The first British Royal Navy Astute-class “super submarine” was launched nearly two decades ago in 2007–and some claim it is as quiet and stealth as a Dolphin. At the time, it was the first nuclear-powered sub to be commissioned in almost a decade.
The technology utilized in its construction was the most advanced in the world at the time, with the characterization being more complex than the engineering methods used in building the United States Space Shuttle.
The ship is almost 100 meters in length. It never needs refueling due to the nuclear-powered propulsion system. The boat’s designers boasted that it could circle the world without ever having to surface—for months at a time essentially.
It is the largest submarine of its type in Royal Navy history and will replace the long-running Trafalgar-class boats.
The Astute-class are armed and equipped with Spearfish heavyweight torpedoes and Tomahawk land attack cruise missiles, which allow them to attack targets on land and sea but also provide a defensive cover for the UK Royal Navy’s fleet of Dreadnought-class ballistic missile submarines.
Special Tiles Designed In
UK submarines have been fitted with external sound-absorbing anechoic tiles for a quarter of a century.
Just like the lining of the anechoic chambers that are used in the aircraft industry to develop radar-absorbing, stealthy designs, these tiles absorb Sonar waves and other sensor signals to make the submarine appear to be a much smaller object than it really is.
The difference between these proceeding submarines and the Astute is that the anechoic surfaces are designed-in with this newest design. The tiles are applied directly to the submarine hull, classifying the application as designed-in.
This innovation is a significant plus-up to the performance of the sub’s overall speed and is a much better fit than adding on these tiles after the boat is entirely built and is ready to launch.
Not only is the Astute-class hull covered in these anechoic tiles, but it is a more sophisticated arrangement than it would seem at first glance. Looking closely, one can discern several types of tiles placed in different positions on the hull.
Depending on the location, the tiles are sometimes fitted in layers, and this is, of course, to provide the maximum reduction of the strength of any echo signal returned from any Sonar ping. A central, visible chine runs from around the bow and the upper hull and includes the sail fin. They are all then angled to reduce any sonar reflections.
Quieter Propulsion Systems on Astute-Class
Stealthy, Sonar-absorbing hull—as any submarine designer will tell you—is only half the battle. Stealth features make the sub appear smaller than what it actually is on an enemy-active Sonar display.
Still, the other requirement is that the sub be as quiet as possible so that it is not picked up by any passive sensing gear that an adversary uses. The Sonar “signature” is one factor, but the noise created by the sub’s power plant or propellor cavitation is another.
The tack that UK designers have taken is to use new-generation turbo-electric drives.
In this configuration, the nuclear reactor generates electricity in what could be called a first phase. In the second phase, this electricity powers an electric motor, which drives the propulsion system.
The nuclear reactor offers a much quieter arrangement than having the reactor power directly connected mechanically to the sub’s propeller shaft.
This is not a new concept, in that turbo-electric drives have been used in nuclear submarine propulsion systems, namely the US Navy’s Columbia-Class boats.
This is one of several reasons the Astute-class will be the basis of the SSN-AUKUS submarine program. SSN-AUKUS, according to the BAE Systems announcement, “will be the largest, most powerful and advanced attack submarines the Royal Navy has ever operated and will eventually replace the Astute class.”
A tribute to the genius of the design and its survivability in the modern naval warfare environment.
About the Author: Reuben F. Johnson
Reuben F. Johnson is a survivor of the February 2022 Russian invasion of Ukraine and is now 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.
