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US Navy debuts the P-8A Poseidon at the Dubai Air Show

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US Navy debuts the P-8A Poseidon at the Dubai Air Show

Old 18th Dec 2013, 07:22
  #81 (permalink)  
Join Date: May 2006
Location: UK
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if you want to know how effective a "coastal" submarine is, I'd start by interviewing a Swedish submarine captain for few hours
And how do you know when a submarinner is lying?....

His lips are moving!
Party Animal is offline  
Old 18th Dec 2013, 08:39
  #82 (permalink)  
Join Date: Jan 2008
Location: UK
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OFO... could you give a short description of why modern SSKs have no magnetic signature?
eerrr...coz there's no iron in em

Knock yer self out...

Type 212 submarine - Wikipedia, the free encyclopedia


The Old Fat One is offline  
Old 18th Dec 2013, 09:26
  #83 (permalink)  
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OFO - but there are moving electrical parts, and thus a magnetic signature.
alfred_the_great is offline  
Old 18th Dec 2013, 13:21
  #84 (permalink)  
Join Date: Apr 2010
Location: London
Posts: 7,071

"The ship and internal fixtures are constructed of nonmagnetic materials, significantly reducing the chances of it being detected" (my emphasis)
Heathrow Harry is offline  
Old 18th Dec 2013, 16:56
  #85 (permalink)  
Join Date: Oct 2013
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And how do you know when a submariner is lying?....
During the briefing for a NATO exercise, Norweigan submariner gave talk on his boat's capabilities in coastal waters - said he had never been detected during freeplay and he wouldn't be in this exercise. We subsequently bounced and attacked him. At debrief he provided evidence to show he was nowhere near the alledged attack position. However in addition to his acoustic signature, we had tapes of a decoy deployed by our target, just happened to be the type used by RNoN subs and he was the only one in the exercise. Do submariners lie.....not much!
nimbev is offline  
Old 18th Dec 2013, 20:37
  #86 (permalink)  
Join Date: Jul 2006
Location: by the Great Salt Lake, USA
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So they have a "significantly reduced" magnetic signature... NOT "no" magnetic signature.
GreenKnight121 is offline  
Old 19th Dec 2013, 09:43
  #87 (permalink)  
Join Date: Apr 2010
Location: London
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that's what it says

there is a detailed review of the Type 212A class in the latest (2014) edition of World Naval Review

it says

"Fabrication..... makes extensive use of non-magnetic steel. This is supplemented by the use of lightweight glass-fibre reinforced plastics for some structures including some outer hull coverings and large parts of the fin"

The British Stainless Steel Assoc state:-
Is stainless steel non-magnetic?

It is commonly stated that “stainless steel is non-magnetic”. This is not strictly true and the real situation is rather more complicated. The degree of magnetic response or magnetic permeability is derived from the microstructure of the steel. A totally non-magnetic material has a relative magnetic permeability of 1. Austenitic structures are totally non-magnetic and so a 100% austenitic stainless steel would have a permeability of 1. In practice this is not achieved. There is always a small amount of ferrite and/or martensite in the steel and so permeability values are always above 1. Typical values for standard austenitic stainless steels can be in the order of 1.05 – 1.1. See Composition effects on the magnetic permeability of austenitic stainless steels
It is possible for the magnetic permeability of austenitic steels to be changed during processing. For example, cold work and welding are liable to increase the amount of martensite and ferrite respectively in the steel. A familiar example is in a stainless steel sink where the flat drainer has little magnetic response whereas the pressed bowl has a higher response due to the formation of martensite particularly in the corners.
In practical terms, austenitic stainless steels are used for “non-magnetic” applications, for example magnetic resonance imaging (MRI). In these cases, it is often necessary to agree a maximum magnetic permeability between customer and supplier. It can be as low as 1.004.
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