When submarines became a frightening threat to the navies during World War 2,
military developers were forced to find innovative ways to combat the sneaky vessels.
Many weapons were created during and after the war, but when the Soviets
came up with the Soviet Smerch-2 Reaktivno-Bombovaja Ustanovka,
or RBU-6000, during the Cold War, it immediately became the stuff of nightmares.
A 90P missile and RGB-60 depth-charge launcher,
the RBU-6000 was among the favorite anti-submarine defenses throughout the 1960s and beyond, and was
fitted in countless surface ships. But as powerful as it was, the platform was fundamentally blind.
It wouldn’t be until the new century, with the acquisition of precision mechanisms,
homing underwater gravitational charges, and hydro-acoustic jamming,
that the system would meet its true potential in the upgraded RPK-8.
Post-War Developments
Submarines became a palpable threat to navies as early as the beginning of World War 1,
and soon, the development of anti-submarine weapons became a top priority for military
forces worldwide. Then, through World War 2 and the Cold War,
anti-submarine systems flourished, and some are even popular today.
One such model is the Soviet-made RBU-6000.
The weapon entered service with the Soviet Navy Fleet in 1961, and as of the early 2020s,
it is still in operation despite being among the oldest of its class.
The Smerch-2 Reaktivno-Bombovaja Ustanovka reaction engine-bomb installation
consists of a 213-millimeter rocket launcher, very similar in principle
to the legendary Royal Navy Hedgehog system developed during World War 2. From the onset,
the ingenious system was fitted on a wide range of Russian surface vessels.
The system itself comprises a dozen launch barrels laid out radially in a horseshoe-shaped
arrangement. The barrels are remotely controlled by the Burya fire control system,
also featured in the shorter-ranged RBU-1000.
Designed to fire 90P anti-submarine missiles and RGB-60 unguided depth charges
in multiple and single rounds, the stationary platform has special hinged brackets located on
the front and rear sections of the barrels. It can also be used for shore bombardment.
The bracket in the front accommodates the mechanism and plug connectors for
firing preparation and also sets the depth of the RGB-60 bomb fuse.
On the other side, the one on the back launches the 90P
or RGB-60 missile’s marching engine, with salvos comprising rounds of 1, 2, 4, 8, or 12.
Meanwhile, the launcher is automatically charged through an anti-submarine missile's 60UP storage
device. Whenever the ammunition runs out, the unit immediately switches to the charging position,
lowering the package of barrels by 90 degrees, and turning to charge each barrel.
This storage device has a capacity of 25 or 61 missiles, or weight of 4,700 kilograms.
RBU-6000s were among the most widespread anti-submarine rocket
launchers in the Soviet Navy, and they were eventually upgraded for modern warfare.
RPK-8
Russia’s state hi-tech corporation Rostec and its research and production association,
Splav, were in charge of the modernization
of the anti-submarine rocket launcher in the new millennium.
The upgraded RPK-8 Zapad anti-submarine warfare system is an improvement over the RBU-6000.
It entered service in 1991 and was first mounted on the Project 11540 and 11356 frigates.
The device was first featured at the Saint Petersburg International Maritime Defense
Show in 2017 and was capable of firing the more advanced 90R rocket. That summer,
the projectile had already gone into production and was in the process of entering service.
The RPK-8 is actively guided in water and can therefore home in on targets at depths up to
one kilometer. Its warhead weighs 19.5 kilograms and is shaped to punch through submarine hulls,
but it can also be deployed as an anti-torpedo and anti-subversive weapon.
Its system response time is only 15 seconds, while its hit probability is 0.8.
At the Saint Petersburg event, the company’s press office stated:
(QUOTE) "We have completed the upgrade and launched the serial production of munitions
for the RPK-8 anti-submarine warfare complex. The forum will demonstrate
the 90R rocket (the upgraded 90R1 version) that is part of the complex.”
The new projectile was also used to develop a hydro-acoustic jamming shell
to provide protection against homing torpedoes. The Magnetit-MN
was showcased along the 90R1, creating false targets for enemy torpedoes.
Independent military analyst and Svobodnaya Pressa contributor Vladimir Tuchkov explained: (QUOTE)
"The rocket is aimed at its target (vessel or torpedo) using information about its location
received from the ship's sonar station. After splashdown, the gravitational projectile separates
and, with the aid of an acoustic homing head, finds its target and directs itself toward it."
The analyst added: (QUOTE) "The projectile sinks to a depth of 25 meters, and produces
interference for a period of eight minutes, enough time to counter an enemy torpedo attack.
The Magnesit-MN is capable of operating in two modes – as a generator of interference for guided
torpedos, and as an imitator of acoustic signals typical for surface ships. In the first case,
enemy torpedoes are disoriented; in the second, they rush to a false target."
To improve efficiency, the projectile includes an inductive noncontact fuse that detonates the
mine after a predetermined distance is reached. While the RPK-8 differs from its predecessor,
it maintains a high level of continuity, as it is still able to launch bombs from the older complex.
Specialization
The new munition is 8 to 10 times more effective than its predecessor
when it comes to destroying underwater targets, mainly due to its separating
homing underwater gravitational charge, which replaced RGB-60 depth charge bombs.
The system can operate at a distance of 600 meters to over four kilometers, and the rocket’s
trajectory is adjusted with the aid of a sonar system, which has a response radius of 130 meters.
Tuchkov added that the Smerch-2, unlike the newer system, would launch bombs:
(QUOTE) “Figuratively speaking, by blind luck."
When the rocket is launched towards the enemy submarine,
its head separation system and 90SG gravity submarine missile split.
The projectile then hydroacoustically locates the surrounding space and captures the target.
Despite the fact that the 90R1 is believed to have an improved range, details have not been revealed
in open sources. But as the expert put it: (QUOTE) "It can be assumed that designers did not increase
its depth characteristics, since 1,000 m is beyond the limits of any NATO submarine or torpedo."
In addition, there are other variants, including the 90P PR missile with inert equipment of
gravity submarine projectile combat unit, and the 90PRN with submarine projectile overall layout,
both of which were created for firing training.
However, Tuchknov noted: (QUOTE) "The 90R has advantages over traditional torpedoes
in use against submarines. Because its gravitational projectiles lack an engine,
they can move without being tracked by enemy sonar.
They can be detected with the help of active sonar, but this mode of operation by an enemy
vessel gives away its location even further. Moreover, it doesn't make much sense anyway:
As a rule, major underwater targets are targeted by volleys of twelve rounds at once, and due to
the reflection of the sonar waves from all twelve projectiles, a complex interference pattern is
obtained, making it impossible to accurately determine the position of attacking warheads."
Limitations
The Minister of Defense implemented the RPK-8 complex through order No. 055 on November 26,
1991. As a direct result, albeit decades later, the Navy received a highly effective
means of fighting enemy submarines. When Splav specialists finalized the rocket’s launch chain,
the system was ready for deployment in new-generation warships.
Besides its use on Project 11540 on the Undaunted and Yaroslav the Wise patrol ships,
the system is exported as the RPK-8E and is currently
part of the armament of the new Indian Shivalik-class frigates.
Nevertheless, as the analyst emphasized, the RPK-8 and its projectiles were specially
designed for close-quarters combat, and he concluded that: (QUOTE) "Offensive weapons
designed to destroy subs at great distances also exist,
and can be based on a variety of platforms, including ships, subs, and aircraft."
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