How a Swedish submarine “ranne” around American aircraft carriers and escorts
- In 2005, the US Navy’s new aircraft carrier, USS Ronald Reagan, “sank” after being hit by torpedoes.
- This happened during a war game between an aircraft carrier task force and its escorts against a Swedish submarine.
- This submarine, the HSMS Gotland, achieved this feat despite being a relatively inexpensive diesel-powered boat.
In 2005, the USS Ronald Reagan, a newly built $ 6.2 billion aircraft carrier, sank after being hit by torpedoes.
Fortunately, this did not happen in actual combat, but was simulated as part of a war game between an aircraft carrier task force that included numerous anti-submarine escorts at HSMS Gotland, a small sub -Swedish marine with diesel engine displacing 1,600 tons. Yet despite multiple attacks on the Reagan, the Gotland has never been detected.
This result has been repeated over and over again over two years of war games, with opposing destroyers and nuclear attack submarines succumbing to the stealthy Swedish submarine.
Naval analyst Norman Polmar said the Gotland “ran rings” around the US carrier strike task force. Another source claimed that US anti-submarine specialists were “demoralized” by the experience.
How did the Gotland escape Reagan’s elaborate anti-submarine defenses involving multiple ships and planes using a multitude of sensors? And even more importantly, how did a relatively inexpensive submarine costing around $ 100 million – roughly the cost of a single F-35 stealth fighter today – able to accomplish this? After all, the US Navy decommissioned its last diesel submarine in 1990.
In the past, diesel submarines were limited by the need to run noisy, gas-guzzling engines, which meant they could only stay underwater for a few days before they had to come to the surface. Naturally, a submarine is the most vulnerable and can be more easily followed when surfacing, even when using a snorkel.
Submarines powered by nuclear reactors, on the other hand, do not need large reserves of air to operate and can operate much quieter during month both underwater – and they can swim faster while they’re at it.
However, the 200-foot-long Swedish Gotland-class submarines, introduced in 1996, were the first to use an air-independent propulsion system – in this case, the Stirling engine. A Stirling engine charges the submarine’s 75 kilowatt battery using liquid oxygen.
With the Stirling, a Gotland-class submarine can stay underwater for up to two weeks maintaining an average speed of 6 mph – or it can use its battery to boost up to 23 mph. A conventional diesel engine is used for surface operation or when using the snorkel.
The Stirling-powered Gotland runs quieter than even a nuclear-powered submarine, which has to use noise-producing coolant pumps in their reactors.
The Gotland class has many other characteristics that make it adept at evading detection.
It mounts 27 electromagnets designed to counter its magnetic signature to magnetic anomaly detectors. Its hull has sonar-resistant coatings, while the tower is made of radar-absorbing materials. The machines inside are covered with acoustic damping rubber pads to minimize detectability by sonar.
The Gotland is also extremely maneuverable thanks to its six maneuvering surfaces combined with its X-shaped rudder and sail, allowing it to operate close to the seabed and make tight turns.
Because the stealth boat proved to be the ultimate challenge for US anti-submarine ships in international exercises, the US Navy hired the Gotland and her crew for two years to conduct anti-submarine exercises. . The results convinced the US Navy that its underwater sensors were simply not up to par with stealth AIP boats.
However, the Gotland was only the first of many models of AIP-powered submarines, some with twice the underwater endurance. And Sweden is by no means the only country to align them.
China has two types of diesel submarines using Stirling engines. Fifteen of the first Yuan Type 039A classes were built in four variants, with more than 20 more planned or already under construction.
Beijing also has a single Type 032 Qing-class vessel that can stay underwater for 30 days. It is the world’s largest operational diesel submarine and has seven vertical launch system cells capable of firing cruise missiles and ballistic missiles.
Russia made its debut with the Lada Sankt Peterburg experimental class, which uses hydrogen fuel cells for its power. It is an evolution of its widely produced Kilo-class submarine. Sea trials, however, revealed that the cells provided only half of the expected production and the type was not approved for production.
But in 2013, the Russian Navy announced it would produce two heavily redesigned Lada – the Kronstadt and Velikiye Luki – due by the end of the decade.
Spain, France, Japan and Germany are other producers of AIP diesel submarines. These countries in turn sold them to navies around the world, including India, Israel, Pakistan and South Korea.
Submarines using AIP systems became larger, more heavily armed, and more expensive types, including German Dolphin class and French Scorpene class submarines.
The US Navy does not intend to deploy diesel submarines again, however, preferring to stick with nuclear submarines that cost billions of dollars. It is tempting to see that the Pentagon is once again choosing a more expensive weapon system over a much more profitable alternative. It’s not quite as simple, however.
Diesel submarines are ideal for patrolling near friendly coasts. But American submarines off Asia and Europe must travel thousands miles just to get there, then stay deployed for months. A diesel submarine may be able to travel this distance, but then it would require frequent refueling at sea to complete a long deployment.
Do you remember Gotland? He was sent back to Sweden on a mobile dry dock rather than making the trip on his own.
While new diesel submarines equipped with the AIP can go weeks without surfacing, it’s still not as good as going month without having to do it. And furthermore, a diesel submarine – with or without AIP – cannot withstand high underwater speeds for very long, unlike a nuclear submarine.
A diesel submarine will be more effective at ambushing a hostile fleet whose position has already been “reported” by friendly intelligence resources. However, the slow and durable underwater speed of AIP diesel powered submarines makes them less than ideal for stalking prey in large bodies of water.
These limitations do not pose a problem for diesel submarines operating relatively close to friendly bases, defending coastal waters. But while diesel submarines can be great when operating near home, the U.S. Navy typically doesn’t.
Yet the fact that you can build or acquire three or four diesel submarines for $ 500 million to $ 800 million each for the price of a single nuclear submarine gives them an undeniable appeal.
Proponents argue that the United States could deploy diesel submarines to bases in allied countries, without facing the political constraints posed by nuclear submarines. Additionally, advanced diesel submarines could serve as a good counterbalance to an opponent’s stealthy submarine.
However, the US Navy is more interested in continuing to develop drone submarines. Meanwhile, China is working on long-lasting AIP systems using lithium-ion batteries, and France is developing a new large version of a diesel submarine equipped with the AIP of its nuclear-class attack submarine. Barracuda.
The advent of cheap, stealthy, and durable diesel submarines is another factor that puts aircraft carriers and other expensive surface warships at increased risk when operating near defended coasts.
The diesel submarines benefiting from the AIP will serve as a deadly and cost-effective means of defending coastal waters, although they may carve out a role in naval forces in blue waters operating far from home is less clear.
SÃ©bastien Roblin writes on the technical, historical and political aspects of international security and conflict for publications such as The National Interest, NBC News, Forbes.com and War is Boring. He holds a master’s degree from Georgetown University and served with the Peace Corps in China. You can follow his articles on Twitter.