[PSUBS-MAILIST] gyroscope compass

Wed Dec 3 15:07:25 EST 2014

Thank you Carsten,
Well that settles it, I am back to the fluid filled ball magnetic compass that Gamma came with.
Hmm seems like simple is best
Hank--------------------------------------------
On Wed, 12/3/14, Carsten Standfuß" via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] gyroscope compass
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Wednesday, December 3, 2014, 2:46 PM

 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. 

 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. 

 I have both
 types in 
 the Euronaut. And a magnetic one also. 
 The
 gyros are both cheap Ebay
 ones. 
 One from a aircraft one from a ship. 
 And
 both not working anymore.
 And the 
 third magnetic one has a big error because of the 60 ts
 steel below.

 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. 

 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. 
 Cross check with another compass
 (or the same  one)
 far away 
 from the sub. 

 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. 

 vbr 
 Carsten

 "hank
 pronk via
 Personal_Submersibles" <personal_submersibles at psubs.org>
 schrieb:
 > 
 > 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.
 > Hank 
 --------------------------------------------
 >
 On Wed, 12/3/14, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:
 > 
 >  Subject:
 Re: [PSUBS-MAILIST] gyroscope
 compass
 >  To: "Personal
 Submersibles General Discussion" <personal_submersibles at psubs.org>
 >
  Received: Wednesday, December 3, 2014, 1:48 PM
 >  
 > 
 Absolutely. You can get small ones for civil
 >  aviation and they
 are used in subs. One challenge is that
 >
  most airplane ones are
 powered by a vacuum, but there are
 >  12V
 models. Unfortunately
 they're expensive, but a great
 > 
 solution if you can afford
 it. 
 >  Alec 
 >  On
 Wed, Dec 3, 2014 at
 1:28
 >  PM, hank pronk via
 Personal_Submersibles <personal_submersibles at psubs.org>
 >
  wrote:
 >  Hi
 > 
 all,
 >  
 >  Ever hear
 of a
 gyroscopic compass, seems that ships used to
 >  use them.  It
 seems they would not be effected by a
 > 
 submarine hull. 
 What am I missing besides they are very
 >
  big.
 >  
 > 
 Hank
 >  
 > 
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