Sunday, July 5, 2015

Saab unveils superstealth 'ghost submarine'

  • Special pod allows divers to enter and exit sub while underwatwer
  • Built to include rubber damping and acoustic baffling to reduce noise
  • Hull shape and fins designed to make it appear almost invisible 
  • Can also 'play dead' at the bottom of the sea to remain undetected

Mark Prigg/DailyMail
2 July 2015
Saab has unveiled what it claims is the world's most advanced stealth submarine.
The A26 sub is 207 feet long, and features a 'ghost mode' to make it virtually undetectable when underwater.
It also features a unique pod that allows special forces divers to enter and exit the sub while it is underwater.  

The A26 sub is 207 feet long, and features a 'ghost mode' to make it virtually undetectable when underwater.The A26 sub is 207 feet long, and features a 'ghost mode' to make it virtually undetectable when underwater.
It can also 'play dead' at the bottom of the sea to remain unfound - while divers can still exit to lay minesIt can also 'play dead' at the bottom of the sea to remain unfound - while divers can still exit to lay mines

STEALTH SUB SPECS 

Type A26 submarines are nearly 207 feet in length, 21 feet in the beam.
The have an endurance of 45 days or 18 days underwater.
They have a test depth of about 658 feet. 
They will be conventional diesel-electric submarines equipped with the Kockums Stirling AIP (air-independent propulsion) system for enhanced stealth.
The firm has already signed a $1 billion deal to build two of the new submarines for the Swedish Navy.

'Extreme stealth is at the heart of the Kockums A26 submarine,' the firm said.
'Sweden is unleashing its GHOST (Genuine HOlistic STealth) technology, thus making the Kockums A26 submarine effectively invisible.'
The order, with a value of about $1.04 billion, is for construction of two Type A26 submarines and conducting mid-life upgrades to two Gotland-class submarines.
Work on the two A26s is to be completed by 2024.
Type A26 submarines are nearly 207 feet in length, 21 feet in the beam and have an endurance of 45 days or 18 days underwater. 
They have a test depth of about 658 feet. 
They will be conventional diesel-electric submarines equipped with the Kockums Stirling AIP (air-independent propulsion) system for enhanced stealth.
'Sweden has long experience in designing very silent submarines,' the firm says.
'In the Kockums A26 submarine, an extremely resilient platform technique incorporating extensive rubber mountings and baffles is used to minimise noise from operating machines and transient noise, as well as absorbing shocks. 
To further reduce emitted noise, the space between the frames is equipped with acoustic damping plates.
'Intelligence gathering, surveillance and sea denial along coastlines are becoming increasingly important, ' Saab said. 
'Operations in shallow water enable submarines to carry out covert monitoring of targets on land or sea using a range of electro-optical and electromagnetic sensors. 
'Moreover, the ability of a submarine to lie motionless on the ocean floor, or 'bottom out', makes it almost impossible to find.'
The two vessels will be delivered to Sweden's Defense Materiel Organization in late 2018 and late 2019, respectively.
'Saab will deliver world-class submarines to Sweden,' said Hakan Buskhe, president and chief executive officer of Saab. 'Our ability to work closely with customers, to meet their needs with modern manufacturing and products, is one of Saab's greatest skills.
'Saab is also exploring export opportunities to provide complete submarine systems to a select number of countries, plus sub-systems across the wider market.'

How 'Ghost Mode' works

Extreme stealth is at the heart of the Kockums A26 submarine, and it depends on good design right from the very beginning, Saab claims.
'Sweden has long experience in designing very silent submarines,' it says.
'In the Kockums A26 submarine, an extremely resilient platform technique incorporating extensive rubber mountings and baffles is used to minimise noise from operating machines and transient noise, as well as absorbing shocks. 
To further reduce emitted noise, the space between the frames is equipped with acoustic damping plates.
This approach is used in combination with, for example, encapsulated Stirling and diesel engine modules; flexible hoses and compensators; and specifying maximum flow speed in air ducts, minimum bending radius on cables and pipes, and the design of out-board holes and cavities. 
To become invisible, further ways of keeping silent are exploited by the Kockums A26 submarine:
The target strength of the Kockums A26 submarine is minimal because of the vessel's unique hull shape, the unique fin design, sonar and equipment accommodation, and a new type of surface acoustic absorption or reflection coatings. 
This highly optimised design also cuts the hydrodynamic signatures and flow noise around the submarine, both in deep water and near the surface.
The magnetic signature is suppressed by an advanced degaussing system that is controlled by external sensors to facilitate compensation in all geographical locations and headings. 
Galvanic signatures, primarily electrical but including secondary magnetic signatures are reduced by a specially designed cathodic protection system and careful material selection that minimise electrical signatures without compromising the corrosion protection of the submarine.

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