667BDRM Dolphin DELTA IV
The 667BDRM Delta IV submarine, which was constructed parallel to the Typhoon class, is a further modification of the previous Delta. When in the middle of the 1970s it became clear that the deployment of solid R-39 missile may or may not live up to expectations (which actually happened) as a reply to the American Trident, the Soviet Navy had to look at the well-known path of improving combat characteristics of existing designs. Big problems were not expected - the successful construction of Project 667 submarines and R-29 missiles left this great opportunity.
Missilemen faced two major challenges. Firstly, it was required to restore an intercontinental range of the R-29RM missile, which had been lost when the design added MIRVS. Secondly, it was needed to significantly improve the accuracy. A CEP of 900 m with the R-29RM missile MIRVS did not provide sufficient damage against well-protected targets. Another challenge to shipbuilders was to further reduce submarine noise, because that parameter was still detectable by American ASW.
In comparison with the Delta III submarine the diameter of the pressure hull was increased and the bow was lengthened. Simply to reduce noise the length was increased by 12 ft (167 m instead of 155), which of course led to an increase in tonnage (13 600 tons instead of 13 000) and a slight decrease in maximum underwater speed (from 25 to 23 knots). To increase the reliability of the pressure hull, the tip and intercut-off bulkheads are made of specially processed steel.
A combination of the most important combat performance was entirely different. There were considerably enhanced defensive arms on the ship. Unlike the Delta III, it is capable of using all types of torpedos, anti-submarine torpedo-missiles and anti-hydroacoustic devices. Unlike the torpedo procured for earlier Soviet submarines, four Water Mist-671 RTM universal rocket torpedoes launching apparatus were installed, which enables all types of 533 mm anti-submarine torpedoes, missiles, cruise missiles, as well as mobile devices hydroacoustic counters (false stun target).
But mostly, the new R-29RM liquid-fueled missiles mounted on the D-9RM launch complexes became a masterpiece of the rocket production. This three-stage rocket with four MIRVS (tested in version with ten MIRVS), was an intercontinental range (8300 km), high accuracy (500 m) and was only slightly heavier than its predecessor R-29P (40.3 t instead of 35.3 tonnes). The design of the R-29RM left considerable scope for further improvements during the series production of these missiles from adopting in 1983 to 1988.
Unlike previous modifications, the Delta IV submarine was able to fire missiles in any direction from a constant course in a circular sector. The underwater firing of the ballistic missiles can be conducted at a depth of 55 meters while cruising at a speed of 6-7 knots. All the missiles can be fired in a single salvo.
The battle management system "Omnibus-BDRM" controls all combat activities, processing data and commanding the torpedo and missile-torpedo weapons. The "Shlyuz" navigation system provides for the improved accuracy of the missiles and is capable of stellar navigation at periscope depths. The navigational system also employs two floating antenna buoys to receive radio-messages, target destination data and satellite navigation signals at great depth. The submarine is also equipped with the "Skat- VDRM" hydroacoustic system.
During the development of the 667BDRM SSBN several measures were included to reduce its noise level. First and foremost, the designers at LPMB Rubin agreed that noise reduction features palliative exhausted and had to radically new solution. All machinery and equipment of the ship were mounted on a frame [what in the West was termed a raft], amortized over durable chassis. The gears and equipment are located on a common base isolated from the pressure hull, and the power compartments are also isolated.
The efficiency of the antihydroacoustic coatings of the light outer hull and inner pressure hulls have been increased. Newly designed five-bladed propellers with improved hydroacoustic characteristics are employed. The quiet propellers, incidentally, gave US an excuse to blame the Japanese firm Toshiba for giving the USSR precision jig boring machines. As a result, this was first established underwater not to exceed the level of noise American submarines. But Soviet SSBNs remained louder than the quietest Soviet SSNs.
With the help of key information supplied by the Walker-Whitworth espionage ring, Soviet intelligence learned of the remarkable American success in tracking Soviet submarines at long range. Thus, beginning shortly after John Walker’s first treasonous revelations in 1968, the Russian navy embarked belatedly on a rapid submarine quieting program, and within five years, the radiated noise levels of their first-line boats had begun to drop recipitously.
The Soviet Navy had to convince Soviet shipyards to incur the costs involved with a serious quieting program. The Soviet Navy clearly had more trouble than did the US Navy in winning this battle with its own shipyards. In contrast to the major 1975 worldwide Soviet naval maneuvers called Okean 75, when Soviet tactics emphasized projecting power into distant waters, subsequent maneuvers focused on finding and destroying enemy submarines and protecting their own missile subs. This radical change in Soviet behavior was a mystery to US naval intelligence analysts when it first began in the mid and late 1970s. The mystery was resolved in 1981 when the Navy first broke the Walker espionage ring, whose information had shown the Soviets how vulnerable their SSBNs were.
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