Key Points and Summary: In a stunning display of asymmetric warfare, Sweden’s Gotland-class submarine, equipped with an innovative Stirling Air-Independent Propulsion (AIP) system, “sank” the USS Ronald Reagan during 2004 naval drills.
-Costing just $100 million compared to the carrier’s $6.2 billion, the Gotland’s quiet propulsion and radar-absorbent materials allowed it to evade U.S. sonars repeatedly.
-The sub’s unique AIP technology extended underwater endurance to weeks, showcasing its stealth and maneuverability.
-These exercises highlighted vulnerabilities in the U.S. Navy’s defenses, especially against ultra-quiet diesel-electric subs, a growing threat from adversaries like China.
-The Gotland’s success underscores the potency of superior technology in modern warfare.
How a Swedish Submarine “Sank” a U.S. Aircraft Carrier in Mock Battle
Asymmetric warfare is when a smaller, weaker force successfully attacks a larger, stronger adversary. Sometimes, a cheaper weapons system wins the day against more expensive military hardware. Such was the case with the Swedish Gotland-class submarine that virtually “sunk” an American aircraft carrier during mock combat drills in 2004.
Observer controllers of the naval drill determined that the Gotland-class boat got the best of the USS Ronald Reagan – a Nimitz-class carrier – and won the simulated battle.
Undersea Warfare Success on the Cheap: How An Aircraft Carrier
The Swedish sub, the HSwMS Gotland, cost around $100 million to produce, and the Reagan weighed in at an eye-watering $6.2 billion. That’s quite a bargain if you are Sweden – a real-life David and Goliath scenario.
Gotland-Class: Unique Diesel-Electric Swedish Subs
The Gotland-class are relatively inexpensive diesel-electric subs – cheaper than nuclear-powered boats. Most smaller navies that are equipped with submarines choose low-tech diesel-electric models. However, the Swedes boast a unique feature built by their indigenous defense industry.
(Oct. 30, 2007) – Aircraft Carrier USS Ronald Reagan (CVN 76) conducts rudder checks as part of the ship’s Board of Inspection and Survey (INSURV) following a six-month Planned Incremental Availability. All naval vessels are periodically inspected by INSURV to check their material condition and battle readiness. U.S. Navy photo by Mass Communication Specialist 2nd Class M. Jeremie Yoder (RELEASED)
This system is called a Stirling engine Air-Independent Propulsion (AIP). AIP is ingenious and allows the Gotland-class to run stealthily.
Most diesel-electric subs must surface and charge their batteries after only a few days submerged. This allows them to be discovered easily. Moreover, their engines are noisy underwater, and enemy sonar can sniff them out.
More Details About AIP
The Stirling engine AIP is different from regular diesel-electric propulsion. These AIP engines do not need air as most diesel-electric power plants do. Instead of only days of endurance, the Gotland-class subs can stay underwater for weeks.
“The Stirling engine is quiet and vibration-free. No vibrations spread out to the hull, making the submarine silent in the water and therefore difficult to find. This technology is unique to Swedish submarine,” said Sebastian Lenander, a manager for submarine testing and evaluation at defense contractor Saab Kockums.
AIP allows the piston to move in a cylinder by rapidly heating and cooling the gas inside. The engine cools down with cold seawater and heats up with liquid oxygen and diesel fuel. This efficient cold and heat system is unique to Gotland-class boats. It creates a quiet and fuel-efficient power plant. Batteries are only used when the AIP is engaged, allowing for better endurance. Saab Kockums has made AIP even better since the Gotland eliminated Ronald Reagan in the famous drill 20 years ago.
The USS Ronald Reagan (CVN-76), a Nimitz-class Aircraft Carrier of the United States Navy (USN) as seen from the SM by the Bay Amusement Park.
Gotland-class Specs
The Gotland was delivered to the Swedish navy in 1996, followed by two other sister-subs that year: the HSwMS Uppland and HSwMS Halland. One interesting aspect of the Gotland-class is that they are small. They are only 200 feet long and displace just 1,599 tons when submerged. This allows for better speed at 20 knots and more maneuverability. Only 24 to 32 sailors are on board.
The Gotland-class has two different torpedo tubes, and they can launch four different kinds of heavyweight and lightweight “Torped” torpedoes.
The Gotlands are deathly quiet. According to the National Interest, “the Gotland class possesses additional cutting-edge features, including the twenty-seven electromagnetics mounted to counteract its magnetic signature to Magnetic Anomaly Detectors. Additionally, its hull is protected with sonar-resistant coatings, while its tower is composed of radar-absorbent materials.”
Running Circles Around the American Aircraft Carrier
These advantages gave the USS Ronald Reagan fits. The “sinking” didn’t happen just once. Evaluators ran the exercises repeatedly, and the Gotland came out on top each time. It showed it could “run rings” around the Nimitz-class carrier. Other experiments happened over the following year to see if the Gotland could evade surface ships and sonobuoys from a carrier strike group. The Gotland still enjoyed success.
A U.S. Navy F/A-18E Super Hornet of Strike Fighter Squadron (VFA) 115 launches from the flight deck of the aircraft carrier USS Ronald Reagan (CVN 76) in the western Pacific Ocean Nov. 11, 2017. The Ronald Reagan, Theodore Roosevelt and Nimitz strike groups are underway conducting flight operations in international waters as part of a three-carrier strike force exercise. The U.S. Pacific Fleet has patrolled the Indo-Pacific region routinely for more than 70 years promoting regional security, stability and prosperity. (U.S. Navy photo by Mass Communication Specialist 2nd Class Janweb B. Lagazo)www.dvids.hub.net
This was asymmetric warfare at its best. The Gotland had the Stirling AIP and sonar and radar-absorbent materials. It had a daring and skilled crew that knew the ins and outs of the submarine. It darted around the carrier’s defenses like it was just another day at sea. This shows that David can beat Goliath with superior technology and engineering prowess.
Hopefully, the Swedes will not sell their Stirling AIP system to other navies, and it will remain indigenous to their military. Meanwhile, the U.S. Navy assuredly conducted an after-action review to determine what the problem was with their sonars and other undersea warfare equipment. But that’s why you conduct battle drills – to learn strengths and weaknesses.
The Americans found that ultra-quiet diesel-electric subs, which they would be facing against the Chinese navy, had excellent attributes that allowed them to sneak inside a defensive screen. Thus, the U.S. submarine fleet has its work cut out for it to survive in undersea warfare in the future.
About the Author: Dr. Brent Eastwood
Brent M. Eastwood, PhD, is the author of Don’t Turn Your Back On the World: a Conservative Foreign Policy and Humans, Machines, and Data: Future Trends in Warfare, plus two other books. Brent was the founder and CEO of a tech firm that predicted world events using artificial intelligence. He served as a legislative fellow for U.S. Senator Tim Scott and advised the senator on defense and foreign policy issues. He has taught at American University, George Washington University, and George Mason University. Brent is a former U.S. Army Infantry officer. He can be followed on X @BMEastwood.
