Throughout most of the Cold War, American and NATO nuclear submarines held a decisive
advantage in terms of noise levels and sonars over their Soviet counterparts.
Western submarines were able to track down Soviet boats reliably, without a serious risk
of being detected in return.
This all changed in the late 1980s with the introduction of the Akula class nuclear attack
submarines, also known as the Project 971.
They represent the third generation of Soviet nuclear attack submarines, or SSN for short.
They are the quietest SSN designed by the Soviet Union, and was the most capable nuclear
boat in the Russian Navy until the introduction of the Project 885 Yasen in 2013.
In the closing years of the Cold War, the Soviet Navy finally possessed a nuclear submarine
as quiet as the most advanced NATO SSN.
As we shall see, Soviet espionage activity contributed to improving the Akula.
The low noise level of the Akula class came as a huge surprise to Western intelligence.
Stealth, first and foremost, is the most critical factor behind the survivability of an attack
submarine, and its area denial capability.
This makes the Akula one of the most dangerous late Cold-War attack submarine.
The history of the Akula can be traced back to the late 1970s, when the Soviet Union was
building the Project 945 Sierra class SSN.
The Sierra class is most notable for its titanium pressure hull, which enabled the class to
dive to great depth.
But the Sierra was also very expensive to produce, as a result of its titanium hull.
The industrial infrastructure simply was not available in the Soviet Union to mass produce
the Sierra class.
Consequently, the Project 971 was initiated in 1976, and it received the NATO designation
the Akula class.
The initial Akula class SSN was basically designed to the same specification as the
titanium-hulled Sierra class, but constructed out of steel.
This made the Akula much more affordable both to build and maintain than its predecessor.
A total of 15 Akula class boats have been produced since 1983.
They were built by the Sevmash Shipyard in the northern city of Severodvinsk, and also
by the Amur Shipyard located in the Russian Far East.
Some of these boats have been decommissioned after the collapse of the Soviet Union.
But around 10 boats remain in service with the Russian navy.
The original Akula class was not much better than earlier Soviet submarines when it came
to noise levels.
But major modifications were made beginning with the fifth unit, and these can be seen
with a four-meter extension to the hull.
These changes had a profound impact in terms of lowering the noise level.
A Soviet spy ring in the US Navy was responsible for passing on the information to reduce the
sound profile of Russian submarines.
The spying efforts of American naval personnel John Walker and radioman Jerry Whitworth made
the Soviet Navy realise just how far advanced American submarines were.
Efforts to reduce the noise levels of the Akula class can be traced back to intel gained
from the two spies.
These include information on US Navy sonars and its underwater network of hydrophones.
In particular, the Russians became aware that the cavitation produced by submarine propellers
were giving their positions away.
The second major factor, behind the reduction of noise levels, was the sale of certain machine
tooling technology to the Soviet Union, by the Japanese firm Toshiba and the Norwegian
firm Kongsberg.
This happened over a series of transactions between 1974 and 1980.
This equipment basically allowed the Soviets to produce quieter propellers for their submarines,
including for the Akula class.
The combination of Soviet espionage, and the purchase of propeller technology, led to a
steep fall in the noise level of Russian submarines.
The Akula class are big submarines.
The majority of the class displace 8,140 tons while surfaced, and 12,800 tons submerged.
Length is about 110 meters.
These are the original Akulas and the Improved Akulas we discussed earlier.
However, a couple of later boats completed after the turn of the 21st century are even
larger and longer, at 13,400 tons submerged.
But keep in mind that the Akula is double-hulled.
This means the interior pressure hull is actually quite small relative to the displacement.
Total complement is 73, much lower than on most US Navy SSNs.
The Akula class is rated for a maximum operating depth of around 600 meters.
The main propulsion machinery consists of a single VM-5 pressurised water nuclear reactor,
also known as the OK-650M high-density reactor, rated at 190 MW.
They have four steam generators using this energy to power a steam turbine engine, rated
at 50,000 horsepower, which in turn drives a seven-bladed fixed-pitch propeller.
This arrangement provides a maximum submerged speed of 33 knots and a surface speed of 10
knots.
There are two steam turbine generators producing electricity for the onboard systems, along
with two sets of lead acid batteries to store electricity.
There are also two auxiliary electric motors for secondary back-up propulsion – these
can drive the submarine at about 5 knots.
These auxiliary motors, due to their slow speed, are quite useful in ports, to navigate
presumably a very busy environment, but they are probably of little use out in the ocean,
except during emergency.
Unlike the later Yasen class, the reactors on the Akula needs to be refuelled with fresh
nuclear fuel throughout service life.
Of course, being nuclear powered, the Akula does not need conventional diesel fuel, but
still need other upplies like food and torpedoes.
The boat carries sufficient supplies for 100 days at sea.
The Akula is double-hulled, which dramatically increases the reserve buoyancy, by as much
as three times as that of a similarly-sized single-hull submarine.
Ballast tanks are located between the inner and outer hulls.
There is a substantial distance between the inner and outer hulls to reduce the possible
damage to the inner hull, in the case of a near miss by enemy fire.
The hull is constructed of low magnetic steel, to reduce the risk of detection to magnetic
detectors.
The Akula is divided into eight water-tight compartments, and features a distinctive high
tail fin.
It has a long rounded sail, flared into the hull, containing a U-shaped rescue pod for
crew members.
The noise reduction efforts include installing vibration isolation equipment for the propulsion
plant, anechoic rubber tiles on the outside and inside of the hulls, and other measures
including active noise cancellation.
The eight different zones on the boat are separated from each other, and from the hull,
by rubber-based shock absorbers, with a double layer of shock absorbers for the engine room.
That said, there are credible reports, based on Russian sources, suggesting that much of
the sound insulation equipment are poorly maintained due to budgetary issues, which
would reduce their effectiveness.
The overall noise level of the Improved Akula class is generally believed to be on par with
the Improved Los Angeles class, or even lower.
Aside from stealth capabilities, certain torpedo countermeasure systems, mainly acoustic decoys,
form a last line of defence.
The Akula class is armed with four 533 mm torpedo tubes, and four more of the 650 mm
torpedo tubes, all located at the front.
The 533 mm torpedoes can use the Type 53 series of Russian heavyweight torpedoes.
The latest iteration is the Fizik-1 homing torpedo, which has a state-of-the-art propulsion
system that allows for a long range of 60 km at a high speed of 65 knots.
It has a comprehensive guidance system, including active sonar guidance, wake tracking and wire
guidance.
The 650 mm torpedo tubes can fire the larger Type 65 torpedo, which has a bigger warhead,
and traditionally has a longer range than the Type 53 torpedo.
But the 650 mm torpedo tubes can also fire the 533 mm weapons if needed.
The Akula can also fire a variety of missiles from its torpedo tubes.
These include the RPK-6 and RPK-7 anti-submarine missiles, also known to NATO as the SS-N-16.
These missiles can engage submarines at a longer range than torpedoes.
The Akula also carries the Kalibr cruise missile for anti-shipping purposes.
There is also a short-range surface-to-air missile launcher, also known as a manpad,
on top of the mast, allowing the Akula to defend itself if caught on the surface by
anti-submarine aircraft.
The Akula class carries around 40 torpedoes and missiles, including reloads, although
some of the 650 mm torpedo tubes do not reload from within the pressure hull, and can only
be reloaded in port or by specialised submarine tenders.
One area where the Akula is still somewhat lacking is the sonar systems.
It has the MGK 540 active/passive cylindrical sonar, aka the Skat 3, and two flank array
sonars of an unknown classification.
The Akula has a visible pod on top of its rudder, which houses its towed array sonar
when retracted.
This is basically the same outfit as the sonar on its predecessor, the Sierra class, with
only minor improvement.
There is also a wake detection sensor.
However, the Akula class is said to be at a disadvantage in terms of sensors compared
to the contemporary American SSNs.
My understanding is that the cylindrical array sonars have weaker vertical resolution and
field of view in general when compared to the spherical sonars on the US Los Angeles
class.
So, the AKula’s bow sonar is supposedly much less sensitive than the Improved Los
Angeles class.
The majority of the Akula class SSN have served in the Pacific Fleet, but a smaller number
also prowls the Arctic and the Atlantic Oceans.
The Russian Navy often deploys the Akula class close to North America for the purpose of
intelligence gathering, and to track US Navy nuclear ballistic missile submarines.
These missions take advantage of the long range of the Akula compared to most Russian
surface warships.
In early August 2009, the New York Times reported that the Pentagon had been tracking 2 Akula
class submarines off the East Coast of the United States.
The US Navy was supposedly able to monitor one of these vessels, but was unable to track
the other one.
In 2012, an Akula class submarine reportedly went on patrol in the Gulf of Mexico, completely
undetected.
Elsewhere, for example in the North Sea and the Mediterranean, the Akula often forms part
of the escorts for Soviet and Russian carrier battle groups, including the Russian aircraft
carrier, the Admiral Kuznetsov.
As an aside, the most recently completed Akula submarine was leased to India between 2012
and 2021.
It was named the Chakra by the Indian Navy.
By most accounts, India used the Chakra for training purposes, to prepare key personnel
for deployment onto its future nuclear submarines.
The Chakra was returned to Russia in 2021, one year before the expiry of the 10-year
lease, owing to what India claimed to be “increasingly unreliable powerplant and maintenance issues”.
The boat has reported suffered multiple serious and fatal incidents.
Altogether, the Akula class is the most capable nuclear attack submarine built by the Soviet
Union, and remained the most capable SSN in the Russian Navy before the Yasen class.
The noise level of an Improved Akula was basically on par, if not lower, than the contemporary
US Navy submarines.
Its introduction came as a major shock to Western intelligence agencies, sparking fear
at the time that NATO had lost its underwater advantage.
Today, the Akula is gradually overshadowed by more modern SSNs, but the class remains
a very competitive fast attack submarine by global standards.