Air-independent propulsion
Encyclopedia
Air-independent propulsion (AIP) is a term that encompasses technologies which allow a submarine to operate without the need to surface or use a snorkel
Submarine snorkel
A submarine snorkel is a device which allows a submarine to operate submerged while still taking in air from above the surface. Navy personnel often refer to it as the snort.-History:...

 to access atmospheric
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

 oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

. The term usually excludes the use of nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

, and describes augmenting or replacing the diesel-electric propulsion system of non-nuclear vessels. The United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 uses the hull classification symbol
Hull classification symbol
The United States Navy, United States Coast Guard, and United States National Oceanic and Atmospheric Administration use hull classification symbols to identify their ship types and each individual ship within each type...

 "SSP" to designate boats powered by AIP, while retaining "SS" for classic diesel-electric attack submarines.

AIP is usually implemented as an auxiliary source. Most such systems generate electricity which in turn drives an electric motor for propulsion or recharging the boat's batteries
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

. The submarine's electrical system is also used for providing "hotel services"—ventilation, lighting, heating etc.—although this consumes a small amount of power compared to that required for propulsion.

A benefit of this approach is it can be retrofitted into existing submarine hulls
Hull (watercraft)
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...

 by inserting an additional hull section. AIP does not normally provide the endurance or power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

 to replace the atmospheric dependent propulsion, but allows it to remain submerged longer than a more conventionally propelled submarine. A typical conventional power plant will provide 3 megawatts maximum, and an AIP source around 10% of that. A nuclear submarine's propulsion plant is usually much greater than 20 megawatts.

History

In 1867 Narcís Monturiol i Estarriol
Narcís Monturiol i Estarriol
Narcís Monturiol Estarriol was a Spanish Catalan intellectual, artist and engineer. He was the inventor of the first combustion engine-driven submarine, which was propelled by an early form of air-independent propulsion....

 successfully developed an anaerobic air independent propulsion system powered by a chemical reaction. In 1908 the Imperial Russian Navy launched the submarine Pochtovy
Russian submarine Pochtovy
Pochtovy was a submarine built for the Imperial Russian Navy. The boat was designed by Drzewiecki and built at the Metal Works St Petersburg in 1908. She was funded by Public subscription....

 which used a gasoline engine fed with compressed air and exhausted under water.

During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 firm Walter
Hellmuth Walter
Hellmuth Walter was a German engineer who pioneered research into rocket engines and gas turbines...

 experimented with submarines that used concentrated hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 as their source of oxygen under water. These used steam turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

s, employing steam heated by burning diesel fuel in the steam/oxygen atmosphere created by the decomposition of hydrogen peroxide by a potassium permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...

 catalyst.

Several experimental boats were produced, and one, U-1407, which had been scuttled at the end of the war, was salvaged and recommissioned into the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 as HMS Meteorite
HMS Meteorite
HMS Meteorite was an experimental U-boat developed in Germany, scuttled at the end of World War II, subsequently raised and commissioned into the Royal Navy. The submarine was originally commissioned into the Kriegsmarine in March 1945 as U-1407...

. The British built two improved models in the late 1950s, , and HMS Excalibur
HMS Excalibur
HMS Excalibur was the sister ship of , the two submarines being the only High test peroxide powered submarines to be constructed by the Royal Navy...

.

The Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 also experimented with the technology and one experimental boat was built
Soviet submarine S-99
The S-99 experimental submarine was the only ship of Whale class that the Soviet Union built during the early cold war period and the only soviet submarine which had a Walter engine fuelled by high test peroxide .- Design :Initial design of submarine was based on project XXVI documentation taken...

. Hydrogen peroxide was eventually abandoned since it is highly reactive when in contact with various metals, is volatile, and submarines had a high rate of consumption. Both the British and the Soviets, the only countries known to be experimenting with it, abandoned it when the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 developed a nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

 small enough for submarine propulsion.

It was retained for propelling torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

es by the British and the Soviet Union, although hastily abandoned by the former following the HMS Sidon
HMS Sidon (P259)
HMS Sidon was a submarine of the Royal Navy, launched in September 1944, one of the third group of S-class submarines built by Cammell Laird & Co Limited, Birkenhead...

 tragedy. Both this and the loss of the Russian Submarine Kursk were due to accidents involving hydrogen peroxide propelled torpedoes.

Closed cycle diesel engines

This technology uses a submarine diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

 which can be operated conventionally on the surface, but which can also be provided with oxidant, usually stored as liquid oxygen
Liquid oxygen
Liquid oxygen — abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries — is one of the physical forms of elemental oxygen.-Physical properties:...

, when submerged. Since the metal of an engine will burn in pure oxygen, the oxygen is usually diluted with recycled exhaust gas
Exhaust gas
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack or propelling nozzle.It often disperses...

. As there is no exhaust gas upon starting, argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

 is used.

During World War II the Kriegsmarine experimented with such a system as an alternative to the Walter peroxide system, including a variant of the Type XXVIIB Seehund midget submarine, the "Klein U-boot". It was powered by a 95 hp Diesel engine of a type commonly used by the Kriegsmarine and which was available in large numbers, supplied with oxygen from a tank in the boat's keel holding 1,250 litres at 4 atm (405,300 Pa). It was thought likely that the boat would have a maximum submerged speed of 12 kn (6.5 m/s) and a range of 70 mi (112.7 km), or 150 mi (241.4 km) at 7 kn (3.8 m/s).

The German work was subsequently expanded upon by the Soviet Union who invested heavily in this technology, developing the small 650 ton Quebec-class
Quebec class submarine
The Quebec-class submarine was the NATO reporting name of the Soviet Project 615 submarine class, a small coastal attack submarine of the late 1950s.-Background:...

 submarine of which thirty were built between 1953 and 1956. These had three diesel engines—two were conventional and one was closed cycle using liquid oxygen.

In the Soviet system, called a "single propulsion system", oxygen was added after the exhaust gases had been filtered through a lime-based chemical absorbent. The submarine could also run its diesel using a snorkel. The Quebec had three engines: a 32D 900 bhp diesel on the centre shaft and two M-50P 700 bhp diesels on the outer shafts. In addition a 100 hp "creep" motor was coupled to the centre shaft. The boat could be run at slow speed using the centreline diesel only.

Because liquid oxygen cannot be stored for any great length of time these boats could not operate far from a base. It was also a dangerous system; at least seven submarines suffered explosions, and one of these, M-256
Soviet submarine M-256
M-256 was a Project 615 short-range, diesel attack submarine of the Soviet Navy. She was commissioned into the Baltic Fleet.-Design:...

, sank following an explosion and fire. They were sometimes nicknamed cigarette lighters. The last was scrapped in the early 1970s.

The German Navy
German Navy
The German Navy is the navy of Germany and is part of the unified Bundeswehr .The German Navy traces its roots back to the Imperial Fleet of the revolutionary era of 1848 – 52 and more directly to the Prussian Navy, which later evolved into the Northern German Federal Navy...

's former Type 205 submarine
Type 205 submarine
The Type 205 was a class of diesel-electric German hunter-killer U-boat submarines. They were single-hull vessels optimized for the use in the shallow Baltic Sea. The Type 205 is a direct evolution of the Type 201 class with lengthened hull, new machinery and sensors...

 U1 was fitted with an experimental 3000 horsepower (2.2 MW) unit.

Closed cycle steam turbines

The French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 MESMA (Module d'Energie Sous-Marine Autonome) system is being offered by the French shipyard DCNS. MESMA is available for the Agosta 90B
Agosta 90B class submarine
The Agosta class submarines are French diesel attack submarines used by Spain, Pakistan and formerly by France. The French Navy grouped this model of submarine in their most capable class as an océanique, meaning "ocean-going." A modernised version built for Pakistan, the Agosta 90B, has a crew of...

 and Scorpène class submarines. It is essentially a modified version of their nuclear propulsion system with heat being generated by ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 and oxygen. Specifically, a conventional steam turbine power plant is powered by steam generated from the combustion of ethanol (grain alcohol) and stored oxygen at a pressure of 60 atmospheres. This pressure-firing allows exhaust carbon dioxide to be expelled overboard at any depth without an exhaust compressor.

Each MESMA system costs around $50–60 million. As installed on the Scorpène, it requires adding a new 8.3 meter (27 foot), 305 tonne hull section to the submarine, and results in a submarine able to operate for greater than 21 days underwater, depending on variables like speed, etc.

An article in Undersea Warfare Magazine notes that: “although MESMA can provide higher output power than the other alternatives, its inherent efficiency is the lowest of the four AIP candidates, and its rate of oxygen consumption is correspondingly higher.”

Stirling cycle engines

The Swedish
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 shipbuilder Kockums
Kockums
Kockums AB is a shipyard in Malmö, Sweden owned by the German shipyard Howaldtswerke-Deutsche Werft in Kiel. HDW itself is a subsidiary of the German ThyssenKrupp Marine Systems....

 has constructed three Gotland class
Gotland class submarine
In 2004, the Swedish government received a request from the United States of America to lease HMS Gotland – Swedish-flagged, commanded and manned, for a duration of one year for use in anti-submarine warfare exercises. The Swedish government granted this request in October 2004, with both...

 submarines for the Swedish Navy
Swedish Navy
The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...

  which are fitted with an auxiliary Stirling engine which uses liquid oxygen and diesel fuel to drive 75 kilowatt generators for either propulsion or charging batteries. The endurance of the 1,500 tonne boats is around 14 days at 5 kn (6.1 mph; 9.8 km/h).

Kockums
Kockums
Kockums AB is a shipyard in Malmö, Sweden owned by the German shipyard Howaldtswerke-Deutsche Werft in Kiel. HDW itself is a subsidiary of the German ThyssenKrupp Marine Systems....

 has also delivered Stirling engines to Japan. The new Japanese submarines will all be equipped with Stirling engines. The first submarine, Sōryū
Soryu class submarine
The Sōryū class submarine or 16SS is a new class of diesel-electric submarine being built in Japan for use by the Japan Maritime Self-Defense Force...

, in the class was launched on 5 December 2007 and were delivered to the navy in March 2009.

Fuel cells

Siemens
Siemens AG
Siemens AG is a German multinational conglomerate company headquartered in Munich, Germany. It is the largest Europe-based electronics and electrical engineering company....

 has developed a 30-50 kilowatt fuel cell unit. Nine of these units are incorporated into Howaldtswerke
Howaldtswerke
Howaldtswerke-Deutsche Werft is a German shipbuilding company, headquartered in Kiel. In 2009 it was the largest shipyard in Germany and has more than 2,400 employees. It has been part of ThyssenKrupp Marine Systems owned by ThyssenKrupp, since 2005...

 Deutsche Werft AG's 1,830t submarine U31, lead ship for the Type 212A
Type 212 submarine
The German Type 212 class, also Italian Todaro class, is a highly advanced design of non-nuclear submarine developed by Howaldtswerke-Deutsche Werft AG and Fincantieri S.p.a. for the German and Italian Navy. It features diesel propulsion and an additional air-independent propulsion system using...

 class of the German Navy
German Navy
The German Navy is the navy of Germany and is part of the unified Bundeswehr .The German Navy traces its roots back to the Imperial Fleet of the revolutionary era of 1848 – 52 and more directly to the Prussian Navy, which later evolved into the Northern German Federal Navy...

. The other boats of this class and HDW's AIP equipped export submarines (Type 209 mod
Type 209 submarine
The Type 209 is a class of diesel-electric attack submarine developed exclusively for export in the late 1960s by Howaldtswerke-Deutsche Werft of Germany...

 and Type 214
Type 214 submarine
The Type 214 is a diesel-electric submarine developed by Howaldtswerke-Deutsche Werft GmbH . It features diesel propulsion with an air-independent propulsion system using Siemens polymer electrolyte membrane hydrogen fuel cells...

) use two 120 kW modules, also from Siemens.

After the success of Howaldtswerke
Howaldtswerke
Howaldtswerke-Deutsche Werft is a German shipbuilding company, headquartered in Kiel. In 2009 it was the largest shipyard in Germany and has more than 2,400 employees. It has been part of ThyssenKrupp Marine Systems owned by ThyssenKrupp, since 2005...

 Deutsche Werft AG's in its export activities, several builders have developed their own fuel-cell auxiliary units for submarines but as of 2008 no other shipyard has a contract for a submarine so equipped.

Nuclear power

Nuclear reactors have been used for 50 years to power submarines, the first being USS Nautilus
USS Nautilus (SSN-571)
USS Nautilus is the world's first operational nuclear-powered submarine. She was the first vessel to complete a submerged transit beneath the North Pole on August 3, 1958...

. The United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, and the People's Republic of China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

 are the only countries currently operating nuclear powered submarines. India is developing Arihant class nuclear submarines, the first submarine, INS Arihant (s-73), is undergoing sea trials and induction is expected in 2011. India in the past has leased a Charlie class
Charlie class submarine
The Charlie class submarine is a nuclear powered cruise missile submarine built for the Soviet Navy and later operated by the Russian Navy.-Background:...

 nuclear powered submarine from Russia and plans to acquire two used Akula class submarine
Akula class submarine
Project 971 Щука-Б , is a nuclear-powered attack submarine first deployed by the Soviet Navy in 1986...

s which would be used for training purposes. Many other developing countries have also attempted to research nuclear propulsion for submarine use in the past, but with disappointing results. However, Air Independent Propulsion is a term normally used in the context of improving the performance of conventionally propelled submarines.

There have nevertheless been suggestions for a reactor as an auxiliary power supply, which does fall into the normal definition of AIP. For example, there has been a proposal to use a small 200 kilowatt reactor for auxiliary power (styled a "nuclear battery") to improve the under-ice capability of Canadian submarines.

Production non-nuclear AIP submarines

As of 2009, some nations have non-nuclear AIP submarines:
  • the French-Spanish Scorpène-class submarine
    Scorpène class submarine
    Scorpène class submarines are a class of diesel-electric attack submarine jointly developed by the French DCN and the Spanish company Navantia and now by DCNS. It features diesel propulsion and an additional air-independent propulsion ....

     (1,700 tonnes) (MESMA)
  • the Spanish S-80 class
    S-80 class
    The S-80 Class is a series of submarines of advanced technology that is currently under construction for the Spanish Navy. Initially there will be four units, with a future expansion to six, two of which are in production by the Spanish company Navantia at its factory in Cartagena...

     (2,400 tonnes) of the Spanish Navy
    Spanish Navy
    The Spanish Navy is the maritime branch of the Spanish Armed Forces, one of the oldest active naval forces in the world. The Armada is responsible for notable achievements in world history such as the discovery of Americas, the first world circumnavigation, and the discovery of a maritime path...

  • the German Type 209-1400mod
    Type 209 submarine
    The Type 209 is a class of diesel-electric attack submarine developed exclusively for export in the late 1960s by Howaldtswerke-Deutsche Werft of Germany...

     (1,810 tonnes) (Fuel cell)
  • the German Type 212 submarine
    Type 212 submarine
    The German Type 212 class, also Italian Todaro class, is a highly advanced design of non-nuclear submarine developed by Howaldtswerke-Deutsche Werft AG and Fincantieri S.p.a. for the German and Italian Navy. It features diesel propulsion and an additional air-independent propulsion system using...

     (1,830 tonnes) (Fuel cell) of the German Navy
    German Navy
    The German Navy is the navy of Germany and is part of the unified Bundeswehr .The German Navy traces its roots back to the Imperial Fleet of the revolutionary era of 1848 – 52 and more directly to the Prussian Navy, which later evolved into the Northern German Federal Navy...

     and Italian Navy
    Italian Navy
    Italian Navy may refer to:* Pre-unitarian navies of the Italian states* Regia Marina, the Royal Navy of the Kingdom of Italy * Italian Navy , the navy of the Italian Republic...

  • the German Type 214
    Type 214 submarine
    The Type 214 is a diesel-electric submarine developed by Howaldtswerke-Deutsche Werft GmbH . It features diesel propulsion with an air-independent propulsion system using Siemens polymer electrolyte membrane hydrogen fuel cells...

     (1,980 tonnes) (Fuel cell)
  • the Russian Project 677 Лада (Lada)
    Lada class submarine
    The Russian Navy's Project 677 Лада is a submarine class designed by the Russian Rubin Design Bureau. The class is also referred to as the Petersburg class, after the lead ship...

  • the Russian Project 1650 Амур (Amur)
    Amur class submarine
    The Amur class submarine, designated as the project 950 Амур, , is one of the latest Russian submarine class which are advertised as the export version of the Lada class, a highly improved version of the with much better quieting, new combat systems, and an option for air-independent...

  • the Japanese Asashio
    Harushio class submarine
    The Harushio is a Japanese diesel-electric submarine class operated by the JMSDF. The design is an evolution from the Yūshio class being slightly larger and with better noise reduction...

     (2,750 tonnes) (Stirling AIP) of the Japan Maritime Self-Defense Force
    Japan Maritime Self-Defense Force
    The , or JMSDF, is the naval branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. It was formed following the dissolution of the Imperial Japanese Navy after World War II....

  • the Japanese Sōryū class submarine
    Soryu class submarine
    The Sōryū class submarine or 16SS is a new class of diesel-electric submarine being built in Japan for use by the Japan Maritime Self-Defense Force...

     (4,200 tonnes) (Stirling AIP) of the Japan Maritime Self-Defense Force
    Japan Maritime Self-Defense Force
    The , or JMSDF, is the naval branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. It was formed following the dissolution of the Imperial Japanese Navy after World War II....

  • the Swedish Gotland class submarine
    Gotland class submarine
    In 2004, the Swedish government received a request from the United States of America to lease HMS Gotland – Swedish-flagged, commanded and manned, for a duration of one year for use in anti-submarine warfare exercises. The Swedish government granted this request in October 2004, with both...

     (1,450 tonnes) (Stirling AIP) of the Swedish navy
    Swedish Navy
    The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...

  • the Swedish Södermanland class submarine
    Södermanland class submarine
    The Swedish Södermanland class of diesel-electric submarines consist of the HMS Södermanland and HMS Östergötland. These two submarines were originally launched as Västergötland class submarines in 1987 and 1990, and have been relaunched as a new class after extensive modernization 2003 and 2004 by...

     (1,500 tonnes) (Stirling AIP) of the Swedish navy
    Swedish Navy
    The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...

  • the Singaporean Archer class submarine
    Archer class submarine
    The Archer class submarines are the newest class of diesel-electric submarines in active service with the Republic of Singapore Navy . Originally launched as the Swedish Navy Västergötland class submarines HMS Hälsingland and HMS Västergötland in 1986 and 1987, the two submarines were sold to...

    . Its two submarines are originally Swedish Västergötland class submarine
    Västergötland class submarine
    The Västergötland class of diesel-electric submarines was introduced in 1987 by the Swedish Navy. The original four ships of her class, HMS Västergötland, HMS Hälsingland, HMS Södermanland and HMS Östergötland, were built between 1983 and 1988 by Kockums AB...

    s. They are upgraded to Södermanland class submarine
    Södermanland class submarine
    The Swedish Södermanland class of diesel-electric submarines consist of the HMS Södermanland and HMS Östergötland. These two submarines were originally launched as Västergötland class submarines in 1987 and 1990, and have been relaunched as a new class after extensive modernization 2003 and 2004 by...

     standards.
  • the Chinese Type 041 submarine (Stirling AIP) of the PLAN
    People's Liberation Army Navy
    The People's Liberation Army Navy is the naval branch of the People's Liberation Army , the military of the People's Republic of China. Until the early 1990s, the navy performed a subordinate role to the PLA Land Forces. Since then, it has undergone rapid modernisation...



Also several shipbuilders offer AIP upgrades for existing submarines:
  • German Nordseewerke
    Nordseewerke
    Nordseewerke is a shipbuilding company located in Emden, Germany. The name Nordseewerke means "North Sea shipyard" in German. The shipyard employs some 1,400 people and is the second-largest plant in Emden, following Volkswagen...

     (Closed-cycle diesel)
  • Sweden Kockums
    Kockums
    Kockums AB is a shipyard in Malmö, Sweden owned by the German shipyard Howaldtswerke-Deutsche Werft in Kiel. HDW itself is a subsidiary of the German ThyssenKrupp Marine Systems....

     (Stirling), owned by German company ThyssenKrupp
    ThyssenKrupp
    ThyssenKrupp AG is a German multinational conglomerate corporation headquartered in Duisburg Essen, Germany. The corporation consists of 670 companies worldwide. While ThyssenKrupp is one of the world's largest steel producers, the company also provides components and systems for the automotive...

  • Pakistan Agosta 90B class submarine
    Agosta 90B class submarine
    The Agosta class submarines are French diesel attack submarines used by Spain, Pakistan and formerly by France. The French Navy grouped this model of submarine in their most capable class as an océanique, meaning "ocean-going." A modernised version built for Pakistan, the Agosta 90B, has a crew of...

     Made with cooperation with France
  • French Scorpene made by French Company DCNS

External links

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