Kilo Class – Russia’s Submarine Menace


The Kilo is a capable small attack submarine that’s been widely exported.

One of this week’s most alarming defence news articles was about the Indian Navy submarine INS Sindhurakshak, which exploded and sank in a Mumbai naval base. The submarine was part of the Indian Navy’s Sindhugosh class, which is actually the Indian name for the Russian Project 877. In the west the Project 877 and the newer Project 636 are known by the NATO reporting name Kilo-class. This class is one of the Russian arms industry’s export successes, with 24 boats either built or on order and several more governments interested in buying them.

The Kilo-class (the 636 is sometimes known as the Improved Kilo) is a relatively small diesel-electric submarine, designed for anti-shipping and anti-submarine warfare in relatively shallow waters. Compared to the big nuclear attack boats that make up the bulk of NATO submarine forces it has limited endurance and a small weapon load, but as compensation it’s more agile and can be very, very quiet.

kilo class project 877
A lot of power and weaponry is crammed into these compact hulls

The 636 is 74 metres long (the 877 is slightly shorter at 70 metres) and displaces 2,350 tonnes on the surface (3,950 submerged.) It is powered by a 6,800 shaft horsepower electric motor, driven by a large battery bank charged by two 1MW diesel generators. Running on the surface it can manage a maximum speed of 12 knots; the hull hydrodynamics are optimised for submerged running at depths of up to 300 metres, and underwater she can achieve up to 25 knots. The limiting factor in underwater performance is the battery charge, and power consumption rises exponentially as speed increases; at 3 knots a Kilo can cover 400 miles on her batteries, but at 21 knots this is reduced to only 13 miles. Where possible a Kilo commander will try to run on the surface or snorkelling at periscope depth; with the diesel generators running to maintain battery charge the maximum range is up to 7,500 miles. For a boat designed to operate close to a friendly coast that’s usually more than enough. The boat can carry enough stores for 45 days at sea.

Of course when manoeuvring tactically the Kilo will operate on electric power only. Even when not moving a nuclear boat produces reactor noise from her steam generating plant, but a conventional submarine running on electric motors is almost completely silent. Russian submarines were once known for being much noisier than western ones, but that changed with the Project 971 (NATO – Akula-class) nuclear attack oats, and the Project 636 makes use of a lot of the technology developed for the Akulas. The Kilo isn’t quite as undetectable as some novelists would have you believe but it is extremely quiet, and in shallow water – where sonar performance is often poor – it can easily gain an edge over a nuclear attack boat. To assist in quieting the hull is covered with anechoic tiles, a hard rubber coating that absorb incoming active sonar pulses as well as muffling any noise generated inside the boat.

To detect targets for its own weapons the 636 is fitted with Russia’s newest passive and active sonars, the MGK-400EM. This is somewhat behind western systems but is capable enough in shallow water, where engagement ranges tend to be shorter than in the open ocean. Some foreign customers replace these with their own preferred systems; for example the Indian Navy’s 877s have the locally developed USHUS sonar, which Indian sources claim is equal to the latest western systems (although many western naval operators are sceptical.)

The basic armament is a battery of six 533mm (21 inch) torpedo tubes in the bow. At least two of these are capable of launching wire-guided torpedoes, and in newer 636 boats this capability may be fitted to all of them. A wide range of Russian and foreign torpedoes can be launched as well as the VA-111 Shkval rocket-propelled torpedo. Some export boats are fitted to launch the SS-N-27B “Klub-S” anti-ship missile, and mines can also be laid through the torpedo tubes. Russian Navy Kilos also carry man-portable anti-aircraft missiles, usually SA-N-8 or SA-N-10 navalised versions of the SA-14 and SA-18. Up to 18 torpedoes or antiship missiles, or 24 mines, can be carried.

kilo class project 636
Six Improved Kilos will give Vietnam a powerful submarine flotilla. These officers are inspecting the first of them in Kaliningrad.

The Kilo has been widely exported, including to countries not friendly to the west. Iran has three 877s; Algeria has two 877s and two 636s. The largest operator is the People’s Republic of China, which has a fleet of ten upgraded 636 boats as well as two older 877s. Vietnam will start taking delivery of six latest-model 636s in late 2013 or 2014. Of course friendlier nations also use the class; NATO member Romania has one, and India has nine operational modernised 877s. Depending on who owns the boat in question the Kilo is either a cheap way to build a capable littoral submarine force or a dangerously proliferating menace.