
Rick
Bertie the Bunyip
> >"OK, that answers that question. Must also be a nav input to
> >compensate for latitude, I presume. And according to the doc
> >Jeff posted and to waht someone mentioned before, there seems
> >to be a NS error as well. I'm taking that as coriolis? "
>
>No nav input for latitude. There is a latitude "knob" that is initially
>set at startup. That sets the gyro axis at the meridian angle and the
>north seeking feature of the gyro mount automatically corrects the axis
>as latitude changes.
>
>The NS error is called a "ballistic error." Imagine yourself standing on
>the equator facing north. You toss a ball toward the pole. The ball will
>travel in a straight line, a ballistic path. The earth is rotating
>beneath the ball at 900 knots when the ball leaves your hand. If the
>ball left a smoke trail it would appear to curve westward relative to
>the surface of the earth. That is "ballistic error." A north seeking
>gyro is built (the old ones used little oil tanks) so that a slight bias
>on the gyro axis will utilize precession to supply a force to the east
>equivalent to the effect of the earths rotation and counteract the
>westerly error.
OK, that's coriolis.
>
>Latitude changes the amount of force and the degree of correction
>required, that is why aero gyros needed constant latitude input. Marine
>gyros do not since the axis of the gyro has time to align itself with
>the meridian due to the lower speed of a ship.
OK, this makes sense. Still can't understand why they went to all this
trouble though! The article posted mentioned th elarge amount of
steel, so that must be it.
>
>There is much more to the art of this than I have described. I am not a
>gyro technician and my comprehension of the art is bound to be flawed so
>we must await Jax's inevitable reaction so that we may all learn how
>they really work ...
Snort! I got the jist. Very clever, particularly for the period in
which they first arose.
Bertie
Bertie the Bunyip
>Rick wrote:
Well, I would imagine theat there would be a fairly large correction
for lattitude, especially if you assume that the correction is the
cosine of lattitude, which would make sense.
Free gyros use this with a primitive system called a latitude nut.
Basically this is an adjustable weight which hangs out th eside of the
gyro forcing a precession in the opposite direction to the drift
caused by the lat you're at. It's a shop job and is generally set to a
mean latitude around whjich th eairplane lives.
Bertie
Bertie the Bunyip
>ertie, inertial nav was good enough 44 years ago for a sub to go Atlantic to
>Pacfic under the polar ice cap.
>
>they've gotten better since then, even if they are *still* incapable of
>"seeking" anything, let alone North.
Do you ever tire of being wrong Jaxhole?
Is there some sort of sexual thrill obtained by being battered time
and time again by people who know more than you?
Bertie
Bertie the Bunyip
>metaphor, ertie. it exists as a metaphor.
>
>[check the meaning of the word before responding]
What error, or metaphor?
I know what both mean, fjuckwit.
Pretty strange that someone with an IQ of 154 , even someone as
undereducated as you obviously are, is incapable of understanding the
simple workings of a gyroscope.
Bertie
Bertie
Bertie the Bunyip
>change the word "seek" to "aligned by the operator" and then becomes a
>good-enough-for-a-deckhand explanation.
Nope, checked up Jaxhole, they're right.
You are, as always, wrong.
Bertie
Bertie the Bunyip
> >"change the word "seek" to "aligned by the operator ..."
Kind of the Grand Casnyon of ignorance, ain;t he?
Bertie
Bertie the Bunyip
>ricky, half of the world is below average. more than half (probably 97+%) of
>deckhands are below average.
And jax, even tfurther, apparently.
Bertie
Bertie the Bunyip
>>Subject: Re: Compass in a submarine?!
>>From: jaxa...@aol.com (JAXAshby)
>>Date: 12/31/2002 2:35 PM Eastern Standard Time
>>Message-id: <20021231143515...@mb-mr.aol.com>
>
>
>>half of the world is below average. more than half (probably 97+%) of
>>deckhands are below average.
>
>jaxy, I read a post (rec. somewhere) about you ragging some guy about a seagull
>motor,and him looking up your address, and wanting to drive over and knock the
>snot out of you (ring a bell?).
Now that's not very sporting!
Much more fun to watch him die a slow death by his own hand right here
for the world to see.
Bertie
Bertie the Bunyip
>On 31 Dec 2002 14:56:02 GMT, jaxa...@aol.com (JAXAshby) wrote:
>
>>a *gyro* can't do that, stveie. yup, a magnetic compass can and does "seek"
>>but a gyro can't.
>
>You're too funny! I know you won't admit you're wrong when you finally
>realize that a gyro *does* "seek" north. That's ok, you're silence will
>be more than good enough.
Noo!
We can't have him being silent!
Bertie
Bertie the Bunyip
>I posted this a day and a half ago..... don't know why you haven't
>caught on yet. Can't figure: ignorance or trolling.
>
>A gyroscope will always point to a fixed point in space if left
>undisturbed. If force is exerted upon it, it will react at right
>angles to the force applied. This characteristic of a gyro combined
>with other elements of precession, pendulocity, and damping will allow
>the gyro to settle toward true north.
>
Been thinking about this. I'm assuming that the pendulocity means that
the Gyro has a bias on one side either by gimbal or added weight that
induces this. Seems to me that would be necessary to bring about any
kind of tendencay for it to align itself,. Otherwise, it would just
keep pointing towards whatever point in space you fired it up at,
given no friction etc.
Bertie
Bertie the Bunyip
>On 31 Dec 2002 16:02:39 GMT, B...@vesuviius.com (Bertie the Bunyip) wrote
>in rec.boats:
>
>>salad...@aol.com (SaladinoJA) wowed me with :
>>
>>>>Subject: Re: Compass in a submarine?! - flux.jpg (0/1)
>>>>From: B...@vesuviius.com (Bertie the Bunyip)
>>>>Date: 12/31/2002 9:03 AM Eastern Standard Time
>>>>Message-id: <3e1214b2...@news.alt.net>
>>>>
>>>>salad...@aol.com (SaladinoJA) wowed me with :
>>>>
>>>>>>Subject: Re: Compass in a submarine?! - flux.jpg (0/1)
>>>>>>From: B...@vesuviius.com (Bertie the Bunyip)
>>>>>>Date: 12/30/2002 9:59 PM Eastern Standard Time
>>>>>>Message-id: <3e1176d6...@news.alt.net>
>>>>>
>>>>>>Harry Krause <harry...@hotmail.com> wowed me with :
>>>>>What about the flux capacitor? What role does that play in navigation?
>>>>>
>>>>>Bunyip says
>>>>>
>>>>>>Beats the fuck outa me. I just use 'em.
>>>>>
>>>>>I'm guessing, you missed those movies?
>>>>
>>>>
>>>>And what movies are those?
>>>>
>>>>
>>>>Bertie
>>>>
>>>>
>>>I think you're putting me on, but I'll bite.
>>>The flux capacitor, was the power source, in the Back To The Future movies. (I
>>>have no idea if there is a real life flux cap... Harry?)
>>
>>I said flux gate, not capacitor, and they're real..
>>every airliner on the planet has one in each wingtip!
>>
>>Honest.
>
>;-) Well actually, newer AHRS systems (for instance), do not use flux
>detectors anymore. They get the initialization fix from either last
>known position or a fresh GPS position, and then use an RLG array to
>maintain position throughout the flight. The accuracy of the RLG sensors
>is adequate to negate the need for external mag sensors.
OK, that's true, but we still have flux gates in my airplane!
I'll be drug, kicking and screaming, into the new airplane this year
and I'll learn all about that shit then, I'm sure!
I just hope the FO with me on the course isn't too much of a smartass.
Bertie
Rick
>trouble though!"
'Cause ships travel all over the world except at the geographic poles
(where gyrocompasses aren't much good anyway) and they are great masses
of steel and mag compasses go whacko from acceleration errors as you
well know and by adding the north seeking features nobody had to diddle
the things. The last thing you want a mate to do is touch something like
a gyrocompass ... substitute flight attendant for mate and you will
understand.
Mag compasses at sea must be cross checked regularly by sextant and when
no sight is available for long periods as the ship moved through
regions of magnetic variation the dead reckoning plots could go pretty
wide ... one of the reasons there used to be so many wrecks all along
the world's coastlines. With the advent of steamships that could
maintain high speeds for long periods this lack of accurate course
keeping became much more critical.
Once Anschutz and Sperry figured out how to allow the rotor axis to
align itself to the current latitude via the pendulous mount most of the
battle was won, the compass became north seeking (sorry Jax). The
addition of a second rotor 90 degrees to the primary rotor, ballistic
error correction, and vessel speed correction circuits combined with the
motor driven "phantom" removed the need for further human interference
and the certainty of human error. It also allowed the installation of
remote reading repeaters which exactly match the primary nav instrument.
Happy New Year ... I am outa here and am not going to be thinking about
gyros tonight unless someone suggests Greek food.
Rick
Rich Johnson
> Rick
>
Working from memory, there is a definite error at higher latitudes on
east/west courses, which increases with speed. On the ships I worked on
speed was certainly not a factor
Bchbound
me..
In article <auoj0t$f...@dispatch.concentric.net>, 20...@concentric.net
says...
> Sorry for such a stupid question but how can a compass work inside a
> submarine when it is entirely encased in steel? I guess I 've seen one to
> many WWII movies?
>
> M
>
>
>
Steven Shelikoff
wrote:
>Working from memory, there is a definite error at higher latitudes on
>east/west courses, which increases with speed. On the ships I worked on
>speed was certainly not a factor
It should be the other way, that is, the error should be on north/south
courses, and greater at higher latitudes.
Steve
NOYB
"programmed" by a magnetic compass.
"Steve" <est...@hctc.com> wrote in message
news:v10reuj...@corp.supernews.com...
>
> A flux gate is a magnetic compass that utilizes electronics to detect the
> earths magnetic flux fields. A traditional magnetic compass uses a
magnetic
> compass needle to detect and align with the earths magnetic flux fields.
>
> A gyro compass has nothing what so ever to do with the magnetic flux
fields
> of the earth. The gyro aligns with the earths rotating axis, True north
and
> True south.
>
> There is seldom if ever any connection between the magnetic compass and
the
> gyro, wheather it be flux gate or traditional magnetic compass.
>
>
> --
> My opinion and experience. FWIW
>
> Steve
> S/V Good Intentions
>
>
>
Rich Johnson
> On Wed, 01 Jan 2003 03:21:38 GMT, Rich Johnson
> wrote:
>
>
> >Working from memory, there is a definite error at higher latitudes on
> >east/west courses, which increases with speed. On the ships I worked on
> >speed was certainly not a factor
>
>
> It should be the other way, that is, the error should be on north/south
> courses, and greater at higher latitudes.
>
> Steve
I sit corrected, the link to bowridge supports your point. I changed
jobs a while back and haven't been doing the day to day gyro stuff, and
so was working completely from memory
JAXAshby
and hurry because the first offer he got he was going to take.
In other words, he was looking for an ill-informed sucker.
>and him looking up your address, and wanting to drive over and knock the
>snot out of you
yeah, what an idiot. he was going to drive from British Columbia to NY, find a
place to park in midtown NYC then beat the snot out of some guy whose size,
quickness, armaments (btw, I have none and can't imagine needing any), etc he
had no clew of? All because it was simply and politely pointed out that the
engine he was trying to sell for a grand today was selling for only $25 four
years ago in the days before eBay.
gee, crossing a continent and an international border to attempt assault on
someone you have no idea who might be? Do you think the guy could even get
past my doorman, let alone figure out who to get up the elevator?
JAXAshby
enough to search out and find North. ricky brags about being "trained" but
never mentions "educated"
Bertie the Bunyip
> >"Still can't understand why they went to all this
> >trouble though!"
>
>'Cause ships travel all over the world except at the geographic poles
>(where gyrocompasses aren't much good anyway)
Well, actually, a standard gyro, with no gadgets to make it do
anything strange, regularly updated by celestial means, is one of th
ebetter ways to get around polar regions.
>
>
Bertie the Bunyip
>On Wed, 01 Jan 2003 03:21:38 GMT, Rich Johnson <rw...@gosympatico.ca>
If I understand this correctly you'd have errors from both!
Bertie
Bertie the Bunyip
>salad, the guy was pushing a $25 engine as a spectacular deal at only $1,000,
But you said you lived on your boat, Jaxhole..
Bertie
Bertie the Bunyip
>JAXAshby wrote:
>> salad, the guy was pushing a $25 engine as a spectacular deal at only $1,000,
>> and hurry because the first offer he got he was going to take.
>>
>> In other words, he was looking for an ill-informed sucker.
>>
>>
>>>and him looking up your address, and wanting to drive over and knock the
>>>snot out of you
>>
>>
>> yeah, what an idiot. he was going to drive from British Columbia to NY, find a
>> place to park in midtown NYC then beat the snot out of some guy whose size,
>> quickness, armaments (btw, I have none and can't imagine needing any), etc he
>> had no clew of?
>
>
>Just about everyone can tell just about everything one needs to know
>about you, Jax, from that raunchy Speedo bathing suit photo you
>published. You present as if an average fourth grade boy wearing specs
>could bloody your nose.
>
You wouldn't have a copy of that , would you?
bertie
Bertie the Bunyip
>don't be so impressed, rich. ricky thinks something inside a gyro is smart
>enough to search out and find North. ricky brags about being "trained" but
>never mentions "educated"
Bwawahhwhahwhahwhhahwhahhwhahwhahhwhahhha!
Wheras you're niether!
Bertie