<HTML><HEAD></HEAD><BODY><font face="Courier New" size=2>Gyros in
aricraft are not north stable - they need a
magnetic compass or other device to set course. But they are
okay
if you set course according to your GPS course before you dive.
They can
hold the course for some hours with a movment of 2-4 deegre per hour.
Okay for a
slow and small Psub. They are vaccum driven or electric. Vaccum driven
you can
not use in a small submarine. (Or you need a silencer and eardrums as in
Spurdog). Electric you can use if it is a 12 or 24 V DC driven one. For
other
voltage you need a special power converter. The Ebay units are sometimes
cheap -
between 100-800 USD - but most of them work not proper. They are
build out
of the planes for exact that reason and sold as they are and without any
waranty.. Size is around 100x100x400mm. Volume 4 Liters.. Good solution
if you
buy a unit in aircraft condition with papers from a aircarft surplus
dealer with
a working garanty. Make sure that they get not wet or 100% humidity.
<BR><BR>Gyros in ships are north stabilzed. The need around 40 Minutes
to warm
up. They are much bigger - the smallest one are around 300 x 400 x
300 mm.
Volume at minimum 36 liter. They need no calibration or reference and
they are
stable over month/years. Problem is that they normal switch on in a ship
and
never switch off.. If you switch of them - make sure that you not move
the sub
in the next hours - otherwise they can be damaged. They are expensive -
about
30000 USD new and 3000-9000 USD second hand. There life time is
limited
30000 - 40000 hours between first failtures. <BR><BR>I have both
types in
the Euronaut. And a magnetic one also. <BR>The gyros are both cheap Ebay
ones.
One from a aircraft one from a ship. <BR>And both not working anymore.
And the
third magnetic one has a big error because of the 60 ts steel below.
<BR><BR>I
will by next a second hand one north stabilzed ship gyro for around 3000
USD
from a ship scrap yard electronic dealer with a confirm that they test
it and
its run stable but without any further waranty. <BR><BR>A fluxgate its a
kind of
electronic coils magnetic field compass and will in most cases not work
proper
on a strong magnetic metal shell like a submarine with strong electric
motor
fields etc. To test on your submarine if these cheap devices runs on you
submarine install a simple magnetic compass temporary on the sensor spot
in
mind and than turn the submarine 360 degree. Switch on and off all
electric
devices. <BR>Cross check with another compass (or the same one)
far away
from the sub. <BR><BR>In most cases an electric 12 or 24 V Dc driven
Airplane
direction gryro in combination with a gps course before diving will do
the job.
But in 99% a ebay 100 USD item will not work proper. <BR><BR>vbr
Carsten<BR><BR><BR><BR><BR></font><BR><BR>"hank pronk via
Personal_Submersibles" <<A
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>
schrieb:<BR>> <BR>> There are all kinds of them on ebay for under
100 dollars, problem is how to make it work. I assume they just have a
small motor that spins. There is a nice ship gyro sitting at 50 dollars
right now but it is about 1 foot dia. That would be awesome in a big
sub.<BR>> Hank --------------------------------------------<BR>>
On Wed, 12/3/14, Alec Smyth via Personal_Submersibles <<A
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>
wrote:<BR>> <BR>> Subject: Re: [PSUBS-MAILIST] gyroscope
compass<BR>> To: "Personal Submersibles General Discussion" <<A
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><BR>>
Received: Wednesday, December 3, 2014, 1:48 PM<BR>> <BR>>
Absolutely. You can get small ones for civil<BR>> aviation and they
are used in subs. One challenge is that<BR>> most airplane ones are
powered by a vacuum, but there are<BR>> 12V models. Unfortunately
they're expensive, but a great<BR>> solution if you can afford
it. <BR>> Alec <BR>> On Wed, Dec 3, 2014 at
1:28<BR>> PM, hank pronk via Personal_Submersibles <<A
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><BR>>
wrote:<BR>> Hi<BR>> all,<BR>> <BR>> Ever hear of a
gyroscopic compass, seems that ships used to<BR>> use them. It
seems they would not be effected by a<BR>> submarine hull.
What am I missing besides they are very<BR>> big.<BR>> <BR>>
Hank<BR>> <BR>>
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