Key Points: Russia’s Kilo-class submarines, nicknamed “Black Hole” for their stealth capabilities, have been a reliable component of Moscow’s naval power since the 1980s.
-Designed for shallow, coastal defense, these diesel-electric subs have evolved significantly over several decades.
-While the newest Project 636.3 variant includes advanced digital systems and Kalibr cruise missile capabilities, Russia’s next-generation Lada-class has struggled with reliability and performance issues.
-Consequently, Russia continues producing Kilo-class vessels, underscoring their lasting value. With their proven track record, versatility in littoral waters, and recent modernizations, Kilo-class submarines are likely to remain a strategic naval asset for Russia and its partners for years to come.
The Kilo-Class Submarine Just Won’t Go Away
Russia’s Kilo-class submarines are among the more widely operated and exported diesel-electric submarines of the post-Cold War era. Originally developed for the Soviet Navy in the late 1970s, the Kilos were introduced to replace the earlier Tango-class submarines, which were also diesel-electric.
The Kilo-class first entered service in the early 1980s. The submarine’s design placed an emphasis on antishipping operations and coastal defense, with the intention of operating in the shallower waters of the Baltic and Black Seas or the littoral waters nearer to the coasts.
The Black Hole Submarine
In addition to its intended role as an antiship and antisubmarine platform, the Kilo-class also performs some intelligence gathering. It can do this thanks to its relatively low acoustic signature, which long ago led to its moniker, Black Hole.
“During the Cold War the then-new submarine gained a reputation for stealth, sometimes with the nickname ‘black hole’. The term is still used and much is made of its stealth even today,” H.I. Sutton, a naval expert, explains.
“But that was relative. Older Russian submarines, still widespread when the KILO was introduced, were incredibly noisy. Although exact details are naturally not available, there os no reason to suppose that the KILO family is any quieter than the latest western non-nuclear submarines.
In fact, the lack of AIP (air independent power) will limit overall stealth. That’s not to say it’s noisy, Russia is experienced at noise reduction and has excellent anechoic tiles. But the ‘black hole’ label has become a bit of a myth.”
How It Stayed Around for So Long
Compared to the preceding Tango-class, the Kilo-class offered significant improvements in sonar performance, stealth capabilities, and crew habitability.
Although the Tango was a relatively large submarine, designed with increased battery capacity to allow for extended underwater endurance, it lacked the stealth improvements incorporated into the Kilo-class.
Thanks in part to the Kilo-class’ relatively streamlined hull and sonar-absorbant anechoic tiling, the newer class of submarine is much harder to detect. Thanks as well to the submarine’s smaller size, they are more maneuverable in the shallow littoral waters in which both the Tango-class and Kilo-class were made to patrol.
There have been several tranches or variants of the Kilo-class since it was first introduced. Under Soviet nomenclature, it was originally called the Kilos Project 877 and was primarily built for the Soviet Navy.
Later, however, a Kilo-variant intended for export, known as Project 636, was developed, and this submarine incorporated some updates.
A third more updated variant, called Project 636.3, builds upon the preceding variants and includes modernizations such as digital fire-control systems and the ability to launch Kalibr cruise missiles.
This means the submarine has the ability to attack land-based targets, and this variant also has an expanded power-projection capability.
Pumpjet
A single, experimental Kilo-class submarine, the B-871 Alrosa, was outfitted with a pumpjet propulsor. “This is unusual for a non-nuclear submarine since pump jets are generally optimal for higher underwater speeds,” H.I. Sutton writes. “Possibly it was for testing since similar pumpjets are fitted to some Russian ballistic missile submarines. Although its use aboard Alrosa is questionable, it remains fitted after the submarine’s recent (and protracted) refit. It remains the only diesel-electric submarine with a pump jet.”
Although the Kilo-class is still in service with the Russian Navy—as well as the navies of several other countries—it may gradually be supplanted in Russian service by the newer Lada-class submarine.
This updated sub design was intended as a next-generation non-nuclear submarine with improved stealth, greater automation, and the incorporation of air-independent propulsion (AIP) technology, which allows for extended underwater endurance without surfacing. In theory, the Lada-class would offer similar performance to some of the more advanced Western AIP and diesel-electric designs.
However, the Lada-class has run into difficulties. The lead submarine of the class, the Sankt Peterburg, was launched in 1997 but didn’t enter service with the Russian Navy until more than 10 years later.
Reliability issues, poor acoustic performance, and high operating costs lead to delays and dissatisfaction.
The Kilo-Class Is Still Deadly
While development of the Lada-class nominally continues, the Russian Navy has also decided to continue investing in the newest 636.3 Kilo-class boats, underscoring the difficulties with the Ladas and the advantages of working with a mature Kilo-class design.
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The Kilo-class submarines have proven to be both versatile and resilient, particularly for navies with a requirement for submarine operations in shallower littoral waters. Given the teething problems with the Lada-class, the Kilo-class could serve for many more years to come.
About the Author: Caleb Larson
Caleb Larson is an American multiformat journalist based in Berlin, Germany. His work covers the intersection of conflict and society, focusing on American foreign policy and European security. He has reported from Germany, Russia, and the United States. Most recently, he covered the war in Ukraine, reporting extensively on the war’s shifting battle lines from Donbas and writing on the war’s civilian and humanitarian toll. Previously, he worked as a Defense Reporter for POLITICO Europe. You can follow his latest work on X.
