Key Points – Sweden’s Saab-built Gotland-class diesel-electric submarine, the world’s first to be equipped with an Air-Independent Propulsion (AIP) system, famously demonstrated its profound stealth capabilities during training exercises with the US Navy.
-In 2005, while on lease to the US as an opposing force training asset, the HSwMS Gotland reportedly evaded an entire US carrier strike group’s defensive screen and successfully “sank” the multi-billion dollar aircraft carrier, USS Ronald Reagan.
-The Gotland’s success is attributed to its ultra-quiet Stirling-cycle AIP engines, which allow it to remain submerged and virtually silent for extended periods, highlighting the significant threat posed by modern conventional submarines.
Gotland-Class Submarines: It Can Take Out Aircraft Carriers
WARSAW, POLAND – Examining the line of weapon systems from the defense conglomerate Saab, immediate impressions about how the Swedish firm differs from its peer competitors are evident. The example of the JAS-39E/F Gripen fighter demonstrates an effective combat platform developed at a fraction of the cost of a comparable US weapon system.
One of the company’s strengths that makes this aircraft and other major Saab best-sellers so successful is the Nordic firm’s talent for rapid prototyping. One of the company’s chief executives explained how the Saab’s innovation center, Skapa, supports this process.
“Saab has a long, successful history of producing exceptional products, and Skapa will enhance those products with emerging technologies, such as artificial intelligence and robotics, to make them smarter and ultimately solve operational problems and deliver solutions,” said Erik Smith, President and CEO of Saab’s US division.
“Skapa is a symbol of our commitment to continuous evolution and excellence,” he said. “We see the emerging threats around the world that need to be tackled, we know there is a need for new scalable solutions, and Skapa is our contribution to helping solve these challenges for and with our customers. We have the unique skill set, portfolio of products and people to drive the solution.”
The AIP Pioneers
An older and lesser-known example of this Saab ingenuity is the Gotland-class (Type A-19) submarines.
Saab only built three of the boats—the Gotland, the Uppland, and the Halland. Construction of this class began in 1992 at the Kockums shipyard in Malmö, which Saab later acquired.
The Gotland-class boats were ordered in 1990 and were the first operational submarine class equipped with an air-independent propulsion (AIP) system. Despite them being twenty-five years old, they have been kept current through upgrades and other modifications to their design.
The first in the class, the Gotland, was commissioned in 1996, and its sister ships, the Uppland and Halland, joined the fleet in 1997. These boats were designed with a heavy emphasis on holistic stealth for operations in Swedish waters, which was what drove the designers to perfect the AIP technology integrated into their design.
Other capabilities of this class include anti-surface and anti-submarine warfare mission capability, forward surveillance, special operations, and minelaying. These subs are also designed with an X-rudder system to enhance maneuverability. Part of the secret of the AIP system was an inventive adaptation of the Stirling-cycle external-combustion engines.
How Sweden Sank A U.S. Navy Aircraft Carrier in a Drill
Eventually, all the capabilities and innovative design of this class of sub attracted the attention of the US Navy, which ultimately leased the Gotland as a joint exercise training platform from 2005 to 2007. The boat was literally based at the San Diego naval base as if it were part of the US fleet. Its crew was also homeported at the facility.
The function of the boat was to play the role of an opposing force in training exercises and served as the leading platform for simulated US anti-submarine warfare engagements.
It was in 2005, during one of these exercises, that the Gotland, a $100 million submarine, “sank” a $6 billion aircraft carrier, the USS Ronald Reagan.
As incredible as it might seem, the Swedish submarine successfully evaded the destroyer screen and all other defensive measures of a US carrier strike group, ultimately taking out the carrier despite facing a far superior and orders of magnitude more expensive adversary.
On top of it all, the Gotland managed to sneak away without the same defensive surface and air assets deployed for anti-submarine assets, being able to “punish” it for winning the exercise.
The US publication Popular Mechanics later explained how the Swedes pulled off this embarrassing win of the century against the world’s most advanced navy:
“It’s all thanks to a very old-school engine. Instead of using its diesel to power an internal combustion engine (which is quite loud, what with the explosions and all), the Gotland-class sub instead uses highly optimized Sterling engines, not unlike what you might find as a desk toy, but considerably more high-tech. These exceedingly quiet engines are used to charge batteries, which in turn can directly run the engines. The result is a sub that’s quieter than any other diesel, and even quieter than its nuclear cousins which require a constant churn of coolant that can give away their position.”
Apparently, concluded the author, “sometimes it pays to be out of date.”
About the Author:
Reuben F. Johnson is a survivor of the February 2022 Russian invasion of Ukraine and is an Expert on Foreign Military Affairs with the Fundacja im. Kazimierza Pułaskiego in Warsaw. He has been a consultant to the Pentagon, several NATO governments, and the Australian government in the fields of defense technology and weapon systems design. Over the past 30 years he has resided in and reported from Russia, Ukraine, Poland, Brazil, the People’s Republic of China and Australia.
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